Installed radiant floor (concrete) in a walled off 21'x60' section of the
shop. Works wonderful. (Northwest, Oregon). Have used it for two winters.

My propane supplier said that I should have gone with a "tankless" heater
instead of the ordinary (heavy duty) tank type water heater. Claims the
savings would be tremendous by not keeping 50 gallons hot, on tap 24/7.

I'm trying to do the math and need some advice. Logic tells me that I would
have to sit in the shop for 24 hours and add up all the RUN times, while the
water is circulating through the floor, in order to calculate the OFF time
within 24 hours. Then I would have to figure out the cost of keeping water
hot during all of the OFF times. This would be a factor of heater
insulation etc. and might be available from manufacturers etc.
BTW, in addition to floor heat I will be adding one bathroom (maybe three
handwashings a day?) with shower (maybe two three showers a month, if I am
too dirty to be allowed into the house).

Any simpler advice from any of you out there? These on demand units are not
cheap. My supplier tells me that he runs a four bathroom house (4 family
members) with a single "on demand" unit.

Thanks, Ivan Vegvary

In article Gndtf.30$uv.5@trnddc06, Ivan Vegvary says...

My propane supplier said that I should have gone with a "tankless" heater
instead of the ordinary (heavy duty) tank type water heater. Claims the
savings would be tremendous by not keeping 50 gallons hot, on tap 24/7.

Unless I'm missing something here, it doesn't cost anything to keep
50 gallons of water hot. Any losses from the tank to the surrounding
area will show up as heat in the area where the tank is. And seeing
as that's the idea of the radiant heat in the first place (to
actually heat the building) I can't see where the 'tremendous'
savings would come from.

Does this guy want to sell you a tankless heater, by any chance?

:^)

Jim


--
==================================================
please reply to:
JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com
==================================================

"jim rozen" wrote in message
...
In article Gndtf.30$uv.5@trnddc06, Ivan Vegvary says...

My propane supplier said that I should have gone with a "tankless" heater
instead of the ordinary (heavy duty) tank type water heater. Claims the
savings would be tremendous by not keeping 50 gallons hot, on tap 24/7.

Unless I'm missing something here, it doesn't cost anything to keep
50 gallons of water hot. Any losses from the tank to the surrounding
area will show up as heat in the area where the tank is. And seeing
as that's the idea of the radiant heat in the first place (to
actually heat the building) I can't see where the 'tremendous'
savings would come from.

Does this guy want to sell you a tankless heater, by any chance?

:^)

Jim
Excellent point Jim!! While my tank sits in the 'unheated' area of the
shop, you are right, heat loss normally would add to the ambient unless its
summer and you don't want the heat. I did not think of your good point.
No, he doesn't sell these units. I looked into them because you see them
all over Europe most often just a small unit sitting on the bathroom wall.
You turn on the hot water in the lav and it scares the bejeezus out of you
when the tankless fires up, flames and all. Supposed to be tremendous
savings.

Ivan

Ivan Vegvary wrote:
"jim rozen" wrote in message
...

In article Gndtf.30$uv.5@trnddc06, Ivan Vegvary says...


My propane supplier said that I should have gone with a "tankless" heater
instead of the ordinary (heavy duty) tank type water heater. Claims the
savings would be tremendous by not keeping 50 gallons hot, on tap 24/7.

Unless I'm missing something here, it doesn't cost anything to keep
50 gallons of water hot. Any losses from the tank to the surrounding
area will show up as heat in the area where the tank is. And seeing
as that's the idea of the radiant heat in the first place (to
actually heat the building) I can't see where the 'tremendous'
savings would come from.

Does this guy want to sell you a tankless heater, by any chance?

:^)

Jim

Excellent point Jim!! While my tank sits in the 'unheated' area of the
shop, you are right, heat loss normally would add to the ambient unless its
summer and you don't want the heat. I did not think of your good point.
No, he doesn't sell these units. I looked into them because you see them
all over Europe most often just a small unit sitting on the bathroom wall.
You turn on the hot water in the lav and it scares the bejeezus out of you
when the tankless fires up, flames and all. Supposed to be tremendous
savings.

For actual hot-water supply, it makes sense. You don't want to maintain
50 gallons of heated water for the 30 minutes in 24 hours that you
actually need it.
But for radiant heat supply, you are requiring constant heat. The
main thing you need efficient heat transfer from heating elements to the
water. I bet a good tank heater is more efficient than a tankless in
transferring heat.
I'd go with a small, highly-efficent tank heater.

If you plan to use the space at least several times a week, and you
have a concrete floor and radiant heat, you are typically forced to
keep the floor at least warm through the heating season. Otherwise it
takes too long to heat up the thermal mass of the concrete.

For this usage pattern, there would be little benefit from a tankless
heater. And as Jim Rozen points out, if the water heater had been in
the enclosed space, any heat loss just serves to heat the building
anyway. There would be almost zero benefit to a tankless heater, even
if it were free.

For a water heater in an unconditioned space, it is not difficult to
compute the standby losses of the tank full of water. It's a basic
problem in heat flow that any decent HVAC contractor should be able to
work out for you. And you should be able to follow this yourself.

Assume: 50 gallon tank, call it a cyliner 60 inches tall and 16 inches
in diameter
Water temp 125 degrees
Average unconditioned ambient temp 40 degrees
(pessimistic)
Water heater tank insulated to R11 (this varies from one
model to the next)
80 percent efficient water heater
Heating season is 5 months
Cost of propane is $2.00 per gallon

Surface area of tank is about 3400 square inches or 23.6 square feet
Heat loss = (125 - 40) * 23.6 / 11 = 182 BTU per hour or
131000 BTU per month
Propane yields about 71000 BTU per gallon
Propane used per month for standby = 131000 / (71000 *
0.8) = 2.3 gallons
Cost per month = $4.60
Cost per year = $23.00

So your cost per month for the tank of water "just sitting there" is
about $5.00 per month. If the tankless unit reduced it to 0.00, is this
a "tremendous" savings?

Assume a suitable tankless unit costs $600 and has a service life of 15
years. Your "savings" per year from a tankless unit is NEGATIVE $17.00,
and this does not consider the net present value of money. If you move
within 15 years, and do not take the tankless unit with you, the
"savings" picture is far worse (a much bigger loss). To put it another
way, your payback period for the capital investment is "NEVER".

As the cost of energy rises, the equation becomes more favorable for
the tankless unit. If the cost of propane doubled, you would just start
to see some savings on a straight line basis. Factor in NPV of money,
and the cost pf propane would probably have to quadruple for this to
make economic sense.

I suspect the Europeans use these units because:
1) The houses are smaller, and there is less room for a big water
heater tank
2) The price of energy is higher there








The thermal mass of the concrete is high enough that
Ivan Vegvary wrote:
"jim rozen" wrote in message
...
In article Gndtf.30$uv.5@trnddc06, Ivan Vegvary says...

My propane supplier said that I should have gone with a "tankless" heater
instead of the ordinary (heavy duty) tank type water heater. Claims the
savings would be tremendous by not keeping 50 gallons hot, on tap 24/7.

Unless I'm missing something here, it doesn't cost anything to keep
50 gallons of water hot. Any losses from the tank to the surrounding
area will show up as heat in the area where the tank is. And seeing
as that's the idea of the radiant heat in the first place (to
actually heat the building) I can't see where the 'tremendous'
savings would come from.

Does this guy want to sell you a tankless heater, by any chance?

:^)

Jim
Excellent point Jim!! While my tank sits in the 'unheated' area of the
shop, you are right, heat loss normally would add to the ambient unless its
summer and you don't want the heat. I did not think of your good point.
No, he doesn't sell these units. I looked into them because you see them
all over Europe most often just a small unit sitting on the bathroom wall.
You turn on the hot water in the lav and it scares the bejeezus out of you
when the tankless fires up, flames and all. Supposed to be tremendous
savings.

Ivan

wrote in message
oups.com...
If you plan to use the space at least several times a week, and you
have a concrete floor and radiant heat, you are typically forced to
keep the floor at least warm through the heating season. Otherwise it
takes too long to heat up the thermal mass of the concrete.

For this usage pattern, there would be little benefit from a tankless
heater. And as Jim Rozen points out, if the water heater had been in
the enclosed space, any heat loss just serves to heat the building
anyway. There would be almost zero benefit to a tankless heater, even
if it were free.

For a water heater in an unconditioned space, it is not difficult to
compute the standby losses of the tank full of water. It's a basic
problem in heat flow that any decent HVAC contractor should be able to
work out for you. And you should be able to follow this yourself.

Assume: 50 gallon tank, call it a cyliner 60 inches tall and 16 inches
in diameter
Water temp 125 degrees
Average unconditioned ambient temp 40 degrees
(pessimistic)
Water heater tank insulated to R11 (this varies from one
model to the next)
80 percent efficient water heater
Heating season is 5 months
Cost of propane is $2.00 per gallon

Surface area of tank is about 3400 square inches or 23.6 square feet
Heat loss = (125 - 40) * 23.6 / 11 = 182 BTU per hour or
131000 BTU per month
Propane yields about 71000 BTU per gallon
Propane used per month for standby = 131000 / (71000 *
0.8) = 2.3 gallons
Cost per month = $4.60
Cost per year = $23.00

"Jacket losses" are only part of the standby losses calculated for
boilers/water heaters. What you are neglecting, if the propane heater is
normally aspirated and draws inside air for combustion, is the heat and air
loss caused by the movement of air through the stack. In that case you are
losing heat through the center of the tank and also losing heated air
through the stack, which draws in outside air through cracks in the
building. That loss can be mitigated by using an ID fan fed by outside air.
If the water heater is serving radiant heat only it can be also be
controlled by outside reset and kept at the lowest non-condensing temp
possible based on outside air. The controller can be overridden for DHW.

So true, when I went to a shop stove that used outside air for
combustion I was amazed. ANY negative pressure in the building will
draw cold air from every nook and cranny!

Ivan Vegvary wrote:


"jim rozen" wrote in message
...
In article Gndtf.30$uv.5@trnddc06, Ivan Vegvary says...

My propane supplier said that I should have gone with a "tankless" heater
instead of the ordinary (heavy duty) tank type water heater. Claims the
savings would be tremendous by not keeping 50 gallons hot, on tap 24/7.

Unless I'm missing something here, it doesn't cost anything to keep
50 gallons of water hot. Any losses from the tank to the surrounding
area will show up as heat in the area where the tank is. And seeing
as that's the idea of the radiant heat in the first place (to
actually heat the building) I can't see where the 'tremendous'
savings would come from.

Does this guy want to sell you a tankless heater, by any chance?

:^)

Jim
Excellent point Jim!! While my tank sits in the 'unheated' area of the
shop, you are right, heat loss normally would add to the ambient unless
its
summer and you don't want the heat. I did not think of your good point.
No, he doesn't sell these units. I looked into them because you see them
all over Europe most often just a small unit sitting on the bathroom wall.
You turn on the hot water in the lav and it scares the bejeezus out of you
when the tankless fires up, flames and all. Supposed to be tremendous
savings.

Bear in mind that in Europe many domestic hot water systems are retrofits to
buildings that were old when the US was new, and in that situation it's a
lot easier to hang something small on the wall than to find a place for a
tank.

Even in the US that's sometimes the case for different reasons--for example
my mother had one in her condo because it was originally a rental apartment
with hot water provided by a central boiler for the whole complex and when
they went condo the association decided to do away with that service
without considering that there was no room in the individual units for a
conventional water heater unless one wanted to give up one of the two
closets.

Ivan

--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)

I don't have hot water in the shop - but figured if I wanted it,
I'd put in an electric -in - line unit - demand switch and instant hot.
On the short term, I have the same thing in my water cooler - room water, cold and
hot on demand.

Martin
Martin Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
NRA LOH & Endowment Member
NRA Second Amendment Task Force Charter Founder



Ivan Vegvary wrote:
"jim rozen" wrote in message
...

In article Gndtf.30$uv.5@trnddc06, Ivan Vegvary says...


My propane supplier said that I should have gone with a "tankless" heater
instead of the ordinary (heavy duty) tank type water heater. Claims the
savings would be tremendous by not keeping 50 gallons hot, on tap 24/7.

Unless I'm missing something here, it doesn't cost anything to keep
50 gallons of water hot. Any losses from the tank to the surrounding
area will show up as heat in the area where the tank is. And seeing
as that's the idea of the radiant heat in the first place (to
actually heat the building) I can't see where the 'tremendous'
savings would come from.

Does this guy want to sell you a tankless heater, by any chance?

:^)

Jim

Excellent point Jim!! While my tank sits in the 'unheated' area of the
shop, you are right, heat loss normally would add to the ambient unless its
summer and you don't want the heat. I did not think of your good point.
No, he doesn't sell these units. I looked into them because you see them
all over Europe most often just a small unit sitting on the bathroom wall.
You turn on the hot water in the lav and it scares the bejeezus out of you
when the tankless fires up, flames and all. Supposed to be tremendous
savings.

Ivan



----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----

"jim rozen" wrote in message
...
In article Gndtf.30$uv.5@trnddc06, Ivan Vegvary says...

My propane supplier said that I should have gone with a "tankless" heater
instead of the ordinary (heavy duty) tank type water heater. Claims the
savings would be tremendous by not keeping 50 gallons hot, on tap 24/7.

Unless I'm missing something here, it doesn't cost anything to keep
50 gallons of water hot. Any losses from the tank to the surrounding
area will show up as heat in the area where the tank is. And seeing
as that's the idea of the radiant heat in the first place (to
actually heat the building) I can't see where the 'tremendous'
savings would come from.

I agree, although there are some stack losses during standby in a naturally
aspirated water heater that might be significant. Setting up the control to
only maintain temperature in the tank when heat is called for might save a
little. Since warming up a radiant floor takes a while anyway the lag would
be no big deal, until he starts using domestic hot water. At that point a
switch could be thrown for DHW priority.

On 30 Dec 2005 09:06:26 -0800, with neither quill nor qualm, jim rozen
quickly quoth:

In article Gndtf.30$uv.5@trnddc06, Ivan Vegvary says...

My propane supplier said that I should have gone with a "tankless" heater
instead of the ordinary (heavy duty) tank type water heater. Claims the
savings would be tremendous by not keeping 50 gallons hot, on tap 24/7.

Unless I'm missing something here, it doesn't cost anything to keep
50 gallons of water hot. Any losses from the tank to the surrounding
area will show up as heat in the area where the tank is. And seeing
as that's the idea of the radiant heat in the first place (to
actually heat the building) I can't see where the 'tremendous'
savings would come from.

Does this guy want to sell you a tankless heater, by any chance?
:^)

No doubt. One of the things that irks me (more than the 4,000+ s/f
home sizes nowadays) is their penchant for putting in the conveniences
like recirculating hot water to make instant tap water available.
They often don't insulate the hot water pipes, either. What a waste!
Some idiot shown on This Old House did it "for convenience" a decade
ago and it has become a national energy-wasting nightmare. sigh

Tankless heaters are nice, but the last time I looked at specs, even
the residential models were fairly expensive and couldn't handle the
flow for a shower or bathtub. The commercial models were in the
thousands of dollars.


------------------------------------------
Do the voices in my head bother you?
------------------------------------------
http://diversify.com Full-Service Web Development

"Ivan Vegvary" wrote in message
news:Gndtf.30$uv.5@trnddc06...
Installed radiant floor (concrete) in a walled off 21'x60' section of the
shop. Works wonderful. (Northwest, Oregon). Have used it for two
winters.

My propane supplier said that I should have gone with a "tankless" heater
instead of the ordinary (heavy duty) tank type water heater. Claims the
savings would be tremendous by not keeping 50 gallons hot, on tap 24/7.

I'm trying to do the math and need some advice. Logic tells me that I
would
have to sit in the shop for 24 hours and add up all the RUN times, while
the
water is circulating through the floor, in order to calculate the OFF time
within 24 hours. Then I would have to figure out the cost of keeping
water
hot during all of the OFF times. This would be a factor of heater
insulation etc. and might be available from manufacturers etc.
BTW, in addition to floor heat I will be adding one bathroom (maybe three
handwashings a day?) with shower (maybe two three showers a month, if I am
too dirty to be allowed into the house).

Any simpler advice from any of you out there? These on demand units are
not
cheap. My supplier tells me that he runs a four bathroom house (4 family
members) with a single "on demand" unit.

Thanks, Ivan Vegvary


I assume that the "run time" you want to measure is that of an electric
recirc pump. Simply connect an old analog electric clock to the motor.
When the motor runs, the clock runs...

I doubt that there is much cost in keeping the water in the heater tank hot.
And, if the tank is inside the shop, any heat loss from it contributes to
the heating of the shop. If not, make sure the tank is well-insulated. But
I think you will observe that the heater runs very little unless you are
taking hot water from it.

Jerry

Ivan Vegvary wrote:

Installed radiant floor (concrete) in a walled off 21'x60' section of the
shop. Works wonderful. (Northwest, Oregon). Have used it for two
winters.

My propane supplier said that I should have gone with a "tankless" heater
instead of the ordinary (heavy duty) tank type water heater.

My first reaction is "what's in it for him".

Claims the
savings would be tremendous by not keeping 50 gallons hot, on tap 24/7.

Does he know you're using it for heat and not just hot water? Estimates
I've seen range from 10% to 30% savings when used only for hot water and
not for heat, and the higher estimates are making a lot of assumptions
about infrequent usage and flow controlled fixtures and the like. When you
use it for heat the thermal loss from water circulating through the heating
coils vastly outweighs any loss through the insulated tank so I would
expect the savings to be even less.

If you were using it only for the occasional shower or handwash then an
on-demand unit would make a lot more sense.

I'm trying to do the math and need some advice. Logic tells me that I
would have to sit in the shop for 24 hours and add up all the RUN times,
while the water is circulating through the floor, in order to calculate
the OFF time
within 24 hours. Then I would have to figure out the cost of keeping
water
hot during all of the OFF times. This would be a factor of heater
insulation etc. and might be available from manufacturers etc.
BTW, in addition to floor heat I will be adding one bathroom (maybe three
handwashings a day?) with shower (maybe two three showers a month, if I am
too dirty to be allowed into the house).

Any simpler advice from any of you out there? These on demand units are
not
cheap. My supplier tells me that he runs a four bathroom house (4 family
members) with a single "on demand" unit.

One can run a four bathroom house on a total loss system passing long pipes
over an open fire too--this doesn't address efficiency at all.

Thanks, Ivan Vegvary

--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)

On Fri, 30 Dec 2005 16:37:58 GMT, Ivan Vegvary wrote:
Installed radiant floor (concrete) in a walled off 21'x60' section of the
shop. Works wonderful. (Northwest, Oregon). Have used it for two winters.

My propane supplier said that I should have gone with a "tankless" heater
instead of the ordinary (heavy duty) tank type water heater. Claims the
savings would be tremendous by not keeping 50 gallons hot, on tap 24/7.

Doesn't make sense. You're using that energy to heat the shop. The
water heater, presumably, is in the shop. So the heat that leaks out of
the water heater, well, heats the shop. Which is what it's for.

I'm trying to do the math and need some advice. Logic tells me that I would
have to sit in the shop for 24 hours and add up all the RUN times, while the
water is circulating through the floor, in order to calculate the OFF time
within 24 hours. Then I would have to figure out the cost of keeping water
hot during all of the OFF times. This would be a factor of heater
insulation etc. and might be available from manufacturers etc.

You're overanalyzing it. I recognize this because I tend to do the same
thing. Set the thermostat on the water heater as low as it'll go -
warmer than your air, but not at normal bath termperature. Sure, it'll
be on sometimes when you're not in the shop, but that little bit of
waste heat is minimal, and not really wasted because you need to have
some warmth in there.

I'd say keep the water heater, turn it down to minimum, and switch off
the circulation pump when you don't need the floor to be heated. It's
what I do in my shop and it works well for me.

Dave Hinz

Dave Hinz wrote:



Doesn't make sense. You're using that energy to heat the shop. The
water heater, presumably, is in the shop. So the heat that leaks out of
the water heater, well, heats the shop. Which is what it's for.

I am going to disagree slightly with this, and everyone else who is
saying the same thing.
Yes the heat goes into the same overall space, and results in the same
average air temp, but how it is getting there makes a difference.

The radiant floor is heating from the floor up, heating him, and his
equipment.

The stray loss heat, is mostly convective, and while it heats the air
immediately around the tank, is convected upwards and out of the part
of the space you really want to heat.

In my shop space this would make a big difference.

jk

If the water heater is in the same room that you are heating, what's the
difference? Any heat lost from the tank is just heating the room
anyway. I suppose that "tremendous" is a relative term, but I doubt
that it would make a very big difference unless the tank isn't insulated
at all. In any event, you sure could add insulation to the tank if it's
an issue.

Come to think of it, Even if you keep the water hot in the summer, a
little extra heat in the Seattle area might just help minimize rusting
of your tools.

Pete Stanaitis


Ivan Vegvary wrote:

Installed radiant floor (concrete) in a walled off 21'x60' section of the
shop. Works wonderful. (Northwest, Oregon). Have used it for two winters.

My propane supplier said that I should have gone with a "tankless" heater
instead of the ordinary (heavy duty) tank type water heater. Claims the
savings would be tremendous by not keeping 50 gallons hot, on tap 24/7.

I'm trying to do the math and need some advice. Logic tells me that I would
have to sit in the shop for 24 hours and add up all the RUN times, while the
water is circulating through the floor, in order to calculate the OFF time
within 24 hours. Then I would have to figure out the cost of keeping water
hot during all of the OFF times. This would be a factor of heater
insulation etc. and might be available from manufacturers etc.
BTW, in addition to floor heat I will be adding one bathroom (maybe three
handwashings a day?) with shower (maybe two three showers a month, if I am
too dirty to be allowed into the house).

Any simpler advice from any of you out there? These on demand units are not
cheap. My supplier tells me that he runs a four bathroom house (4 family
members) with a single "on demand" unit.

Thanks, Ivan Vegvary

"Ivan Vegvary" wrote in message
news:Gndtf.30$uv.5@trnddc06...
Installed radiant floor (concrete) in a walled off 21'x60' section of the
shop. Works wonderful. (Northwest, Oregon). Have used it for two
winters.

My propane supplier said that I should have gone with a "tankless" heater
instead of the ordinary (heavy duty) tank type water heater. Claims the
savings would be tremendous by not keeping 50 gallons hot, on tap 24/7.


I work for a HVAC company that installs Buderus boilers like this,
http://www.buderus.net/Default.aspx?...ng%20 heaters
Great boilers, efficiencies run in the high 90% for floor heat. For domestic
hot water heat you will need to add a indirect hot water tank too. Now the
down side! These units are very expensive, the indirect water heater will
run you a $1000 alone, the good side of it all is the efficiency, plus the
quality of the equipment. The indirect water heater may be the last one you
will ever buy.
On the other hand I would not tear out a working system just to upgrade it.
Keep in mind you may trim 15 maybe 20% off your propane bill, so you may
save a $100-$200 a year on propane, but spend $5000-$6000 doing so! It may
take 25 years to break even on the deal! You will not see "tremendous"
savings!! Say you spend $1000 a year on propane, 20% saings will be $200. Is
it worth it to you?? (I doubt you will save 20% on your fuel bill!)
You really need to do the math for your specific situation to decide which
is best. The best answer for you maybe two standard water heaters, one for
the floor heat, one for domestic hot water.
Greg

In article Gndtf.30$uv.5@trnddc06, "Ivan Vegvary"
wrote:
My propane supplier said that I should have gone with a "tankless" heater
instead of the ordinary (heavy duty) tank type water heater. Claims the
savings would be tremendous by not keeping 50 gallons hot, on tap 24/7.

Not likely true, especially if you have a good tank system. Good as in
high-efficiency - but in any case, at this point, your payback on
replacing it will stink, as you already bought it and it's not worn out,
so it would have to be terribly inefficient to warrant replacing,
dollars and sense-wise. Some of the better (and costly) tank type
heaters have better efficiency numbers than the tankless units.

If you are concerned about this, (and I think your supplier is probably
selling the tankless units to be so gung-ho on them), you'll want to add
insulation to your hot water pipes, and (if permitted, as permitted) to
the outside of the hot water tank. You can't do much about flue losses
on a gas heater.

Figure it this way, and you might be less concerned - where is any heat
loss from the tank going? Into the heated space. So the "lost" heat is
heating the space you want to heat - so it's not "lost" until it makes
it through the wall/floor/ceiling, which it would do anyway if you made
if by some other means and then used it to heat with as needed.

So, your cost comparison should be the present heater's cost, and
efficiency, .vs. the cost of a more efficient heater (tank or no tank),
and compare the propane you use with this heater to the propane you
would use with a more efficient heater. No need to look at on or off
times at all.

For example, let's say you use 400 gallons of propane per year and your
present heater has a rated efficiency of 80% (lousy for gas water
heaters these days). You replace it with one that's 92% efficient
(pretty good, and costly). (400 * 0.8)/0.92=348 so you save 52 gallons
of propane per year (in this example). Guesstimate life of the expensive
heater, guesstimate cost of propane, you'll soon know if it will
actually save you any money.

--
Cats, coffee, chocolate...vices to live by

On Sat, 31 Dec 2005 03:00:34 GMT, Ecnerwal
wrote:

If you are concerned about this, (and I think your supplier is probably
selling the tankless units to be so gung-ho on them), you'll want to add
insulation to your hot water pipes, and (if permitted, as permitted) to
the outside of the hot water tank. You can't do much about flue losses
on a gas heater.

Well, you can cut the flue losses when you use the larger
'commercial' gas water heaters - they have a powered flue damper at
the top of the water heater that is interlocked with the gas valve,
with safeties and time delays both ways. When the damper is closed,
it cuts heat loss up the flue to a bare minimum. Combine that with a
well-insulated tank and water lines, and you cut the heat losses a
LOT.

I don't think it can be retrofit at a reasonable cost. Most
commercial water heaters are running electronic ignition controls with
spark or hot-surface ignitors, some are running combustion blowers and
forced-air "inshot" burners for low NoX. And almost all 'residential'
water heaters are mechanical click-disc thermostats and normal venturi
burners with standing pilot and millivolt safeties. In most cases
there isn't a power receptacle in the area.

And if you went through all the rigmarole of changing it over to
have a flue damper, the Impossible Mission For... Umm... I Mean the
American Gas Association and Underwriters Laboratories will deny all
knowledge of your actions. ;-P

-- Bruce --

--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
5737 Kanan Rd. #359, Agoura CA 91301 (818) 889-9545
Spamtrapped address: Remove the python and the invalid, and use a net.

Actually, the retail uplift cost to get a full forced vent, no pilot hot
water heater from Rheem is about $100 to $150 over the equivilent
standard heater. (I picked Rheen because they are stocked locally)
http://www.rheem.com/consumer/catalo...tail.asp?id=68

Bruce L. Bergman wrote:
On Sat, 31 Dec 2005 03:00:34 GMT, Ecnerwal
wrote:


If you are concerned about this, (and I think your supplier is probably
selling the tankless units to be so gung-ho on them), you'll want to add
insulation to your hot water pipes, and (if permitted, as permitted) to
the outside of the hot water tank. You can't do much about flue losses
on a gas heater.


Well, you can cut the flue losses when you use the larger
'commercial' gas water heaters - they have a powered flue damper at
the top of the water heater that is interlocked with the gas valve,
with safeties and time delays both ways. When the damper is closed,
it cuts heat loss up the flue to a bare minimum. Combine that with a
well-insulated tank and water lines, and you cut the heat losses a
LOT.

I don't think it can be retrofit at a reasonable cost. Most
commercial water heaters are running electronic ignition controls with
spark or hot-surface ignitors, some are running combustion blowers and
forced-air "inshot" burners for low NoX. And almost all 'residential'
water heaters are mechanical click-disc thermostats and normal venturi
burners with standing pilot and millivolt safeties. In most cases
there isn't a power receptacle in the area.

And if you went through all the rigmarole of changing it over to
have a flue damper, the Impossible Mission For... Umm... I Mean the
American Gas Association and Underwriters Laboratories will deny all
knowledge of your actions. ;-P

-- Bruce --

I really don't understand why you are using a hot water heater to run
radiant space heating. What you really need is a small gas boiler with a
propane burner assembly. I think they make some with less than 100,000 btu
output, about the size of a breadbox.

Kinda comical to see the bunch of mechanics here claim that a hot water
heater has no standby losses, since it only loses heat to the room. Losses
up the flue are one of the many reasons oilheat is inherently more efficient
than gas, since the retention head oil burner greatly reduces standby losses
by convection of air cooling the contents of a boiler/furnace as compared to
an atmospheric gas burner.

Tony


"Ivan Vegvary" wrote in message
news:Gndtf.30$uv.5@trnddc06...
Installed radiant floor (concrete) in a walled off 21'x60' section of the
shop. Works wonderful. (Northwest, Oregon). Have used it for two
winters.

My propane supplier said that I should have gone with a "tankless" heater
instead of the ordinary (heavy duty) tank type water heater. Claims the
savings would be tremendous by not keeping 50 gallons hot, on tap 24/7.

I'm trying to do the math and need some advice. Logic tells me that I
would
have to sit in the shop for 24 hours and add up all the RUN times, while
the
water is circulating through the floor, in order to calculate the OFF time
within 24 hours. Then I would have to figure out the cost of keeping
water
hot during all of the OFF times. This would be a factor of heater
insulation etc. and might be available from manufacturers etc.
BTW, in addition to floor heat I will be adding one bathroom (maybe three
handwashings a day?) with shower (maybe two three showers a month, if I am
too dirty to be allowed into the house).

Any simpler advice from any of you out there? These on demand units are
not
cheap. My supplier tells me that he runs a four bathroom house (4 family
members) with a single "on demand" unit.

Thanks, Ivan Vegvary

Where's the water heater? If it's in another part of the building, bring
it to the walled off section. All the waste and ineficency (spelling?)
that turns to heat...

Hul

Ivan Vegvary wrote:
Installed radiant floor (concrete) in a walled off 21'x60' section of the
shop. Works wonderful. (Northwest, Oregon). Have used it for two winters.

My propane supplier said that I should have gone with a "tankless" heater
instead of the ordinary (heavy duty) tank type water heater. Claims the
savings would be tremendous by not keeping 50 gallons hot, on tap 24/7.

I'm trying to do the math and need some advice. Logic tells me that I would
have to sit in the shop for 24 hours and add up all the RUN times, while the
water is circulating through the floor, in order to calculate the OFF time
within 24 hours. Then I would have to figure out the cost of keeping water
hot during all of the OFF times. This would be a factor of heater
insulation etc. and might be available from manufacturers etc.
BTW, in addition to floor heat I will be adding one bathroom (maybe three
handwashings a day?) with shower (maybe two three showers a month, if I am
too dirty to be allowed into the house).

Any simpler advice from any of you out there? These on demand units are not
cheap. My supplier tells me that he runs a four bathroom house (4 family
members) with a single "on demand" unit.

Thanks, Ivan Vegvary

I really don't understand why you are using a hot water heater to run
radiant space heating. What you really need is a small gas boiler with a
propane burner assembly. I they make some with less than 100,000 btu output,
about the size of a breadbox. Heating a room with a hot water heater isn't
the best way to do the job in the first place, not to mention your taking
all that yucky heating loop water and comingling it with your domestic
supply, can we say backflow preventer?

Kinda comical to see the bunch of mechanics here claim that a hot water
heater has no standby losses, since it only loses heat to the room. Then we
jump to the conclusion that the contractor's greed must be the reason for
wanting to sell a tankless heater.

Losses up the flue is one of the biggest standby losses.

Incidentally it is one of the reasons why oilheat is inherently more
efficient
than gas, since the retention head oil burner greatly reduces standby losses
by convection of air cooling the contents of a boiler/furnace as compared to
an atmospheric gas burner.

Then I read in the Sunday New York Times business section where some nitwit
is touting geothermal heat pumps. Ahhhh, tell me another fairy tale Santa.
Its an old saw in how the media likes to offer false hope to the uninformed
so they will keep buying the rag.

Tony



"Ivan Vegvary" wrote in message
news:Gndtf.30$uv.5@trnddc06...
Installed radiant floor (concrete) in a walled off 21'x60' section of the
shop. Works wonderful. (Northwest, Oregon). Have used it for two
winters.

My propane supplier said that I should have gone with a "tankless" heater
instead of the ordinary (heavy duty) tank type water heater. Claims the
savings would be tremendous by not keeping 50 gallons hot, on tap 24/7.

I'm trying to do the math and need some advice. Logic tells me that I
would
have to sit in the shop for 24 hours and add up all the RUN times, while
the
water is circulating through the floor, in order to calculate the OFF time
within 24 hours. Then I would have to figure out the cost of keeping
water
hot during all of the OFF times. This would be a factor of heater
insulation etc. and might be available from manufacturers etc.
BTW, in addition to floor heat I will be adding one bathroom (maybe three
handwashings a day?) with shower (maybe two three showers a month, if I am
too dirty to be allowed into the house).

Any simpler advice from any of you out there? These on demand units are
not
cheap. My supplier tells me that he runs a four bathroom house (4 family
members) with a single "on demand" unit.

Thanks, Ivan Vegvary

"Tony" wrote in message
news
I really don't understand why you are using a hot water heater to run
radiant space heating.


Simple answer? Initial Cost!
A gas water heater can be bought by anyone for around $400. A gas boiler is
not as easy to obtain, generally you need to buy it from a HVAC company,
unless you have some connections, and a boiler will run $1500 and up,
depending on what you get.
Put the cost of each into the equation and in a moderate climate the water
heater may come out on top!
Greg

small gas boilers are under $1000, are easily obtained at any plumbing
supply. Boilers are more efficient than water heaters.Water heaters are
designed to heat potable drinking water, boilers are designed for space
heating. When you consider the lifespan of a boiler is 4x that of a water
heater, (cast iron vs. thin enamel steel) the boiler is the winner. oh, and
don't forget to replace that anode in your water heater.

Tony

"Greg O" wrote in message
...


"Tony" wrote in message
news
I really don't understand why you are using a hot water heater to run
radiant space heating.


Simple answer? Initial Cost!
A gas water heater can be bought by anyone for around $400. A gas boiler
is
not as easy to obtain, generally you need to buy it from a HVAC company,
unless you have some connections, and a boiler will run $1500 and up,
depending on what you get.
Put the cost of each into the equation and in a moderate climate the water
heater may come out on top!
Greg

On Mon, 2 Jan 2006 00:29:43 -0500, "Tony"
wrote:

small gas boilers are under $1000, are easily obtained at any plumbing
supply. Boilers are more efficient than water heaters.Water heaters are
designed to heat potable drinking water, boilers are designed for space
heating. When you consider the lifespan of a boiler is 4x that of a water
heater, (cast iron vs. thin enamel steel) the boiler is the winner. oh, and
don't forget to replace that anode in your water heater.

But the OP already has the water heater purchased, installed and in
service. So until it fails from old age, it's a moot point, as there
is no payback for yanking out a working unit to install a boiler.

If the equipment costs three to four times as much up front, even
with the longer service life it has to save a LOT of energy to make it
economically viable for smaller systems. The small boiler needs the
same gas controls or oil burner, flame safeties, water level safeties,
etc. hung off the front that a big boiler takes, so the small ones are
almost as expensive as the large ones. Only the orifice in the burner
is changed to control the firing rate.

For heating a large house to comfort levels 24/7/365, yes, you want
to use a real boiler - the system at the root of this discussion is
for a small detached shop building where the primary duty is freeze
protection and rust prevention, and it's cranked up for comfort only
for short periods.

Here in Southern California where the weather is mild and heat needs
low, they've built 100+ unit Condo buildings with Studio and 1-bedroom
units heated by the domestic gas potable water heater, a Grundfos circ
pump and a fan coil. Even with the losses in the water heater, the
gas heat still beats the efficiency of a Heat Pump, and it trounces
the holy heck out of electric resistance heat.

-- Bruce --

--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
5737 Kanan Rd. #359, Agoura CA 91301 (818) 889-9545
Spamtrapped address: Remove the python and the invalid, and use a net.

"Tony" wrote in message
...
small gas boilers are under $1000, are easily obtained at any plumbing
supply. Boilers are more efficient than water heaters.Water heaters are
designed to heat potable drinking water, boilers are designed for space
heating. When you consider the lifespan of a boiler is 4x that of a water
heater, (cast iron vs. thin enamel steel) the boiler is the winner. oh,
and
don't forget to replace that anode in your water heater.

Tony



Sure they are easily obtained, but by Joe Homeowner? You are in the
business, so no problem for you.
In my area unless you have a heating, or plumbing license you need to buy
from a HVAC company because the wholesale house will toss you out the door.
How many do you SELL for under $1000??
My bet not too many go out your door for less than $1500, unless it is to a
friend.
If just anyone just walked in your door to buy a boiler you would not sell
it to him. I know the majority of the HVAC companies around here won't.
Greg

Just for fun i'll call my local plumbing supply as just a Joe off the
street and get some numbers. Greg, they'll sell them to anyone who plunks
cash on the counter. You can even buy complete boilers at my local Home
Depot.

http://www.weil-mclain.com/netdocs/aheframes.htm

http://www.weil-mclain.com/netdocs/cgaframes.htm

Tony


"Greg O" wrote in message
...
"Tony" wrote in message
...
small gas boilers are under $1000, are easily obtained at any plumbing
supply. Boilers are more efficient than water heaters.Water heaters are
designed to heat potable drinking water, boilers are designed for space
heating. When you consider the lifespan of a boiler is 4x that of a
water
heater, (cast iron vs. thin enamel steel) the boiler is the winner. oh,
and
don't forget to replace that anode in your water heater.

Tony



Sure they are easily obtained, but by Joe Homeowner? You are in the
business, so no problem for you.
In my area unless you have a heating, or plumbing license you need to buy
from a HVAC company because the wholesale house will toss you out the
door.
How many do you SELL for under $1000??
My bet not too many go out your door for less than $1500, unless it is to
a
friend.
If just anyone just walked in your door to buy a boiler you would not sell
it to him. I know the majority of the HVAC companies around here won't.
Greg

Tony wrote:

I really don't understand why you are using a hot water heater to run
radiant space heating. What you really need is a small gas boiler with a
propane burner assembly. I they make some with less than 100,000 btu
output, about the size of a breadbox. Heating a room with a hot water
heater isn't the best way to do the job in the first place, not to mention
your taking all that yucky heating loop water and comingling it with your
domestic supply, can we say backflow preventer?

How does passing it through a few more feet of pipe make it "yucky" compared
to the miles that it passed through on the way from the water works?

Kinda comical to see the bunch of mechanics here claim that a hot water
heater has no standby losses, since it only loses heat to the room. Then
we jump to the conclusion that the contractor's greed must be the reason
for wanting to sell a tankless heater.

Losses up the flue is one of the biggest standby losses.

So how much does a current production energy-star rated water heater lose up
the flue, and how does that compare to the amount that another type of
heating device loses up the flue?

Incidentally it is one of the reasons why oilheat is inherently more
efficient
than gas, since the retention head oil burner greatly reduces standby
losses by convection of air cooling the contents of a boiler/furnace as
compared to an atmospheric gas burner.

According to DOE both oil and gas furnaces are available with efficiencies
in excess of 95%, with neither seeming to have any advantage in that
department. Looks like you're working with old data.

Then I read in the Sunday New York Times business section where some
nitwit is touting geothermal heat pumps. Ahhhh, tell me another fairy tale
Santa. Its an old saw in how the media likes to offer false hope to the
uninformed so they will keep buying the rag.

Uh, what do you perceive to be the problem with geothermal heat pumps?

It looks to me like you're stuck in the '50s or something.

Tony



"Ivan Vegvary" wrote in message
news:Gndtf.30$uv.5@trnddc06...
Installed radiant floor (concrete) in a walled off 21'x60' section of the
shop. Works wonderful. (Northwest, Oregon). Have used it for two
winters.

My propane supplier said that I should have gone with a "tankless" heater
instead of the ordinary (heavy duty) tank type water heater. Claims the
savings would be tremendous by not keeping 50 gallons hot, on tap 24/7.

I'm trying to do the math and need some advice. Logic tells me that I
would
have to sit in the shop for 24 hours and add up all the RUN times, while
the
water is circulating through the floor, in order to calculate the OFF
time
within 24 hours. Then I would have to figure out the cost of keeping
water
hot during all of the OFF times. This would be a factor of heater
insulation etc. and might be available from manufacturers etc.
BTW, in addition to floor heat I will be adding one bathroom (maybe three
handwashings a day?) with shower (maybe two three showers a month, if I
am too dirty to be allowed into the house).

Any simpler advice from any of you out there? These on demand units are
not
cheap. My supplier tells me that he runs a four bathroom house (4 family
members) with a single "on demand" unit.

Thanks, Ivan Vegvary



--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)

How does passing it through a few more feet of pipe make it "yucky"
compared
to the miles that it passed through on the way from the water works?

Well, in my experience as a licensed master plumber, try opening the boiler
cock on a boiler and notice the brown water coming out. Actually thats the
good stuff, because the oxygen in the water has reacted with the metal in
the boiler & piping, been consumed, and corrosion stops at that point.
Intoduce fresh water into the system and corrosion starts again. But I
wouldn't want to drink it. The difference between the water in the street
and the water in your heating pipes, about 120 degF.


Losses up the flue is one of the biggest standby losses.

So how much does a current production energy-star rated water heater lose
up
the flue, and how does that compare to the amount that another type of
heating device loses up the flue?

That wasn't the issue. The prior posters were making incorrect statements
about standby losses. As far as I know the DOE doesn't directly rate heating
appliances for standby losses. I don't think AFUE rating calculations for
boilers are comparable to water heaters, as they serve different functions.
AFUE is a seasonal efficicency rating when it comes boilers.


According to DOE both oil and gas furnaces are available with efficiencies
in excess of 95%, with neither seeming to have any advantage in that
department. Looks like you're working with old data.

Nope, not old data. I was at the last heating symposium at Brookhaven
National Lab Brookhaven Long Island 2005. It's nice to hype 95%, but to
really get over 90% you enter the realm of condensing boilers, which means a
direct vented system as opposed to a conventional chimmny. Most gas boilers
installed today are around 78% ~85%. Some gas boilers less than that. Some
local building codes do not permit direct vented heating systems, NYC for
instance.


Uh, what do you perceive to be the problem with geothermal heat pumps?


It's just common sense that you can't heat your house with 45 degF ground
water for a lower cost than burning fuel in a conventional boiler/furnace.
Maybe aircondition it with a chiller system, i'll buy that.

Now if I could tap into a hot water spring, or lived near a volcano, then I
would give geothermal heating a try!!!

It looks to me like you're stuck in the '50s or something.
Gee, maybe that's why i like watching Honeymooners reruns so much.
I hold 5+ licenses for master plumber, boiler inspector unlimited horsepower
NYC, oil burner installer all fuels NYC unlimited gallons per hour. And your
HVAC background?



Tony

On Mon, 2 Jan 2006 01:28:27 -0500, "Tony" wrote:




Nope, not old data. I was at the last heating symposium at Brookhaven
National Lab Brookhaven Long Island 2005. It's nice to hype 95%, but to
really get over 90% you enter the realm of condensing boilers, which means a
direct vented system as opposed to a conventional chimmny. Most gas boilers
installed today are around 78% ~85%. Some gas boilers less than that. Some
local building codes do not permit direct vented heating systems, NYC for
instance.



Just out of curiosity, what's the matter with condensing boilers and direct
venting systems in your neck of the woods. I fitted my balanced flue
condensing boiler (stainless primary and aluminium secondary and tertiary heat
exchangers with entirely copper water path) 8 years ago and have been very
happy with it, although my gas price/Btu is probably a lot more than yours.



Mark Rand (in the UK)
RTFM

Due to the closeness of the buildings in NYC, (row houses you call them
flats I think) apartment buildings and the like, the neighbors might not
like your boiler venting into their window with a side vent arrangement.
That notwithstanding, unfortunately many building codes (and the bureaucrats
that administer them) here are unable to adapt to new technology.

Tony

"Mark Rand" wrote in message
...
On Mon, 2 Jan 2006 01:28:27 -0500, "Tony"
wrote:




Nope, not old data. I was at the last heating symposium at Brookhaven
National Lab Brookhaven Long Island 2005. It's nice to hype 95%, but to
really get over 90% you enter the realm of condensing boilers, which
means a
direct vented system as opposed to a conventional chimmny. Most gas
boilers
installed today are around 78% ~85%. Some gas boilers less than that.
Some
local building codes do not permit direct vented heating systems, NYC for
instance.



Just out of curiosity, what's the matter with condensing boilers and
direct
venting systems in your neck of the woods. I fitted my balanced flue
condensing boiler (stainless primary and aluminium secondary and tertiary
heat
exchangers with entirely copper water path) 8 years ago and have been very
happy with it, although my gas price/Btu is probably a lot more than
yours.



Mark Rand (in the UK)
RTFM

Tony wrote:


How does passing it through a few more feet of pipe make it "yucky"
compared
to the miles that it passed through on the way from the water works?

Well, in my experience as a licensed master plumber, try opening the
boiler cock on a boiler and notice the brown water coming out. Actually
thats the good stuff, because the oxygen in the water has reacted with the
metal in the boiler & piping, been consumed, and corrosion stops at that
point. Intoduce fresh water into the system and corrosion starts again.
But I wouldn't want to drink it. The difference between the water in the
street and the water in your heating pipes, about 120 degF.

Most infloor radiant heat uses PEX these days, so no brown water, further
you're describing closed systems, not open.

Losses up the flue is one of the biggest standby losses.

So how much does a current production energy-star rated water heater lose
up
the flue, and how does that compare to the amount that another type of
heating device loses up the flue?

That wasn't the issue. The prior posters were making incorrect statements
about standby losses. As far as I know the DOE doesn't directly rate
heating appliances for standby losses. I don't think AFUE rating
calculations for boilers are comparable to water heaters, as they serve
different functions. AFUE is a seasonal efficicency rating when it comes
boilers.

Actually, that _is_ the issue. You're asserting that the water heater loses
more up the flue than does a purpose made boiler. I'm asking how much
really goes up a flue when the exhaust gases are cool enough to go through
a PVC pipe, as is the case for a modern high-efficiency water heater.

According to DOE both oil and gas furnaces are available with
efficiencies in excess of 95%, with neither seeming to have any advantage
in that
department. Looks like you're working with old data.

Nope, not old data. I was at the last heating symposium at Brookhaven
National Lab Brookhaven Long Island 2005. It's nice to hype 95%, but to
really get over 90% you enter the realm of condensing boilers, which means
a direct vented system as opposed to a conventional chimmny.

And what leads you to believe that I was referring to any other kind?

Most gas
boilers installed today are around 78% ~85%. Some gas boilers less than
that. Some local building codes do not permit direct vented heating
systems, NYC for instance.

Who in NYC can afford a personal shop big enough to need its own heating
system?

Uh, what do you perceive to be the problem with geothermal heat pumps?


It's just common sense that you can't heat your house with 45 degF ground
water for a lower cost than burning fuel in a conventional boiler/furnace.
Maybe aircondition it with a chiller system, i'll buy that.

It may be "common sense" but heat pumps are one case where "common sense"
goes out the window. The heat output of a properly designed heat pump
working across a reasonable temperature differential is greater than the
energy input via shaft work with the remainder being extracted from the
environment. This is something one learns in any intro thermodynamics
class. The difficulty is that the efficiency goes down if the temperature
differential between hot and cold is too high, which is a problem in cold
areas--using the ground water as the cold sink eliminates this problem.

Now if I could tap into a hot water spring, or lived near a volcano, then
I would give geothermal heating a try!!!

It looks to me like you're stuck in the '50s or something.
Gee, maybe that's why i like watching Honeymooners reruns so much.
I hold 5+ licenses for master plumber, boiler inspector unlimited
horsepower NYC, oil burner installer all fuels NYC unlimited gallons per
hour. And your HVAC background?

Appears to be sufficient to back you into a corner from which you are forced
to appeal to authority rather than supporting your argument with facts and
figures.

Tony

--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)

"J. Clarke" wrote in message
...
It may be "common sense" but heat pumps are one case where "common sense"
goes out the window. The heat output of a properly designed heat pump
working across a reasonable temperature differential is greater than the
energy input via shaft work with the remainder being extracted from the
environment. This is something one learns in any intro thermodynamics
class. The difficulty is that the efficiency goes down if the temperature
differential between hot and cold is too high, which is a problem in cold
areas--using the ground water as the cold sink eliminates this problem.

The problem here is the cost of electricity compared to gas/oil. That
multiple has to be less than the coefficient of performance. Gas has gone up
significantly so those numbers are better now than ten years ago. The
drilling/excavation for ground source loops and the expense of running a
compressor year round are also considerations. A need for air conditioning
helps the ground source case significantly.

"Tony" wrote in message
news
I really don't understand why you are using a hot water heater to run
radiant space heating. What you really need is a small gas boiler with a
propane burner assembly. I they make some with less than 100,000 btu
output,
about the size of a breadbox. Heating a room with a hot water heater isn't
the best way to do the job in the first place, not to mention your taking
all that yucky heating loop water and comingling it with your domestic
supply, can we say backflow preventer?

Using the same water heater for DHW would definitely require isolation via a
heat exchanger of some type. The hot water heater would have to be used like
a boiler, it would not be available for direct production of domestic hot
water.

Kinda comical to see the bunch of mechanics here claim that a hot water
heater has no standby losses, since it only loses heat to the room. Then
we
jump to the conclusion that the contractor's greed must be the reason for
wanting to sell a tankless heater.

Losses up the flue is one of the biggest standby losses.

Incidentally it is one of the reasons why oilheat is inherently more
efficient
than gas, since the retention head oil burner greatly reduces standby
losses
by convection of air cooling the contents of a boiler/furnace as compared
to
an atmospheric gas burner.

Oil burners also have a greater combustion efficiency than naturally
aspirated gas, even before considering standby losses.

Then I read in the Sunday New York Times business section where some
nitwit
is touting geothermal heat pumps. Ahhhh, tell me another fairy tale Santa.
Its an old saw in how the media likes to offer false hope to the
uninformed
so they will keep buying the rag.

Tony

Geothermal has limited applications. You can take advantage of a COP
"coefficient of performance" which allows you to extract more BTU's than you
expend, but using electricity costs several times more than oil or gas, so
there is no net gain economically on the heating side. Cooling is a
different story.


"Ivan Vegvary" wrote in message
news:Gndtf.30$uv.5@trnddc06...
Installed radiant floor (concrete) in a walled off 21'x60' section of the
shop. Works wonderful. (Northwest, Oregon). Have used it for two
winters.

My propane supplier said that I should have gone with a "tankless" heater
instead of the ordinary (heavy duty) tank type water heater. Claims the
savings would be tremendous by not keeping 50 gallons hot, on tap 24/7.

I'm trying to do the math and need some advice. Logic tells me that I
would
have to sit in the shop for 24 hours and add up all the RUN times, while
the
water is circulating through the floor, in order to calculate the OFF
time
within 24 hours. Then I would have to figure out the cost of keeping
water
hot during all of the OFF times. This would be a factor of heater
insulation etc. and might be available from manufacturers etc.
BTW, in addition to floor heat I will be adding one bathroom (maybe three
handwashings a day?) with shower (maybe two three showers a month, if I
am
too dirty to be allowed into the house).

Any simpler advice from any of you out there? These on demand units are
not
cheap. My supplier tells me that he runs a four bathroom house (4 family
members) with a single "on demand" unit.

Thanks, Ivan Vegvary