Would like a perspective on cycling of an oil boiler.

So I replaced a spent Burnham RSA110 steel boiler with a Peerless WBV
cast iron boiler. Everything else remained the same -- still three
zones, configured essentially the same way, and the same size / model
Taco circulator.

I was expecting, due to the increased water capacity and thermal mass of
the Peerless (new) boiler, plus a smaller nozzle, that there would be
less frequent cycling. However, the new boiler, when all three zones
are cranked open, cycles approximately like this:

- 2 minutes on
- 4 minutes off.

That strikes me as excessive, and as more frequent than the previous RSA
boiler which is counter-intuitive to me for the reasons above.

Does this rate of cycling seem excessive and/or inefficient for a new
cast-iron boiler ?

A couple more data points:

The Aquastat is different, a newer digital model, but the settings are
confirmed the same: 180F high limit, with a (fixed) 10F differential. I
made sure the new digital temp sensor bulb was well seated in the well.
Judging both by the digital readout on the 'stat and the temp guage,
the new Aquastat seems to be doing the job "OK".

The old boiler had a nozzle that flowed 1.00 GPH. I put in the smaller
of the nozzles available on the new boiler -- it flows 0.85 GPH. Now I
know that the cast-iron model will be a tad more efficient, but I would
not expect shorter on-cycle times with the lower flow rate!

I had the burner adjusted by the oil company guy -- seems to have the
right flame -- but he has no idea about the cycle times.

I'm pretty sure the system is substantially evacuated of air, and the
zones seem to be flowing well. And in the correct direction of flow .

The old boiler was about 150 lbs of steel and 8 gallons of water. The
new one is about 400 lbs of iron and 17 gallons of water.

Everything tells me the cycle should be longer -- but it's not. What
else could I be missing.

Tman.

Bubba wrote:
It appears you have missed quite a few things.
Yes. The cycling you are describing is way too much.
Did you do a "load" on what you have in the home? Im not concerned
with the size of the home. You need to calculate the amount of
radiation you have. Then and only then can you decide on which size
boiler to use.

SO I can do a load and have done them before... but what I don't get.
The original boiler was sized professionally to the load, and certainly
did not have any cycling issues. Now this boiler is very close to the
same BTU rate, if anything (intentionally) a little lower. I would
expect the lower output to result in a longer "on-time"... but something
else is not right.
T

"Tman" wrote in message

SO I can do a load and have done them before... but what I don't get.
The original boiler was sized professionally to the load, and certainly
did not have any cycling issues. Now this boiler is very close to the
same BTU rate, if anything (intentionally) a little lower. I would expect
the lower output to result in a longer "on-time"... but something else is
not right.
T


The load may be the same, but the efficiency is greater. If you went from
putting 50% of the heat up the stack to only 15% up the stack, the same
sized burner will cycle more often. There is a difference between input BTU
and output BTU. I went from 100,000 Btu to 85,000 Btu due to better
efficiency.

In either case, you must have a very large house to need a boiler of that
size. Mine has 4 gallons of water and gets up to temperature in 90 seconds.

Ed Pawlowski wrote:

The load may be the same, but the efficiency is greater. If you went from

I've thought of this, but it doesn't stand up. The old boiler was not a
terribly inefficient unit. Specifically, the IBR rating of the old
boiler was 111,000 BTUH and the new boiler is 90,000 BTUH -- this is as
per the installed nozzle. So it went down a bit. My understanding is
IBR ratings are not the heat input (fuel rate), but rather the heat
output after adjustment for various inefficiencies such as stack heat
loss, etc.

In either case, you must have a very large house to need a boiler of that
size.
The WBV-03 installed is actually one of the smaller (not the smallest)
residential boilers that Peerless makes.

I live in a development that was built by one builer. All the houses
are similar... about 2400 sq ft, 2 stories, some with finished / heated
basement, some without. Everyone I know has either a RSA110 (my
original) boiler, or this Peerless unit, if they opted to pay a couple
extra bucks.

So, I'm just not seeing that there is a terrible mismatch in boiler size
to house, and the new boiler is quite similar to the old, just a little
smaller in terms of heating capacity.

T

On Feb 10, 8:16*pm, Tman wrote:
Would like a perspective on cycling of an oil boiler.

So I replaced a spent Burnham RSA110 steel boiler with a Peerless WBV
cast iron boiler. *Everything else remained the same -- still three
zones, configured essentially the same way, and the same size / model
Taco circulator.

I was expecting, due to the increased water capacity and thermal mass of
the Peerless (new) boiler, plus a smaller nozzle, that there would be
less frequent cycling. *However, the new boiler, when all three zones
are cranked open, cycles approximately like this:

- 2 minutes on
- 4 minutes off.

That strikes me as excessive, and as more frequent than the previous RSA
boiler which is counter-intuitive to me for the reasons above.

Does this rate of cycling seem excessive and/or inefficient for a new
cast-iron boiler ?

A couple more data points:

The Aquastat is different, a newer digital model, but the settings are
confirmed the same: 180F high limit, with a (fixed) 10F differential. *I
made sure the new digital temp sensor bulb was well seated in the well.
* Judging both by the digital readout on the 'stat and the temp guage,
the new Aquastat seems to be doing the job "OK".

The old boiler had a nozzle that flowed 1.00 GPH. *I put in the smaller
of the nozzles available on the new boiler -- it flows 0.85 GPH. *Now I
know that the cast-iron model will be a tad more efficient, but I would
not expect shorter on-cycle times with the lower flow rate!

I had the burner adjusted by the oil company guy -- seems to have the
right flame -- but he has no idea about the cycle times.

I'm pretty sure the system is substantially evacuated of air, and the
zones seem to be flowing well. *And in the correct direction of flow ..

The old boiler was about 150 lbs of steel and 8 gallons of water. *The
new one is about 400 lbs of iron and 17 gallons of water.

Everything tells me the cycle should be longer -- but it's not. *What
else could I be missing.

Tman.

I would not want a 2 min on cycle, you never get rated efficiency and
its hard on controls cycling so much, does temp remain the same
through cycles. I have about 2 degree spread from on to off and
adjusted it in the thermostat to the maximum I feel comfortable with.
I am about 30 min on 1 hr off at 32f. Was a real load calculation
done that you saw in writing. Your thermostat should have a swing-
differential setting, or anticipator, or get one that does have it. I
saw a cheap Honywell that can be also be set to 30 or 1 hr off periods
to allow temp to fall. Go for the longest fall back that you can feel
comfortable with to get a longer cycle. I thought the newer units
trend was less water in the boiler for highest efficiency.

I guess I made this a little unclear.
In this situation:
The boiler unit itself is not cycling.
The oil burner is cycling.

E.g. house is at 60deg.
Thermostats (all three zones) are set at 70F and remain _on_.
Circulator and zone valves remain open, return water lines to boiler on
all three zones are pretty hot.

In this situation, the unit stabilizes at "2 min on 4 min off",
approximately, for the oil burner unit. I would expect a longer cycle.

**Is that too frequent of a cycle?

OK now that I made that clear (it wasn't; sorry). A few more factoids.

High limit setpoint for the burner is 180. I observe the digital
readout swing between 180 and 170 as the burner turns on and off -- as
expected given the 10deg differential. There is a little bit of
overshoot on the high side, e.g. the burner is off at 180 but the temp
swings up to say 185 before sliding down to 170. The boiler temp guage
(tridicator) indicates a reading that is roughly commensurate with the
aquastat readout.

If this stimulates any ideas:

Water circulating through the radiator loops looses about 10-15 deg on
the trip. E.g. 180 deg out of boiler, 167 into boiler, typically.

Oh yeah, this has a tankless coil on it. I haven't hooked that up (yet)
-- I plan to in the next day or so. So the tankless coil is vented to
the air.

T



Tman wrote:
Would like a perspective on cycling of an oil boiler.

So I replaced a spent Burnham RSA110 steel boiler with a Peerless WBV
cast iron boiler. Everything else remained the same -- still three
zones, configured essentially the same way, and the same size / model
Taco circulator.

I was expecting, due to the increased water capacity and thermal mass of
the Peerless (new) boiler, plus a smaller nozzle, that there would be
less frequent cycling. However, the new boiler, when all three zones
are cranked open, cycles approximately like this:

- 2 minutes on
- 4 minutes off.

That strikes me as excessive, and as more frequent than the previous RSA
boiler which is counter-intuitive to me for the reasons above.

Does this rate of cycling seem excessive and/or inefficient for a new
cast-iron boiler ?

A couple more data points:

The Aquastat is different, a newer digital model, but the settings are
confirmed the same: 180F high limit, with a (fixed) 10F differential. I
made sure the new digital temp sensor bulb was well seated in the well.
Judging both by the digital readout on the 'stat and the temp guage,
the new Aquastat seems to be doing the job "OK".

The old boiler had a nozzle that flowed 1.00 GPH. I put in the smaller
of the nozzles available on the new boiler -- it flows 0.85 GPH. Now I
know that the cast-iron model will be a tad more efficient, but I would
not expect shorter on-cycle times with the lower flow rate!

I had the burner adjusted by the oil company guy -- seems to have the
right flame -- but he has no idea about the cycle times.

I'm pretty sure the system is substantially evacuated of air, and the
zones seem to be flowing well. And in the correct direction of flow .

The old boiler was about 150 lbs of steel and 8 gallons of water. The
new one is about 400 lbs of iron and 17 gallons of water.

Everything tells me the cycle should be longer -- but it's not. What
else could I be missing.

Tman.

Tman wrote:

I guess I made this a little unclear.
In this situation:
The boiler unit itself is not cycling.
The oil burner is cycling.

E.g. house is at 60deg.
Thermostats (all three zones) are set at 70F and remain _on_.
Circulator and zone valves remain open, return water lines to boiler on
all three zones are pretty hot.

In this situation, the unit stabilizes at "2 min on 4 min off",
approximately, for the oil burner unit. I would expect a longer cycle.

**Is that too frequent of a cycle?

OK now that I made that clear (it wasn't; sorry). A few more factoids.

High limit setpoint for the burner is 180. I observe the digital
readout swing between 180 and 170 as the burner turns on and off -- as
expected given the 10deg differential. There is a little bit of
overshoot on the high side, e.g. the burner is off at 180 but the temp
swings up to say 185 before sliding down to 170. The boiler temp guage
(tridicator) indicates a reading that is roughly commensurate with the
aquastat readout.

If this stimulates any ideas:

Water circulating through the radiator loops looses about 10-15 deg on
the trip. E.g. 180 deg out of boiler, 167 into boiler, typically.

Oh yeah, this has a tankless coil on it. I haven't hooked that up (yet)
-- I plan to in the next day or so. So the tankless coil is vented to
the air.

T

Tman wrote:
Would like a perspective on cycling of an oil boiler.

So I replaced a spent Burnham RSA110 steel boiler with a Peerless WBV
cast iron boiler. Everything else remained the same -- still three
zones, configured essentially the same way, and the same size / model
Taco circulator.

I was expecting, due to the increased water capacity and thermal mass of
the Peerless (new) boiler, plus a smaller nozzle, that there would be
less frequent cycling. However, the new boiler, when all three zones
are cranked open, cycles approximately like this:

- 2 minutes on
- 4 minutes off.

That strikes me as excessive, and as more frequent than the previous RSA
boiler which is counter-intuitive to me for the reasons above.

Does this rate of cycling seem excessive and/or inefficient for a new
cast-iron boiler ?

A couple more data points:

The Aquastat is different, a newer digital model, but the settings are
confirmed the same: 180F high limit, with a (fixed) 10F differential. I
made sure the new digital temp sensor bulb was well seated in the well.
Judging both by the digital readout on the 'stat and the temp guage,
the new Aquastat seems to be doing the job "OK".

The old boiler had a nozzle that flowed 1.00 GPH. I put in the smaller
of the nozzles available on the new boiler -- it flows 0.85 GPH. Now I
know that the cast-iron model will be a tad more efficient, but I would
not expect shorter on-cycle times with the lower flow rate!

I had the burner adjusted by the oil company guy -- seems to have the
right flame -- but he has no idea about the cycle times.

I'm pretty sure the system is substantially evacuated of air, and the
zones seem to be flowing well. And in the correct direction of flow .

The old boiler was about 150 lbs of steel and 8 gallons of water. The
new one is about 400 lbs of iron and 17 gallons of water.

Everything tells me the cycle should be longer -- but it's not. What
else could I be missing.

Tman.

If you're loosing 15 degrees worth of heat from the boiler every 6
minutes, it's going somewhere. Makes me think you have an issue with a
missing check valve and continuous convection circulation through the
loop. With the circulator pump off, there should be no flow through the
loop and the boiler temp should take a lot longer than 6 min to loose 15
degrees.

Pete C. wrote:
Tman wrote:

E.g. house is at 60deg.
Thermostats (all three zones) are set at 70F and remain _on_.
Circulator and zone valves remain open, return water lines to boiler on
all three zones are pretty hot.

In this situation, the unit stabilizes at "2 min on 4 min off",
approximately, for the oil burner unit. I would expect a longer cycle.

**Is that too frequent of a cycle?

OK now that I made that clear (it wasn't; sorry). A few more factoids.


If you're loosing 15 degrees worth of heat from the boiler every 6
minutes, it's going somewhere. Makes me think you have an issue with a
missing check valve and continuous convection circulation through the
loop. With the circulator pump off, there should be no flow through the
loop and the boiler temp should take a lot longer than 6 min to loose 15
degrees.

I'm getting quite a complex for not being able to communicate, lol.
Sorry buddy. I know where that 15 deg of heat is going every 6 minutes
-- into the rooms via the radiator! Why do I think this? Cause the
circulator is on and the zone valves are open -- as it should be during
the call for heat.

"Tman" wrote in message

High limit setpoint for the burner is 180. I observe the digital readout
swing between 180 and 170 as the burner turns on and off -- as expected
given the 10deg differential. There is a little bit of overshoot on the
high side, e.g. the burner is off at 180 but the temp swings up to say 185
before sliding down to 170. The boiler temp guage (tridicator) indicates
a reading that is roughly commensurate with the aquastat readout.

If this stimulates any ideas:

Water circulating through the radiator loops looses about 10-15 deg on the
trip. E.g. 180 deg out of boiler, 167 into boiler, typically.

Oh yeah, this has a tankless coil on it. I haven't hooked that up
(yet) -- I plan to in the next day or so. So the tankless coil is vented
to the air.

T

Try setting the differential to 15 or 20 degrees. IMO, 10 is very tight,
but even at 160 you'll be getting good heat transfer. Some new systems will
reduce the temperature of the boiler in warmer weather for just that reason.
They use an outside sensor to determine the water temperature to circulate.
I've not timed my burner, but I know it will go more than 10 deg.
differential. It will shut down the circulator if it drops below 120.

As for the tankless coil, I'd skip it. They are very inefficient when no
heat is needed. They put out a lot of hot water and can keep up with your
shower forever, but the chamber is poorly insulated and you lose a lot of
heat to the house. OK when you need heat, wasted when you don't. You add an
indirect fired tank and zone. How many times in the summer do you hear the
burner kick on just to keep that water hot? Too many. Think about that 400
pounds of cast iron being kept hot "just in case" 24 hours a day. Move the
hot water into a 40 gallon well insulated tank instead.

Bubba says your boiler is oversized. I don't know you climate, but I tend
to agree with him. My house is 2000 sq. feet and the output is 15,0000 Btu
less than yours. During the coldest weather we had in 27 years, it easily
maintained temperature, an 80 degree rise.

On Feb 11, 8:33*pm, "Ed Pawlowski" wrote:
"Tman" wrote in message

High limit setpoint for the burner is 180. *I observe the digital readout
swing between 180 and 170 as the burner turns on and off -- as expected
given the 10deg differential. *There is a little bit of overshoot on the
high side, e.g. the burner is off at 180 but the temp swings up to say 185
before sliding down to 170. *The boiler temp guage (tridicator) indicates
a reading that is roughly commensurate with the aquastat readout.

If this stimulates any ideas:

Water circulating through the radiator loops looses about 10-15 deg on the
trip. *E.g. 180 deg out of boiler, 167 into boiler, typically.

Oh yeah, this has a tankless coil on it. *I haven't hooked that up
(yet) -- I plan to in the next day or so. *So the tankless coil is vented
to the air.

T

Try setting the differential to 15 or 20 degrees. *IMO, 10 is very tight,
but even at 160 you'll be getting good heat transfer. *Some new systems will
reduce the temperature of the boiler in warmer weather for just that reason.
They use an outside sensor to determine the water temperature to circulate.
I've not timed my burner, but I know it will go more than 10 deg.
differential. It will shut down the circulator if it drops below 120.

As for the tankless coil, I'd skip it. They are very inefficient when no
heat is needed. *They *put out a lot of hot water and can keep up with your
shower forever, but the chamber is poorly insulated and you lose a lot of
heat to the house. OK when you need heat, wasted when you don't. *You add an
indirect fired tank and zone. How many times in the summer do you hear the
burner kick on just to keep that water hot? *Too many. *Think about that 400
pounds of cast iron being kept hot "just in case" 24 hours a day. *Move the
hot water into a 40 gallon well insulated tank instead.

Bubba says your boiler is oversized. *I don't know you climate, but I tend
to agree with him. My house is 2000 sq. feet and the output is 15,0000 Btu
less than yours. *During the coldest weather we had in 27 years, it easily
maintained temperature, an 80 degree rise.- Hide quoted text -

- Show quoted text -

I am having trouble finding the issue yet because the information is
incomplete. The thermostat is calling for heat so the circulator stays
on but the burner cycles by the aquastat, right. He says house is 60,
he wants it 70 and to warm it the boiler cycles 170-180 and back. That
to me is normal the house is taking all that the radiators can give to
warm it back up. The question is what happens maintaining 70 without
setback. And how long at 170-180f water does it take to go from 60-70
and at what temp outside. Increase the differential if you want to
cycle less, but what happened on the coldest day this year, how much
did it run. I set mine down from 180 to 165 this year and will go
lower as it warms up out, I heat and get more even heat. I have read
you save by setting aquastat lower and some new controls track outside
temp to vary water temp high limit, but I have no idea if it really
saves money.

ransley wrote:
On Feb 11, 8:33 pm, "Ed Pawlowski" wrote:
"Tman" wrote in message

High limit setpoint for the burner is 180. I observe the digital readout
swing between 180 and 170 as the burner turns on and off -- as expected
given the 10deg differential. There is a little bit of overshoot on the
high side, e.g. the burner is off at 180 but the temp swings up to say 185
before sliding down to 170. The boiler temp guage (tridicator) indicates
a reading that is roughly commensurate with the aquastat readout.
If this stimulates any ideas:
Water circulating through the radiator loops looses about 10-15 deg on the
trip. E.g. 180 deg out of boiler, 167 into boiler, typically.
Oh yeah, this has a tankless coil on it. I haven't hooked that up
(yet) -- I plan to in the next day or so. So the tankless coil is vented
to the air.
T
Try setting the differential to 15 or 20 degrees. IMO, 10 is very tight,
but even at 160 you'll be getting good heat transfer. Some new systems will
reduce the temperature of the boiler in warmer weather for just that reason.
They use an outside sensor to determine the water temperature to circulate.
I've not timed my burner, but I know it will go more than 10 deg.
differential. It will shut down the circulator if it drops below 120.

As for the tankless coil, I'd skip it. They are very inefficient when no
heat is needed. They put out a lot of hot water and can keep up with your
shower forever, but the chamber is poorly insulated and you lose a lot of
heat to the house. OK when you need heat, wasted when you don't. You add an
indirect fired tank and zone. How many times in the summer do you hear the
burner kick on just to keep that water hot? Too many. Think about that 400
pounds of cast iron being kept hot "just in case" 24 hours a day. Move the
hot water into a 40 gallon well insulated tank instead.

Bubba says your boiler is oversized. I don't know you climate, but I tend
to agree with him. My house is 2000 sq. feet and the output is 15,0000 Btu
less than yours. During the coldest weather we had in 27 years, it easily
maintained temperature, an 80 degree rise.- Hide quoted text -

- Show quoted text -

I am having trouble finding the issue yet because the information is
incomplete. The thermostat is calling for heat so the circulator stays
on but the burner cycles by the aquastat, right. He says house is 60,
he wants it 70 and to warm it the boiler cycles 170-180 and back. That
to me is normal the house is taking all that the radiators can give to
The issue / concern is that the oil boiler cycles 2 min on, 4 min off,
which seems excessively frequent to me.


warm it back up. The question is what happens maintaining 70 without
setback. And how long at 170-180f water does it take to go from 60-70
and at what temp outside. Increase the differential if you want to
cycle less, but what happened on the coldest day this year, how much
On these Honeywell Aquastats in general, and mine in particular, the
only adjustable differential is on the low limit, not the high limit --
it is fixed at the manufacturer (somehow) at 10F.

did it run. I set mine down from 180 to 165 this year and will go
lower as it warms up out, I heat and get more even heat. I have read
you save by setting aquastat lower and some new controls track outside
temp to vary water temp high limit, but I have no idea if it really
saves money.

On Feb 12, 9:11*am, Bubba wrote:
On Wed, 11 Feb 2009 21:33:47 -0500, "Ed Pawlowski"
wrote:







"Tman" wrote in message

High limit setpoint for the burner is 180. *I observe the digital readout
swing between 180 and 170 as the burner turns on and off -- as expected
given the 10deg differential. *There is a little bit of overshoot on the
high side, e.g. the burner is off at 180 but the temp swings up to say 185
before sliding down to 170. *The boiler temp guage (tridicator) indicates
a reading that is roughly commensurate with the aquastat readout.

If this stimulates any ideas:

Water circulating through the radiator loops looses about 10-15 deg on the
trip. *E.g. 180 deg out of boiler, 167 into boiler, typically.

Oh yeah, this has a tankless coil on it. *I haven't hooked that up
(yet) -- I plan to in the next day or so. *So the tankless coil is vented
to the air.

T

Try setting the differential to 15 or 20 degrees. *IMO, 10 is very tight,
but even at 160 you'll be getting good heat transfer. *Some new systems will
reduce the temperature of the boiler in warmer weather for just that reason.
They use an outside sensor to determine the water temperature to circulate.
I've not timed my burner, but I know it will go more than 10 deg.
differential. It will shut down the circulator if it drops below 120.

As for the tankless coil, I'd skip it. They are very inefficient when no
heat is needed. *They *put out a lot of hot water and can keep up with your
shower forever, but the chamber is poorly insulated and you lose a lot of
heat to the house. OK when you need heat, wasted when you don't. *You add an
indirect fired tank and zone. How many times in the summer do you hear the
burner kick on just to keep that water hot? *Too many. *Think about that 400
pounds of cast iron being kept hot "just in case" 24 hours a day. *Move the
hot water into a 40 gallon well insulated tank instead.

Bubba says your boiler is oversized. *I don't know you climate, but I tend
to agree with him. My house is 2000 sq. feet and the output is 15,0000 Btu
less than yours. *During the coldest weather we had in 27 years, it easily
maintained temperature, an 80 degree rise.

Dont need to know his climate unless you are actually sizing it. The
burner runs 2 mins !! then shuts off because it reaches limit temp on
the water. Either that not water is not circulating or it is. The op
stated it is because all zones are open, pump is running and heat is
being sent to the radiators. ITS WAY OVERSIZED! Id be concerned that
the home is very poorly insulated too. It losses those 10 or 15
degrees of water and then comes right back on in 4 mins!? Are the
radiators sitting outside? *:-)
Bubba- Hide quoted text -

- Show quoted text -

A question here, could radiators be undersized, Baseboard needing
180f.? And What is outside temp, 65f like it was Saturday or -15f
below with 30 mph winds like it was 2 weeks ago. Still no ext temp or
rise info, its a trick question with no answer, Mrs Poster.

On Feb 12, 9:11*am, Bubba wrote:
On Wed, 11 Feb 2009 21:33:47 -0500, "Ed Pawlowski"
wrote:







"Tman" wrote in message

High limit setpoint for the burner is 180. *I observe the digital readout
swing between 180 and 170 as the burner turns on and off -- as expected
given the 10deg differential. *There is a little bit of overshoot on the
high side, e.g. the burner is off at 180 but the temp swings up to say 185
before sliding down to 170. *The boiler temp guage (tridicator) indicates
a reading that is roughly commensurate with the aquastat readout.

If this stimulates any ideas:

Water circulating through the radiator loops looses about 10-15 deg on the
trip. *E.g. 180 deg out of boiler, 167 into boiler, typically.

Oh yeah, this has a tankless coil on it. *I haven't hooked that up
(yet) -- I plan to in the next day or so. *So the tankless coil is vented
to the air.

T

Try setting the differential to 15 or 20 degrees. *IMO, 10 is very tight,
but even at 160 you'll be getting good heat transfer. *Some new systems will
reduce the temperature of the boiler in warmer weather for just that reason.
They use an outside sensor to determine the water temperature to circulate.
I've not timed my burner, but I know it will go more than 10 deg.
differential. It will shut down the circulator if it drops below 120.

As for the tankless coil, I'd skip it. They are very inefficient when no
heat is needed. *They *put out a lot of hot water and can keep up with your
shower forever, but the chamber is poorly insulated and you lose a lot of
heat to the house. OK when you need heat, wasted when you don't. *You add an
indirect fired tank and zone. How many times in the summer do you hear the
burner kick on just to keep that water hot? *Too many. *Think about that 400
pounds of cast iron being kept hot "just in case" 24 hours a day. *Move the
hot water into a 40 gallon well insulated tank instead.

Bubba says your boiler is oversized. *I don't know you climate, but I tend
to agree with him. My house is 2000 sq. feet and the output is 15,0000 Btu
less than yours. *During the coldest weather we had in 27 years, it easily
maintained temperature, an 80 degree rise.

Dont need to know his climate unless you are actually sizing it. The
burner runs 2 mins !! then shuts off because it reaches limit temp on
the water. Either that not water is not circulating or it is. The op
stated it is because all zones are open, pump is running and heat is
being sent to the radiators. ITS WAY OVERSIZED! Id be concerned that
the home is very poorly insulated too. It losses those 10 or 15
degrees of water and then comes right back on in 4 mins!? Are the
radiators sitting outside? *:-)
Bubba- Hide quoted text -

- Show quoted text -

But is it heating it at the lowest temp of the year, or is his info
total BS...

Bubba wrote:
On Thu, 12 Feb 2009 18:32:11 -0800 (PST), ransley
wrote:

- Show quoted text -
A question here, could radiators be undersized, Baseboard needing
180f.? And What is outside temp, 65f like it was Saturday or -15f
below with 30 mph winds like it was 2 weeks ago. Still no ext temp or
rise info, its a trick question with no answer, Mrs Poster.

Certainly undersized radiators, which in turn, still means the boiler
is oversized for the amount of radiators.
Depends how well the system has or has not heated in the past.
Bubba


Well, system has heated quite well in the past, with the same radiators
and a slightly larger (in terms of BTU output) boiler. That boiler did
not cycle the burner anywheres near as frequent.

I believe (not so sure though) that the heating effectiveness of this
unit is inferior, from the standpoint of how quickly the house comes up
to temperature. Not so sure, cause it's all the variables e.g. wind and
temp are different and I have to go by memory.

My current thinking is that their is something in the current setup that
is preventing effective circulation through the zones. It has the same
circulator setup, a 1/25 TACO on three zone valves....

T

"Tman" wrote in message
Well, system has heated quite well in the past, with the same radiators
and a slightly larger (in terms of BTU output) boiler. That boiler did
not cycle the burner anywheres near as frequent.

I believe (not so sure though) that the heating effectiveness of this unit
is inferior, from the standpoint of how quickly the house comes up to
temperature. Not so sure, cause it's all the variables e.g. wind and temp
are different and I have to go by memory.

My current thinking is that their is something in the current setup that
is preventing effective circulation through the zones. It has the same
circulator setup, a 1/25 TACO on three zone valves....

T

I never timed mine,but this morning it did run for 5 minutes and I've not
heard it go back on yet and it has been 10 minutes or so. It is so quiet I
don't usually year it anyway.

If the water is 180 degrees and the same as the old unit, the house should
be heating up at the same rate. The speed of the temperature rise is a
function of the radiation area and as long as the water temperature is the
same, the heat rate will be also. If the temperature is lower or the heat
rate is faster (as in more radiation) the burner would stay on longer to
keep up.

If you can get an IR thermometer, take a reading of the temperature of each
radiator in the loops and see how much variation there is from first to
last. It is possible that in the swap, some scale in the pipe got loose and
there is a blockage of some sort restricting flow.

On Feb 14, 5:40*am, Tman wrote:
Bubba wrote:
On Thu, 12 Feb 2009 18:32:11 -0800 (PST), ransley
wrote:
- Show quoted text -
A question here, could radiators be undersized, Baseboard needing
180f.? And What is outside temp, 65f like it was Saturday or -15f
below with 30 mph winds like it was 2 weeks ago. Still no ext temp or
rise info, its a trick question with no answer, Mrs Poster.

Certainly undersized radiators, which in turn, still means the boiler
is oversized for the amount of radiators.
Depends how well the system has or has not heated in the past.
Bubba

Well, system has heated quite well in the past, with the same radiators
and a slightly larger (in terms of BTU output) boiler. *That boiler did
not cycle the burner anywheres near as frequent.

I believe (not so sure though) that the heating effectiveness of this
unit is inferior, from the standpoint of how quickly the house comes up
to temperature. *Not so sure, cause it's all the variables e.g. wind and
temp are different and I have to go by memory.

My current thinking is that their is something in the current setup that
is preventing effective circulation through the zones. *It has the same
circulator setup, a 1/25 TACO on three zone valves....

T

Are pumps new this year and same output, did you re-blead all
radiators of air and only water comes out, were any main valves shut
off during install. Air can be hard to remove reducing radiator
output. Is it baseboard radiator.