Hi Folks -

I live in NY where it's cold, and I have a question here that I'm literally
afraid to ask. I have a contractor doing a new kitchen for me and he's
almost done and has 80% of his money. The kitchen is 12'x17' and, unlike the
rest of the house, sits on a slab extension out back (there's a full
basement under the main footprint of the house, which is 90 years old, and
this kitchen extension is an appendage off the rear).

The extension was actually pre-existing from about ten years ago when the
previous owner put in a laundry room and a few walk in storage rooms there.
Anyway, my goal was to have the entire area over the slab gutted (12x17) and
make it our new kitchen, with ceramic tile floors, and have radiant heat.

Here's the deal... we're almost done, the contractor put in the radiant heat
tubing long ago, laid the tile done weeks ago (but never hooked up the
heating system to the boiler till now) and has continued to build the
kitchen and is almost done with everything.

But yesterday, they finally hooked up the radiant heat to the boiler, and
there is bad news. After running it for two hours at 180 degrees the damn
floor is still cold... and the return water is barely luke warm!

I'm starting to worry that this whole damn thing has to be jack hammered up
and redone -- an unimaginable thing given the amount of time we've been
without a kitchen (my wife will not survive this if it's true!).

My question is, based on the original requirements I gave, did my contractor
do everything right?

First, since the new kitchen is on the north end of the house, while radiant
heat sounded like a good idea, I warned him profusely that it gets cold
there... and wanted his assurance that the system he installs had plenty of
power to get this space warm and keep it comfortable at a reasonable cost.

These were the steps he took --

1. The whole heating project was done by him with direction given by his
"plumbing and heating guy"

2. First, he basically reframed the whole extension (12x17) because it was
poorly built by a do it yourselfer, insulated it with the best new stuff,
and put a new roof on top... this part seems good ... you can definitely
feel that the above ground part of this kitchen extension was done right;

3. Now for the slab and heat, where I'm really worried -- first, although he
was able to jack hammer away the very poor concrete laid by the previous
owner, there was some incredibly hard concrete below that that made it
impossible to go any more than 2 inches deep (the house probably had a patio
or landing out back originally, the house is 90 years old)

4. With the slab cleared down to the 2" depth, he said "to be safe" he'd put
in 50% more "tubing" than would normally be required for the space - this
was to address my heating worries - and he didn't lay the tubing under the
24" cabinet perimeter. Is it correct to use 50% more tubing than is normally
necessary?

5. Ok, this is what I'm horrified of - he didn't insulate the slab.
Originally, he said he WOULD be putting some insulation on the slab, and
then lay the tubing on top. But after it was all done, with the rest of the
floor poured over it and the tile man had laid his floor and had gone --
after that -- I asked him about the insulation below, and he broke me the
news -- "we couldn't put the insulation bed under the tubing because that
would have raised the floor height too high -- you would have hated it."

Shocked and a bit worried about the lack of insulation on the slab, I asked
him if that would affect the ability to heat up the room satisfactorily or
create a heating cost issue -- he said "no, it won't be an issue, don't
worry about it."

But again, since that conversation, it seems like he's been putting off
getting the heat hooked up to the boiler forever, and here I am today ---
with this dilemma.

Worried about the issue last night, I called him and he said he'd come over
and talk about next steps with me today. He's mentioned a few things, like
insulating the perimeter of the slab (outside the house), installing a stand
alone water heater in the basement just for the extension heat (my 80 year
old boiler, while it heats the main house fine, might no be well suited to
handle this radiant area he says)... so basically, he's talking about plan
B's with me now.

My question is this... is NOT insulating the slab below the heating tubes a
fatal flaw ? that dooms any solution short of jack hammering the whole place
and starting over?

Thanks for any assistance.

Tom

Tom Newton wrote in message
...
Hi Folks -

I live in NY where it's cold, and I have a question here that I'm
literally
afraid to ask. I have a contractor doing a new kitchen for me and he's
almost done and has 80% of his money. The kitchen is 12'x17' and, unlike
the
rest of the house, sits on a slab extension out back (there's a full
basement under the main footprint of the house, which is 90 years old, and
this kitchen extension is an appendage off the rear).

The extension was actually pre-existing from about ten years ago when the
previous owner put in a laundry room and a few walk in storage rooms
there.
Anyway, my goal was to have the entire area over the slab gutted (12x17)
and
make it our new kitchen, with ceramic tile floors, and have radiant heat.

Here's the deal... we're almost done, the contractor put in the radiant
heat
tubing long ago, laid the tile done weeks ago (but never hooked up the
heating system to the boiler till now) and has continued to build the
kitchen and is almost done with everything.

But yesterday, they finally hooked up the radiant heat to the boiler, and
there is bad news. After running it for two hours at 180 degrees the damn
floor is still cold... and the return water is barely luke warm!

I'm starting to worry that this whole damn thing has to be jack hammered
up
and redone -- an unimaginable thing given the amount of time we've been
without a kitchen (my wife will not survive this if it's true!).

My question is, based on the original requirements I gave, did my
contractor
do everything right?

First, since the new kitchen is on the north end of the house, while
radiant
heat sounded like a good idea, I warned him profusely that it gets cold
there... and wanted his assurance that the system he installs had plenty
of
power to get this space warm and keep it comfortable at a reasonable cost.

These were the steps he took --

1. The whole heating project was done by him with direction given by his
"plumbing and heating guy"

2. First, he basically reframed the whole extension (12x17) because it was
poorly built by a do it yourselfer, insulated it with the best new stuff,
and put a new roof on top... this part seems good ... you can definitely
feel that the above ground part of this kitchen extension was done right;

3. Now for the slab and heat, where I'm really worried -- first, although
he
was able to jack hammer away the very poor concrete laid by the previous
owner, there was some incredibly hard concrete below that that made it
impossible to go any more than 2 inches deep (the house probably had a
patio
or landing out back originally, the house is 90 years old)

4. With the slab cleared down to the 2" depth, he said "to be safe" he'd
put
in 50% more "tubing" than would normally be required for the space - this
was to address my heating worries - and he didn't lay the tubing under the
24" cabinet perimeter. Is it correct to use 50% more tubing than is
normally
necessary?

5. Ok, this is what I'm horrified of - he didn't insulate the slab.
Originally, he said he WOULD be putting some insulation on the slab, and
then lay the tubing on top. But after it was all done, with the rest of
the
floor poured over it and the tile man had laid his floor and had gone --
after that -- I asked him about the insulation below, and he broke me the
news -- "we couldn't put the insulation bed under the tubing because that
would have raised the floor height too high -- you would have hated it."

Shocked and a bit worried about the lack of insulation on the slab, I
asked
him if that would affect the ability to heat up the room satisfactorily or
create a heating cost issue -- he said "no, it won't be an issue, don't
worry about it."

But again, since that conversation, it seems like he's been putting off
getting the heat hooked up to the boiler forever, and here I am today ---
with this dilemma.

Worried about the issue last night, I called him and he said he'd come
over
and talk about next steps with me today. He's mentioned a few things, like
insulating the perimeter of the slab (outside the house), installing a
stand
alone water heater in the basement just for the extension heat (my 80 year
old boiler, while it heats the main house fine, might no be well suited to
handle this radiant area he says)... so basically, he's talking about plan
B's with me now.

My question is this... is NOT insulating the slab below the heating tubes
a
fatal flaw ? that dooms any solution short of jack hammering the whole
place
and starting over?

Thanks for any assistance.

Tom

Give things a chance to warm up before you panic. If you have 180 degree
water going in and tepid water coming out of the slab pipe, the heat is
going someplace. Given your description, eventually 50% will be going up
into the room and 50% will be going down into the ground. Probably, more is
going into the ground right now because it us colder and so until the ground
under the slab gets warmed up, you'll not have a warm floor. But when that
great mass of concrete and earth does get to a stable temperature, you'll
feel the floor warm and it will stay at a constant temperature no matter
whether the boiler is on or off -- at least for some time (days). This is
not a system that will react to a night setback thermostat.

Depending upon the "R" value of the ground under the slab, this could be a
fairly inefficient heating system. Your fuel bill will tell you that
eventually. Under-slab insulation would have been a good idea; but you can
mitigate the situation somewhat with insulation around the perimeter since
that's where the extreme cold temperatures will be. Underneath the slab,
the coldest temperature will be the average ground temperature in your area.
Anything to keep the heat in the slab will help. If there is sand/gravel
under the slab and the ground is dry rather than wet, that will help too.
Water or wet ground conducts heat away faster than dry ground or porus
materials.

It sounds as if you have a good contractor who is experienced in the
practicalities of installing such systems; but it would have been better to
have had the design done by an experienced heating/cooling engineer rather
than the contractor. The engineer would have done the heat flow
calculations, for example, so you would know how much heat is going into the
ground for your particular situation and oversizing the pipe by 50% may or
may not have been needed. That was a guess.

TKM

"Mark" wrote in message
...
On Wed, 4 Feb 2004 09:33:19 -0500, "Tom Newton"



Is the same volume of water coming out that is going in? In other words,
is
there a leak somewhere? Also, 180 for radiant floor is way too high.
That
normally runs no more than 100.


Checking for leaks is the first thing you should do. Mark recommneds a
simple test (see above) for this. Check the in-going water rate with what
comes out. You may also do a pressure test to rule out leaks. If you do
have leaks, you have fix them before you go any further with your remodel
project.

The concrete slab you are trying to heat is probably very cold and it'll
take a *long* time to heat it to anything near comfort levels - 60 F or
above. Be patient. radiant heat systems typically run in the range 100-110
F. You are running it very hot. I have a home in the SF Bay area with
radiant floor heating (copper pipes in concrete slab). It takes atleast six
hours to heat the house from 55 F to 70 F. It's going to take at least that
long, probably longer to heat the slab from low 40s to about 70.

-ken

Thanks so much guys for sharing your knowledge. I had a long talk with the
contractor today... here's an update. By the way, my location is Long Island
NY... average evening temp in Feb about 25 or so, the ground below is dry
and densly packed earth with some clay

We just had a frank talk...

1. He explained why the insulation didn't go down (the subconcrete below the
first two inches was too hard and too dense to get any lower... his guys
were jackhammering it for several days... it would have taken TNT to blast
it down any further -- based on what I saw at the time, I take him at his
word.) So, one inch of insulation on top of the slab as it was would have
translated to 2" or more height to the final product... which would
admittedly have been undesireable -- but again -- perhaps baseboard heat
would have been a better reccomendation at that point... even though I did
express distaste for baseboard from the start...;

2. I explained that -- while I did want the end result tile floor to be as
flush as possible as the oak in the main part of the house (he's done a goo
sjob achieving that.. it's only 1/2" higher) -- I didn't feel that he had
educated me to what the ramifications would be by not insulating the slab
(ie heatup time, and heating costs)... but again, he says... Tom, we hooked
this up 24 hours ago, don't freak out yet, it takes a long time to get this
baby up to temp... lets not freak out yet...;

3. We called the heating guy... who helped my contractor (Bill) with the
heat calculations, the pressure tests, the hookups to the boiler, and when I
asked him if putting radiant heat on an uninsulated slab is OK, he says
"optimally no... but does it happen often? yes -- does not having it
insulated mean you're doomed? No.;

4. He had put 6MM plastic below the pex tubing , which sits on a rack of
sorts and then the whole thing gets flooded with the cement etc... 6MM of
plastic seems minor, but the heat guy says that it helps;

5. He has agreed to insulate the exterior perimeter of the foundation (6"
above ground, and 18' below) around the slab "at cost" ... but I'm working
with him on a number as close to free as possible;

6. I explained that the I hear the water temp should be closer to 130 than
180, and he agrees. There was a mixing valve installed to step the water
temp down... but he's had it off so we can heat up the slab.

Anyway, we're continuing to attack the problem --- I haven't told you al
labout my 90 year old boiler! Well, it appears that we're at a crossroads
with this old war horse too. Hopefully we're able to get an acceptable
heating arrangement going shortly.. wish me luck.

Tom

PS. If 130 degree water is going in, and there's 230 ft of pex in the 12x17
area, what's a good target temp for the return water to be? 30 degrees less?
20 degrees less?

On Wed, 4 Feb 2004 09:33:19 -0500, someone wrote:

But yesterday, they finally hooked up the radiant heat to the boiler, and
there is bad news. After running it for two hours at 180 degrees the damn
floor is still cold... and the return water is barely luke warm!

How much flow is going through the tubing????

If there is a blockage, it will have this result. Sure you put 180
degree water in at one end (that is standard boiler temp). But if you
don't get enough flow, what little water is in there, will indeed come
back luke warm, and not be able to impart enough btus to the thing
being heated.

A 'regular' heating zone that has a partially blocked tube will do the
same thing.

I think you have a kinked tube. Have your contractor get an
experienced heating tech in there who can measure the rate of flow,
even by eyeball (like run the return into a bucket and observe it).

The water should be coming back too hot to comfortably hold the return
pipe, like 140+, not luke warm.

-v.

On Wed, 04 Feb 2004 12:49:52 -0500, someone wrote:

Yes, it takes a long time to heat the room, but he shouldn't be having luke
warm water on the other end of a run after 2 hours with the input temp being
180.

Guys guys guys

WHAT IS THE FLOW RATE.

Like I said already, if the flow is partially blocked, it can run
forever and still be luke warm. BTUs delivered is by temp x volume.
If volume is low from a blockage it will never heat up.

If the flow rate has been tested I will drop this theory, but has it
been????

-v.

Thanks for your help, actually, today, the heat guys came back because some
water came out of the valve and filled a bucket in the basement... they
checked and found that there was still some air in the pex ... they ran a
bunch of water into a slop sink for a while... said the air is now gone, and
within two hours the return is pretty hot.

Funny thing about the return pex that goes to copper... then backinto the
boiler. The pex itself is only warm, but the copper is way hot -- rather
odd. But I guess it means the return is hot.

Thanks

Tom

"Tom Newton" wrote:
Funny thing about the return pex that goes to copper... then backinto the
boiler. The pex itself is only warm, but the copper is way hot -- rather
odd. But I guess it means the return is hot.

Copper's a much better heat conductor than PEX -- the water inside's the same
temp, but it gets transferred to you hand much more efficiently by the copper.

On Wed, 04 Feb 2004 15:22:54 -0700, someone wrote:


Copper's a much better heat conductor than PEX -- the water inside's the same
temp, but it gets transferred to you hand much more efficiently by the copper.

What he said. Bottom line, the PEX is like insulation, like its an
insulated pipe (compared to the copper). Because it is thin it still
conducts significant heat, but not anything like the copper (which in
addition to being a better conductor, is probably even thinner
walled).

-v.

"Tom Newton" wrote in message ...

4. He had put 6MM plastic below the pex tubing , which sits on a rack of
sorts and then the whole thing gets flooded with the cement etc... 6MM of
plastic seems minor, but the heat guy says that it helps;

I expect that that plastic is "6 mil", which is 6/1000 of an inch, not
6 millimetres. The latter would be over 1/4". Mils are the normal
non-metric thickness units for sheets of plastic etc.

I wouldn't raise such a minor point if it didn't look like your
heating problem was being resolved ... I do hope it's as simple as
getting the air out of the pex!

Chip C
Toronto