Re: GAS hot water heater, can its BTU be
Posted by Douglas Foster on March 03, 19100 at 23:38:41:
In response to Re: GAS hot water heater, can its BTU be
: Doug
: we have some questions for you that we need answered. is you floor insulated under the slab? what is the square footage that you are trying to heat?what is the 1st hour recovery rating of your hot water heater? did anyone do a heat loss calc. for you? how many zones? I have a feeling that your water heater will not be big enough what is the water temp on your return line? i hope you are not using the same tank for your domestic hot water! if you can answer some of these questions we might be able to steer you in the right direction.
: I hope you enjoy your new home
: John
: Midwest Home Comfort

Thanks for responding!!
Here is the info...
It is a 36'x48' boatbuilding shop one level with a 17' high side wall.
Single zone, insulated under the outer 2', and the entire outer wall with 2"
of ridged foam. Slab is 8-9" outer and 5-6" in main body. The innerslab
was not insulated as to act as a heat sink once the slab is heated, since
the temp will remain set at one 60 degree setting for its life. ( I heard
mixed feelings about this but felt that was mainly due to the long time
involved to change the temp at all.) The building has a fair amount of high
placed non opening windows of a good quallity double pane insulated type.
Two entry doors, insulated steel, the walls are a combo of r-19 batt
insulation on 16" centers and double faced foam panels r-7 on the inside
coverd with plywood. For a total of r-26. The trusses are sheathed on the
bottom with plywood and there is blown in insulation in the attic at a
r-23-24. The temp going out of the tank is around 80 degrees and coming
back at around 70. This has been slowly rising since I started it up, but
seems to be holding now. It (the pump)has kicked off a few times now(from
the thermostat) and then the heater will heat to about 100(I have it set for
that temp). The temp outside has been pretty warm though, 32-45 and a
little colder at night. Yes I do plan on getting my SHOP hot water off this
tank. I am a one/two man shop no big demand. The pump is a special
stainless unit and all the tube is rated for drinking. (1200' of 7/8"
pex......4 - 300' lenths, one zone) The heater is a GE brand 50 gal, 36,000
btu that I was told would be enough by the company I purchased the tube and
manifolds etc from. They specified a 35-45,000 btu and since it is very
rare that I open the large doors in the winter I went on the low side. (
the bis doors are a well sealed wooden swinging barn type door (R-19), 16'
high and 10' wide each (two).
I first started it up with 43 degree water in the tank, 15 degree temps
outside a 15-20 degree slab and probably a foot of frost under it!! After
about 5 days it had reached the going out at 55 and back at 50 instead of
out at 47 and back at 34!! I hope this is helpfull info and again thanks
for your help, I can't tell you enough how much I appreciate it. Douglas
Foster, owner Desert Boat Co, Mount Desert Island Maine.

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