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[ssr]

i was going to get the insulated pex but i was told in that short of a run it would not be worth it to do so.

[Scott7m]

50ft is a pretty good run, that's 100ft of un-insulated 1" pex..   Willie had some numbers on how much btu were lost per our per foot, I'll find them

[RSI]

there  is 2'' insulation under the concrete.i dont have insulated pipe in the ground,but it is ran 4' deep in 4'' pvc   for only 50 ft.

If you have the PVC sealed and no sharp bends, I would pull the pipe out of it and buy triple wrap and pull it through. (take out of the outer pipe it comes in)

To see how much heat you are losing, you could make a bypass at the floor loops so no water goes through the floor and check the temperature drop.

[Scott7m]

52
General Outdoor Furnace Discussion / Re: D.I.Y. Pex line insulation?
« on: October 28, 2011, 07:43:57 PM »
ball park figure here of heat loss of 1 inch uninsulated pex pipe burried inside a hollow air filled pipe..somewhere in the area of (this is a guess and likley a low ball one at that) 40 to 50 btu per foot per hour

for easy figuring lets say 50 btu per foot per hour. you say 400 feet (is that one way?) this could be 800 feet round trip taht gives us 800 x 50 btu that give us 40000 btu of heat loss per hour or  960,000 per day  that in my opinion would be about wasting one years wood supply each year

now i am basing this on only guessing as i have figures for copper pipe that use an hot temp of 140 and the outside temp of 70 (1 inch copper would lose about 30 btu per foot per hour)  i beleive that pex would not lose heat as fast as copper but  in the scenerio we have, we would have a temp spread much larger 180 in the pipe and only about 50 in the air around the pipe and then the dirt around the air would be drawing a little ahrder as well so i say 50 btu per foot of pipe per hour is a fair number to use? (some one maybe able to do better)

these are just guesses but i can tell you this..when you see 400 feet of thawed ground in mid january that is about 2 feet wide you will say...AH HA that is where all my wood is going!



Compliments of willieg

[Scott7m]

In regards to willies figures, I think that 50 btu is a low estimate, just my opinion.  So, you can figure out where a lot of your btu's could be going.

However, I don't think there is one major thing causing your problems.  I think it's a combo of a lot of things, pump on top and starting and stopping the pump could cause mixing problems, lack of zone valve and zone pump, the un insulated line, and if it's a shaver copy that's not a real efficient design but it should do what your asking once you figure out this other stuff

[willieG]

holy smokes...those uninsulated pipes are going to cost you wood and plenty of it..however i agree with scott that there are many things contributing to  your problem.. if you fix all the ones but your underground pipe your stove should do the job but you will be wasting lots and lots of wood you burried your pipes deep but without insulation they will still be giving up many thousands of btu's

i am not sure how you could let someone tell you that in that short of distance you dont need to insulate, after all you  insulated below your cement floor?

you do need to insulate that underground pipe. there is no way i know of that can show you how much heat you are losing because if your pump in moving 40 GPM you may or may not see a dramatic heat loss? But rest assured you are losing way more heat to the ground than you  should be willing to give.

my pipes were 3 feet down and when they got waterlogged you could see a strip in my yard that was 2 feet wide in mid january that never had snow on it more than an hour or two after a fresh snow

my water logged pipes i think would draw more heat off than pipes in a tile but you are still going to lose mega btu's