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loosing heat

Started by trapper, January 25, 2012, 09:21:53 PM

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trapper

The snow above the line going from the owb to my house is melting.  I have the old central boiler line pex +foam + plastic bag.  I think this means the plastic bag is letting water in.  Any sugestions other than replacing the line with the new style line?  I will have to wait until summer to do it.  I filled the trench with sand on the orginal instalation to make it easier to redo in case something like this happened.
stihl ms241cm ms261cm  echo 310 400 suzuki  log arch made by stepson several logrite tools woodmizer LT30

wayno12

Trapper, I wouldn't run right out and grab a shovel to start digging up your pex.  I installed the Thermo Pex from CB 14 months ago when I installed my boiler and from the boiler to the house (85') I buried my line @ 24" depth.  I am about 18" below sidwalk where it enters the block and I melt snow between the house and boiler and also have a 3' wide patch on the sidewalk that is ice free and dry when the rest of the cement is a solid layer of ice.  Everyone says you need to bury 48" etc, but lets face it, heat loss is heat loss, I don't see where it would matter if you are above ground or 10' deep.  Only difference is at 10' deep you would see the melted snow and it would make you feel much warmer and fuzzier!  If you'd like, let me know and I'll post some pics of right now how I have no snow on ground over buried pex.  I paid $12.00+ per foot for this and I'm in your boat too.

wayno12

As a side note, I did call CB about this and they said heat loss from the Thermo Pex is to be expected but they still feel it is the best thing out there.

dlabrie

I have the same set up and there has always been some melting above the line.
David in NH

Clam77

Wayno - if you ran the pex inside some foam-core pvc pipe and then heavily insulated that, do you think it would work to lessen the loss??  How warm is your sidewalk and ground where it's melted??
Andy

Stihl 009, 028, 038, 041, MS362
Mac 1-40, 3-25

boilerman101

Trapper, correct me if I'm wrong, but I believe you are talking about an older water delivery system that was assembled with multiple lengths of insulation tubes, pull the pex lines through it and then pull a plastic baggie over it correct? I think you are referring that the baggie has torn or got a hole in it and allowing water to possibly saturate your insulation?  I think the Thermopex product that many of us are using today is much better and can't allow that to happen with the hard semi flexible shell and urethane insulation.

trapper

boilerman101  you are right
stihl ms241cm ms261cm  echo 310 400 suzuki  log arch made by stepson several logrite tools woodmizer LT30

mrwood

Wayno, Snow melt with the current thermopex? I find this odd. I know alot of people who have the current thermo and have no issue. I can understand it from the older style stuff. I personally installed my thermopex at 30 inches with about a 4 inch sand barrier all around it and I have absolutely no signs of any snow melting to indicate any idea of heat loss. I am not sure as to a true measurement of my heat loss from boiler to house. I did not install a temp gauge inside. I have been meaning to get one of those laser inferred temp guns to test. But I have not got around to it yet. But even on the upward curl where I come out of the ground to the boiler has no snow melt. I wonder if you could have some faulty thermopex that maybe wasn't made right at the factory. You should test your water temp inside the house. If it is significant loss maybe cb would give you thermopex free of charge if you are interested in doing the work again. That would be the worst part.

stumper

I installed my thermopex (new style) 4 1/2 feet deep (typical frost depth in Maine is 4 to 5 feet).  Below it I installed a 6 inch perferated under drain encased in 3/4 inch stone that I day lighted.  I then have 2 inches of foam below the pipe on each side of the pipe and on top of the pipe all encassed in stone.  then normal back fill.  With no heat draw in the house I can not detect any change in temperature from the water leaving the boiler to the water returning.

I would not do anything about your heat loss not, but would consider dig down and exposing the pipe this summer and hiring a spray foam company to come in and insulate it.  This is what they now do for water lines that they can anot install below frost do to ledge.  It is supposed to work great and is a lot less work then what I did.

hockeyguy

Mine is two year old 1 1/4 thermopex. I get some snow melt on the last 6' as it   approaches the house at a depth of 12"(too much ledge to stay deeper).
I wonder if the high water table in that area has something to do with this also?
I have fond memories of that day spent wrestling with that stuff. >:(

stumper

Water table will absolutely affect your heat loss.  If I had a choice of below the water table or in the frost zone I would take the frost zone every time.  That is the reason I installed the under drain below my pipe, to keep it dry.  Water transfers heat well (that is why we use it in the boiler to transfer heat to the house). 

thecfarm

I have some heat loss too. Snow will melt above my lines too after a few weeks,if it does not snow. But mine is only down about 18 inches,filled with sand. Mine pex was put inside of 4 inch black drainage pipe. Yes,I know I use more wood,but when the power is out for 4 hours I know the ground is keeping my pipes warm.
Model 6020-20hp Manual Thomas bandsaw,TC40A 4wd 40 hp New Holland tractor, 450 Norse Winch, Heatmor 400 OWB,YCC 1978-79

wayno12

OK, this morning on the way out I snapped a couple pics to show my situation.  Last night we had a light freezing rain and you can see the sidewalk is dry, except for he tracks left by fido.  You will see the snow melt is "L" shaped by the sidewalk and that is because the pex is buried from the boiler to the garage and then from the garage around the house to the addition.  My question is, if you are having heat loss, does depth really matter?  I would have to think your tubing is transferring heat at a constant rate regardless of depth.  Right now, we only have about 1 to 2 inches of frost thanks to a very mild winter (I'm not complaining!).

Here are the pics to check out:





wayno12

It only stands to reason that if you bury your line 48 inches as opposed to 24 inches you will not see any snow melt because the ground would have absorbed all the lost heat before it surfaces and starts to melt snow whereas if you are closer to the surface the heat exits the ground sooner and therefore melts the snow.  It doesn't necessarily mean less heat loss because you are deeper.  My temp drop from boiler to garage which is 85' distance is about 5 degrees.  I have temp guage where pex from boiler enters my manifold, have temp gauge at each entry and exit point of each appliance ie: DHW heater, pool, etc., and a temp gauge where lines return to manifold, I have also verified all temps using a instant meat thermometer to test accuracy of the guages.  They are right on the money.

stumper

You are correct as far as you went.  I beleive I am loosing less heat because the ground around me pipe is warmer.  Less temperature differentian means less heat loss if everything else is the same. 

Dean186

One could always pull the Thermopex through PVC pipe, and then insulate around the PVC pipe, but who is crazy enough to do that when installing a OWB water line. 

Oh wait, I did.  ;D

It is a good idea to add some blue board or spray insulation to the Thermopex during installation.  My line is buried about 28 inches from the top of pipe to the surface and I have never seen an indication of heat loss at the surface, nor can I measure any heat loss.

Trapper, If you end up redoing the water line next summer, don't skimp on the pipe or the extras.  Good drainage underneath and extra insulation on top and the sides. 

boilerman101

My Thermopex was buried in just a 16 inch deep trench and has been in the ground since 2006. Something I have noticed with my Thermopex is that when we have had a dry fall going into freeze up, I see no melting at all. When the ground was wet and saturated going into the winter season, I may see some narrow melt in some spots over the line, probably because even a little warmth coming off the casing conducts through the moist soil. In either case, I have a temp guage on my return line on my E Classic and if my fan on my indoor furnace is not blowing, the return water is coming back within 2 degrees of the temp I'm reading on my firestar controller, which should be the supply temp. So bottom line, 85 ft in and 85 ft back and I'm not losing much temp regardless if I see a small degree of snow melt or not. I'm a believer and feel it was worth the cost.

True North

I was crazy enough to run the pex through PVC too!  Then we boxed around it with foam board and used spray foam to fill in the box.  We then covered this with a reflective bubble wrap type cover.  We had no snow melting. 

WI Fire

I installed the Pex, foam tube, plastic bag from CB about 12 years ago. Over the years I noted more snow melt,(I was at the recommended depth from CB, not 4 feet deep). My wood consumption also seemed to go up, though we had some mighty long and cold Wisconsin winters.

This past fall, I replaced the line with the fancy stuff, and noted water in the plastic bag of the old line. I also went to the e-classic 2300, and I am amazed at how much less wood we have used, though it has been a mild winter. There is no doubt in my mind that it was worth it replacing the line, which is probably a large part of my heat savings.

red oaks lumber

i just went and looked my whole line 120 ft. is fully covered in snow, right up to the house. even where it goes under the sidewalk.spend the money on new line.
the experts think i do things wrong
over 18 million b.f. processed and 7341 happy customers i disagree

Clam77

For those that live where you have warm spells like we have this winter, once the snow melts off naturally the ideal time to check for heat loss would be as it's actually snowing - ANY warmth in the ground is gonna melt it off till the ground cools off.   ;)
Andy

Stihl 009, 028, 038, 041, MS362
Mac 1-40, 3-25

sparky1

I guess my feeling is, if you get the wood for free and have a little spare time. meaning you dont mind cutting a little extra wood. I wouldnt fix it, as long as not leaking.  at $11.50 a foot its not a cheap fix! My cb dealer told me you could burry the line (thermapex) at 8 inches below and hes heard of it not having a snow line (he didnt recomend this). 
Shaun J

Gary_C

I too am surprised at the snow melt over the new Pex. I installed my CB in December one year and had to leave the line on top of the ground for the winter. I watched and the snow layed right on top of the pex with no snow melt. I never could see where the line was laying under the snow. It's been buried for two winters now and you can't even see where is is run.  ???

I just looked now and you can't tell where the line is underground. There's about two inches of snow and I have cleared most of the snow off and there is no pattern to where the grass shows thru.
Never take life seriously. Nobody gets out alive anyway.

wayno12

Red Oaks Lumber, I could see replacing pex 10 years old, but what's your take on my situation?  I paid $12.55 ft for the good stuff buried at the depth suggested, and still see melting.  CB says this is acceptable and normal.  Interesting observation made though about a dry fall and wet fall.

doctorb

I try to give credit where credit is due, and Dean186 started a great thread a while back on the topic of the amount of heat loss with OWB use.  It's an interesting read that's closely related to this topic.  For those of you concerned about heat loss, and how much actual work you have to do because of it, I would suggest spending a little time there.

https://forestryforum.com/board/index.php/topic,48429.0.html
My father once said, "This is my son who wanted to grow up and become a doctor.  So far, he's only become a doctor."

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