OWB snow melt

[big_z]

Hello,
We bought some property that came with a Heatmor 200 to heat the house, outbuilding, and hot water. This is my 2nd winter using it and it seems to be running well -- much better than my first season! However, I have noticed that the snow is melting along the path between the boiler and the house. Approx 50-60ft. I know this means that I'm loosing heat into the ground but when I look at the water temp on the front of the boiler and then go look at the temp on the supply line into the house they are within 5 degrees. So my questions is how much heat am I loosing into the ground and is it worth the effort to dig up the lines and replace them?

Thanks,
Aaron

 

[Eureka]

I have a 115 foot run to my house and 80 foot run to my shop with 1-1/4" Rehau foam filled underground line. It's about as good as it gets for the underground line. I have thermometers on both the supply and return lines in both buildings and cannot see a difference in temperature from out at the OWB to inside the building and back out with no heat loads calling. I can still see about a 3-4" ring of thawed soil right where the lines go into the ground, but fresh snow will stay piled against it for a day or so. I know people that have gone cheap with the underground lines and they make green grass all winter long and knowing that made me fork over the money for the good stuff. It is actually very common for the underground lines to be less than ideal, simply because it costs a lot (I paid $10.50/foot which is a GOOD deal). The losses to the ground can be very large and I've seen some calculations showing that a few degrees can mean several cords of wood over a winter.
Can you get a picture of the back of your Heatmor to show us what the water lines look like?

 

[Fred61]

5 degrees is huge if you have a high flow rate.

 

[big_z]

The lines in the basement are pex with what looks like fiberglass wrapped around it in a black corrugated pipe. I will try to get some photos tonight. I will also look more closely at the temps reported on both ends to get exact numbers. I think the system was put in 10+ yrs ago by previous owner.

 

[Eureka]

5 degrees x 8.33(BTUs to raise 1 gallon 1 degree)= 41.65 btu
41.65 btu x 5 GPM(generic flow rate for OWB)= 208.25 btu
208.25 x 1440 (minutes in a day)= 299,880 BTU

Anybody above my pay scale willing to confirm my work?

 

[Eureka]

Now that I think of it, it could be worse because we don't know what temperature the water returns back to the furnace at, but if 5 degrees one way then I guess it'd mean 10 degrees round trip?

 

[big_z]

I'm trying to put this figure I can understand. So I was looking for how much BTU in wood. This link (https://www.mha-net.org/docs/v8n2/docs/WDBASICS.pdf) indicates that 6,000 BTU per pound of wood (obviously varies by type, moisture,etc) so that would be approx 50lbs of wood that is being wasted per day?

 

[salecker]

I have Rehau lines foamed in place.No snow melt here,and we have snow cover for at least 6 months.
I almost went with bubble wrapped lines, then i found this site and read what others had discovered about those lines.
THANK YOU HEARTH SUBSCRIBERS
After reading here for about 3 months,everything that i was going to do got scraped.Now i have a system on its 9th year doing great,we just went through a week of -40 and the only way you can tell it's that cold is we have to start burning sooner in the day.House is warm and comfortable with the Cast Iron rads.The cast iron rads are the only thing that i was going to use originally,that made it to my current system.

 

[maple1]

Hello,
We bought some property that came with a Heatmor 200 to heat the house, outbuilding, and hot water. This is my 2nd winter using it and it seems to be running well -- much better than my first season! However, I have noticed that the snow is melting along the path between the boiler and the house. Approx 50-60ft. I know this means that I'm loosing heat into the ground but when I look at the water temp on the front of the boiler and then go look at the temp on the supply line into the house they are within 5 degrees. So my questions is how much heat am I loosing into the ground and is it worth the effort to dig up the lines and replace them?

Thanks,
Aaron

If it is melting snow it is losing a lot. Whether it is worth it to dig & replace kind of depends if you are minding burning the extra wood & if it is keeping you warm or not.

It is pretty hard to know accurately how much you are losing - that would require knowing how exactly many GPM you are flowing. And would need accurate temp measuring on both pipes at each end. Gauges can vary in accuracies between them. You might get a decent handle on it using a good IR temp gun & repeated measurements. If what you are pointing it at is any kind of shiny, you should spray it with flat black paint first, they don't do good measuring shiny stuff.

 

[warno]

Take a measurement of the underground line supply in the boiler shed about 1 foot before it goes into the ground and about 1 foot after it enters the home and do the same with the return. That will tell you your heat loss to the ground. Like maple said get an IR temp gun, harbor freight is good enough, and use that to take the readings. Spray some flat black spray paint on the lines to make sure you don't hit a bright or shiny spot.

 

[big_z]

Sorry for the delays it was been a busy and cold week. Here are pics of temps at the boiler and inside as well as pictues of the current pipe and insulation. I tried to measure with IR gun but it seemed to always read lower. The temp between the boiler and the house thermometers was about 2-3 degrees?
https://drive.google.com/drive/folders/1h5U2yQc-CDBiMhX1lc5akrmIJpBIQeMW?usp=sharing

 

[big_z]

Hello,
I am revisiting this thread and issue after a couple more years of running the OWB. Last year I had alot of issues with the Heatmor Boiling over so I contacted the company and they said the inlet/outlets on the door will scale up and cause flashboil. I tried to remove the hoses and clean it last winter but it requires you to drain down a bunch of water so I waited til the off season and did some much needed maintenance. i drained down the OWB and replaced a leaking shutoff in the back and also did a thorough cleaning of the door and flushed out a lot of scale. I also had a pump fail and my blower fan failed last winter so lots of work has been done!

So far this season it has been running good and no boilovers. Due to boil overs I had previously turned down my setpoint from 180 to 160 (which didn't help the issue). So I turned it back up to 180 with 25 degree swing. The unit is handling the setpoint fine but I have noticed that i'm only getting 165 degreen water in the house (as measured at the inlet pipe with a digital thermocouple. So i'm loosing a TON of heat into the ground.

I'm looking for options besides digging up the lines because of all th work inolved and i'd have to dig under sidewalks and where the lines enter the house there is also well plumping, septic, and eletrical all underground so i'm not in a hurry to start digging. Plus i'm not sure what I would do after I dug it up (try to reinsulate?, try to run new lines?).

So, my question:
My pumps (Grundfos) are currently always on when the boiler is running and constantly circulating water. When I need heat in the house it turns on the furnace fan which pulls heat off the heat exchanger in the plenum. Would it be more efficient if I was able to control the pumps with the thermostat to only pump hot water when I need the heat? Would this shorten the life of the pump with a lot cycling on/off vs always on? Any other reasons to consider or avoid this line of thinking?

Thanks!

Aaron

 

[salecker]

Maybe abandon the existing lines and pick a better spot for the unit.
A straight shot to the house with nothing to dig around or under.
Chances are that unless you dig up the existing lines clean them and sprayfoam them they aren't worth anything.
You could go with above ground lines in a enclosure which would be quick and easy other than have a new above ground obstical.

 

[chew72]

I'd replace the lines. I'll also add from the look of what little insulation there is, it's essential non existent. Also you might be heating the return water quite a bit.

 

[maple1]

The situation won't be improved without replacing the lines with new thermopex or the like. Existing ones are no good. You won't hurt the pump by turning off and on but I don't think you will improve the situation any. When off, your lines will quickly drop in temp and the longer they are off the more they and the surrounding ground will cool. When you turn back on it will then take a long time for the temp of water getting to the house to get back up to 165. You have a giant heat sink there. For this winter you could either buy the thermopex and lay it out on the ground and use like that, and bury it after winter and maybe also relocate the boiler at the same time. Or just make sure you have enough wood and feed the beast the next few months. But you need new lines.