OWB Performance Loss

[Biglurr54]

I don't know how it was installed. I have 4 inch schedule 80 on each end. The pex is wrapped in a reflectix material. Almost like like a sock. I can imagine it is buried very deep. The ground had frozen over the top so I can dig to find out.

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[cantoo]

Sounds to me like you might be able to pull it out and install new lines like the way I did mine. Might be a decent temporary fix. I assume the Drainage tile style ones can be pulled out and replaced?
I would even consider buying this cheap stuff and just laying it on the ground for now. Throw it in a 1/4" wall steel pipe and cover it with gravel on the driveway for now. Dig in in the summer when you have time.
http://www.outdoor-wood-furnace-parts.com/Insulated-Underground-Pex-Pipe.htm

 

[NSMaple1]

I think on the ground would be a lot better than in wet ground.

 

[Biglurr54]

Anyone use maxx-r. Seems affordable and I have the pex already. I figured I could silicone it all together with 3m 5200. It's designed for under water fitting on boats. It will make the pieces water tight.

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[hupte]

I have a 135 ft. run of Thermopex buried 18" from OWB to house, temperature on boiler output line vs temperature on same line entering through basement wall is within 1 degree F. This is the last place to go cheap.

this^^^

 

[hupte]

Faster water flow might help you out some too. What exactly do your home made lines consist of? Any pics of the install?
For my short homemade section I used 2 runs of 4"x 10' PVC pipe, 1" pex lines in each pipe, each pex line had the same type of closed cell foam shown in my earlier link but was thicker, then the foam and pex was wrapped with red Tyvek tape just to keep them together. Then they were slide into the 4" pvc and buried 8' deep in gravel. Used long sweeps at OWB so I could remove and replace if needed. I also ran electrical and a pull rope in the runs in case I wanted to add something in the future. Also ran wire to the pump inside for the generator but been too lazy to hook it up.
View attachment 480765

how much heat do you loose in how many feet?

 

[cantoo]

hupte, that run is only 35' so there is no noticeable difference in the temp. I don't even lose much on the exchanger due to the short run. My other house is a 100' run of logstor and from the owb to the exchanger it is too small to be measured too. Maybe a really good accurate digital gauge would show it.

 

[Iska3]

When I was going to install my OWB, I did a lot of research and talked to as many people as I could about their underground pipes. My friend did his own insulating and after a few years he was soon melting snow along his water lines but his so called heat loss was only a few degrees as far as he knew because his pump had enough volume to carry the extra hot water. Long story short, I went with ThermoFlex and not the thermoplex that most used. My water lines are 125 feet from the house and only 18 to 24 inches underground in most of the area and through my crawl space it's on top of the ground. The water lines going to the garage are 18 inches underground and going in to the garage they are above ground... (see pictures) This is two pictures that I took of my water line that goes into my garage, as you can see, the frost and snow stay on the flex pipe throughout the winter so what little heat is lost through the pipes are soon cooled down by the colder weather.. This may not be the best underground insulated pipe but it works for me.. I think I paid $8.00 per foot at the time and I'm sure I saved more than that in wood and my extra time loading the stove over the years.

This is the Thermoflex http://www.gtglobeindustries.com/insulated-pex.php

 

[ash man]

I also replaced my homemade underground pex pipe with thermoflex 2 years ago and it specs a 1% heat loss over 100' which seems pretty close to what I'm loosing. I paid @ $7 a foot. It's no thermopex or logstore, but I think a good cheaper alternative.

 

[Iska3]

I think I paid $6.50 back then and I received free shipping because it came direct from Globe Ind. I paid for 125 feet and they sent 150 feet, so I ran the extra to the garage. I have a friend who is a plumber so he could buy direct from the factory and I got it as his cost. I ran this above ground the first year and it never did melt the snow. My other buddy ran his 24 inches underground but he passes under two major driveways and a big lot that is always plowed and never has a problem. If I were to do this again, I'd buy the same stuff..

 

[Biglurr54]

Well I by passed the heat exchanger to see if it was restrictions the flow. No change in Temps when that happened. Any chance the circ pump could be tired or worn out? It's a taco 0011 been on there unserviced for about 8 to 10 years.

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[NSMaple1]

Doesn't sound like it. If the pump was tired, I would expect to see some difference in some temps somewhere with a reduction in head that bypassing the HX would give. Also the temps from before across your HX show that water is flowing across both sides, both sides fairly even matched.

There is no getting over the fact that your underground piping is pretty much toast, unfortunately.

Also on the Maxx R stuff you asked about, I would be very leery of piping with that many undergound joints in wet ground. It would have one joint every 8 feet & would only take one getting leaky to start the heat loss again.

 

[Biglurr54]

OK I have done some more digging. My owb circulator is connected to the lower port and is pushing water to the exchanger and then the water return to the upper port. This seems backwards. Shouldn't I be taking water from the top of the boiler where it's warmest and returning it to the bottom where it's coldest.

Also my circ pumps inside pull instead of push. Should my circ on the boiler do the same?

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[tawilson]

Sounds ok.

 

[lefturnfreek]

Mine is the other way around, on both.

It takes water from the upper line and the pump push's water towards the house. These pumps are made to push water not pull it. Can you contact the boiler company to find out which line you should take water from?

I have a snow melt issue also but my system was installed by the previous home owner. It's 2 runs of PEX, 1 to the 1 to the shop. I covered my lines in flax bales this year and the wood usage has dropped significantly. I do plan on replace the lines with thermopex or flex but want to move the stove at the same time. I live in a high water table area so this going to be the best and only option.

 

[Oldman47]

An ideal circuit will move water from cold to hot in your boiler and then from the top, hot to cold, in the house and return. The best location for the pump is on the lowest level point of the cold leg where the water is returning to the boiler from the house heat exchanger. In that location it will be sure to be submerged and will have the best available suction pressure, NPSH. If your pump is anywhere on the hot leg of a boiler system it will have less available suction head, because of the elevated temperature, so it will have a better chance of cavitating and causing pump damage. Unless you like to replace the pump impeller every year it needs to be located in the cold leg of any closed system.

 

[Biglurr54]

Woodmasters are open systems. The pump pushes from the lower port to the house and returns the colder water to the upper port. This is confirmed by the installation manual. I agree with your ideal situation because that's how it works with a closed loop where the air can be bled and the pump sucks instead of pushes.

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[cantoo]

My pump is inside my basement. 35' from the owb which is 10' higher than the pump. The pump is on the hot side, goes to the hot water heater and then up 6' to the furnace exchanger then it returns to the owb. My other line is 100' and runs from owb to the pump in the house right at the furnace exchanger and plate exchanger which is 4' higher than the owb. 35' run is on all year long and has been for 3 years. 100' run is only run in the heating season but runs 24/7 then. Never had an issue with pumps yet.

 

[lefturnfreek]

Hows this for snow melt on the left....

 

[Biglurr54]

Got me beat hands down. Yikes.

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