OWB Performance Loss

[Biglurr54]

To add to the ground loss issue there is a spring above where the pipe is so water coninuously runs over the ground and I'm assuming over the buried pipes.

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[ChoppyChoppy]

FYI the trench for the 4" pipe and lines can be easily accomplished in about 30 minutes with a walk behind ditch witch trencher. I rented one for the day for about $75. How deep is the frost line where you live?

Not if you have gravel or rocks in the soil!

 

[Mike Van]

If you have y - strainers on your lines, check those first. Otherwise cut the HX free, clean it, put shutoffs in this time -

 

[StihlKicking]

Not if you have gravel or rocks in the soil!

^this^

 

[Biglurr54]

No y strainers. I have to cut her free.

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[tawilson]

The oil boiler flucuates from 130 to 160 degrees. I haven't got it going on oil in a while.

I am in the market for a tractor that I can put a 3pt backhoe on so I have been waiting for that to dig the trench. The frost here is about 4 feet.

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Make sure to get some sand for backfilling. One sharp rock and you are back in the same boat.

 

[NSMaple1]

I think there is some confusion in the thread about what kind of heat exchanger you're talking about. I thought it was a flat plate, but sounded like others were telling you how to clean a water-to-air.

Still haven't heard any temperature reports.

And you really should spring for good underground pipe or you'll be throwing good money after bad. Thermopex or logstor. Expensive but worth it in any environment that is not absolutely dry all the time. If you get it now you can lay it on the ground and get by with it there for the winter, bury in spring or summer. Anything else will soak up groundwater and send your wood into the earth.

 

[Biglurr54]

Wood is free for me. I have a lot of land and I clear dead stuff. I burn 9 cord a year this way. I plan on doing new piped but it won't be any time soon as it's hard to justify the cost at the moment. I plan on logstor pipe. My exchanger is a plate exchanger.

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[NSMaple1]

It could be dirty hx (which would require flushing of primarily the OWB side), or it could be that your heat is going into the ground before it gets to the HX. Or both. Temps should tell the tale, my bet is mostly on heat going into the ground.

And its not about how little or how much the wood is costing you, its about being comfortable. If its the pipes, you won't get comfy no matter how much wood you put through it.

 

[JCMC]

Have you checked the impeller yet! I have heat loss into the ground as it melts the snow off also but would check the impeller first as it is inexpensive to replace.

 

[cantoo]

If you are melting snow then you likely aren't getting enough heat to exchanger anyway. If it doesn't go over a driveway I would just buy PVC pipe and just put 1" pex in it wrapped with the 6' pieces of foam insulation. Would still be much better than the water wicking away most of the heat on your underground lines now. Speed up the pump to move water faster and I bet you still use a lot less wood and get the heat you need. Of course this is after you do the easy, cheap stuff like checking temps and cleaning the exchanger. There is a good water line insulation that has a rubber outer but it's a lot more money too. The cheap stuff will work and will pay for itself quickly.

 

[Biglurr54]

The lines cross the driveway and parking area. It has always left a patch of melted snow but had no problem heating the house. It's a woodmaster 4400 and it's heating 1500 Sqft house. And 130 feet of ground.

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[hupte]

It could be dirty hx (which would require flushing of primarily the OWB side), or it could be that your heat is going into the ground before it gets to the HX. Or both. Temps should tell the tale, my bet is mostly on heat going into the ground.

And its not about how little or how much the wood is costing you, its about being comfortable. If its the pipes, you won't get comfy no matter how much wood you put through it.

this^^^^^

 

[cantoo]

Note to everyone else reading this " don't run lines under driveway or buildings if possible"

 

[StihlKicking]

I apologize, in my advice earlier I thought you were dealing with a water to air exchanger. I don't have any experience with radiant heat or plate exchangers. Sorry if I muddied the water. Heat loss through your underground lines is still probably at least 50% of your problem if your melting snow.

 

[Biglurr54]

U have a question about making my own pipes. What do I use for insulation? Someone mentioned a sleeve. What should I use for the outside pipe?

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[NSMaple1]

I think the only alternative to Thermopex or Logstor I would consider would be spraying foam in trench. Lay the pipe out in the trench, make sure the lines are separated by a couple inches, then spray it with 4" or so all around. It needs to be closed cell foam, done by a spray foam contractor. Not sure how that would compare price wise with the other stuff, you'd have to get prices for pipe & foam contracting for what you can get there. But usually the longer the trench the more money there is to be saved. I don't see anything else lasting & keeping moisture out with the conditions you described, sounds like it is basically immersed in water with the spring there.

 

[anlrolfe]

Efficiency of an OWB is an misnomer. Most run circ pump(s), combustion air blowers and if a heat exchanger into forced air system the furnace fan as well. Running 3-4-motors for heat just seems counter intuitive to me but I guess if you can afford the time and trouble to feed it cordwood go ahead. Now what they do have is burn time.

 

[tawilson]

As long as you will have to dig a new trench anyways, could you relocate the boiler so you are not crossing driveways and maybe get it closer to save pipe?

 

[Deleted member 117362]

I have a Woodmaster 4400 and i have noticed that its preformance is dropping. The boiler could keep up with heating the house no problem to about -10 degrees then it would have a hard time recovering when the thermostat is turned up. This has been the case for the last 4 years. This year it does not seem to be able to bring the house up to temp when it is in the low teens outside. Nothing has changed this year compared to previous years other than our house he been more and more insulated. I am suspecting that the w to w plate heat exchange is plugging up. I use well water for fill ups and treat with woodmaster treatment each spring. The owb is holding temperature no problem. I would like to clean the plate exchanger but have to cut it out as there is no tee on the pex lines. I may cut the pex and put in tees with a valves so i can easily clean the exchanger in the future. Do i need to clean the oil burner side of the exchanger? I have done nothing with the water on that side ever. Could it be another problem? I believe the circ pump is about 10 years old. Its a taco 011. Could that be getting tired and slowing the amount of hot water to the oil boiler?

I had the same problem after switching stoves from a 434 to 3300. Are you running an inline water filter, mine had a build up of scale and rust. Pulled the pump and cleaned it, then installed a high temp inline filter, problem solved and putting out heat again. I would be surprised if it's your pump. Neighbor purchased the 434 that has run 14 years with the same pump. I installed a filter on another friends OWB and he could not believe how much junk it collected.