Incorporating geothermal furnace & storage

bupalos

Member
Jan 26, 2009
193
ne ohio
I just picked up a 42K btu geothermal furnace, and now I have to install it. Anyone have that setup and have some thoughts? I was using the plenum and blower of my old (otherwise decommissioned) oil furnace to distribute heat from the wood boiler through a coil in there. I never ran those two together, never had need of them communicating or negotiating demand from thermostat. Now I guess I need to do that. Quick-like. It's getting cold. I ripped out the oil furnace yesterday and just realized what I've done!

I also picked up a 350 gallon stainless tote as a buffer tank for the boiler, but I guess getting that in seems a little bit secondary right now.

Anyone have experience with this kind of setup?
 

maple1

Minister of Fire
Sep 15, 2011
10,008
Nova Scotia
All I know about a geo install, is there are a lot of things to get right to make it work right. Dont know what all those things are though. Also thinking hot air vs hot water is the way to go, unless you have low temp radiant distribution.

What about the in ground stuff - is that in place? Thinking that would be the main and hardest thing to get right.

That's assuming that what you did get is a good unit.

I think I would be looking for a local geo pro at this point.
 

bupalos

Member
Jan 26, 2009
193
ne ohio
All I know about a geo install, is there are a lot of things to get right to make it work right. Dont know what all those things are though. Also thinking hot air vs hot water is the way to go, unless you have low temp radiant distribution.

What about the in ground stuff - is that in place? Thinking that would be the main and hardest thing to get right.

That's assuming that what you did get is a good unit.

I think I would be looking for a local geo pro at this point.
I do have a pro advising on the issues related to the functioning of the ground loop with the unit and so forth. (Actually this is an open install drawing off a spring, and dumping in a creek, so that's actually very simple. What I don't know is controls for how to interface the unit itself with the wood system. And I'm really terrible at that kind of thing.

Its really a question of how I set up and use thermostats, relays, etc so it's like "IF the incoming loop water temp is above 40 degrees AND the house thermo is calling for heat AND the wood storage tank is below 120 THEN the geothermal pump runs."

It's thinking like computer programming which I'm terrible at.
 
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HitzerHillbilly

Burning Hunk
Oct 18, 2014
215
Northern Indiana
I do have a pro advising on the issues related to the functioning of the ground loop with the unit and so forth. (Actually this is an open install drawing off a spring, and dumping in a creek, so that's actually very simple. What I don't know is controls for how to interface the unit itself with the wood system. And I'm really terrible at that kind of thing.

Its really a question of how I set up and use thermostats, relays, etc so it's like "IF the incoming loop water temp is above 40 degrees AND the house thermo is calling for heat AND the wood storage tank is below 120 THEN the geothermal pump runs."

It's thinking like computer programming which I'm terrible at.
I have an open loop geo system which I just hooked our “new to us” Heatmor to. It was a brain scratcher but I got it! Lol. Ended up using an aqua stat switch on my incoming boiler lines. As long as incoming water is a over 100 degrees my Geo doesn’t kick on. Only the fan.
 
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sloeffle

Minister of Fire
Mar 1, 2012
573
Central Ohio
I do have a pro advising on the issues related to the functioning of the ground loop with the unit and so forth. (Actually this is an open install drawing off a spring, and dumping in a creek, so that's actually very simple. What I don't know is controls for how to interface the unit itself with the wood system. And I'm really terrible at that kind of thing.
You might to check with the state and make sure that a "pump and dump" system is still legal to install. Also, I'd make sure your spring can supply enough water for your needs if it is indeed legal.
 

peakbagger

Minister of Fire
Jul 11, 2008
4,691
Northern NH
A geothermal unit is going to put out cooler water than a wood or oil boiler. It sounds like you have a hot air system so you may have an issue that the coil is under sized or far worse the ductwork is undersized to deal with the cooler geowater. Since you may need a coil anyhow the easiest control may be to put a second coil in the ductwork upstream of the wood boiler coil and keep the systems separate.

Control wise you need to decide which system is the priority, geo or wood. Ideally a PLC based control is the way to go but there is probably an off the shelf control out there probably a Tekmar set up to control two boilers. The controller would run one heat source as primary and then if the primary unit does not have enough capacity the second heat source turns on.
 

bupalos

Member
Jan 26, 2009
193
ne ohio
You might to check with the state and make sure that a "pump and dump" system is still legal to install. Also, I'd make sure your spring can supply enough water for your needs if it is indeed legal.
Yeah that's all good legal-wise here in ohio. In this case it would be kind of insane if it wasn't, the spring is the source of the little creek, my diversion will only put the same water back about 10 feet away from where it was.
 

bupalos

Member
Jan 26, 2009
193
ne ohio
I have an open loop geo system which I just hooked our “new to us” Heatmor to. It was a brain scratcher but I got it! Lol. Ended up using an aqua stat switch on my incoming boiler lines. As long as incoming water is a over 100 degrees my Geo doesn’t kick on. Only the fan.
Do you have storage that's isolated from the boiler though? That sounds good except it would seem to mean treating boiler and storage as one?
 

HitzerHillbilly

Burning Hunk
Oct 18, 2014
215
Northern Indiana
Do you have storage that's isolated from the boiler though? That sounds good except it would seem to mean treating boiler and storage as one?
No. My Heatmor holds 114 gallons of water that circulated through a flat plate HX for domestic hot water, and a water to air HX I installed in my plenum. The geo uses ground water directly from a well when needed. No separate storage tank.


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sloeffle

Minister of Fire
Mar 1, 2012
573
Central Ohio
Yeah that's all good legal-wise here in ohio. In this case it would be kind of insane if it wasn't, the spring is the source of the little creek, my diversion will only put the same water back about 10 feet away from where it was.
Good luck with it.

We love ours in the summer time. It does okay in the winter with temps above 25F or so. When it is below those numbers it seems to run a lot. They are made to run a lot, but I don't like paying power bill. I'd rather heat my house via the million dead ash trees I have in my woods.
 
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HitzerHillbilly

Burning Hunk
Oct 18, 2014
215
Northern Indiana
Good luck with it.

We love ours in the summer time. It does okay in the winter with temps above 25F or so. When it is below those numbers it seems to run a lot. They are made to run a lot, but I don't like paying power bill. I'd rather heat my house via the million dead ash trees I have in my woods.
Same with us, love it for cooling the house, not a fan of the heating capabilities.


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sloeffle

Minister of Fire
Mar 1, 2012
573
Central Ohio
Same with us, love it for cooling the house, not a fan of the heating capabilities.
So you have an OWB to help with winter heating ?

We have a wood burning furnace to help with winter heating too. I installed the wood burning furnace because I knew I couldn't afford a generator big enough ( our geo pulls 100AMPS at startup ) to start the geo if we had a power outage. Now the wood burning furnace is our main source of heat when temps are below 32F.
 
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maple1

Minister of Fire
Sep 15, 2011
10,008
Nova Scotia
Still a little uncertain on what exactly was purchased. Said to be a furnace - I think my approach would be to just set it up as a stand alone furnace and run it completely independant of anything else. On it's own simple stat. My understanding is they work best when running steady and constant, so I'd just try to let it do its thing, see how it does, and make adjustments to it or fill in with wood burning as necessary. And major changes next year if needed once you see how good it does or doesnt do. Especially since it seems its capabilities are a pretty big uncertainty going in.
 

HitzerHillbilly

Burning Hunk
Oct 18, 2014
215
Northern Indiana
So you have an OWB to help with winter heating ?

We have a wood burning furnace to help with winter heating too. I installed the wood burning furnace because I knew I couldn't afford a generator big enough ( our geo pulls 100AMPS at startup ) to start the geo if we had a power outage. Now the wood burning furnace is our main source of heat when temps are below 32F.
Yep! Temps get below about 35 and the heat just isn’t the same


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