Can condensing boiler and geothermal work together?

[reader2580]

My electric co-op offers a 50% discount on electricity for heating if there is a backup heat source utilizing oil, natural gas, or propane.

I am looking at eventually putting in geothermal system. Could a condensing boiler be used as a backup heat source? I have forced air. I know a regular gas furnace with an A coil on top is an option, but then I need a place to put the geothermal heat pump. I can find space for a condensing boiler much easier than the space for the heat pump.

There are outdoor geothermal units, but they are not as common and probably more expensive.

 

[Jackfre]

Yes, quite easily. Multi stage stat with the boiler as second stage. Set points to be decided by watching geos operation and your comfort. You put the appropriate sized hot water coil into the plenum. You could pick up your hot water load with the boiler as well running an indirect water heater

 

[reader2580]

A typical geothermal heat pump that replaces a forced air furnace appears to have a flat coil instead of a typical A coil. The blower is in the top part of the unit which is opposite of a furnace. The compressor is in the bottom.

It appears that I could fit another coil above a geothermal heat pump. One of the tricks would be figuring out the controls so the propane boiler kicks in when power to the geothermal is cut. The blower fan power would need to be separate.

I would have to talk to the CO-OP about how this would work with my solar electric. Normally, they just install a second meter for the electric heat. I wouldn't want any power from my solar array flowing through that meter.

 

[Jackfre]

Adding coils will increase the static pressure on the system. Watch that on HP selection and know how the manuf feels about your plan. Increased static =increase kw. The alternate method which can be a pitn is dampers in the S/R ducting to an independent AH for the hot water coil. What is your proposed geo source? Are you looking to add the alternate source to simply qualify for the discount? If so, skip the complicated set-up and just add a wall furnace or two. Check out Rinnai Energysavers.

 

[reader2580]

Yes, the alternate heat source would only be to qualify for the 50% discount on electricity through the dual fuel program. Electricity to my heating system could be turned off for up to 12 hours on the coldest days. I want to find an alternative system that will be able heat the entire house evenly while taking up as little space as possible.

This is a long term plan that might not happen for 10 years. Who knows if the CO-OP will still even offer the dual fuel program by then? The state of Minnesota is proposing that all use of fossil fuels cease by 2050 and electricity will be the only heating source available.

An air source heat pump wouldn't work well, or at all, on a day the outside temps drop to -20F. There is no way I could afford the $25,000 to $30,000 for a professional geothermal system install. This would need to primarily be a DIY project. I found firms online that will do residential geothermal system designs.

 

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I am on the “Back up relief” program here in MN on both the house and the shop. The house ROI was about 6 years ago. The shop should be “even” by August.

NG is my back up. I have yet to see Excel cut the power when heating. I have seen it in the summer on only the shop for 1-2 hours starting at 9 pm on only the shop and never the house.