Share pictures or your geothermal: plumbing

[Redneck in training]

Not a very accurate statement. A modern air-air heat pump will still generate more heat in watts compared to the power draw it uses. Generally the break-even point is in the low teens. The problem in cold weather is not low efficiency, but a loss of capacity. The BTU capacity will drop the colder it gets, but the heat produced is still generated at relatively high efficiency. Since the capacity (heat output) drops as it gets progressively colder, and the building needs more heat as it gets colder, additional heat is required, usually electric supplemental heat. The temp where the heat pump can not keep up with the house loss at cold temps is called the "balance point".

Since I installed geo units, I have never had supplemental heat come on, even when it is 0 deg. Additionally the geo in the summer uses very little power since the water temp is close to the desired air temps. My yearly KWH dropped 30% with geo installed, despite another person in the house and all of the additional electric devices added over the years.

paul

Additional loss is deicing cycle. If you live in temperate climate air to air are hard to beat but in cold and humid deicing cuts the the energy efficiency.

 

[Redneck in training]

Speaking about efficiency. Customary design of small heat pumps is based on single stage compressor. If you split the compression to two stages with a side stream the heat pump would use about 60% of power. With three stage compression and two side streams it will use about 40% of power. With four stage about 30% etc.The problem is complexity and cost I suppose

 

[truckdiagnostics]

Not a very accurate statement. A modern air-air heat pump will still generate more heat in watts compared to the power draw it uses. Generally the break-even point is in the low teens. The problem in cold weather is not low efficiency, but a loss of capacity. The BTU capacity will drop the colder it gets, but the heat produced is still generated at relatively high efficiency. Since the capacity (heat output) drops as it gets progressively colder, and the building needs more heat as it gets colder, additional heat is required, usually electric supplemental heat. The temp where the heat pump can not keep up with the house loss at cold temps is called the "balance point".

Since I installed geo units, I have never had supplemental heat come on, even when it is 0 deg. Additionally the geo in the summer uses very little power since the water temp is close to the desired air temps. My yearly KWH dropped 30% with geo installed, despite another person in the house and all of the additional electric devices added over the years.

paul

He lives in GA, big difference to PA. His house is well insulated, temp is not going to get below 32 that often or for that long. If I remember correctly he has wood stove back up. IMO spending the money for a ground source heat pump in the southern states, does not make financial sense. Neither does putting mini splits in when the ducting is already in the house. Mini splits work great for say one location, you start getting multiple locations off one compressor troubleshooting is a nightmare. He already has a heat pump and it is working, newer multistage would work even better. In our area(northern states) heat pump would not work well, that is why I have geothermal. So in IMO it is just a question of what flavor heat pump he replaces his current one with.

 

[JimRB]

I live in GA. We sometimes get a week or two of days that do not get above 32F. I have a geothermal unit that keeps up, even when it gets down to 10F which is out of the Manual J spec. No booster heat. Banking on wood heat booster is fine when healthy. Not so helpful if you get sick, infirmed or injured. Or if if you sell the house.

 

[truckdiagnostics]

I live in GA. We sometimes get a week or two of days that do not get above 32F. I have a geothermal unit that keeps up, even when it gets down to 10F which is out of the Manual J spec. No booster heat. Banking on wood heat booster is fine when healthy. Not so helpful if you get sick, infirmed or injured. Or if if you sell the house.

Ok?, In my mind to have to run off supplemental back up heat for only what 3 weeks, it doesn't make sense to pay almost twice as much for ground source heat pump. Even running off wood or back up electric. I also think the changes in technology such as the mulitstage compressor negates the need down south to run ground source. Up north we are installing heat pumps and using gas furnace as back up heat. I am on propane so the numbers won't come out. However, if we were on NG I would look long and hard about going that way as, opposed to spending twice as much for ground source heat pump. The numbers will change from application to application.