Geothermal vs High Efficiency Heat Pumps

[fromchaptico]

Hi everyone,

I have posted here before about the possibility of installing a geothermal system, and a bunch of you were kind enough to respond with information about your own experiences. My oil furnace has finally met its maker, so the to-geothermal-or-not-to-geothermal moment is finally at hand. I have had a few contractors out to the house (@3500 square feet, built in the 1920s.) I have duct work for the existing central air. It looks like I am going to need two 3 ton units. I was pretty committed in my mind to going with a geothermal system, but all of the contractors have said that the new 20 SEER variable speed air/air heat pumps offer comparable performance and energy efficiency, and of course, the air/air units would not require the mess or expense of drilling wells for the ground source system.

So, I am wondering whether any of you have experience in this area (climate!) with these 20 SEER systems, especially in a larger or older home. I don't have quotes yet, but this is going to be an expensive project no matter which choice I make. I am really worried about choosing something that either doesn't heat the house well or that results in $800 electric bills in the winter. Since I have been heating with oil, I just don't know what to expect. (A new oil system is an option also.)

Any feedback would be appreciated.

Thank you!

 

[itsbob]

2 ton Carrier GreenSpeed upstairs, 20.5 SEER 13 heat rating.. out of pocket 7k.. almost 3k in rebates from SMECO and Carrier...

Should be good for the 1500 sq ft 2nd floor plus an additonal 500 sq feet we are running duct work to for the room over the garage (detached).

Going to go back in a few months and add the 4 ton unit for the downstairs and finished basement with the inline gas furnace. No more electric heating elements for emergency heat.

We havent had an upstairs unit in probably 3 years and weve had this running for about a month (a little more than) with no additinal electrical costs that we've seen.

Looking forward to seeing howuch we save this winter woth both units providing heat.

 

[sm8]

https://m.facebook.com/profile.php?id=380189132099179&tsid=0.5127133247946052&source=typeahead

301-542-6498 you should call and set up a free consultation, solar sales and leasing options which include a solar compatible heat pump are available.

 

[MADPEBS1]

TWO 3 Ton units seems like overkill to me. New systems are very efficient, you'd be amazed at the heat that comes out of vents in winter...

How well is house insulated? I'd recommend getting a blower door test done, fix all those issues and then get a couple quotes on sizing the units.

 

[awpitt]

When using heat pumps, insulation is very important. How well insulated is your house?

 

[GopherM]

When using heat pumps, insulation is very important. How well insulated is your house?

Not just insulation but the house needs to be sealed very well (where pipes, wires, and other utilities enter and exit walls). I would think a heat pump would not meet the requirements for a home built in the '20s once the temp drops below about 38 degrees and the heater bars kick in. I had a well sealed and insulated house and still had a dual system (heat pump and gas furnace) that crossed over to the furnace at around 36 degrees.

 

[awpitt]

Not just insulation but the house needs to be sealed very well (where pipes, wires, and other utilities enter and exit walls). I would think a heat pump would not meet the requirements for a home built in the '20s once the temp drops below about 38 degrees and the heater bars kick in. I had a well sealed and insulated house and still had a dual system (heat pump and gas furnace) that crossed over to the furnace at around 36 degrees.

Exactly... The dual system is the way to go so the "emergency" heat isn't electric.

 

[officeguy]

I was advised by two (out of state) HVAC contractors to stay away from the 20 seer systems with either inverter controlled variable speed compressors or the Trane two compressor setup. Iif they break, they are more difficult to troubleshoot than the two-speed compressors commonly found in the 18SEER range.

With an older house I would be careful with a heat pump conversion. Your heat output is not as hot as that from a gas furnace, your duct-work needs to be sufficient to move enough air to make all rooms comfortable.

If you have oil (I assume baseboard) now, I would consider replacing the boiler with a high efficiency design and call it a day.

 

[NIU_Huskies]

I can't comment on the Geothermal units, but if you go heat pump I would suggest replacing your oil furnace with a new one. This way your backup heat is oil. I wouldn't want my backup heating element to be another electric source. I had my heat pump system replaced last year, but its only a 13 SEER unit since it was covered by the home warranty after the 35-year old GE unit had issues and the coil unit drain pan started leaking all over my utility room floor because it rusted out. I have the heat pump and oil backup combo and my electric bill is in the $90s in summer now and was around $120-130s in winter (plus cost of oil).

 

[officeguy]

Exactly... The dual system is the way to go so the "emergency" heat isn't electric.

You still need electric for the draft blower and the AC fan to run, but you don't need quite the silly amperage resistive backup heat demands.

 

[steppinthrax]

Have you done any analysis on the "cost benefit" and "return on investment" with a geothermal system. I understand the high efficient, however I do a lot of research in A/C Engineering and threads are showing Geothermal to go out soon in favor of newer high efficiency ASHP (Air Source heat pumps). There are newer emerging A/C technologies that are going to be more efficient than ASHP and Geothermal (i.e. Magnetic refrigeration).

When you do this analysis, you need to consider how much you tend to actually save v.s. the psychology of using the newer system more since you "have a feeling" it's more energy efficient. Also the repair cost, I understand they will likely give you a lifetime warranty on everything under the sun, but read the fine print. The items that high a high warranty probably almost never fail.

 

[alicejohn]

If I recall, I paid about $8K more to put in a geothermal system when I build our house new in 1998. In hindsight, I am not sure I would do it again. Since I don't know how much it costs to heat and cool the house with a conventional heating system, I don't know if I have gotten my $8k back from reduced energy bills.

The main advantage is a back-up heat source is really not needed. I have electric heat backup and I keep the circuit breakers pulled to prevent it from turning on. Since the well water temperature is not affected by the outside air temperature, I get the same temperature split out of my ducts regardless of weather. The house is always comfortable.

 

[fromchaptico]

TWO 3 Ton units seems like overkill to me. New systems are very efficient, you'd be amazed at the heat that comes out of vents in winter...

How well is house insulated? I'd recommend getting a blower door test done, fix all those issues and then get a couple quotes on sizing the units.

My existing central air system, about 16 years old, is one 3 ton unit and one 2.5 ton unit. The contractor who specified two 3 ton units did run manual j calculations, so I hope it is accurate - but I too thought that 6 tons was a lot.

The house has been insulated, but it is old and I'm sure it has leaks. My current energy costs aren't horrible, so maybe this means the insulation isn't too awful? You're right though - a blower door test would make sense before I spend all the money on a new system. Thank you!!

 

[fromchaptico]

You still need electric for the draft blower and the AC fan to run, but you don't need quite the silly amperage resistive backup heat demands.

You make a great point! Changing over to either air/air or geo with electric resistance backup is apparently going to require some extensive electrical work to get the amperage we need - an upgraded panel, etc. I'm not sure how much of the very large bid I received was the electrical piece, but good grief!!

 

[fromchaptico]

If I recall, I paid about $8K more to put in a geothermal system when I build our house new in 1998. In hindsight, I am not sure I would do it again. Since I don't know how much it costs to heat and cool the house with a conventional heating system, I don't know if I have gotten my $8k back from reduced energy bills.

The main advantage is a back-up heat source is really not needed. I have electric heat backup and I keep the circuit breakers pulled to prevent it from turning on. Since the well water temperature is not affected by the outside air temperature, I get the same temperature split out of my ducts regardless of weather. The house is always comfortable.

It looks like the back-up heat source is going to cost me some real money since it will require upgraded electrical service, etc. I would love not to need it, which is one of the reasons I was considering geothermal - but everyone is specifying it, so I guess if I go with one of these systems I will have it whether I ever use it or not.

Did you need the back up over the last two winters, when the temperatures spent a few days/nights below 10 degrees?

 

[fromchaptico]

Have you done any analysis on the "cost benefit" and "return on investment" with a geothermal system. I understand the high efficient, however I do a lot of research in A/C Engineering and threads are showing Geothermal to go out soon in favor of newer high efficiency ASHP (Air Source heat pumps). There are newer emerging A/C technologies that are going to be more efficient than ASHP and Geothermal (i.e. Magnetic refrigeration).

When you do this analysis, you need to consider how much you tend to actually save v.s. the psychology of using the newer system more since you "have a feeling" it's more energy efficient. Also the repair cost, I understand they will likely give you a lifetime warranty on everything under the sun, but read the fine print. The items that high a high warranty probably almost never fail.

Are the new ASHP you mention the 20 SEER systems, or something even more efficient? Unfortunately, since the house has no heat at this point, I won't be able to wait for something that isn't available now.

I haven't done any analysis on the cost benefit and return on investment yet because I have been waiting for actual numbers from the contractors. The geo systems are much more expensive until you take out the 30% federal tax credit that is available on systems installed through the end of 2016. After that, they are slightly, but not hugely, more expensive. Keeping what I have is not an option since it is broken beyond repair (40 year old oil boiler) so I do need to put in something within the next few months - just weighing all the options!

 

[PeoplesElbow]

fromchaptico

8 years ago I needed a new furnace, my 35 year old oil burner's combustion chamber was cracked. I got a new oil furnace/heat pump hybrid system. The heat pump is only a 13 SEER but barely raises the electric bill compared to months that I don't need any heat/AC like October and April. The oil part kicks on when it is under 40 degrees outside, I spend less than 1/3 on oil of what I did with the old oil burner.

I believe strongly in the oil or gas/heatpump hybrid systems as they give you the heat when you really need it but are fairly cheap to operate in 40-50 degree weather. My entire system cost me $6k.

I could see plunking down the extra for geothermal farther north, but around here I don't think it is necessary.

 

[fromchaptico]

Dual system

Thanks so much for your replies, everyone!!

To those of you recommending a dual system - let me see if I understand what you mean. Basically, I would have either an air/air or geothermal system WITHOUT electric resistance backup - and then have a new (maybe smaller??) oil boiler to act as backup heat for when the temps dropped too low. Is that what you are suggesting? I can see how that might be a great idea. To clarify, gas is not available where I am - my house is in farm country. It has steam radiators, and they do give out a great heat, so I have been kind of resistant to giving up the oil.

The other thing I have learned over the last week is that in order to have electric resistance back up (and electric hot water -currently I have oil hot water,) I am going to need to change one of my electrical panels (for the hvac, I need a total of five two pole breakers for 2 hvac units, back up heat, and hot water. Did I say that correctly? I have no idea what I'm talking about!) I assume that this is going to cost me several thousand dollars - it wasn't called out separately in any of my bids.

Soo...maybe if I didn't have electric back up and kept a boiler for back up and hot water, I could both have a backup system that actually heats the house when necessary and avoid the panel upgrades?

 

[fromchaptico]

fromchaptico

8 years ago I needed a new furnace, my 35 year old oil burner's combustion chamber was cracked. I got a new oil furnace/heat pump hybrid system. The heat pump is only a 13 SEER but barely raises the electric bill compared to months that I don't need any heat/AC like October and April. The oil part kicks on when it is under 40 degrees outside, I spend less than 1/3 on oil of what I did with the old oil burner.

I believe strongly in the oil or gas/heatpump hybrid systems as they give you the heat when you really need it but are fairly cheap to operate in 40-50 degree weather. My entire system cost me $6k.

I could see plunking down the extra for geothermal farther north, but around here I don't think it is necessary.

Some of my bids are coming in with an extra zero attached to your numbers!! Yikes!!! I am actually more interested in the geothermal for its cooling and dehumidifying capabilities than for its heating power - though of course in this area we need both!

 

[fromchaptico]

fromchaptico

8 years ago I needed a new furnace, my 35 year old oil burner's combustion chamber was cracked. I got a new oil furnace/heat pump hybrid system. The heat pump is only a 13 SEER but barely raises the electric bill compared to months that I don't need any heat/AC like October and April. The oil part kicks on when it is under 40 degrees outside, I spend less than 1/3 on oil of what I did with the old oil burner.

I believe strongly in the oil or gas/heatpump hybrid systems as they give you the heat when you really need it but are fairly cheap to operate in 40-50 degree weather. My entire system cost me $6k.

I could see plunking down the extra for geothermal farther north, but around here I don't think it is necessary.

I forgot to ask in my last post - is your hot water oil or electric?