Geothermal heat pump - Anyone have one?

Frank Catena · **Joined:** Wed Aug 27, 2003 1:08 pm **Posts:** 418

Brian Marks wrote:

Thanks, guys. I'm interested to see how August works out after my thermostat changes. My HVAC are SEER10, pretty old tech, but after $1k worth of attic insulation and penetration sealing, I would think even with those we'd be "okay" enough to avoid $450 for a power bill.

WFH doesn't help (2 of us) plus having the kid and nanny here all day using lights and power, but $450 is just nutso.

I would think those SEER10 pumps are costing you over $100/mo at $450/mo usage compared to the new minimum SEER13.

Frank

Brian Marks · **Posted:** Thu Aug 11, 2011 12:34 pm

Frank Catena wrote:

Brian Marks wrote:

Thanks, guys. I'm interested to see how August works out after my thermostat changes. My HVAC are SEER10, pretty old tech, but after $1k worth of attic insulation and penetration sealing, I would think even with those we'd be "okay" enough to avoid $450 for a power bill.

WFH doesn't help (2 of us) plus having the kid and nanny here all day using lights and power, but $450 is just nutso.

I would think those SEER10 pumps are costing you over $100/mo at $450/mo usage compared to the new minimum SEER13.

Frank

Could very well be. I know they are terribly inefficient. That's why I was curious about geothermal - or if not, a much more efficient system. People say to wait until the old ones fail, but if it's costing me several hundred a year, I wonder if it makes sense to replace earlier and take a tax credit (if they are even still available).

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

How much are your October and May electric bills?

Steven Carter · **Posted:** Thu Aug 11, 2011 12:56 pm

Brian Marks wrote:

Could very well be. I know they are terribly inefficient. That's why I was curious about geothermal - or if not, a much more efficient system. People say to wait until the old ones fail, but if it's costing me several hundred a year, I wonder if it makes sense to replace earlier and take a tax credit (if they are even still available).

Progress Energy still has rebates available for upgrades, don't know about tax incentives. Although the tax credit had expired for our windows, Andersen still had them "on sale" by transferring the tax credit into a price reduction. Maybe the same exists for HVAC ? :whoknows:

https://www.progress-energy.com/carolinas/home/save-energy-money/energy-efficiency-improvements/heip/index.page

Brian Marks · **Posted:** Thu Aug 11, 2011 1:58 pm

MikeWhitney wrote:

How much are your October and May electric bills?

** NOTE: I have severe spring allergies and we have to keep windows closed in spring or I can't breathe, so we often use A/C at times to keep it from getting stuffy

Here are the ones you asked about plus my lowest usage months:

Nov 2010 - 28 days, 1408 kWh ($146.22)
Nov 2009 - 28 days, 1074 kWh ($113.90)
Oct 2010 - 29 days, 1517 kWh ($172.58)
Oct 2009 - 31 days, 1133 kWh ($131.42)

April 2011 - 29 days, 1802 kWh ($177.44)
April 2010 - 32 days, 1574 kWh ($162.61)
May 2011 - 29 days, 2502 kWh ($243.43)
May 2010 - 28 days, 1531 kWh ($158.33)

Steven Carter · **Posted:** Thu Aug 11, 2011 8:09 pm

That's interesting. Typically, May and Oct are lowest HVAC months, and your lowest rates are near my summer peaks, given similar size homes. you may run AC earlier than me given the allergy situation, but it begs the question that HVAC may not be the primary issue...On a related note, do you think the cost of allergy shots would offset the increased springtimeAC use? I don't mean to pry, but I suspect allergy shots may mitigate some of your power bill, if that is the case. Of course, if you 've been through allergy shots already then disregard....

JamesMilko · **Posted:** Thu Aug 11, 2011 8:46 pm

What style houses do you guys all have?

We have a ~1650sqft split level house with a lot of sealing issues around doors/windows. My bills are 1/2 to 1/3 most of the ones in this thread think a lot of that has to do with the fact that my lower level doesn't need the HVAC vents open at all in the summer time. No dehumidifiers/pools/kids but we do leave the computers on all the time. AC unit is the original with the house, ~15 year old 10 SEER unit I believe. Gas bill is <$20 a month in the summer which covers the hot water heater and clothes dryer.

AC is 82 daytime, 78 morning/evening and 76 night. I'm also in the same boat as Brian, my windows stay shut during pollen season. Could it really all come down to my bottom level being right on the slab and staying somewhat cold reducing my energy costs so much?

Brian Marks · **Posted:** Thu Aug 11, 2011 8:52 pm

Steven Carter wrote:

That's interesting. Typically, May and Oct are lowest HVAC months, and your lowest rates are near my summer peaks, given similar size homes. you may run AC earlier than me given the allergy situation, but it begs the question that HVAC may not be the primary issue...On a related note, do you think the cost of allergy shots would offset the increased springtimeAC use? I don't mean to pry, but I suspect allergy shots may mitigate some of your power bill, if that is the case. Of course, if you 've been through allergy shots already then disregard....

Steven, you bet. We are on the IBM "high deductible" plan this year and everything is waaaay too expensive. I priced out allergy shots and they would have been over $1000 so I figure I'll wait until fall and price out all the "medical stuff" I want to do and see if it makes sense to switch back to the lower deductible plan and set some pre-tax money aside instead. There's other stuff we need to do so I will do all the math and see.

Keep in mind my electricity numbers above are somewhat flawed because I didn't consider until it was too late that my basement system (installed under 2 years ago) is a heat pump and I probably had the heat set too high for the system's efficiency. I use a much lower setting now.

Brian Marks · **Posted:** Thu Aug 11, 2011 8:54 pm

JamesMilko wrote:

What style houses do you guys all have?

We have a ~1650sqft split level house with a lot of sealing issues around doors/windows. My bills are 1/2 to 1/3 most of the ones in this thread think a lot of that has to do with the fact that my lower level doesn't need the HVAC vents open at all in the summer time. No dehumidifiers/pools/kids but we do leave the computers on all the time. AC unit is the original with the house, ~15 year old 10 SEER unit I believe. Gas bill is <$20 a month in the summer which covers the hot water heater and clothes dryer.

AC is 82 daytime, 78 morning/evening and 76 night. I'm also in the same boat as Brian, my windows stay shut during pollen season. Could it really all come down to my bottom level being right on the slab and staying somewhat cold reducing my energy costs so much?

James, my house is 3 levels (includes partially finished basement). About 4400sf total plus the dehumidifiers in unfinished areas (those areas total about 1000sf of unfinished basement) and the pool stuff. I did more calcs today on the pool equipment and I'm at about $25/mo of usage with that, so it's not making the huge difference. My DVRs are about $2.50/mo each based on data I found on them, so they aren't responsible either (of course, they're turned on year round so they can't be).

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

JamesMilko wrote:

Could it really all come down to my bottom level being right on the slab and staying somewhat cold reducing my energy costs so much?

No, look at the spring/fall figures. Brian and I are using 1400 kwh per month with no HVAC versus your 400 kwh.

Has a lot more to do with kids (leaving shit on all the time), lots of laundry, lots of cooking and microwave use, and people being at home all day than heating and cooling. For the difference between you and "us" that is.

With that said, I do still think Brian has something strange going on...

Brian Marks · **Posted:** Fri Aug 12, 2011 9:15 am

MikeWhitney wrote:

JamesMilko wrote:

Could it really all come down to my bottom level being right on the slab and staying somewhat cold reducing my energy costs so much?

No, look at the spring/fall figures. Brian and I are using 1400 kwh per month with no HVAC versus your 400 kwh.

Has a lot more to do with kids (leaving shit on all the time), lots of laundry, lots of cooking and microwave use, and people being at home all day than heating and cooling. For the difference between you and "us" that is.

With that said, I do still think Brian has something strange going on...

I bought a Kill A Watt meter and also a clamp-meter to do some checking into power usage of my various devices and will report back. Just like Mike, we also have 2 fridges but at least one of them is VERY efficient and almost never turns on.

We do a lot of laundry and dishwasher runs all the time - kids seem to use up more dishes and clothes per capita than adults and I'm not sure how that happens!

Scott Johnson · **Posted:** Fri Aug 12, 2011 11:20 am

I don't suppose you leave the HVAC fans blowing all of the time (Fan = "on" vs "auto")? My peak winter electric is about 2/3 of the summer, and almost double spring/fall. That gives an idea of what a single blower can do to a bill.

Look for an HVAC vent open in an attic space - one that is air conditioning the attic space. Stranger things have happened. What about the duty cycle on your HVAC units. Even on the hottest days mine were turning off for short periods. If the refrigerant is low on one/multiple units that will increase the usage dramatically.

On a related note, I just discovered a standing pilot light costs $50-60/year (PSNC prices). I never really thought about it before, but that is a crap load of waste.

Brian Marks · **Posted:** Fri Aug 12, 2011 11:26 am

scottjohnson wrote:

I don't suppose you leave the HVAC fans blowing all of the time (Fan = "on" vs "auto")? My peak winter electric is about 2/3 of the summer, and almost double spring/fall. That gives an idea of what a single blower can do to a bill.

Look for an HVAC vent open in an attic space - one that is air conditioning the attic space. Stranger things have happened. What about the duty cycle on your HVAC units. Even on the hottest days mine were turning off for short periods. If the refrigerant is low on one/multiple units that will increase the usage dramatically.

On a related note, I just discovered a standing pilot light costs $50-60/year (PSNC prices). I never really thought about it before, but that is a crap load of waste.

Yes, due to uneven cooling (for example with office doors closed when I don't want my daughter to bust in and bother me while working) I do sometimes leave the fan turned to on, but had "heard" that it didn't really use that much energy. I wonder what the real usage is, now....

Attic was recently insulated so I should check for an open vent. Anyone have an IR camera I can borrow?

Yup, the pilot lights can cost a few bucks a month up to about $5-8/mo depending on how much gas flow you have. I shut my fireplace off when not in use and fire pit usually stays on but it often blows out on it's own due to rain, wind, etc, so in reality it's not on all that much either.

Jason Tower · **Joined:** Wed Jun 11, 2008 3:31 pm **Posts:** 1173

do you know joachim (or his wife andrea) vinson? they've done thscc track events before. he's in wake forest and has a little business doing airflow audits or something for houses. might be a useful resource for you. ping me if you want his contact info.

Brian Marks · **Posted:** Tue Oct 30, 2012 10:53 am

Still not sure if I should investigate this versus adding another 4kW solar array to my roof. Going forward, with gas as cheap as it is (LNG, not propane) and with higher efficiency HVAC units I might come out ahead by adding more solar and just replacing HVAC with more efficient units when they die, using gas furnace for heat.

On the flip side, newer HVAC systems seem to have an even lower lifespan than the older ones from what people are telling me, so I'm not certain which way to go. There is also added difficulty because I could only drill in my front yard and I'm not sure if the added cost of putting lines under my driveway makes sense or not.

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