Geothermal heat pump - Anyone have one?

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

I doubt that you could justify the cost of geo UNLESS (1) you need to replace your unit(s) anyways and/or (2) energy costs rise dramatically in the future.

Try the calculator I pointed out a few pages back and see what your expected payback period is, and figure how that compares to other places you have money invested (or other opportunity cost). The numbers have been pretty much spot on.

My electric bills are about the same as last summer, but I believe that's due to higher heating degree days versus 2010, and I have been running the AC in the garage a lot more this year (it's a 2 ton AC).

With that said, though, $450 is absurd ... I have a big house (not as big as yours) and run the garage AC a lot and it's still only $300 here. Maybe an energy audit would be a good idea.

Brian Marks · **Posted:** Tue Aug 09, 2011 10:04 pm

MikeWhitney wrote:

I doubt that you could justify the cost of geo UNLESS (1) you need to replace your unit(s) anyways and/or (2) energy costs rise dramatically in the future.

Try the calculator I pointed out a few pages back and see what your expected payback period is, and figure how that compares to other places you have money invested (or other opportunity cost). The numbers have been pretty much spot on.

My electric bills are about the same as last summer, but I believe that's due to higher heating degree days versus 2010, and I have been running the AC in the garage a lot more this year (it's a 2 ton AC).

With that said, though, $450 is absurd ... I have a big house (not as big as yours) and run the garage AC a lot and it's still only $300 here. Maybe an energy audit would be a good idea.

I might have to break down and do an audit....

I will try (again) the calculator but it has a lot of assumptions and I wasn't sure how much I should trust it.

I have been trying to keep the house 1-2 degrees warmer all over than last month. Obviously if we don't get higher temps during August like we did in July it won't be a direct comparison but I suspect the HVACs are a very large part of our bills. I can't imagine the two upper floor units have much longer to live...they're 10 years old now.

Lots to think about. Do you know of any good audit companies, or haven't you had one done?

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

You should be able to get a non-heat/cool baseline from your October and May statements. That's how much you use with little heat/cool use. The delta to Jul/Aug should show how big your AC use is

Here's my data ... 3300sqft home, 836sqft garage. "Above average" energy use, we do some efficiency measures (CFLs) but I work at home and we have 2 kids, so lots of lights and HVAC during the day, lots of cooking and washing, etc. And a lot of lights, welding, and HVAC in the garage.

Oct 2010 (low) = 1464 kwh, $166
(this is right after geo install)
Jan 2011 (hi heat) = 3747 kwh, $360
(so $200 for heat, which INCLUDES probably $75 in IR garage burn)
May 2011 (low) = 1526 kwh, $151
(consistent with Oct, this is our "baseline")
Jul 2011 (near-high) = 2491 kwh, $268
(about the same as Jul 2010, but Aug 2010 was much higher)

Net is that we're spending about $125 a month for heat and probably $80 for cooling. I'm roughly removing the very expensive costs to heat and cool the garage ... when it's hot out and I'm doing something intensive (banging on Chump car) I set the garage AC to 72F which burns a LOT of electricity.

If your baseline May and Oct numbers are a lot higher than $150 (which is admittedly high, we run a lot of electronics, tools, appliances, and lights), then you better start figuring out what you have plugged in that's killing your bills. If your summer HVAC shows a draw of $125+ over Oct/May numbers it's time to figure out why your system is so inefficient.

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

FYI I remember just hearing earlier today on Clark Howard that the #2 electricity sink in a modern home after AC is the DVR. We don't have one, but if that figure is correct then a big house with 2-4 DVRs could be adding $50+ to an electric bill.

Scott Lusted · **Joined:** Tue Oct 27, 2009 9:52 am **Posts:** 215

Last year I picked up one of the Kill-a-Watt meters and decided to do some testing around the house to see how the energy consumption was split out. It was very informative to get a general breakdown since you can do a weekly kwh average and then go from there.

I'll dig up my spreadsheet tonight if anyone is interested. I do remember some of the surprising things that were tacking on 10-12$ each month. Kids Fish tank and this dang plug in air fresher my wife loves.

Fridge consumption was really close to the energy star rating.

Dryer is about $0.50 per load and we do 7-10 a week (family of 6).

Upstairs dell family computer only pulled 40W which was pretty good. My workstation is another story, 300W.

In my typical quest for new projects... I found this really awesome diy home energy monitoring stuff but I'm not sure what the investment / payback would work out to. The family already does a really good job of keeping things turned of when not in use.

http://www.kondra.com/circuit/circuit.html

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

For energy audits -

We've had work done by Peak Energy. Nathan is as honest and hard working as they come. He has a construction degree from NCSU and has a real passion for energy efficiency.

http://www.peakenergync.com/

Frank

Brian Marks · **Posted:** Wed Aug 10, 2011 10:33 am

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.

Steven Carter · **Posted:** Wed Aug 10, 2011 9:39 pm

We cut 15-20% off our summer energy use when we swapped out 9 of our southwest facing 5 year old windows for Andersen replacements back in April. Not cheap, but we got a tax credit and a Progress energy rebate. Plus, our appraiser "added value" to the house for our recent refi as a result. We added higher R-value insulation to our attic when the house was built back in2005. cheaper stuff (80-82 degree thermostat setting), CFLs, window shades and tint also help. July bill $230 This summer (1500kwh) for a 3900sqft home, as a point of reference.

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

this past winter i moved my home office from the second floor to the first floor, now our top floor is totally unused (yes our house is too big) so we haven't turned on the a/c up there. this month's bill is $132, last month's was $105 and we don't have any gas, just electric. compare to last summer when i had two summer bills in the $200 range.

BretLuter · **Posted:** Wed Aug 10, 2011 10:22 pm

WTH are you guys keeping your AC set on?? Ours is usually around 77-78 at night, and 80-81 during the day.

Our bills have been sub-$200 during the recent hot weather, but we have a relatively small, newish house with 2x6" exterior walls and pretty decent insulation.

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

BretLuter wrote:

WTH are you guys keeping your AC set on?? Ours is usually around 77-78 at night, and 80-81 during the day.

Our bills have been sub-$200 during the recent hot weather, but we have a relatively small, newish house with 2x6" exterior walls and pretty decent insulation.

78F downstairs all the time (work at home), 78 up at night and 82 during the day.

Brian Marks · **Posted:** Thu Aug 11, 2011 11:15 am

BretLuter wrote:

WTH are you guys keeping your AC set on?? Ours is usually around 77-78 at night, and 80-81 during the day.

Our bills have been sub-$200 during the recent hot weather, but we have a relatively small, newish house with 2x6" exterior walls and pretty decent insulation.

For me, around 76-77 downstairs (work at home, and it gets hot down here), 77 or so upstairs, and 77 in basement. Kid and nanny are all over the house and my daughter is always warm, so I don't want her being too uncomfortable. Wife works upstairs and her office gets hot, partially due to sun and partially due to reflected heat from our pool solar heater panels which are just outside her window.

All the house windows are tinted and I've gone through and made sure they are all sealing as well as possible. I also added R-38 insulation recently and sealed up all possible attic penetrations including the fold-down stairs.

Total sf is about 4400 or so, plus 3 large size dehumidifiers running and of course a pool pump. Our pool pump is a variable speed so it doesn't really use that much overall, certainly not enough to justify the entire difference between summer and winter. I have a mini-split in my shop/garage but we don't use it THAT much either. It's an 18K BTU model that does heat and a/c but again, we hardly use it.

My house is 10 years old and was built with 2x4 walls for top 2 floors, 2x6 for basement, and is insulated even in interior walls throughout. All high usage areas have CFL bulbs or fluorescent. I use timers for outside lights and only leave themo n for security and only use CFL out there also. We turn off lights when not in use. It's got to be my crappy old HVAC causing this!

Steven Carter · **Posted:** Thu Aug 11, 2011 11:44 am

Well, you do have legitimate needs for using a lot of power...I bet the dehumdifiers and pool pump use more than you suspect.

Our neighbors, with a nearly identical house, keep their thermostat at 73, and they routinely pay >$400 per month in the summer. They complain about it, but ultimately would rather be cool than save the money. Maybe it's just about priorities, I guess-- How much do you want to spend/cutback in order to save a couple hundred dollars a year in power use?

Seems you've done all the stuff you can. An energy audit I suspect would be quite revealing--please share your findings!

Vincent Keene · **Posted:** Thu Aug 11, 2011 11:52 am

Steven Carter wrote:

Well, you do have legitimate needs for using a lot of power...I bet the dehumdifiers and pool pump use more than you suspect.

I need to put one of those 'kill-a-watt' meters on our pool pump. My wife swears it doesn't have significant impact on the electric bill, but I disagree.

FYI, our pump is variable speed too, but we simply have a timer that shuts the entire pump off at night.

Brian Marks · **Posted:** Thu Aug 11, 2011 11:57 am

Vincent Keene wrote:

Steven Carter wrote:

Well, you do have legitimate needs for using a lot of power...I bet the dehumdifiers and pool pump use more than you suspect.

I need to put one of those 'kill-a-watt' meters on our pool pump. My wife swears it doesn't have significant impact on the electric bill, but I disagree.

FYI, our pump is variable speed too, but we simply have a timer that shuts the entire pump off at night.

Which pump? Ours is a Pentair IntelliFlo and I have it set to spend 6 of 8 filtering hours per day on around 1900rpm which uses under 500W. For the last 2 hours I have it on high speed and it probably uses 1800-2000W. The curious thing with mine is that I have software to interface with it, and the power usage is not linear with RPM - i.e. you can reduce the pump speed by only 500rpm (max pump speed is 3450 as you know) and it will reduce the wattage by 25% or more.

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Geothermal heat pump - Anyone have one?

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