Steve Bailey
New Member
Posts:1
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| 19 Jan 2009 10:15 AM |
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In Oct. 2008 I moved into a new, 2,400-square-foot house on the Eastern Shore of Maryland. We have a three-zone geothermal heat pump system with two 2,000-BTU Climatemaster Tranquility units and one 5,000-BTU. We have Carrier air handlers. All three have electric-heat auxilliary units, though we had the installer disconnect the auxilliary heat function from the large zone because it kept coming on. The house has nine pairs of 8'-tall Andersen sliding glass windows, most of which are uncovered, along with 10 small skylights and a number of Andersen casement windows, also uncovered. Water heating is propane.
We keep one of the smaller zones at 62 degrees (unused guestrooms), the large zone, which is the kitchen/livingroom/dining room, at 72 degrees (thermostat setting; room is actually cooler) and the second small zone, the master suite, at 69. We just got an electric bill showing that we used 3,243 kWh in the last month. That cost us $462. We had hoped for bills around half that amount.
Does anyone else have a similar-size house and geothermal system? What is your electric usage? If anyone has any comments on our situation, I'd appreciate them. We're sort of at sea, with our only source of information being the installer. |
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genebduremdes
New Member
Posts:4
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| 19 Jan 2009 10:23 AM |
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steve,
we just moved into our new home too and once we get settled and completely moved in, we will get some numbers for you. sorry I don't have an opinion but I will have our personal experience soon.
gene |
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conniepangan
Basic Member
Posts:112
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| 19 Jan 2009 11:02 AM |
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Ours was in full operation since November, I think I already had updated the forum. Again, from Nov. to December was about $277 (includes other electric appliances) then Dec. to January was $258. We minus our current electric bill from our last year average usage. It came out to be $150 per month. I am anticipating this coming month will be really big bill because of the extreme cold weather. We have 2 zone. Upstairs auxilliary never comes on but downstairs with a lot of windows and bigger area, the aux. heat always comes on.
We have less than 2000 SF.
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engineer
Veteran Member
Posts:2749
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| 19 Jan 2009 11:11 AM |
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"We have a three-zone geothermal heat pump system with two 2,000-BTU Climatemaster Tranquility units and one 5,000-BTU"
The above makes no sense. Need a whole lot more info to try to help you:
Total tonnage installed
Was a room by room heat load calculation (ACCA Manual J) done as part of design?
Open or closed loop?
Entering and leaving loop temperatures
The glass loads you mention are pretty high for 2400 SF |
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Curt Kinder <br><br>
The truth is incontrovertible. Malice may attack it, ignorance may deride it, but in the end, there it is - Winston Churchill <br><br><a href="http://www.greenersolutionsair.com">www.greenersolutionsair.com</a>
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jongig
New Member
Posts:45
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| 19 Jan 2009 09:20 PM |
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I have a new 2,400 sq-ft house with skylights and quite a few windows and 2,400 sq-ft in the basement which has it's own zone and is heated. I wasn't sure what to think about our electric bills and so I put the GTHP on its own electric meter. The meter reports to an excel sheet every 6 hours. We use about 60 KWH per day when the temperature is under 30 and we set the house at 68. We have a 4-ton Climatemaster with two 300 ft closed vertical ground loops. I think our bills are high but we all pay differing amounts for electric. Our cost is about 10 cents per KWH. |
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Eric D
Basic Member
Posts:104
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| 19 Jan 2009 09:51 PM |
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Steve,
Does your electric company allow a time of day meter? Do you have one? You are paying about 14.2 cents per kWh, that's pretty high.
As Engineer pointed out, we need tonage of the system.
If your propane water heater uses inside air for combustion, you need to get rid of it. This is a huge loss of heated air from inside of your house that is replaced with cold outside air that taxes the geo system big time. Did your installer suggest going electric water heater?
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| Eric D<br>Southern Michigan |
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GRickard
New Member
Posts:45
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| 20 Jan 2009 07:31 AM |
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Steve,
I moved into my new western Kentucky house in June. It is 2400 sq. ft. with a full basement. I had three ducts installed in the basement, everything else is on the main floor. I installed a 3 ton Water Furnace Envision unit with a 2 speed compressor and a variable speed fan, all one zone. The house is ICF with R-50 cellulose in the cieling and nowhere near the amount of glass you have, but my windows are all Low-E glass. House is all electric, no gas.
Now with all that said, my highest electric usage so far has been around 1470kw in one month(about $110). The only time I ever see the unot go to stage two is when I bump the stat up too much, and I've never seen the aux heat come on.
Greg |
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geothermal4592
New Member
Posts:4
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| 20 Jan 2009 07:04 PM |
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We have a 2000 SF ranch home. Our cellar (walkout) is Arxx blocks 9 foot tall and we have 9 foot tall ceilings throughout our house. We are total electric with a 80 gallon electric hot water tank. We heat the cellar to 60 degrees (4 ducts in to the cellar but only 2 are open). We have a 5 ton Water furnace with 2500 feet of 3/4 inch loop in the ground. Our Geo system nevers goes into emergency heating unless I make it. We keep our main floor at 70 degrees 24/7. We have 2 boys at home that add much to our electric bill. We live in Ny near Rochester. So far our November bill was $320 and our Dec. bill was $325. Waiting to see what Jan bill brings as we had a cold wave come thru where it was below 0 at night. I just went to a off peak meter and am going to put a timer on the hot water tank which I think is sucking lots of juice. We pay about 9.25 cents per KW and use between 2700-3000 KW per month. I really did not know if this was good or not but after talking to many people without Geothermal heat my bills are cheap.... |
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arkieoscar
New Member
Posts:57
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| 20 Jan 2009 10:06 PM |
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Northern Arkansas 1800 SF ranch, cellulose, good windows, pretty tight w/ 1000 SF garage, all heated (and cooled) with one home built 2 1/2 ton GSHP -4 400 ft. horizontal loops and one 1.2 ton Trane console with 2 400 horizontal loops. The main unit has been in operation since 1995 and the console since 2000. My last month's bill was $112 but my water temps are lower (38f) than they have ever been this time of year. Normally, they don't fall this low until the end of Feb.
I may have to hook up the heat strips by the end of the heating season. |
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engineer
Veteran Member
Posts:2749
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| 21 Jan 2009 12:35 AM |
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Timers on modern well-insulated storage electric water heaters are a false economy.
Data: My 80 gallon water heater in a 70 degree basement mechanical room is set for 115 deg F. We left house for 3.5 days over holidays and I shut power off to water heater. I measured hot water temp immediately upon return before restarting heater. - 98 degrees. It lost 1 degree every 4 hours.
Based on that, shutting off power to a water heater for 8 hours overnight saves basically nothing.
This is the false premise upon which massive marketing campaigns for expensive instantaneous electric water heaters are based - so much BS! |
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Curt Kinder <br><br>
The truth is incontrovertible. Malice may attack it, ignorance may deride it, but in the end, there it is - Winston Churchill <br><br><a href="http://www.greenersolutionsair.com">www.greenersolutionsair.com</a>
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Dan CGD
New Member
Posts:37
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| 21 Jan 2009 01:07 AM |
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Steve,
Maybe provide a little more info on your loop field. If loop fields get cold, eff drops off some and may increase your bills. Also the model numbers of the heat pumps would be helpful.
D |
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geothermal4592
New Member
Posts:4
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| 21 Jan 2009 08:16 AM |
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Engineer, Thanks for the data. You stated exactly what many people have told me about electric hot water tanks holding temps for days. I problably should of been more specific in my above note. I have switched to a off peak meter and am only going to heat my hot water tank at night when electricity is about 2 cents per KW cheaper. I was hoping to knock some money off my bill by doing this. Do you think it will or am I still wasting money and time? |
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engineer
Veteran Member
Posts:2749
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| 21 Jan 2009 08:30 AM |
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Oh no - completely different question!
Yes, absolutely heat your water at night with that cheaper power.
The only bummer may be that if you run out of hot water you are stuck until the next time the off peak meter comes back on. Be sure your tank is sized to carry you through the off cycle, and insulate both hot and cold water lines near tank. 80 gallons should do it with reasonable care - a dope slap or two to boys who take long showers at the wrong time.
Resist the temptation to stretch hot water supply by raising tank temperature - it'll eat up savings via increased standby losses, poses scald hazard, and shortens element and tank life.
As for savings, the average family pays about $500 / year to heat water via electric resistance. That's an average with huge variation, though - much depends upon number of occupants and their behavior. A 2 cent per kwh savings might save you $100 / year.
If the off peak meter powers only your hot water, you'll be a good source of real hot water cost data. Let us know. |
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Curt Kinder <br><br>
The truth is incontrovertible. Malice may attack it, ignorance may deride it, but in the end, there it is - Winston Churchill <br><br><a href="http://www.greenersolutionsair.com">www.greenersolutionsair.com</a>
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John Clem
New Member
Posts:38
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| 21 Jan 2009 08:22 PM |
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Steve, not sure how much this will help, but here is some data on another house. We have a 3400 sq ft ICF house, 1800 on main floor and 1600 for walkout basement, all of which is conditioned. Seven inches of foam insulation in the vaulted ceilings. We have seven exterior doors and commercial windows with aluminum frames, the largest of which is a 30’ x 8’ window wall. No curtains. We are near Kansas City and the house is all electric.
We have a 4-ton dual speed geothermal heat pump with 450 ft of ground loop. We also have the desuperheater option for heating domestic hot water. Only one zone for the house. Our backup heat has never turned on.
The December bill was for 2320 kwh.
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Home Design<br>
ICF Distributor<br>
http://www.clemdesign.com<br>
http://blog.clemdesign.com/ |
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Brock
Advanced Member
Posts:599
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| 21 Jan 2009 10:33 PM |
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Our house is almost identical in size with spray foam insulation with an indoor pool in the basement. We are in Green Bay, WI. Our electrical consumption in December was 3200 kwh ($.06/kwh) along with 9 therms of natural gas. |
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| Green Bay, WI. - 4 ton horizontal goethermal, 16k gallon indoor pool, 3kw solar PV setup, 2 ton air to air HP, 3400 sq ft |
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Geotech
New Member
Posts:4
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| 22 Jan 2009 05:27 PM |
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Steve, one of the best things you can do is get at least 2 Geothermal CGC acreditited pro's in and take an amperage reading on the hot wire that goes to the copeland scroll compressors. Have them take readings when its at full capacity, second stage. Then, go to this website www.nextenergy.ca and find out the amperage draw its supposted to perform at. If it's out of spec, have your designer replace the pump/s. The design may need the electric backup heat for small amounts of your heating load. When the installer designed the system, they would have done a heatloss/gain on the building, as a requirement for CSA 440, Otherwise, there was no existing system inside the house to take a BTU heat output from to get a BTU heat input for the Geo pump. Rules and Regs are going to tighten up because of cases like these. If I can help, let me know. Timmer |
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