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| Heat pump for hot water | Rate Topic |
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| Posted: Sun Feb 7th, 2010 09:02 pm |
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1st Post |
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catman Member
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I'm considering buying the new Ge Hybrid heat pump electric storage tank combo for heating my domestic hot water. My question is, I live in New England so for about 5 to 6 months out of the year my basement will have an ambient room temp. of about 55 to 60 degrees. I know they say they will work as low as 45 degrees but how efficient would it really be? Are heat pumps only efficient in warmer climates? Should I just buy an electric water heater and get an add on heat pump? I'm currently burning pellets for my main source of heat which heats my whole house but I still have to use my furnace for my hot water and its useing about 350 gallons of oil just for the hot water, at 2.50 a gallon thats pretty pricey. Any info on the heat pumps would be greatly appreciated.
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| Posted: Mon Feb 8th, 2010 05:49 am |
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2nd Post |
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eleent Member 
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Hello: It seems you have three choices; use a heat pump or electric heater or install an oil fired heater. Rheem's new heat pump is something I'd be silly to comment on until it has developed a track record. I'm hoping for the best! It might make sense to look into what is possible to make the distribution system and fixtures as efficient as possible as then there will be less to heat. The savings can be substantial. Randy has been nice enough to start a page of Larry's Lunacy, or something similar which has suggestions on making the entire system perform better  Yours, Larry
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| Posted: Mon Feb 8th, 2010 06:31 am |
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3rd Post |
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elenano Member
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It's actually called Water Heating According to Larry and is in the Basics/Longevity section. You'd better behave, Larry or I WILL CHANGE IT to Larry's Lunacy! Randy Schuyler
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| Posted: Mon Feb 8th, 2010 11:44 pm |
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4th Post |
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energyexpert Member
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Any heat pump manufacturer should be able to provide a performance curve for efficiency vs. temperature. The higher the temperature the more efficient it is. Trane sent me some info once. One of their residential heat pumps had a COP of 3.5 at 47F and and a COP of 1.84 at 7F. COP is coefficient of performance; output is compared to straight resistance heat. At 47F the heat pump will deliver 3.5 times as much heat as resistance heat for the same input kWh. David
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| Posted: Tue Feb 9th, 2010 02:21 am |
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5th Post |
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arcdust Member
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I live in NH and I'm paying about over 13.5 cents per KWH for my electric used for hot water, its on a separate meter. I paid $2.59 for oil today. Per the calculator on the GE website: http://www.geappliances.com/heat-pump-hot-water-heater/water-heater-electricity-calculator.htm The savings per year at that rate of 13.5 would be $419. At $875 (350 gal x $2.5/gal) for oil that would mean you would save about $456 by switching to the hybrid heater. But wait....what the calculator does not address is how much the water heater is using the heat pump and how much the standard elements. Is GE's claim of $251 per year operating costs under 100% heat pump usage (eheat mode) or a mix of hybrid and standard element? I saw a reference somewhere else that stated in the zone NH is in that the heat pump/standard element usage is 50/50. The operating cost of the hybrid heater is $251 per year and a standard electric water heater is $662 per GE's calculator. The cost of operating the hybrid heater at a 50/50 usage would be somewhere between the $251 and $662. I don't know how to tell where it would fall. At a halfway point the operating cost would be 662-251=411. 411/2=205.5 so 251 + 205.5 = 456.5 yearly operating cost. I think that would be optimistic because I used a halfway point just to pick something. Where I think it would be closer to the $662 per year than exactly halfway but that is not by using any concrete numbers. The GE heater cost $1600 before installation. My guess is that it would probably pay off somewhere between 5-10 years. To change from oil to electric you'll have to install electrical service to the heater and probably some minor relocation of water lines. You'll have to add that to the cost of the water heater. That would bring it closer to the guesstimated 10 years but with all of the above considered and the unknowns such as oil prices and electric prices...WHO THE HECK CAN TELL?? This site talks about efficient water heating: http://www.aceee.org/Consumerguide/waterheating.htm#indirect They have some tables with cost per year operating costs of different systems. They seem to say that an indirect storage system is a good option for currently installed oil fired boilers but I can't see where their table addresses it. Their "conventional oil fired storage" numbers are the most expensive but they recommend indirect oil fired storage so I'm confused! Bottom line is that there is a lot of confusing information out there. You have to take into account not only the system cost but what it takes to install it and change from a current system. I think I have an oil boiler and an electric water heater because when they converted the house from electric to oil heat they must have opted to keep the electric water heater because it was only three years old. It was installed in 1984. Its starting to leak so I found a used Kenmore Power Miser 12. It was built in 2004 and taken out of service in 2008. I've torn it down, flushed and cleaned it out, put in two new anodes I got here. I'm spent $100 on the heater, probably $150 in parts, the heater will be like new and it has 3" of insulation all around it. The elements are both 3800W, presently mine are 4500w, and I moving up from a 40 to 66 gallon tank. I'm anxious to see how much better it will be than the old dinosaur that is peeing on my basement floor now! If I had a crystal ball and knew I was going to be here for 20 years I might spring for a new system but I can't see it paying for itself anytime soon.
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| Posted: Tue Feb 9th, 2010 05:17 am |
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6th Post |
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elenano Member
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I just had to compliment you on your phrase, "the old dinosaur that is peeing on my basement floor now." A lot of what you see here in The Tank and all over the place elsewhere just barely passes for English, much less clever English. This was fun! Randy Schuyler
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| Posted: Tue Feb 9th, 2010 10:00 pm |
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7th Post |
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arcdust Member
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LOL...well thank you Randy. Its old and it keeps leaving a puddle on my floor, just seemed like the perfect description!
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| Posted: Fri Feb 12th, 2010 07:41 am |
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8th Post |
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eleent Member
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Hello: As your "new" heater is sound and well insulated, it might be possible to use it as an indirect, off your boiler. If your boiler is efficient it might work out. Possibly the element/s could be used in summer to prevent the need to fire up the boiler then. You might want to ask a question or two at http://www.heatinghelp.com on "The Wall" Yours, Larry
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| Posted: Mon Sep 6th, 2010 12:12 am |
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9th Post |
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musicman-1978 Member
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I have a Phase III 45 gallon indirect hot water heater being fed by a Burnham boiler with a firing rate of 1.36 gph. The system is about 7 years old. I put a timer on the burner, and the system consistantly runs for about 1 hour in a 24 hr period during the summer months, which means at the lowest oil price I can find right now on the CT shoreline of $2.45, it is costing me $3.33 per day or about $100 per month to heat water in a house with just 2 people. Everyone says that the indirect system is supposed to be the most efficient but this seems to be pretty expensive to me considering I know people with gas hot water heaters that are paying only about $30 - $40 per month and using similiar amounts of hot water. I was considering replacing the system this fall with either the new Rheem or GE Hybrid electric heat pump water heater. There is a tax credit going on until the end of the year that would offset some of the cost. Is this typical of what I should expect with an indirect system? Would it be reasonable to assume I would realize any savings with the new system?
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