We are building this summer where natural gas is not available. Propane has gotten very expensive here–some are saying electricity is cheaper. I am leaning toward a Marathon (superinsulated) electric tank-type water heater. Does anyone have any experience with a heat pump water heater? What about the on-demand electric water heaters?
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As an employee of major water heater manufacturer, I will attempt to answer your questions objectively. First, I sincerely doubt that even with expensive propane that electric will be cheaper. Knowing the prices of the two and the specific heater performances, you can easily calculate the costs of operation. In fact, the yellow tag on the heaters will give the energy factor and the estimated annual cost of operation. I would only buy an electric if the propane is truly more expensive. What are you going to heat your house with? I would point out that the estimated annual cost of operation for natural gas is usually one third of that of electricity.
If you consider the lifetime costs of an electric water heater, there is is a very good chance that a heat pump water heater would be a good investiment. The problem is that very few are made and there may be a problem with service, etc. In addition, you will be stunned by the intial costs...of course this high cost is made up in a few years in less energy useage.
A tankless electric will not have the water flow capacity that a normal american house expects unless you live in a very warm climate with very warm incoming water. I would not consider a tankless electric as a via option.
As far as what heater to buy, look at all of the electrics in the size you want and compare on the basis of Energy Factor or E.F. The amount of energy you will use is directly related to the energy factor value. I know nothing about the Marathon heaters but I know that their EF values can not be much better (if at all) than the conventional electric heaters on the market today.
I hope this helps. Feel free to contact me if you have further questions.
Bill
I just checked the Marathon web page to see that there heaters have an EF of 0.94 which is not the highest available. In fact, I think all of the mainline water heater companies offer 0.95 models at prices which are well less than one half of the cost of the Marathon. I could not find the guaraentee on the Marathon but unless it is very, very long, I would think the best electric heater investment is a 0.95 glass coated steel water heater from a major supplier.
Bill
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Bill
Strange that you work for AO Smith as we are living in temporary quarters above my future shop using an AO Smith water heater. Warranty? they claim lifetime, but I know other companies offer the same. What am I heating the house with? That is not resolved yet either. My HVAC man is pushing for dual-fuel--propane 80% furnace with heat pump. Radiant floor heating intrigues me, but since we will air condition, that will require installation of two systems ($$$) Our deal is complicated because our 2200 sq.ft. house will have a wood stove and solar input (that's me asking about which glazing for sunspace in central MO). Propane is over $1/gallon this year--who knows where it,or electricity will be next year or 5-10 years down the road. Are the safety issues of not having any gas in a tight house worth considering? We just moved from a house with a 92% furnace so high efficiency gas with high SEER AC sounds good too. My head keeps spinning. Thanks for everybody's input. Bob
Yeah, the on-demand electric has very limited capacity -- you can be taking a shower OK, but if someone just turns on the hot tap in the kitchen then that's all she wrote. Plus, on-demand units aren't really all that efficient vs tank heaters.
I've seen data on the Marathon and it looks to be about as good as an electric can get in terms of insulation. Relative to a modern WH of standard construction, though, I doubt that it's more than, say, 20% more efficient. Keep in mind that with any decent electric, properly installed (with heat traps, etc), the main cost is for the hot water you actually use, or hot water left in the pipes, vs heat loss from the unit itself. Keeping runs short (and maybe installing several small heaters in different parts of the house vs one large one) can help cut costs.
We've had an electric water heater (same heater) here for 27 years. I've never studied what it costs to operate, but it's nowhere near what it costs to operate AC for a few days a month.
I too am curious about how you plan to heat the house. There are water heaters available for just about any fuel you might use for the furnace.
Does anyone have any experience with a heat pump water heater?
We use one. When I first arrived here and posted a question about it, nobody mentioned any experience.
As was pointed out, your house heating system could very well affect your choice. This would especially be true for a heat pump water heater. We need almost no supplemental heat for our passive annual heat storage (PAHS) and find temps right around 70° comfortable, including a couple º below.
I picked up a tankless HPWH on ebay for a small fraction of normal cost. It's an E Tech WH-6B. Works like a dream with a std electric tank heater. Wall hung and requires a drain line. Byproduct is cool dry air, which in our humid, normally AC, climate is fantastic. Doesn't work very well below 70º so we only use it when we have excess heat. Unfortunately I replaced our std tank heater recently with a Lowe's Whirlpool with electronic control. It's a mismatch, requiring me to figure out some odd wiring. Neither E Tech nor Whirlpool could figure out how to get them to work together. What I did isn't great, but it works.
During our first 6 months of operation we saw enough electricity savings to pay for the unit. Plus getting the dehumidification and cooling free. With current normal pricing that would traslate closer to 4 summers. You'd have to have the correct house design for one to work properly. We did. Further good reading at:
http://www.pnl.gov/fta/3_res.htm#manu
PAHS Designer/Builder- Bury it!