Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
A heat pump water heater when used in colder climate can use more energy and cost you more.
They are robbing heat from the living space, this is ideal if you are in warmer climate and want to remove heat from the living space. In colder climate it's very inefficient and costly.
Suppose they are 50% less than standard electric. If you want to put 2000 BTU's into the water you first need to use your primary heat to put 2000 BTU's into the air. The heater is going to use 1000 BTU's of energy to mechanically extract the heat from the air and put it into the water, that's a total 3000 BTU's. This can never be more efficient than directly heating the water with the 2000 BTU's to begin with.
While the efficiency can never be greater than directly heating the water there is possible scenarios where the cost may be less. I use coal for heat and the cost per BTU is far less than electric. If I had one of these it would cost me less than standard electric water heater because the cost per BTU for the coal is so cheap. The energy efficiency is still bad. This doesn't change the fact directly heating water with the coal is the cheapest and most efficient way for me to heat water.
If you are going to consider one of these and live in a colder climate make sure it has option to switch it between heat pump and regular electric.
Note this only considers the cost for the fuel, the higher expense for the heat pump water heater is also another consideration.
your premise that "it can never be more efficient than heating the water with electricity directly" is incorrect. At even 30 degrees ambient temperature (and you're not putting your hot-water tank outside for reasons that should be obvious) - a heat-pump has a coefficient of performance of about 3.4 - in layman's terms, 1kw of resistance heating = 1kw of hot water. With a heat pump, the same single kw of electricity equals 3.4 kw of hot water.
There isn't really much of a cost premium with heat-pump water heaters either - combo units run about a grand, and the least expensive 50 gallon resistance heater in my area is about $400 now.
Im not trying to talk you out of heating your water with a lump of coal, just get the facts straight before you criticize the tech.
your premise that "it can never be more efficient than heating the water with electricity directly" is incorrect. At even 30 degrees ambient temperature (and you're not putting your hot-water tank outside for reasons that should be obvious) - a heat-pump has a coefficient of performance of about 3.4 - in layman's terms, 1kw of resistance heating = 1kw of hot water. With a heat pump, the same single kw of electricity equals 3.4 kw of hot water.
See the bolded? that is the only thing you have posted relevant to what I posted. This topic is not about heat pumps, it's about hot water heaters using heat pumps inside the home that require a much higher ambient temperature that is heated from your primary heating source.
Quote:
Im not trying to talk you out of heating your water with a lump of coal, just get the facts straight before you criticize the tech.
My facts are 100% accurate unless you have somehow figured out how to break the laws of physics. When the source for your heat is inside air that was heated by you primary heat source it will never be as efficient as directly heating it . Period, end of discussion. Otherwise you just invented the free energy machine.
See the bolded? that is the only thing you have posted relevant to what I posted. This topic is not about heat pumps, it's about hot water heaters using heat pumps inside the home that require a much higher ambient temperature that is heated from your primary heating source.
My facts are 100% accurate unless you have somehow figured out how to break the laws of physics. When the source for your heat is inside air that was heated by you primary heat source it will never be as efficient as directly heating it . Period, end of discussion. Otherwise you just invented the free energy machine.
Not necessarily. You're completely leaving out the summer months.. In that case, it's assisting your in-home heat pump to cool the house. But, in either instance, I think it's minimal, pending on the amount of hot water you use. That's like a politician answer.. "I'm 100% correct, I just didn't give you all the information and left out the part that doesn't support my facts"
I can turn the Hot Water Heater off at my house for 3 days before I run out of hot water. That's with taking a shower each day, though that's about it.. Not washing clothes or dishes. The water heater is far more efficient at keeping the heat in than a house is. So, it's not a 1 to 1 ratio here.
I agree with you, or whoever it was, about the probable repair problems.. Whoever said that HWHs are always inside is wrong, as here in the south, they're quite often under the house so that if they leak, it really doesn't hurt anything. But, we have few days a year that are below freezing.
Does this thing pass along enough savings to justify itself? Well, the sales material says it does, but.. Didn't they say the Ford Pinto was the perfect family car?
Why not just get a solar hot water heater with the rebates and tax credits comes out to the same as this better ROI summer months your not even paying for any hot water. I know friends who have invested in heat pump water heaters for their pools or in-ground spa's and the cost of repair is high.
See the bolded? that is the only thing you have posted relevant to what I posted. This topic is not about heat pumps, it's about hot water heaters using heat pumps inside the home that require a much higher ambient temperature that is heated from your primary heating source.
My facts are 100% accurate unless you have somehow figured out how to break the laws of physics. When the source for your heat is inside air that was heated by you primary heat source it will never be as efficient as directly heating it . Period, end of discussion. Otherwise you just invented the free energy machine.
I didn't invent anything, I've been *using* a heat pump water heater for about 7 years now. I've plugged it in to a "kill a watt" meter, so I know *exactly* how much energy it's using & I know my repair cost has been $zero. Your argument about "inside air" being used by the heat pump is completely invalid in my area of the country, as we put our water heaters in the garage, and in much of the country they go in the basement, or a utility room where dropping the humidity & the temp a few degrees won't hurt anything, or "cost you money" - further, it only takes a few minutes of extra work to vent that cool, dehumidified air outside if you're stubborn and bad at math.
If you like your lump of coal as a heat-source, you can keep your lump of coal as a heat source.
But again, quit knocking technology you've obviously never seen & don't understand.
Why not just get a solar hot water heater with the rebates and tax credits comes out to the same as this better ROI summer months your not even paying for any hot water. I know friends who have invested in heat pump water heaters for their pools or in-ground spa's and the cost of repair is high.
Most of the (unfounded) fears posted in this thread relate to "complexity" & "repair costs" as the disadvantage to a heat-pump water heater. Solar adds a massive amount of complexity to the setup - even with a "solar" system, you'll still have an (inefficient) electric "backup" heater, a circulating pump & a massive amount of plumbing on your roof. The odds of a failure increase exponentially because you've exponentially increased the number of components.
Further, oft-cited (unfounded) fear #2 of the flat-earth brigade here claims that a heat-pump water heater placed in "cold" conditions won't be "efficient".. News flash, there's no where to put a solar system except *outside* your house, so if it's 50 degrees (or 30 degrees!) outside, that's the "free" heat you're getting. If you're taking showers at 6am with a solar setup even here in the desert in the winter, you're using stored water & replacing it with regular old, electrically-heated water.
And last but certainly not least, by "taking advantage" of the tax subsidies & rebates offered for solar, you're making your neighbors & fellow ratepayers kick in $4-$6k for that overly-complex & marginally more "efficient" boondoggle on your roof.
The math here is super-simple.
If a cheap, junky & inefficient electric water heater costs $500 / year to run & has a lifespan of ten years (many in my area only last 5 years), your ten-year "total costs" might be $5000 in energy & $400 for the heater.
If your solar setup costs $5k before incentives & lasts the same exact time, you'ld better be getting a lot of "free" water, because you only have $400 to spend on electricity for it for the next decade. Otherwise, you're really just a "welfare queen" taking a different kind of welfare.. If the subsidy is $4000, spread over a decade, that's $300+ a year coming out of your neighbor's pockets, no different than food stamps, except you get to be smug cause you're "saving the environment", lol..
If you tried to sell me a house with a 5-10 year-old solar setup, I'd be knocking a couple thousand *off* the value for the house, to make up for hiring a crew to toss the setup in the trash, repair the holes in the walls for the piping & patch the roof when it's gone.. (Plus another $400 for an inefficient electric water heater to replace it)..
If you like your lump of coal as a heat-source, you can keep your lump of coal as a heat source.
Actually the EPA did consider them when they were implementing the new regs for woodstoves, the only change in the industry was they had to drop wood/coal designation on some limited models . If you don't know anything about coal I can guarantee anything you are envisioning is wrong. They were making fully automated units with efficiencies in the mid 80's before both of us were born.
A heat pump operating in ideal outdoor temperatures in the 60's will not come anywhere near competing with the fuel cost in the Northeast US let alone colder weather.
Quote:
& I know my repair cost has been $zero.
The repair cost on my coal boiler has been about $500 including motors which is most of that expense over a 35 year span.It will run for at least another 20 or 30. With about $1K in refurbishment in the future it's going to run for 100 years if not more.
Quote:
But again, quit knocking technology you've obviously never seen & don't understand.
Specifically from my first post what is it you find wrong in regards to how this technology operates?
Everything I've written is both informative and accurate. You on the other hand are trying to make blanket statements. I'm not knocking it, it needs to be applied where appropriate and the consumer needs to understand if it's appropriate for them.
Further, oft-cited (unfounded) fear #2 of the flat-earth brigade here claims that a heat-pump water heater placed in "cold" conditions won't be "efficient"..
Once again if the air source for you heat pump is indoor air heated by your primary heating source it will never be as efficient as heating the water directly. It's not the flat earther stating this, it's the law of physics stating this.
Most of the (unfounded) fears posted in this thread relate to "complexity" & "repair costs" as the disadvantage to a heat-pump water heater. Solar adds a massive amount of complexity to the setup - even with a "solar" system, you'll still have an (inefficient) electric "backup" heater, a circulating pump & a massive amount of plumbing on your roof.
You can build a solar collector fairly cheap. If it were me living in an area where there was plenty of sun and hot weather I'd have the solar collector ground level connected to a storage tank/hot water heater above the collector and inside the home. There is fitting for the pressure relief valve on the side of the tank and drain plug on the bottom. Those can be refitted to accommodate the solar collector. Be sure to integrate the PRV and drain when you refit. The hot water will naturally thermosiphon into the tank. No motors needed, set it up and forget it.
If you want to expand on this use a two tank system, use a storage tank for the hot water from the collector. You feed that into the hot water heater. This will maximize the amount of solar heated water going into the powered hot water heater.
Please register to post and access all features of our very popular forum. It is free and quick. Over $68,000 in prizes has already been given out to active posters on our forum. Additional giveaways are planned.
Detailed information about all U.S. cities, counties, and zip codes on our site: City-data.com.
Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
