Review: Rheem HP50RH Water Heater
 

I decided to take advantage of a lovely combination of events and get myself a brand-new heat pump water heater!

First, Home Depot was having a sale, and marked down the 50-gallon Rheem HP50Rh to $1200 from $1500.

Second, they sent me a 10% off coupon.

Third, Maine offers a $500 cash rebate for heat pump water heaters.

Fourth, the Feds give back another 10% ($120) in tax credit.

Fifth and final, Home Depot offered free 18-month financing!

So, for around $460 when all is said and done, I have a new, shiny toy! I figure that amount of cash will be recouped over the life of the heater. Also, I get a perfectly good 50-gallon electric water heater to use for some unspecified purpose in the future... (solar??)

Now, it turns out that this model is being discontinued in favor of a higher COP model that will be coming out sometime soon, so that tempers the usefulness of this report.

Installation was straightforward, with one pointed difference from a normal water heater: the cold water inlet is down onthe bottom, and the hot water outlet it about 3/4 of the way up on the side. This thing, by the way, is almost 7 feet tall (Heavy, too!). It looks a bit like a Dalek sans arms and eyestalk.

http://ecorenovator.org/forum/member...otos/178-a.jpg

http://ecorenovator.org/forum/member...otos/177-a.jpg

You can see the temporary nature of the install, the control panel is around the backside right now, and the condensate line runs down to a small condensate pump on the floor that also serves my dehumidifier, at the foot of the water heater.

It has been installed for about two weeks now, and just looking at the daily energy usage reports from the power company, I can see that power consumption is down noticeably, but I will have to wait until month's end to see what my month-on-month numbers are for electric usage.

The experience has been very positive so far. It has a stated COP of 2.0, though I have no hard numbers to back that up. I'd like to know, but I'm still thinking about how I can datalog to do it.

The heat pump, when operating, blows a fair bit of cold air into the basement, and sounds like an old dehumidifier, with a noticeable noise through the whole basement. In the living spaces, you can hear it in the kitchen, but it sounds like the refrigerator is running, nothing more. It's not audible anywhere else in the house.

It takes a chunk of the dehumidification load off my basement dehumidifier, which cycles noticeably less since I installed the water heater. When operating, you can see a steady trickle of water streaming down the drain tube and into the condensate pump.

All in all, I am very happy with it!

If anyone has specific questions, I'd be happy to answer them.

Future plans for this include installing an electric meter so that I can totalize energy consumption for hot water. Also, I will be moving it to another spot in the basement, as all my copper lines are rotted, and will be replaced with PEX this winter.

Wow thats a steal at that price. Nice find.

Thanks for the review!

I'm surprised it only has a COP of 2, which is 6.8 EER. A cheap window A/C has 9.7 EER or more. (2 is not bad for a solid state unit, which that one is not.)

Perhaps the COP of 2 is due to the higher temp of the water?

That would be my guess as well with regard to the low COP. In a few weeks I will be re-wiring the electric to the water heater, I am going to route it through a refurbished electric meter, so that I will be able to know for certain what my energy consumption is. I am also looking for a cheap water meter to plumb into the water line; then I would know quantitatively what my energy input was per gallon of water out.

Anyone know of a source for cheap water meters?

I just ordered 3 electric meters from Hialeah Meter Company, they were about 30 dollars each for an EZ-Read meter and meter socket, shipped. Seems like the most economical way to submeter, though it does require me to physically go and record the meters. For the price, I can deal with that.

Have you ever put a watt hour meter on your dehumidifier? I'd like to know how much it's saving you in that area, my dehumidifier is one of the largest electrical loads in the house, costing $10 or more per month and a water heater like this should take care of most of the dehumidification.

They should call that unit the lighthouse.

Funny you should ask, Ryland. I am in process of cataloging electrical loads in my house this weekend; I'll update with that value when I have it.

Unfortunately, my basement is very damp in the spring and early summer, so the dehumidifier is a necessary evil. I am very curious to find out what fraction of the dehumidification load the heater will take, but I suspect it will be small, due mostly to the fact that we are a 2-person household, and just don't consume enough hot water daily to make the heater run all that much.

Do you mind me asking a dumb question about that water heater - the heat pump is directly on top of the tank?

Wonder if it might be possible to separate the two without too much piping hassle, or if I would need to maybe circulate outside air past the unit.

I've been looking for ways to heat hot water to circulate under my floors, but haven't found anything fantastic so I'm still hauling wood every year to the woodstove.

Not a dumb question. The pump is mounted directly to the top of the tank, yes.

I suppose anything is possible, but I do not think you would gain anything by remotely mounting this unit, as you would lose energy in the transmission pipes and in the pumping, even if they were insulated. You also need to have this in a room with a lot of volume, not a broomcloset or under the stairs, as it extracts the energy from the air around it, and you need a lot of air to heat 50 gallons of water.

If I were to try heating with this heater, I think I would use the heater as it is, and just run the water through it directly, or with a heat exhanger.

But, I don't belive the heat pump is big enough to handle a large sustained load.

Fair enough. Well done for your domestic hot water then sir. Looks like technology is finally catching up to what the people want!

The condenser is probably going to be copper tubing bonded to the outside of the inner tank, which you cannot easily remove. You might as well just modify a window A/C.

I would agree with you, and would like to do something like that myself, but only if it's a 220/240V A/C. 120V units are easy enough to find, but have their efficiency issues.

Know of any cheap higher voltage A/C units?

Maybe modify a used central A/C?

Because I said I would, see below for the electrical usage of most of my household appliances. Note that a lot of them are not constant, but rather cycle on and off, so I am not accurately capturing long-term usage.

http://ecorenovator.org/forum/member...onsumption.jpg

In other news, I did in fact install an electric meter on the water heater, I'll post up the energy consumption end of this month, when I have a full month's data to talk about.

What were you using for hot water before the heat pump water heater was installed?

I had an electric heater, which was perfectly good, but I couldn't resist the price subsidies on the new one coupled with the promise of lower electric bills.

I do not have any meaningful data about what exactly my hot water bill was prior to installing the new pump, as I did not have the heater sub-metered until this month. There is an all-electric setting on the water heater, but I am loath to engage it, and spend more money, just to answer an academic question. I might do it someday anyways.

One month update!

As of this morning, 32 days since I installed the meter, the water heater has used 91kWh of electricity, for an operating cost of approximately $0.42 per day, and roughly one shower per day. Not too shabby, eh?

I have no idea what the straight resistance heating cost would be, and I don't intend to find out.

Where I lived previously, I had worked out that a shower on my instant propane heater cost me about a dollar, though in its defense, it had a 50 foot uninsulated copper run between the heater and the showerhead.

Honestly, that seems a little high to me. But you probably have more people in your house than I do. My hot water heater is an on demand electric unit. It draws 9.6 kW when on. Therefore, my ~10 minute shower uses ~1.6 kWh. Hot water use is next to nothing besides my shower. So, your 2.8 kWh/day seems a bit high to me. I do have a pretty low flow shower head though, a Niagara Conservation Earth 1.25 gpm (which I love). I suppose with a 2.5 gpm head that would make more sense.

I may have been inaccurate just calling out the one shower; we are a 2-person household, and one of us takes significantly longer showers than the other; we also use a dishwasher on about 2 days out of three. We do have a 1.5 GPM showerhead, which is surprisingly nice.