billinstuart

Heat pumps are rated on COP..coefficient of performance. A COP of 3 indicates it is 3 times as efficient as a straight resistive heating unit..which is 3300+/- btu per kilowatt. Essentially, you will use 1/3 the electricity of a resistive HWH, plus cool the space the heater is located in.

No rewiring, reserve hot water if the power goes out. What's the payback, $250 resistive HWH vs. reverse cycle? You do the math. Remember, a "ton" of a/c is 12,000 BTU's.

firemedc1560

I just completed the install of an electric tankless this afternoon. I bought the unit several years ago, but never got around to the install until my existing 40 gallon tank died over the weekend. I ran a 70 amp circuit to be safe, and my unit is drawing 55 amps at full load. We tested with a clamp on meter after we started the unit, so it is an accurate number. I will update with our results over time, but so far, it does what we need it to do. I have three daughters living here right now, so showers are a problem. We also have a 100 gallon bathtub that we could never fill with our old water heater. We will see how this goes.

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PF-88

What I noticed about the Heat Pump literature is that it compares it's effeciency against the electrics and not the gas which is more effeceint so would the extra cost of the heat pump be worth it over gas?

billinstuart

have to do some number crunching, including factoring in the cost of conversion to gas (including venting), the cost of propane or natural gas per btu at the rated efficiency vs. the cost of btu with electricity factored by the coefficient of performance of the heater and the cost of THAT unit.

Often you'll find that simply replacing your existing unit is hard to beat, especially if you insulate the poo out of it.

Be advised that a point of use unit is NO MORE EFFICIENT at heating the water. It's the storage of hot water and the corresponding heat loss from the tank that makes the difference.

TSA

i considered an electric to replace an aging tank in our house in the Keys, but every plumber we consulted gave the same advice as Tommy.

1Aldog1

Hi Guys, new to the forum, but I am in an unique situation, I have a 40 year old gas furnace that has been on borrowed time for the past couple of years. My house currently does not have a hot water heater and the house is heated by forced HW baseboard heat.
I was reading your posts and and have heard of other people installing one of these units to do everything in the house, HW for the heating as well as the HW for the sinks and shower.

I was planning on replacing the furnace soon, before it dies, and before I am in a bad position with any of the emergency plumbing repair guys that will almost for sure bend me over the barrel for a new system / and not recommend the option of installing a tankless heater.

Does anyone have any recommendations for an installer of a gas system in the Rhode Island area?

Thanks in advance

PF-88

How do you have forced H/W baseboard and a gas furnace, did you mean boiler? Furnace heats air/boiler heats water, I have a hydro-air system were the boiler sends the hot water to a coil in a air handler and a second zone to a inderect hot water heater for my domestic water, it replaces my old furnace/hot air system.

noelm

I guess I might as well add my bit (even though it is from Aus) I have had a Gas storage system, an electric off peak system, and now a tankless NG system, and once it was properly sorted the tankless (we call them instantaneous) system leaves them all for dead, unlimited hot water, no energy use when no taps on, and about a tenth the size of a tank system, and you can get internal fitted ones for new houses, or old houses with mofification, there is a small down side, they are prone to being stolen when new houses are built, I guess they must be worth a few dollars on the black market, so the heater is installed just before the new owners move in, and attached with various anti theft devices.

1Aldog1

PF-88
Sorry, I did mean a boiler...
Thanks

PF-88

As far as I know the tankless hot water heaters are intended for domestic hot water and not sure how well it would work for whole house baseboard heat epecially in the NewEngland area. I would definetly research this and contact there tech. depts. brefore I did it. Having gas you can get modulating condensing boilers with outdoor temp. reset that are up to 98% efficent but your going to have to spend $$$ for it.

ATaylor

Tankless units are not intended for baseboard heat. There are less efficient than a regular gas unit and only overcome that by not keeping stored water continuously hot. In a constant flow scenario your energy use would go upside down in a hurry.

I'm a big fan of the heat pump water heaters, particularly if your water heater is in the garage or attic.

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