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are there any electric combiboilers sold in the U.S.?

Ripping my hair out looking for an electric combiboiler made or sold in the U.S  any help would be greatly appreciated thank you.


  • kcopp
    kcopp Member Posts: 4,187
    never heard....

    of one. Prob need to do 2 seprate units.... huge energy (amps) needed to do that.
  • Paul48
    Paul48 Member Posts: 4,469

    you can get one you'll probably have to get your neighbors for a few miles in each direction to agree to not use any electricity. Just kidding, but check the power requirements for an electric tankless water heater alone.
  • bld999
    bld999 Member Posts: 47
    Using Two electric units

    Assuming you had to use electricity, wouldn't it be possible to use one unit for space heat and another for domestic and have some sort of control system to establish domestic priority? That way, you could attempt to limit the breakers to 3- 60amp 240v, or whatever was required.

    That's two pieces of equipment turned into a combi by means of controls.
  • zacmobile
    zacmobile Member Posts: 211
    make your own

    I have built a custom combi electric using a flatplate heat exchanger & separate pump running on DHW priority triggered by a flow switch in the DHW potable flow.
  • Limamikemike
    Limamikemike Member Posts: 28

    Thermo2000 combomax, never used or seen one. 

  • Harvey Ramer
    Harvey Ramer Member Posts: 2,225
    Calculate the energy usage.

    In order to effectively heat domestic hot water on-demand you need about 200,000 BTU'S  To do this with electric it will take 266 amps. A typical residence has a 200 Amp service. If you really want to go this route I would suggest getting a staking technician from your electric supplier to come out and do a load study on your current system. They will probably have to upgrade the transformer and the service drop. You may end up paying commercial rates.

    Lots of considerations.

    Another option is to store thermal energy via electric. Some electric companies allow you to purchase energy at a cheaper rate if you do load control. Basically you buy electric off-peak, store it in a thermal container and use it at your convenience.

  • NRT_Rob
    NRT_Rob Member Posts: 1,013
    wait a sec

    200KBTU/hr is a large amount of domestic hot water. Even here in maine that would be almost 7 GPM. that's a very large hot water draw... most combi boilers are only delivering about 100kBTU to the water for a 3.5 GPM domestic demand, much more reasonable.

    you don't see a lot of electric combiunits as the electric units are often not much more money than the heat exchanger assembly would be. could usually just do two units and, if amperage were the problem, lock out the space heat unit when the DHW unit runs.

    Or, maybe you can use an electric boiler for heating, and use an indirect just like a regular boiler usually would.
    Rob Brown
    Designer for Rockport Mechanical
    in beautiful Rockport Maine.
  • Harvey Ramer
    Harvey Ramer Member Posts: 2,225
    Even if you go 100kBTU

    that still requires an amp draw of 133. It would still be advisable to do a load study before installing a piece of equipment with this much draw.

    I would personally be a little skeptical of providing my customers with a max of 3.5GPM of hot water. It all depends on the usage habits of the homeowners.

    I'm a little biased against on demand water heaters in a residential application. Whether it's the way the product has been marketed or the huge energy draw required, I'm not sure why but they leave a bad taste in my mouth.

    What I would be really interested in is a thermal storage container with a compressor that would be able to grab btu's whenever there is a call for heat in the house. It would then store the heat at a high temp and could be accessed at any time.
  • NRT_Rob
    NRT_Rob Member Posts: 1,013
    I don't like gas on demands

    usually... the cycling issues and efficiency issues on low draw demands are troubling as well as maintenance.

    for electric though, the only problem is amperage. If you have the amperage, they are cheap and generally infinitely modulatable. good stuff.

    I don't understand your compressor idea though. If you're drawing heat from the heated space... you might as well just use whatever energy is heating the space to heat DHW... do I misunderstand?
    Rob Brown
    Designer for Rockport Mechanical
    in beautiful Rockport Maine.
  • Harvey Ramer
    Harvey Ramer Member Posts: 2,225
    Well I have several different ideas on the compressor

    water heater. Imagine a heat x-changer on the return side of the primary loop. The compressor uses the heat exchanger to tap into the BTU's produced by the boiler. The thermal storage tank might be wax filled allowing potential temps of up to 300 degF. The compressor being on the return side of the primary loop would have the potential to keep the boiler running at max efficiency regardless if there was only one small zone in the house calling for heat. The compressor would activate only when, and always when there was a call for heat from the house. The only exception to this would be if the thermal storage container reached either a high limit or a low limit and of course during the summertime.

    This would hardly fly though because even as we speak there is a company building an Air to Water heatpump that will go one better. This unit will have 2 compressors, each being able to operate independently or in tandem. You will have 2 supplies and to returns to the unit. This will allow you to transfer Btu's throughout the house to whatever device might need them. For example, when you are cooling the house, instead of dumping the BTU's outside you can stuff them in your DHW. During the wintertime imagine the HeatPump running all day while the sun is out and you have decent temps. Any excess Btu's could be stuffed in a thermal storage container. During the nighttime hours the BTU's could be transfered from the container to keep the house warm. I like the idea of a NET ENERGY house!

    For myself, I believe advanced compressors will play a huge role in our industry.
  • NRT_Rob
    NRT_Rob Member Posts: 1,013
    they will

    we are using the Daikin Altherma air to water heat pump in our shop and it works great. Coupling it with thermal storage is an idea being very aggressively pursued and it appears to have some merit. even without that though, up here in Maine solar PV is going in at $3.50/watt... we very well may be net zero or close to it by next year here at the shop.

    Domestic is a fine use as well, but your compressor has really got to be outdoors or in unconditioned space as least or you're just chasing your tail. no likely efficiency increase on a boiler would justify using a boiler plus compressor to make DHW instead of the boiler by itself... you're just adding compressor power to the boiler energy use.
    Rob Brown
    Designer for Rockport Mechanical
    in beautiful Rockport Maine.
This discussion has been closed.