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Electric Tank to Holding tank?

My current system consists of a Burnham single pass 195K btu oil-fired

hot water boiler with a tankless water heater and baseboard heating. I

would like to add an electric tank wh for summer usage in order to shut

down the boiler for the summer and then use it as a hw storage tank in

the winter with the existing tankless wh.  Is this possible and/or

feasible and  if so how would one go about this?

Is there a water heater available that has both unfired and electric

supplemant. My daughter "vaporvac",, has investigated the heatpump type water heaters, but thinks they may not be able to handle the entire heating load in the summer.

  Thanks in advance for any advice.

I have a schematic that I'll post if I can figure out how to scan it in, etc.


New Gloucestor,, Maine


  • icesailor
    icesailor Member Posts: 7,265
    More Hot Water:

    It is easily doable, I do it all the time, and I have done it for over 30 years. Although some say it doesn't work. I've never had a complaint.

    You don't use the electric hot water heater as an energy source. I don't care how high oil is, electricity is more costly and slow to heat water. You use the tankless heater in the boiler as the energy source.

    It is so simple that I have to actually show someone in person because they can't get the concept. They only want to install an indirect and pipe it into the boiler. The "Indirect Coil" is already in the boiler. You just pipe the outlet of the coil into and through a water heater that then acts as a storage tank with a circulator.

    But, you'll end up with a new electric service to the water heater (30 Amp, 240 volts) when you can do it with a fractional Hp circulator motor at 110 volts.
  • cdrltd
    cdrltd Member Posts: 2
    Avoiding heating ALL the boiler water

    Thanks Icesailor.  Just wondering how I can adjust this so I don't have to keep heating the entire boiler during the summer just to take a shower..  Also, how exactly does the circulating pump come into play in your scheme? If the tankless heater is discharging into the WH wouldn't the cold replenishment water go into the tankless heater which then necessitates heating up the entire boiler just to heat that cold water? I understand what you're saying generally, just trying to get the specifics.  thanks Len
  • icesailor
    icesailor Member Posts: 7,265
    Tanks for the tanks:

    You have an electric water heater. Because they are the cheapest tank you can buy. You connect the cold to the cold, and the hot to the hot. You take the bottom drain out and add a 3/4" brass tee and connect a circulator to one side and the drain to the other. You pump the water in the bottom of the tank to the cold inlet of the tankless. You pipe the hot, outlet to the cold water inlet of the water heater. It is advisable to add a swing check valve at the circulator. Connect the loop from the tank to the tankless and back with 1/2" copper tube.

    There are many ways to wire the circulator but use the bottom thermostat of the water heater as a thermostatic switch to start the pump. I've done it with a cord whip. Set the thermostat for 125 degrees or whatever you want. Set the boiler operating temperature to 140 degrees and the high limit to 160 degrees or higher. The water in the boiler will be maintained at 140 degrees unless you get a heat call and it will switch to the high limit.

    Boilers by their design, are supposed to extract large amounts of heat into the water. far more efficiently and cheaper than an electric water heater. There is no electrical connection between the boiler and the water tank. There is no connection between the water in the boiler and the water in the water heater tank.

    I use this concept of a water heating source (like a tankless) to store hot water in a tank. I have used it for years and I just did one with an instantaneous gas water heater. The water heater was already there so I used it. They needed more hot water so I gave it to them.

    It works for me.
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