Load miser

[beanie5]

I am from Canada// i have a tankless water heater requiers a 120 amp breaker .// my house heater requiers a 100 amp breaker // stove 40 amps/ cooktop 40 amps / dryer 40amps /ect... my question is can i and how do i give priority to my water heater when in use and shut off myhouse heat/ so i can use and install this water heater /// i have 200 amp entry // please show me how i can solve this problem without switching to a 400 amp entry/// THANKS also how and where do i get a power miser of that sise 100 ampss??

[bob haller]

go back to a regular electric tank.......

tankless electric are almost never effective.

besides a malfunction of your building heat OR water heat could someday leave your home frozen

[DanG]

My experience with electric tankless is NOT good. You just can't get the delta T up to anything useful at a GPM that makes any sense. Gas fired tankless is outstanding, but will probably require a larger gas supply and venting. Noritz does NOT require proprietary or expensive B venting. If you do not have gas service, stay with conventional electric tanks.

[trader4]

Did the electric tankless just fall off a truck? Otherwise you would think the issue of how to power it would have been addressed before you had it. Googling I see the power miser is a device that allows two loads to co-exist on a single circuit. It will switch off the low priority load when the high priority one wants to come on. So, it probably could be rigged to do what you want.

But it raises some questions. Like everytime you draw some water, it's going to cut off power to the heater. Which means a lot of on and off cycles. Assuming the air handler is on the same circuit, then the motor will be going through those frequent cycles which isn't good for the motor longevity.

Have to wonder about the cost of energy up there. With a 100amp heating system if it's just a resistance one, I hope electricity is cheap.

If it were me, unless this is some kind of unique application that requires electric tankless, I'd just sell the tankless on Ebay and just go with a tank. Simple solution that works.

[EXT]

Are you sure you know what your are doing? Most cooktops and ovens, even when separate units, are built to run on one 40 or 50 amp line, and a dryer normally runs on a 30 amp line. Given your accuracy, on these items, I question your other numbers. I certainly would NOT install an electric tankless water heater, I would use two 40 gallon tanks connected in series to provide enough water for your use. I am in Canada too and my electric rates are skyrocketing, how can you afford to run all this stuff?

[John Grabowski]

*I don't think a power miser is what you need. I think a relay is called for. You could have it controlled by a flow switch on the hot water line. However that would mean that your heating system will cycle on and off more frequently. The relay does not necessarily need to shut down the power. It could just be wired to the heating controls (Thermostat line) which would be cheaper than a 100 amp relay. It only needs to shut down the heating system whenever the water heater is on.

Another possibility is to install an additional electric service and meter just for the hot water or for the heating system.

Double check the specifications for the tankless water heater to determine if it is the right size for your needs.

[Attila.Iskander]

In Quebec, electricity was historically so cheap and abundant that whole houses were built electric only. That changed after the great freeze of 1998