On Jan 2, 8:30*pm, JIMMIE wrote:
My heatpump is already backed up by NG. It also switches over to NG
when outside temp is about 40F, so why add heatstrips. Rumor has it
that in the next couple of years we are going to net metering of our
electrical use. This means nightime rates will be around 2 or 3 cent
per KWH. This would make electricity cheaper than NG. NG would still
be the cheapest to use during cold days when its not practical to use
the heatpump so I want to keep it especially since I already have it.
Are there existing Tsats that could control a system like this that t
would select the proper heat source according to time of day and
outside temperature.

Jimmie

I'm not sure that resistive will ever be cheaper than ng. I also
suspect that your air handler is a ng furnace with a A coil added to
it. There is no place for the addition of heat strips in that set
up. It's not like a regular heat pump air handler that has a section
for heat strips. You also do not presently have enough electricity at
the unit to run heat strips. Once you solve that then I am also not
aware of any controls for a 3 way residential unit. But you could
solve the control problem with a timer and a relay. Run the line that
activates the furnace through that timer/relay and then direct the
output to either the ng furnace or the resistive heat.