Water heater for boiler

[Deleted User]

I would like to add some in floor heat to an area of
my house that is on a slab. I would like to use a water
heater for the heat source. I would like to keep the cost down and use a standard 40 gallon gas water heater. The problem is there is no way to cycle the burner off when the
pump goes off. Would you run the water heater hot all the time, this seems like it would be a waste of energy. Has anybody done this before or do I need to go up to a direct
vent which would be alot more expensive.

David Sutton_2

you could try ...

using a 845 switching relay and run the stat for the tank off the second leg of the relay. power to 1 and 2 jumpper to 3 circ on 4 use the last two 5 and 6 to separate the line running to the stat on the water heater. just a thought

juut question.. are you using the water heater just for the radi, or for domestic h2o as well ??

[Deleted User]

The standard water heaters have no power to them that I can break, the controls are milli volt.

Dave_13

Well,

I think this is what the last post implied, but I say 2 pole relay to shut off the pump (Pole #1) and break the temperature sensor signal (Pole #2). It has to have a temp. sensor to tell it when to come on and shut off.

Craig Patrizio

Wouldn't you be able to let the hot water heater run its normal course set to one of the lower temps... and then have the radiant loop run with the room stat on a mixing valve to adjust the floor temp to 85F?

Unknown

Gas water heaters

The thermostat/gas control is a single unit on most gas water heaters, where the thermostat mechanically operates the gas valve inside the control. No altering is possible or allowed. No electricity is involved.

I don't understand what you want to do with the relay...?

Noel

MikeB34

try this

Use the HWH fo domestic hot water, Tee off the outlet as your supply, and return on the inlet. you need a backcheck on the return to stop mixing. If your flow rate is low enough the burner cycle will be longer than the pump run, but not unbearably so. Plus you get domestic hot water. If this system is for a 1 room addition, your domestic hot water should be adequate to most needs. The downside to using the old t-couple operated unitrols is no electrical to run it. AND you have to keep the entire tank hot, which is why most applications for small heating systems (1 room additions) in my area use the configuration I mentioned from the domestic hot water. you have to keep it heated anyway.Good luck.