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I'm considering getting one of these:

https://www.sainsmart.com/products/24v-relay-cycle-timer-module

...to force my 2nd floor thermostat to force heat on every so often (say, 1 minute every 15) to "warm the pipes" to overcome poor insulation (fixing this is not an easy option). I currently have a simple Honeywell thermostat:

https://yourhome.honeywell.com/~/media/epresence/product%20images/pro-1000-non-programmable-thermostat/th1110dv-c1-3.ashx

I'd like to wire in the above timer module so that it shorts the R (24 Vac power from heating transformer) and W (Heat relay) wires on a cycle. I have no electrical know-how. Can I simply use the 24v power from the thermostat to power the timer? And will this timer work for this purpose?

The timer manual (wiring info starts on page 6):

http://s3.amazonaws.com/s3.image.smart/download/101-30-209/101-30-209.pdf

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The cycle timer you linked to seems to require 24 VDC. The thermostat will be fed with 24 VAC. Do not use that cycle timer!

You can wire a cycle timer just like a thermostat, in parallel to the existing thermostat. You can wire it near your furnace if that's more convenient; it will just connect the two conductors to call for heat at the set intervals, whether the thermostat is doing the same thing or not.

Look for one that's designed for HVAC use, e.g. https://www.supplyhouse.com/ICM-Controls-ICM305-ICM305-Duty-Cycle-Timer-Time-Delay-in-Minutes

  • How would I wire that up? My thermostat only has 2 wires for the heat circuit (red/white). – Jim Cote Jan 2 '18 at 15:54
  • Your heater control will have three 24VAC terminals on it - hot (red), call for heat (white), and common (black). Note these colors are typical but your cable may vary. Your thermostat should currently be connected to red/white (it's just a switch that connects these when calling for heat). This cycle timer should have red + black wired to its inputs, and white wired to the load. You don't have to wire something like this at the thermostat, you can mount it near the furnace controls. Or you can use a two-wire design like the one in your comment. – Shimon Rura Jan 2 '18 at 20:12
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I use cycle timers all the time they do not draw much power from the 24 v supply and the contacts are the same as a thermostat if wired in parallel when the contacts close it is the same as the thermostat calling for heat there are many brands out there but automation direct has some of the least expensive models that can be set from 1/10 of seconds to hours with a dial to adjust the time delay, a second way would be with an artisian timer same idea but the ones I have used in the past have fixed cycle times.

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