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:
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
Best Answer
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