Can two wrong HVACs make a right?

Trying to figure out if my two normally non-compatible HVAC systems could become compatible if used on the same physical WYZE thermostat as they are now currently two separate thermostats.

  1. Cooling: I have a AeroCool Pro Evaporative Cooler (swamp cooler). It is controlled with low voltage lines unlike most swamp cooler which use a dial and line voltage so it currently operates a programmable thermostat (day/night functionality, sleep timer, high and low speed fan, and drain pump). The wires in the back of the thermostat are C, H, L, P, D, R.

  2. Heating: An old natural gas boiler for baseboard heating. Currently a two wire system with W and R, with an R-Rc jumper. No outlet nearby to supply 24V for a C so wondering if C from evap cooler would make it work.

If I cannot combine both systems on to one thermostat would it be kosher to tap a C wire from the cooling system to provide power for the Wyze thermostat to run the baseboard heat since the cooler thermostat is a mere 6 inches from one of the baseboard thermostats and in a location that would require electrical work to install an external 24V transformer for the C terminal. The other two heat thermostats are close enough to run a 24V outlet transformer to them.

Heating thermostat wires: W and R with an R-Rc jumper:

Flow control valves for the boiler, one for each of three zones controlled by an independent thermostat:

Two of the 3 electrical supplies for the boiler zones

I doubt the wyze has an option to control a swamp cooler… I’ve never run across a 24v swamp cooler like yours, so I cannot do anything but guess that its terminals are supposed to be c=common, h= high fan, l= low fan, p= pump, d= drain, r= hot (24v).
Once again, completely a guess, and I wouldn’t try any wiring without testing and verifying each function by watching the swamp cooler’s reaction to removing each wire in turn. ie: without C, the thermostat shouldn’t work, without p, the pump would never kick on, etc…

As for using it as a common wire… you’ve got aquastats, so it’s likely that you don’t have R and W, so much as TT and TTh, which don’t really have any current available to run the thermostat from. In order to run them, you could try getting both Rc and C from the swamp cooler, and connection Rh and W1 to the heating leads. Depending on the sensitivity of your aquastats, you might end up needing isolation relays to control them, with the wyze, sometimes there is a trickle of current leaking between rh and w1 and that is enough to make the heating system never turn off.

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