I have home built in 1988 with zoned in floor heat, heated by a boiler.
The current set up uses 2-wire thermostat wire with old mercury switches. You turn up the thermostat and the mercury completes the circuit. This then opens the zone valve for that zone which when opened triggers the circulating pump and the boiler to fire.
The 2-wire thermostat wire is very limiting for smart thermostats and running new wire isn’t really an option since the basement is 100% finished and some of the runs are upstairs on the opposite side of the house.
My first thought was to just abandoned the current thermostats and wire up new ones right in the room where my boiler and the zone valves are. Then use temperature sensors in each zone to control the new thermostats. This still requires the purchase of 5 new smart thermostats though.
So then I thought what if I skip the thermostats all together. If I could get smart zone valves I could set up automation using the temperature sensors to just open or close each zone valve based on the temperature sensors.
However I’m struggling to find smart zone vales. I find many that are for sprinklers or that are designed to turn a ball valve of some sort. What I need is a real zone valve that when turned triggers the circulating pump and boiler.
Or is there a better easier 3rd option I’m not thinking of?
I’ll also mentioned I’m in the upper midwest, USA.