Quietest stat? Relay vs triac

[stl hvac]

Which electronic thermostat would be quieter during temperature activated switching on and off-one with a relay in it or one with a triac? Any advantages to one over the other? Thanks

[tpa-fl]

Triacs are 100% electronic, therefore silent, while relays make a clicking noise. The larger/more durable the relay, usually the louder the click. The downside to triacs is that they do tend to fail rather easily, to the point that I wouldn't recommend using them. In the case of recording & radio studios, I'll throw a remote temp sensor in the studio and the relay-driven stat in the hallway or other non-sound critcal room.