Very interesting. Not completely clear how that ThermGuard device works. I have 3 thermostats and zone valves so sort of ruled out the idea of having to use three ThermGuards.
Now you seem to be suggesting you could use just one TG (and 1? additional relay). When I installed the zone valves I just followed the schematic on the taco box -- didn't really try to figure it out so not sure how this would work with them and the controller on the boiler.
Main question about the TG is do you use it manually only (i.e. turn it off and on when you need it) or is there some way to control it by sensing the outside temp/and/or can it be turned on remotely?
Okay lets assume it's manual only. I turn it on when I see the temp getting into the single digits. Will it run with the tstat (both could be on) or above the tstat -- when it's on, the tstat is overriden, or will the tstat override the TG when the tstat is calling for heat. Or prolly that doesn't really matter, when either is on all switches will be closed for the zone. Just not sure how to wire it, with the zone valves.
As far as disabling the coil, that may end up too complicated, not sure if your schematic would apply without disabling the coil. So am assuming if using one TG, you could put it near the heater and zone valves to simplify wiring, but then you'd have to go to the heater room to turn it on and off.
Was trying to look up the relay but unfortunately I'd have to key it in-- no way to copy and paste the picture -- and haven't gotten around to it yet. But more important, if there's a link to the user instructions for the TG that might be helpful.
Hi Dave,
That is correct. If you are handy, a simple connection between a ThermGuard and a relay could activate as many as 4 zones simultaneously....3 zones if you wanted to inhibit the ignitor. The idea has been floated to make the ThermGuard outside air temperature controlled, but the variations to meet everyone's needs got too cumbersome. For now, you can just turn ot off when aren't concerned about your pipes freezing.
There is non-volatile storage in the ThermGuard that remembers your programming of interval and duration. So when needed, all you have to do is turn it on and you are ready to go.
Normally, when you use one ThermGuard per thermostat, the thermostat overrides the ThermGuard. That is to say, if the thermostat calls for heat, the ThermGuard goes to sleep and doesn't start timing until the call for heat is met...or... if the thermostat is turned off, the ThermGuard overrides the thermostat and calls for heat periodically to keep the pipes from freezing.
Another question you had was the location of installation. ThermGuard can be installed in the boiler room or at the thermostat.
With regard to the coil, I was really thinking that the circuit interruption could occur on the 24VAC side, rather than the high voltage ignition side. You could basically interrupt one of the signals that is used to enable the ignition. My boiler has for instance: 1) fan proving switch 2) blowout detector 3) over temp sensor. Each of these go into a serial chain and when all are good, the ignitor starts. If you interrupt anywhere in the chain, the ignitor will be disabled and the circulator motor will run and fuel will not be burned.
Of course, if you trade off the inconvenience of interrupting the ignitor vs the small amount of fuel that would be used....say 3 minutes every couple of hours, it may not be worth it.
Here is a link to the relay
(broken link removed)
Here is a link to the ThermGuard installation instructions:
http://www.bearmountaindesign.com/tg_installation_Hot_Water.htm
Here is a link to the ThermGuard programming instructions:
http://www.bearmountaindesign.com/tg_programming_hot_water.htm
This is a great discussion, thanks for your considered questions.
John