Low temperature limit switch

[danjayh]

Hi guys,

I'm installing a new boiler, and I want to install a switch in the water line that will sense if the water temperature drops below ~45 degrees or so ... and when that happens, I plan to have it activate the furnace blower until the water temperature comes up. In this way, if it gets cold outside and for whatever reason my fire is out, I can use the heat in the house (which has a propane backup) to keep the boiler from freezing. Specifically, I'm thinking this would be good for when we go on vacations in case whoever is house sitting for us forgets to feed the beast its pellets .

The problem I have is that I don't seem to be able to find any cheap switches that are designed to do this (on below 45 or so, off above). Does anybody know of an appropriate switch?

(PS - for anyone who is wondering, I did buy the Maxim M175, and I ended up using Rehau's foam insualted "OWB Raupex", buried at ~2.5 feet. It seems like a good product.)

 

[danjayh]

OK, so after much searching, the closest thing I can find to what I want is this: http://www.zorotools.com/g/00062817/k-G0573185

However, it still costs $50, which is about $35-$40 more than I think it should cost to accomplish this (a full-blown electronic device just seems like overkill). Any help would be greatly appreciated. I also found a few snap-action switches, but for something that I'm strapping to copper pipe inside the house (which is what I'd probably have to do with one of those, due to the type of case they come in), I'd really like it to trip at more like 50f, and they're all in the low 40s or high 30s.

 

[R Mannino]

http://www.patriot-supply.com/products/showitem.cfm/RANCO_ETC_111000_000