Circulating Coolant Heaters...???...

Jim B.

Oh yes, I forgot about the thermostat in these tank heaters (that's what we call circulating engine heaters up here in the tundra). In another post I said that these heaters have two check valves that can get stuck, causing the heater to melt hoses. That thermostat is internal to the heater and is a band-aid that is supposed to catch this failure mode, shutting off the heater in case of over heat. Yet another moving part. And since in normal use this themostat never operates, by the time it is needed it can be stuck closed too, leading to overheat and meltdown anyway. Been there, seen it happen, had to clean up the mess. With a

4-cyl engine you will be fine with a freeze plug heater. Even with a big V-8 I would go with two freeze plug heater (one on each side) and possibly an oil pan heater before I would even think about a tank heater. KISS

wes

Man you sure stress about little things....perhaps we should go back to horse and carriages :-o

The check valve and thermosat work just fine, but of course anything mechanical can break.

The > > Google is your friend.

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al use this themostat never operates, by the time it

Wes and RMH You gentlemen are talking about two different animals; Wes's tank heater depended on convection to move the heated coolant. The "in-line" heater (RMH) used steam as both the motive power and a cacarrier of heat. tank heaters had to be mounted vertically and low on the engine in order to work,sometimes convection didn't occur. To the best of my knowledge these heaters had only one "valve"- a peice of rubber across the inlet. The device was almost as dificult to install as a frost-plug heater. The in-line heater used two plastic check-valves and was meant to be mounted horizontally in one of the cab-heater hoses. The idea was to heat the coolant in the chamber till vapour pressure opened te outlet valve and sent a slug of steam and hot coolant into the water-jacket. Problems arose if the unit was installed backwards, blocking flow to th cab heater and when people used 100% glycol.

Both devices were inefficient because they operated at hig temperatures,but often they could be installed where frost-plug heaters couldn't. for more information see U.S pat. 5,408,960. Walt