WMO Safety Switch Not Working

I have a Reading Allegheny Stoker. I am hooked up to a SWG Powerventer from Leisure Line. I placed the WMO safety switch directly below the feed tray . I am thinking that it is possibly to low because today I attempted to test the switch and could not get it to trip by turning off the powerventer. I turned off the powerventer a number of times and waited 10 + minutes with no trip. I could not feel any hot air coming out from around the tube on the safety switch and could actually hold onto the tube without discomfort. This was while the stove was at full power. I went outside and felt around the powervent and I believe it was creating its own draft because with the powerventer off it had a good amount of heat coming out. I was able to trip the switch by placing a heat gun blowing hot air by the intake on the switch and the switch tripped so I am thinking the switch isnt faulty. My question is where do people mount there switch on thier stove and where does Reading mount it on this stove when you send it back to them for factory installation. Thanks!

on my keystoker, it mounted on the back approx. horizontal from the burn plate, about 1/2 up the back of the stove.

Yes, the stove itself will draw some of the hot fumes out if it fails, but should work fine if there is a blockage, the heat will migrate out of the tube to the switch and trip the stove. Your stove is under a vacuum, as long as the heat has a place to go out the exhaust, it may not get that hot to trip it. It has to get like 200 degrees before it will trip the stove off. You exhaust usually isn't much hotter than that. If you tripped it with a heat gun, you should be be good. It is working.

Here a back veiw of an older keystoker, you can see the Flue switch right next to the burner on the left. Mine is actually on the right where the convection fan blower control is.

Common Stoker Terminology

On my Koker the safety fume switch is pretty much even with the burning coals (measured from the back of the furnace) and about 3" below them.
You can see it on the side of the furnace in the attached photo.
I hope this is some help to you.
-Len

By the way, I forgot to add, the Koker uses the Field Controls model WMO-1 200 Blocked Vent Switch
-Len

Thanks guys. I figured that if there was a blockage that the switch would deffinitly trip. I placed a magnetic thermometer on the pipe just before it goes into the powerventer pipe and it never got more then 170. The outer pipe on the double wall pipe that goes through the wall would get hot after about 10 minutes but I could not get a reading on it since the magnet doesnt stick to stainless. I was just worried that if the powerventer motor failed that pipe that goes through the wall only one inch from the combustables in the wall would get hot.

It sounds like your house, prevailing wind, PV piping combination is providing some natural draft.. without this natural draft,, I believe your WMO switch will trip within a few minutes..

You could try your experiment with turning off the PV to test the WMO switch,, then turn on the clothes dryer, bathroom and kitchen exhaust fans.. and see if you can reverse the flow... Just be ready to turn on the PV !! You don't want the room to full with CO or sulphur fumes..

Greg L

I will try that and see if I can reverse it. I need to get a IR thermometer so I can get a look and see how hot that double wall pipe actually gets. It probably doesnt get as hot as I think. It would be a good piece of mind. What does everyone get for temps just before the vent pipe enters the powerventer? I was getting 170 after 20 minutes of running without the venter and that was with the stove at full power.

I use double wall pipe with my direct vent, it gets maybe 200 on the inside (with a probe), I can put my hand and hold it for a while on the outside. It doens't get that hot.

Another questions I have is about my SWG powerventer. Does anybody have the browninsh yellow oil on the outsides fins of the venter? It has somewhat coated that fins and pools up on the edge of the fin. Just lube oil from the venter motor?

Thought I'd mention the infra red thermometers don't work so well of stuff that reflects, like chrome, stainless, galvanized pipe.

Humm, well what is a good way to get the temp of that outer pipe?