thermo snap switch won't turn blower on

18 years ago

I just installed a lennox fbk 250 blower kit in my gas fireplace. the thermosnap switch won't turn on the blower. i thought the switch was malfunctioning so i placed a lighter flame on it and the thermo snap switch did turn on the blower. however when i adjust the switch to touch the bottom of the firebox, it seems the bottom is very warm but not hot to the point i cannot keep my hands on it. it seems the bottom of the firebox is not getting hot enough to activate the thermoswitch. this is after 1-2 hrs of the gas fireplace being on. does the fireplace burner need to be adjusted so the bottom gets hot enough? what type of adjustments can be made? the flame pattern seems to be ok as per the instruction manual. it is set to high on the flame height. sorry for the long explaination. any help is appreciated.

Comments (6)

mountainstoveguy
18 years ago
Are you absoluty shure that you have the disc in the proper location in the firebox? If yes, then make shure the disc is good. Just because it turns on with a lighter doesnt mean that its good. A defective one, or a old one that is worn, can turn on at a much higher temp then designed. Your lighter is a much higher temp then is designed. I doubt very seriously your flame needs any adjustment. Its got to be in the switch or the location of the switch.
jca1
18 years ago
Check the clip that holds the fan switch in place, make sure it tightly pins the swith to the firebox. I will say that in my experience the top of the box is a much better location for the switch. I don't know why everyone dosen't design them that way.
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Macey
18 years ago
What specfic model fireplace is it?
den110
Original Author
18 years ago
My fireplace is a Superior B vent 800 model. The blower kit is a Lennox FBK 250 that has a variable fan speed controller box with a thermosnap switch mounted on the top. The thermosnap is raised to touch metal plate via loosening a wingnut and raising the switch. the metal plate covers the entire bottom of the actual firebox and is about 1-2 inches below the actual firebox. I tried to move the thermo snap switch around different areas of the metal plate. It seems the metal plate is very warm to the touch but not so that I cannot keep my hands on it. I contacted a HVAC dealer who called Lennox and explained my problem. Lennox feels that the thermo snap might be defective. They claim that it is rated to turn on at approx. 100 degrees. How warm is that? Sorry for the long post....
mountainstoveguy
18 years ago
well, 100 degrees is slightly warmer then you body temp, so it would feel warm to the touch.
Macey
18 years ago
The snap switch may be bad. However, since the specific model fireplace you have is a decorative B-Vent fireplace and not a heater rated direct vent fireplace, it simply is not going to produce the heat you are probobly expecting. In any event, make sure the snap switch is installed exactly in the location Lennox says. In the end, if you really want a fan, you may have to go to manual FBK100 on off version.