Sail Switch?

[APR]

Hi I have a 28' BHBE. How do I determine if my sail switch is bad on my furnace?
Thank you I appreciate your help

[Marcm157]

What are the symptoms the furnace is exhibiting?

[Marcm157]

The only true way to diagnose a sail switch failure is to open the furnace and do some checking both physical and with a multi meter. In the 28BHBE that I had the furnace had to be removed from its installed location to access the switch.

[APR]

Im getting gas to it and it tries to light I think. I hear it clicking, so I assume it's trying to light. I also smell gas coming out of the exhaust which I assume is normal when it does not light up?

[APR]

Yes I have to remove it. Its located under the refri. It does not look to difficult

[Marcm157]

If you are getting gas then it's not your sail switch. If the switch was bad you would get blower and then shut down. The fact that you get a gas smell says that the 12 volts is making it past the sail switch, past the high limit switch and to the gas valve.

I would look towards an igniter, or flame sensor.

When I removed my furnace for maintenance from my BHBE, I cut the power, ground and signal wires and added wago connectors to make future removals easier.

[JimD]

Agree with last post. It is not your sail switch if you are smelling gas. The click you may be hearing could be the gas valve opening, which is why you smell gas. You should be getting a spark ignition at the same time. Sounds like that is the area of concern.

What model furnace do you have? Most often you can download a manual for it that will have a troubleshooting section.

I have attached a guide that may give some insight as to what is going on.

[ARoamer]

Had the sail fail fault 4 nights ago, 30 seconds of blower, no flame. 1 led flash, 3 sec pause on circuit board. Switch was clean, tested good in hand with ohm meter. Reinstalled, worked 1 night, faulted again. Looked closer and metal sail was touching the plastic mounting bracket and not depressing switch button enough to make the circuit. Got needlenose pliers and bent the sail to depress the button fully and clear the plasitc mounting bracket. Been OK since. Makes me wonder who designs these things...

[jetlag]

Originally Posted by ARoamer

Had the sail fail fault 4 nights ago, 30 seconds of blower, no flame. 1 led flash, 3 sec pause on circuit board. Switch was clean, tested good in hand with ohm meter. Reinstalled, worked 1 night, faulted again. Looked closer and metal sail was touching the plastic mounting bracket and not depressing switch button enough to make the circuit. Got needlenose pliers and bent the sail to depress the button fully and clear the plasitc mounting bracket. Been OK since. Makes me wonder who designs these things...

I have a new "improved" sail switch on mine. Just got it a week or so ago from our dealer All they did was file down, remove, that area you mention where it was making contact with the mounting bracket. I actually saw a YouTube video where some guy did just that, filed his. The instructions were specific, and said to use all the new parts, and not just replace the sail switch. Now we know why.

[ARoamer]

With all of the sail switch failures, it makes me wonder how many have actually failed vs the metal sail arm not properly operating the switch. Yes, dirt may cause premature failures, but I'm thinking this is mostly a poor design problem.
From a manufacturer of chineesium micro switches-
>>For example, a micro switch rating is “UL/CUL 5A 125VAC”, the mechanical life is 500,000 cycles and electrical life is 100,000 cycles. If it is in 4A 110VAC rating, the electrical life will over 100,000 cycles but less than 500,000 cycles.<<

[jetlag]

Originally Posted by ARoamer

With all of the sail switch failures, it makes me wonder how many have actually failed vs the metal sail arm not properly operating the switch. Yes, dirt may cause premature failures, but I'm thinking this is mostly a poor design problem.
From a manufacturer of chineesium micro switches-
>>For example, a micro switch rating is “UL/CUL 5A 125VAC”, the mechanical life is 500,000 cycles and electrical life is 100,000 cycles. If it is in 4A 110VAC rating, the electrical life will over 100,000 cycles but less than 500,000 cycles.<<

I agree completely, and I am not well versed in sail switches. The new one from the dealer came in and I would have never known anything was different until I stumbled on the video, and then read the instructions on this new one. I kept the old one anyway, as there is nothing wrong with it.
Got to love our site, and how we learn!!

[JimD]

Originally Posted by ARoamer

With all of the sail switch failures, it makes me wonder how many have actually failed vs the metal sail arm not properly operating the switch. Yes, dirt may cause premature failures, but I'm thinking this is mostly a poor design problem.
From a manufacturer of chineesium micro switches-
>>For example, a micro switch rating is “UL/CUL 5A 125VAC”, the mechanical life is 500,000 cycles and electrical life is 100,000 cycles. If it is in 4A 110VAC rating, the electrical life will over 100,000 cycles but less than 500,000 cycles.<<

Agree. The one and only time I had to deal with a sail switch not working was due to dirt buildup. The sail was binding on its pivot and the switch plunger was a bit gummed up. As usual, good old WD40 came to the rescue and everything was freed up.

As a tech who has worked with many micro switches over the years I can say they are very reliable. From what I observed, switch failures were not due to reaching their cycle limit. More often it was either due to very low current being switched or current that was at the upper limit of the switch. The contacts can become resistive after time if very low current is being switched. With the high current, the contacts can arc and get burnt somewhat causing poor contact.