[kwlug-disc] winter and furnace

[William Park]

On 2026-02-09 14:54, Mikalai Birukou via kwlug-disc wrote:
> 
>> There are these little pipes that go between enclosed area in furnace
>> and membrane switches to detect presence of pressure difference between
>> normal/room and that enclosed area with air/fumes flow.
>>
>> Other season, there was a burned ash in one of pipes, after burner, I
>> suppose.
>>
>> One more season, I gently blew in and out of pipe into membrane switch
>> to hear it flip. It got unstuck, and continued proper operation.
>>
>> This season, a pipe had a drop of water in it. Surface tension in a
>> small radius obvious stopped pressure difference from pushing membrane.
>>
>> I guess, cleanup includes dusting furnace, and blowing through some
>> pipes. :) Noting that three events happened over 15 years.
> 
> Better word, little tubes, rubbery tubes few millimeters in diameter.
> Not pipes.

Where is this "tube"?  What does membrane switch do?