View Full Version : honeywell t-stat
04-30-2009, 01:32 PM
i have a honeywell pnuematic t-stat, when set temp and desired air temp match i get a very high pitch noise. do i replace or can i clean one of the air ports in it.
04-30-2009, 02:15 PM
Basically if you have to ask that question replace it !
After you replace it be sure to calibrate the t-stat.
They can be field rebuilt but it's not worth the time unless you're going to do 6-10 of them at once. Requires "Special Knowledge" if you know what I mean.
You may also have valve problems that could cause the "noise" ! Investigate more.
04-30-2009, 07:02 PM
Plug the BRANCH line and see if you get the NOISE when setpoint and ambient temp match ( basically 9 psi ).
If no more noise , check the branch line / device for damage , had 1 HVAC tech with " SPECIAL KNOWLEDGE " change out a TSTAT 3 times before checking and finding a leak on the branchline that caused a squeal when branch pressure built up above 9 PSI.
05-01-2009, 03:20 PM
will do i replaced it but i just did not want to throw it away with out investigating the why.
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