honeywell t-stat

[justtrying]

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.

[Cagey57]

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.

[Control Man]

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.

[justtrying]

will do i replaced it but i just did not want to throw it away with out investigating the why.