universal pressure switch ns2

[oldguy2]

any body know what orifice restrictor peg your suppose to use. or what diameter opening it is. stucco universal pressure switch or if your even suppose to use them. oem pressure switches have them in their factory pressure switches but if I use a universal switch what orifice thingy do you use say for a .65wc

[Admin]

I've never used a universal pressure switch, but I found the installation instructions for the Roberstshaw 2374-510 kit - Here

If you're replacing a single pressure switch designed to shut off the burners when the ventor motor fails you don't need to use the orifice, just use the correct spring.  The Natural colored spring would be used for a .65" w.c. rating.  Some furnaces might also have a high pressure switch that could require delayed switching action.  If that's the case you would use the orifice, but I'm not sure how you know what the orifice size is.  I've never tried to remove one before, but maybe you can remove the old orifice and try to match it up.  The kit comes with 4 different sized orifices, and they give you 2 of each size.  The manual says to use the matching orifice with your manometer to calibrate the set point.

Note that the measuring device and the air switch must both contain the same size restricting orifice in order to obtain an accurate measurement of the set point.

[oldguy2]

I heard there was a huge problem with pressure switches a few years back. all furnace brands had problems. wholesale place says they fixed the pressure switches.so all we are doing is replacing crap for crap. i heard that some guys are using the universal pressure switch in stead with no problems later on

[Admin]

I remember hearing something about "out gassing" that causes pressure switches to trip.  It was caused by a reaction between the rubber diaphragm and metal casing.

I've been replacing alot of Carrier 58MCB pressure switches for code 31 lockouts.  Carrier has made a new replacement switch.

Also the new Carrier 35" furnaces, 59SC5A, 59SP5A, have been also causing alot of code 31 lockouts.  They released a bulletin saying you can't hook the AC drain into the furnace air vent drain tee unless you leave an air gap.  They also told me to use a 3/16" drill bit to enlarge the high pressure switch tubing port on the ventor motor to prevent water droplets from impeding the air flow into the HPS.  These fixes seem to be working.

That universal pressure switch kit has CSA certification, so it should be okay to use them.