Vaporstat Question

LPGasman

I have a Peerless SC/SVT steam boiler It came factory equipped with a Honeywell PA404A pressuretrol ,indicator on front is set at 1/2 lb. no matter where the differential is set burner won't shut off till Gauge hit 3psi minimum. Boiler is 6 months old, pigtail is clear water level 1/2 way in gauge glass. the PA404 is mounted on a pigtail on top of the MM67
LWCO, some say it should be mounted higher above the water level. Some say install a vaporstat in place of the Pa404. System is 2 pipe . Looking for input

KC_Jones

Do you have a good low pressure gauge on the boiler or are you seeing 3 PSI on the 0-30 PSI gauge?

BobC

Pressuretrols have zero quality control at the bottom of the scale so they can be wildly inaccurate. Is the inside dial set to 1 or less?

If your going to try and calbrate it I suggest you add a 0-3PSI gauge beside the pressuretrol so you can see what is going on. One of our members came up with a method to calibrate pressuretrols -

http://forum.heatinghelp.com/discussion/149944/i-figured-out-how-to-calibrate-a-pressuretrol

Mounting a pressuretrol higher is good practice but it does nothing for it's accuracy.

Bob

Jamie Hall

A pressuretrol can be calibrated to turn off at 1.5 and back on a 0.5, but it may take some fussing. Try that first.

LPGasman

I tried the differential dial in various position with little change. So any opinion as to which vaporstat I would need?

KC_Jones

What type of gauge are you verifying the pressure with? the 0-30 that came on the boiler or something with a much lower scale like 0-3 or 0-5? This does matter.

Fred

Follow the recalibration procedure. It is simple and will take care of the issue. As has been said by KC, you need to have a 0-3 PSI gauge on the boiler for accuracy and for future monitoring of what your system is actually doing and as Jamie said, calibration is a little fussy but not that bad. Just make very minor adjustments using the hex screw.

New England SteamWorks

I am with Fred and KC_Jones. Vaporstats aren't cheap and your pressuretrol might be all right. What you need first is an accurate low-pressure gauge. Install, then get back to us.

Dave in QCA

When I was using a pressuretrol I was able to get it to operate at a low setting, but of course, not by using the scale. I turned the differential as low it would go. Then I turned the adjustment as low as it would go, right to the point to where the linkage started to get sloppy like it was going to fall apart. I ran the boiler long enough for it to shut off on pressure. Then, it would not restart. I adjusted the pressure just until the boiler restarted, then about a quarter turn more. This seemed to give a good operating point, shutting off at 1.5 psi and back on about .5 psi.