Pressuretrol Calibration

dabrakeman

Had a question on an earlier thread posted by Fred. Relative to the instructions below what is meant by a 1/32" turn. Is 1/32 of a rotation meant?

Reason: On recoveries my system had been reaching ~3.5psi even though the differential dial was set on one and the cut in at lowest setting (0.5). I made based upon the advise a small adjustment of about a little less than a quarter turn and it seemed to bring the displayed max pressure on recoveries down to just under 3psi. I had an "annual inspection" from my installation company this Wednesday and mentioned the fact that it seems when set as it is it should cutout closer to 1.5psi or 2psi. After cleaning the pigtail the technician ran a cycle and as the pressure was rising past 2psi he adjusted the screw until it shut the burners off. I guess he turned it a good 1-1.5 rotations clockwise (I figured he knewe what he was doing). I didn't witness any issues the next and the house heated fine. Friday evening the house starts getting cold and I go down and see the boiler off even though the stat is calling for heat and everything is getting power. Why the issue didn't arise immediately the morning after the adjustment I don't know but bottom line it appears the screw was way over adjusted. I think I have it adjusted back better now but given the delay in the issue last time I will wait a few days to make judgment. The reason for this post is simply to get a clarification on the 1/32" instructions in case others try to make this adjustment. So, should be short thread.

From Fred's previous post:

Most of us use a 3PSI gauge from WIKI. The supply link is below. I would first check the Pigtail (looped pipe) the Pressuretrol is mounted to. They often get clogged andd the Pressuretrol can't sense the actual presure. Take it off and clean it out good. If that doesn't bring the Pressuretrol into a reasonable range, following is the procedure to recalibrate it:
Inside the Pressuretrol, right below the micro switch, there is a pivot arm. At the end of that arm you will see a screw pin that is activated by the diaphragm at the bottom of the Pressuretrol. If you look very carefully at that screw pin, you will see it actually has a tiny (I mean tiny) hex head on it. It takes a .050 hex wrench and you can turn it clockwise (Towards the bottom of the Pressuretrol to decrease the Cut-out pressure or counter clockwise to increase the cut-out pressure (which none of us want to do but who knows, your Pressuretrol may be really screwed up!). Turn the power to the unit off first. You may find the first attempt to turn that screw a little bit stubborn (relatively speaking) because it has some Locktite on it but it does turn. Don't turn too much, a fraction of a turn goes a long way towards getting it adjusted where you want it (maybe 1/32 inch turn to start with). You may need to play with it to get it exactly where you want cut out to be.

Fred

@dabrakeman Yes, turn that screw in very very small increments and test the cut-out each time. A very small amount of turn goes a long, long way, as you have learned. fortunately, the fix is simple. Start turning it back until you get the calibration right.

Tezak

@dabrakeman @Fred I’m trying this now and the screw pin is really stuck. I’ve used a soldering iron attempting to melt off the loctite but I can only reach the one side. I’m afraid I’m going to strip it. Any advice?

EdTheHeaterMan

Purchase a new pressure control. Since this thread is from 2015, perhaps you can get lower prices from 2015 from the supply house. Just tell then the Ed the Heater Man said it's OK!

These prices are way to high!

Tezak

That’s plan B. I might hit it with a solvent and some more heat after I put the kids to bed though. Not ready to throw in the towel.

dabrakeman

@Tezak Sorry didn't see this. Were you successful? Hopefully you have a good fitting jeweler's screwdriver. I didn't have much problem breaking mine loose. If you are resigned already to getting a new pressuretrol I guess you have little to lose giving it a good twist with some local heat. If you do get it loose do some test runs after each incremental change to verify not only cutout but also cut in. I got mine stabilized just over 1.5psi cutout. Right at 1.5psi cutout it wouldn't cut back in with the dial right at 1.

Tezak

@dabrakeman i was not able to break it loose with the hex key but I cleaned the pigtail which was ridiculously clogged. Should have been my first step, I know. The pressuretrol works now but I don’t think it’s accurate. I’m installing a new brass pigtail with a low pressure gage soon so I can see exactly what’s happening and then I will reassess. Thanks for the reply!

109A_5

I've seen a post or a video somewhere that someone just bent the tab on the actuator linkage that pushes on the microswitches actuator very slightly. I'd find out what it is actually doing first, now that the pigtail is clear.

Jamie Hall

I guess I come from a different school. My approach is to have a nice low pressure gauge on the system, and then adjust the pressuretrol or vapourstat so that it trips when the pressure gauge says what I want it to. If the markings on the pressuretrolnagree, so much the better. Otherwise, who cares?

I do the same thing with thermostats. Am I warm enough? The number on the thermostat is a matter of curiosity…