Testing Honeywell Pressuretrols (with custom rig)

Gordo has several clips on there now- check them out.

Please do test your pressuretrols, we are finding that most of them are turning out to be way off.

i agree Gordo, i too have found most pressuretrols as well as vaporstats to be totally hosed right out of the box.

Mine is set all the way down to 0.5 with 1 cut out but it trips at 1.9 PSI.

@Fred Thank you, I'll make sure to try it.

Speaking of Honeywell micro switches, I wonder if these will make good replacements for the ones in the Pressuretrols.

http://www.goldmine-elec-products.com/prodinfo.asp?number=G21289

It looks more like the one in my pool heat-pump, but it might work.

@Fred Thanks for your posts on calibrating the Pressuretrol. A year or two before I saw your earlier post on the subject, I tried a different approach--changing the tension spring normally used to adjust the cut-in pressure to a compression spring. (On two Pressuretrols I did this to, the cut-out was too high--almost 2 psi--even when the spring for adjusting the cut-in pressure was removed and the differential set to the minimum.

With the setup shown, I could get the cut-out pressure down to about 1.2 psi, but the set-up was touchy. Removing and replacing the Pressuretrol would throw off the calibration.



So after seeing Gordo's post, I decided to try the procedure you described while checking the results with my own version of Gordo's testing rig. With the thread locker used on these things, I could not turn the adjustment screw without fearing I would break the Allen wrench or strip the screw. I found that if I applied some heat near the screw pin with a soldering iron (removing it when I saw or smelled smoke) I could then turn the screw, but still with a lot of effort.



The result was that I could get the cut-out pressure down to 1 to 1.1. psi with a cut-in about 0.2 psi. (I was trying to minimize the cut-out pressure, not calibrate to the scale).

I did this on three Pressuretrols. I couldn't get the pressure down quite as low on the third one because the minimum differential was about 1.5 psi, not 1 psi as shown on the switch. In any case, I'll be using the two others this winter.

I know a lot of people have commented on how inaccurate Pressuretrols are. I don't disagree, but the ones I've checked are very precise (repeatable.) The cut-out and cut-in pressures don't seem to vary by more than about an inch of water from cycle to cycle even if the actual values don't match the indicator. (Using Gordo's testing rig shows this.) So I am not worried that mine won't cut back in after cutting out. But I'll find out for sure in a few months.

I don't want to screw up everybody's fun but just want to point out that your fooling with a safety control. If somebody's boiler blows up with a monkeyed pressure control the insurance company will bail out.

That being said, they won't care if the factory settings aren't accurate.

Believe me I KNOW your just trying to make things better and more accurate.

My suggestion is two controls with the "back up" being a factory set control that hasen't had any modifications.

Everybody remembers the old boiler programmers with the vacuum tubes.

If they failed the first thing the insurance company looked at was if it had a factory tube in it. If it was a generic Sylvania or RCA they would bail

@Jamie Hall ,
HAHA most people are afraid to agree with me lol.

I agree. I hesitate to point out the legal issues as I am sure all the professionals here realize what they are doing. I fear that we could send the wrong message to homeowners and others that playing with safety controls is ok to do when we all know that it "could" have serious ramifications. That's why people have licenses.

we are all trying to do the right thing.

And your exactly right,
. Who cares what the scale says?

I think you're totally missing the point @EBEBRATT-Ed and @Jamie Hall. I have gone on service calls where the boiler is short cycling. I tested the pressuretrol (or vaporstat) to find they're cutting out too low, some at less than an ounce! Your theory of leaving one factor set would therefore not solve this particular issue. All pressuretrols and vaporstats should be checked by installers and field calibrated. If anything, it's a safer measure to take for your customer and your company.

So are there manufacture's approved published guidelines to do field calibrations on these controls? If not, I would leave at least one or two high limit safeties in its original state and perhaps tinker with the controlling device.

From a former expert witness' perspective, the boiler NOT turning on can do more damage than one that didn't shut off...

Frozen and broken pipes generate the highest annual insurance loss claims factor of any potential revenue losses.

Trust me, the insurance companies lawyers WOULD look at everything controlling these systems. Remember, they are looking for a reason to NOT pay out on a claim.

Been there, seen that, won't be doing it again...

Proceed with extreme caution and remember, there are many people who use your advice that don't even bother to comment here...

ME

Gordo said:

Oh, and one more thing:

All the "accuracy" and "precision" of any pressure control is totally meaningless if the friggin' pigtail is clogged, ain't it?

And I am lookin' at YOU, my local utility's captive service arm!

I'm still trying to find out why a pigtail is even necessary. They seem to do nothing more than cause headaches and even dangerous situations. My 18" long 1/2" vertical pipe can't clog, nothing ever gets up that high. I don't even get water or moisture in my gauges anymore and with the magnehelic I'd notice it. I suppose one fear would be if it ever gets a leak, steam will destroy the controls, but at the same time, a clogged pigtail is far more likely and just as dangerous.


These are from before I swapped in the 0 - 2" Magnehelic, but it shows what I did. It uses air to block the steam rather than water and honestly, the pipe stays cold about 6 inches above the boiler.

I still kept the code required pigtail + Pressuretrol + 30 PSIG gauge of course, but all of my controls that I actually care about are on the commando setup. A snubber was required for working with the 2" WC switch and magnehelic.

First, let me say I respect the opinions that have been offered up on this thread. I, for one am puzzled by the fact that Honeywell, who has manufactured these Pressuretrols for probably close to a century has no "Cautions" or "Warnings" on these devices that might say "No field adjustments can be made, except for the Cut-in scale and Differential wheel."
How many products do we buy that have caution and warnings all over the packaging and device/appliance that say "Do not attempt any field repairs to this equipment" or "All repairs must be made by an authorized servicing agent" Or "Return to dealer for repairs/adjustments" ?
I am sure if Honeywell thought this was a significant liability, they would have such language on the box, device and literature, pack with the equipment. Heck, when we buy a step ladder, it barely needs paint because all the "Caution" labels cover most of the ladder. I also suspect that Honeywell probably has service bulletins for their distributors that advise them how to calibrate these devices rather than return them to the factory. I guess we need to ask a Distributor. In any case, I am sure that any that do get returned to Honeywell for calibration follow the same process on their bench as has been outlined here, except they do it with bench equipment that also needs calibration. If Honeywell did not intend for these devices to be calibrated, they certainly could have used a rivet or some other pin that did not facilitate adjusting, like the hex head screw they use. In any case, I don't believe, when we don't have sound reasons for something that we should just say "The insurance Companies will get you" If they go after anyone, it would be Honeywell for not specifying that no field calibration should be attempted. Given they say nothing doesn't make the HO or Pro liable for an adjustment they accommodate, by design.
Having said that, I agree, everyone should be as objective as possible about their own skills and if they do not feel comfortable attempting these adjustments, they should leave it to a Pro.
@ChrisJ , I'm sure their are those who would say mounting your devices on top of the PRV is outside what any Boiler instructions advise and it may in fact be a code violation. I, understand what you have done but I for one prefer to have a pigtail, with water in it than a stand pipe that may or may not leak air and potentially damage the devices, even though I have to clean it annually, but, that's just my preference.

I haven't eliminated it, but I do run the pigtail dry.

Fred said:

@chris, my Vaporstat and my usable gauge are actually on a separete pigtail. Like I said, That's my preference. I can see a water leak from the pigtail or the fittings around these devices much easier than I can see/hear and air leak. It's all good if your local code allows that set up and if Weil Mclain doesn't have a problem with it. I certainly don't. I just offered my opinion as to my preferences, as you so often do.

You don't need to see an air leak, it's easy.
Touch the pipe, is it hot? If so and towards the controls, you've got a leak.

You may be able to see a water leak, but you can't see a clog when you're in bed.


Absolutely you're entitled to your opinion, even if it's wrong.