Testing Honeywell Pressuretrols (with custom rig)

Gordo

Here is a link to a YouTube clip of a custom rig for testing Honeywell Pressuretrols. If you have any questions, please ask!

https://www.youtube.com/watch?v=3vceuKfVg9w

Steamhead

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

Chris_L

This is great!

Gordo, is that squeeze bulb from a blood pressure monitor?

You've got me thinking that I can re-purpose an old blood pressure tester (without the cuff, of course) to check my own pressuretrols.

Gordo

@Chris_L : It is indeed the same type of squeeze bulb from an old style sphygmomanometer to be sure, but I got that particular one from a controls supply house that sells pneumatic hvac control testing equipment.

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

ChrisJ

See, that squeeze bulb is grossly oversized and it's causing short cycling!

gerry gill

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.

Chris_L

Thanks Gordo.

Here is my homeowner's version of your pro setup--made with a sphygmomanometer and some spare fittings.

The pressuretrol is one I found on the street from a boiler that was being removed. The cut-out wasn't bad--1.55 psi with the cut-in set at 0.5 and the differential sat at the minimum (1 psi). But it didn't actually cut in until about 0.2 psi.

For anyone who wants to try this, it would be better to use a low pressure gauge or a manometer than the gauge that comes with a sphygmomanometer if you want to measure below about 0.5 psi. Those gauges typically only read down to 20 mmHg (0.4 psi)

(Remember, you want your steam pressure to be less than your blood pressure.)

Gordo

Here is a clip of what Mr. Gill is talking about.
The setting on the control is 2psi, and it goes to nearly 3psi before it triggers. And this is the safety control.

https://www.youtube.com/watch?v=mwLNeDeYW64

BobC

I suspect they just test them to be sure they trip below 15 psi - that is if they test them at all.

The mercury bulb models were always pretty good.

Bob

Gordo

@BobC: The old Hg bulb pressure controls were easy to see when they cycled, to be sure. And the older ones did seem to work better, overall.

The one good thing about the new micro-switch vaporstats is they are much easier to adjust. It would be nice if the factory did it instead of us, because you void the warranty if you do.

I wonder if that is their plan all along...

Gordo

Here is a better overall view of the tester:

https://www.youtube.com/watch?v=mE1-QuUx4_c

RomanGK_26986764589

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

Fred

RomanGK_26986764589 said:

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

You can fine tune/adjust the Pressuretrol by following this procedure:
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.

RomanGK_26986764589

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

ChrisJ

There's a good chance 0.5 to 1 PSI is going to cause that model to not want to reset after it trips.

For pressures that low you should really be using 4 PSI Vaporstat, not a 15 PSI control in my opinion.

Hap_Hazzard

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.

BobC

I've bought stuff from them before. For $3 it's worth a try, just be aware they charge a bit for shipping.

Bob

Gordo

@ChrisJ : It sure does indeed happen that the Moneywell PA404A will not reliably reset when the pressure drops back, if you try to operate it at a cut-in much below 0.5 psi.

A few cycles on the "healing bench" as shown above will test it out, however.

They seem to be reasonably reliable at a tested cut-in of 0.5 psi. But you are certainly right to point out that is the bleeding edge of the control.

However, the 4 psi vaporstat has issues, too.

I have found in the past with the old Hg units that even the 4 psi vaporstat did not reset if you went to 1/2 psi! Really, really was annoying! I remember having to fiddle with the wires that went to the mercury bulb and lay them "just so" to get it to work right. Fun times.

I have not tested a non-Hg 4 psi vaporstat yet.

ChrisJ

Gordo said:

@ChrisJ : It sure does indeed happen that the Moneywell PA404A will not reliably reset when the pressure drops back, if you try to operate it at a cut-in much below 0.5 psi.

A few cycles on the "healing bench" as shown above will test it out, however.

They seem to be reasonably reliable at a tested cut-in of 0.5 psi. But you are certainly right to point out that is the bleeding edge of the control.

However, the 4 psi vaporstat has issues, too.

I have found in the past with the old Hg units that even the 4 psi vaporstat did not reset if you went to 1/2 psi! Really, really was annoying! I remember having to fiddle with the wires that went to the mercury bulb and lay them "just so" to get it to work right. Fun times.

I have not tested a non-Hg 4 psi vaporstat yet.

@Gordo I hope you understand my comment was directed towards RomanGK and not you. I'm sure you came across that problem before I even knew what a Pressuretrol was.

I'm surprised the 4 PSI Vaporstats also have it, that's disappointing!

Though I still feel using the burner to limit pressure and using the Pressuretrol as an emergency cutoff is the way to go but we've had many of those threads already.

Chris_L

@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.

LionA29

Thank you, I'm trying to calibrate mine!

EBEBRATT-Ed

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

I'm afraid I find myself agreeing with @EBEBRATT-Ed here -- at least one of the pressuretrols really should be left as it came from the factory, for liability purposes. And I would add that barring a major fire, they will be able to tell if it has been altered: that Loctite is not just a thread locker, but also shows if the factory calibration has been altered.

That said, why worry? If you have a nice low pressure gauge (or a Hoffman Differential Loop!) on the system, the simplest way to adjust the controlling control is to watch the gauge (or listen to the Loop!) and adjust it so that it cuts out when you want it to. Who cares what the scale says?

EBEBRATT-Ed

@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?

Fred

I agree with @Hatterasguy on this. It's as if we are saying because the manufacturer did a piss poor job of delivering a control product that is properly calibrated that we should leave it in that piss poor state. The re-calibration is to make the control device work the way it was intended and, as far as anything I've seen, it is always to ensure the device works at a lower pressure, based on a good low pressure gauge. It is clear that many people have boilers that are way over sized and don't have the luxury of lowering the Pressuretrol below its design before the links drop off or there is no Differential. The least a Pro or HO can do is make sure those settings are reasonably accurate or we find a way to get the manufacturer to do their job right. What does the insurance industry say about defective controls and one that is mis-calibrated is, in fact defective???

Danny Scully

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.

Jamie Hall

Um. Well. Different strokes for different folks. I have no problem, though, with a competent individual with appropriate equipment recalibrating the primary pressure control, so long as the individual doing it recognises that he or she then owns the control -- and any problems it might cause.

My comment was a suggestion that at least one of the pressure controls be left as it came from the factory; I probably should have added that that one should be manual reset, and set at about 5 psi cutout for most residential systems. And in my admittedly slightly paranoid opinion, no boiler should operate without at least two pressure controls, one being manual reset (which, incidentally, should be on independent pigtails, too), and two LWCOs, again, one being manual reset.

JUGHNE

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.

Chris_L

Jamie Hall said:

My comment was a suggestion that at least one of the pressure controls be left as it came from the factory; I probably should have added that that one should be manual reset, and set at about 5 psi cutout for most residential systems. And in my admittedly slightly paranoid opinion, no boiler should operate without at least two pressure controls, one being manual reset (which, incidentally, should be on independent pigtails, too), and two LWCOs, again, one being manual reset.

I too think the chance of messing up the P-trol so it doesn't shut off is extremely low. My experience has been as @Hatterasguy indicated. You are more likely to set the cut-in pressure so low so that the boiler never comes back on.

But I also understand the perspective of some of the pros on this. And I agree with Jamie Hall about the redundant pressure controls. What he describes is exactly how my 30-year old Burnham boiler with millivolt controls is set up. (Just one LWCO, though).

I never understood why code calls for an auxiliary pressure control on millivolt residential boilers but not others. After all, a clogged pigtail on any boiler could cause the primary pressure control not to shut off the boiler.

So I didn't have any qualms about calibrating the primary controller on my two boilers. I didn't touch the auxiliary controls--aside from turning down the pressure. The Burnham installation manual says: "set auxiliary pressure limit as high as stop allows." In other words, 10 psi or more before is shuts down. Yikes!

I don't ever want my boilers running at a pressure that high. I turned it down to 4-5 psi. Sometimes it is best not to follow the installation manual.

Mark Eatherton

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

EBEBRATT-Ed

Ok, sorry but some of you (except for Jamie & Mark, Chris L, Jughne) (hope I didn't miss anyone else) are missing my point completely, and I still think your wrong

We have homeowners and others on this site and I am all good with that.

So if we teach them that playing with safety's is ok then how do you feel about them playing with low water cut offs???

Or bypassing a spill switch or any other safety?

For a professional that's willing to take a risk...fine

For others, not so much

Where do you draw the line????

Don't forget on a residential steam boiler (or any boiler) you need an operating control and a safety control.

On Residential the stat is the operator and the pressure control is the safety...don't confuse the 2. If the pressure control "normaly" runs the boiler then it becomes an operating control and you need an additional control for a safety.

That's why on commercial you have an operating aquastat or pressure control and a manual reset safety aquastat or pressure control

As @Mark Eatherton said

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...

It doesn't matter to the Insurance Companies and there lawyers if what you did is right or wrong ...they could care less.

Maufacturers instructions ALWAYS trump any code.

All I am saying is if you want to play with a pressure control..have a safety for a back-up

And the sky is never falling until it lands on you.

Gordo

Please notice in the videos above that there are no instructions that show exactly how to adjust the pressure controls beyond what the "reasonable" person should do.

That is on purpose.

The videos were published with the intent to show just how pervasive the pressure control accuracy problem is (many of them should be sent back as defective, IMHO. That will get Honeywell's attention!), and that they should be tested by a competent individual , and are not intended as a "how to" for fine adjustment purposes.

I wonder what would happen if everyone who wanted to buy one of these controls showed up at their favorite supply house with a test rig and rejected any control that didn't fall within their published design specs?

But to repeat, it not a good idea to adjust these controls yourself, especially if it leaves a trace, such as tampering with the smoo that is on that tiny set screw, as some here have advocated, without a very clear understanding that that individual assumes all risks.

The Honeywell PA404A is, on balance, a reliable and precise control when operated within its minimum design limits of 0.5 psi cut-in and 1.5 psi shut off.

It is just not very accurate. Send 'em back to make 'em right.

Gordo

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!

ChrisJ

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.

EBEBRATT-Ed

@Gordo I agree wit everything you said.
@ChrisJ all the pigtail does is make a water seal to keep steam out of the control and the pressure gage. Some Gage's are marked (internal symphon)

Honestly I have seen pressure controls installed with no pigtail and never noticed any failures with them. But I think code requires a pigtail.


Of course u can always make a water seal with pipe and fittings.

Fred

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.

ChrisJ

@Fred It most certainly is not a code violation as I have my code required dirt trap, er, pig tail and Pressuretrol and 30 PSIG gauge. Out side of that, my own controls do not interfere with anything and are of no concern to anyone including the boiler manufacturer. As I've always said, you must have the code required pigtail, high limit and 30 PSIG gauge. We tell people the same thing when installing a 3 PSI gauge, do we not?

Mounting next to the pressure relief in this manner is also not a concern.

If anyone has a Vaporstat we always recommend having a Pressuretrol as well. In this case, your Pressuretrol and 30 PSIG gauge would be on the required pigtail. Your Vaporstat and useful gauge would be on an airtrap with a snubber.



I believe both @MarkS and @KC_Jones have also eliminated their pigtails on their own secondary controls.

KC_Jones

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

Fred

@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.

ChrisJ

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.

Fred

ChrisJ said:

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.

You can't touch the pipe from bed either and you can't feel a "Hot pipe" unless the boiler is in a heat cycle or shortly thereafter. Proper annual maintenance, something we always encourage, on this site, also precludes a clog.