Pressuretrol failure?

DuggieFresh5

Hello,

I think my pressuretrol is failing (inaccurate?) or I chose the wrong pressure gauge. Please help! I need to know if I have a safety issue.

I installed a low pressure gauge on my system to try and get a more accurate idea of where it is running. I chose a 0-60" WC gauge since I could get one from work and that equates to 2.166 PSI. I have my pressurestrol set to cut in at .5 out at 1.5 PSI and it was serviced in April just before the end of last year's heating season.

Before the boiler cuts out, the needle on the gauge is pointing straight down to what would by 70" if the gauge was designed to measure to that range. Have I diagnosed an issue with the pressuretrol or chosen too narrow of a pressure range in my gauge?

I don't think it is cold enough yet to know if the boiler is cutting out because the thermostat is satisfied or the pressuretrol is cutting out.

Thanks.

BobC

Have you checked the pigtail to make sure it's clear? If the pigtail gets clogged the pressuretrol will never work because it can't sense the pressure in the boiler.

Also pressuretrols can be inaccurate. Does the 0-30 gauge read anything? Send us a picture of the gauges and the pressuretrol.

Bob

KC_Jones

Is the gauge on the same pigtail as the pressuretrol? If it is I doubt it's plugged, BUT cleaning and checking that pigtail should be part of yearly maintenance so I would still check it. The honeywell controls can be off at the very low settings sometimes. Most any control will have some amount of tolerance especially at the extremes of their range. That is why the gauge is handy to verify what is actually happening. You could also check the port on the pressurtrol to make sure it is clear when you clean the pigtail. On occasion gunk can get up there and mess things up as well. Even if it isn't clogged it could be almost clogged and slowing down the reaction of the pressuretrol.

DuggieFresh5

The pressure gauge is on a different pigtail. I'll attach pictures. The boiler was serviced professionally in April and the pigtail was entirely clogged at the time. I think it should be fine.

There was some surging in the site glass this fall and I did drain off some of the old water and refill. The water level tends to be stable now, but you can see some crud on top of the water that has come in from the top of the glass. Some of that crud likely made it to the pigtail.

Is that reason enough to clean it again?

Jamie Hall

It never hurts to clean the pigtail -- but it may not be necessary.

Pressuretrols, on the other hand, tend to be rather flaky at the bottom of their range, which is where you are operating. They can't help it; it's the way they are built. If you really want accurate control in that range, you will need a vapourstat.

vaporvac

It also sounds like you may need to skim the boiler rather that drain and fill in order to get rid of the crud at the top of the site glass.

DuggieFresh5

I wondered about skimming the boiler. The crud is lighter than water and so probably oil mixed with crud. Is that homeowner-grade work or should I call in my local steam professional?

I hear "wanding" in conjunction with skimming and I can't figure out what that means by context clues.

I've read the vaporstat is much more accurate for low pressure. My boiler is approaching end of life; is that hardware that makes sense to transfer to a new unit if I make the investment with this one?

DuggieFresh5

Thanks to everyone for the input so far. I really appreciate it!
Doug

vaporvac

You'll still need a 0-30 pressuretrol by code, but a vaporstat is transferable to any boiler.

The wand is a homemade tool that goes in the skim port and actually washes out the sides of the boiler. I bring it to almost steaming and do a section at a time. A friend made mine out of copper...it really works well, but you will still need to skim a bit.... oil floats, so you probably have oil in your system. I'll try to find a link to a wand pic.
Skimming is something any homeowner can learn to do; it takes hours so better for me to sit in front of the boiler with a laptop than someone I have to pay, but you may feel differently.I'll look for a link with instructions.

KC_Jones

Vaporstat doesn't care which boiler it's on so it can be transferred. Unless your system is running smoothly already, I would view the vaporstat as lipstick and not a necessity. In all honesty you want to get the system to the point that essentially the pressurtrol or vaporstat almost does nothing. They are more or less a safety device or high limit device. To really get the pressure down it's more about the venting than anything. You say the boiler is at the end of it's life?! Do you know how old it is? They can last for a very long time. If you have the skim port available skimming is a very DIY friendly thing to do. Have you recently had work done that there could be oils in the system? Skimming is to remove oils.

KC_Jones

And it seems I was typing at the same time as someone else again.

DuggieFresh5

I'm pretty sure the boiler was neglected by the last homeowner. I purchased this boiler (and the accompanying house) in December of last year. The only service records attached to the boiler all seem to be repairs for system failures. I didn't know what water hammer was before I moved in. My son's definition of water hammer is monsters living in the walls, so I had to learn fast!

By serial #, my boiler is 35+ years old. It's a Kenmore made by Dunkirk.

I don't know what to look for to find a skimming port, but once I do, I know the side comes off of the boiler to reveal the burners/internals pretty readily.

I did add venting with advice from some good folks on The Wall. That conversation is here. I now have two Gorton #2's on the Main and two Hoffman 75's on the return/condensate side. Based on what I am hearing (air flow during the fire), another Gorton on either side may be a good investment.

I know venting will get steam to the radiators in a more uniform way in less time, but will it also reduce the pressure my system runs at? Logically, I would think that would be determined by venting on the condensate side. Is that right?

DuggieFresh5

BobC said:

Also pressuretrols can be inaccurate. Does the 0-30 gauge read anything? Send us a picture of the gauges and the pressuretrol.

Bob

Bob - the 0-30 PSI gauge doesn't move or doesn't work. I've never noticed movement on the needle. I toyed with removing the gauge so I could replace it, but I can't get to the neck without taking apart the flue. I'm pretty sure I would just destroy it trying to torque the plastic housing, so I gave up.

BobC

You could remove the pressuretrol (check the pigtail for a clog by blowing into it, there should just be a little resistance from water in the loop) and then add a T, a couple of nipples and some 90's. Put the pressuretrol back on one and a new gauge on the other.

Also as someone else mentioned look into the pressuretrols brass fitting, there is a small hole at the base of that fitting that has to be clear. They do get plugged from time to time.

Bob

KC_Jones

The pressure is basically a factor of steam production versus venting capacity and condensing speed. If the boiler is over sized or venting isn't the greatest it will build more pressure. If it is an over size situation you will only be able to keep the pressure so low and then the pressuretrol kicks the burner off. Have you done an EDR calculation and compared it to the boiler size? It's not a bad exercise to complete to see where you are and where you would want to be should a replacement become necessary. I always think it's better to be prepared. 35 is definitely getting up there. A skim port will be a large 1 1/2" (it can vary) port or plug on the side of the boiler. If it was never put in it could possibly be behind the casing panels. If that Dunkirk is like the newer ones the skim port is actually the tee that is hooked into the side for the riser connections. Not sure if yours is like this, a couple of pictures would help.

KC_Jones

Actually I just looked at your pics again and that tee next to the red valve in the pic is your skim port. Should have a plug in it. That's the skim port on those.

DuggieFresh5

I have not calculated EDR. I think I should also. Thanks for the suggestion. Attached are pics of the boiler. There is a plug on the tee to the riser. Is that what you were referring to?

KC_Jones

Yes that is the one. The new Dunkirks are the same way. If you don't think it's been out for a long time or ever I would be really cautious. If the boiler is that old it's hard to say if you for sure have an oil problem that requires skimming. If it was me I would hold off on that until you eliminated all other possibilities causing problems. Go for low hanging fruit first. Venting, pipe pitch basically the simpler stuff. If you still aren't happy with the way it works look for other possible causes. A common saying on this site about steam, noises are a cry for help. Sometimes the fix is simple sometimes more complicated. If there is anything you aren't comfortable with...call a pro! I am very mechanical so I will tackle almost anything, but even I admit my limitations.

DuggieFresh5

It looks like it has been a long, long, time since that plug saw any movement.

Most of the noise I hear now seems like expansion sounds at the radiators. The vents (Hoffmans) on the return side start to make some noise -- and they also seem to open and shut, like maybe steam is getting to them, or perhaps just vacuum pulling them closed with condensation in the system?

I haven't had any water hammer like when we first moved in. Gerry Gill is my local expert and he pointed out a pitch problem I was able to improve, if not altogether correct. Gerry also found a radiator without a trap and he took care of that for me. I have another post out there where I'm trying to best figure out how to test or determine if my other traps are any good. There was definitely some steam in the returns before I added the new trap. I found out my thermostat was set to a 1 degree differential and adjusted that to 3 -- the closest I can get to setting CPH with what I have.

I just want to button up the details and make sure I won't have issues when the mercury really drops in another few weeks... I am probably more ambitious the naturally mechanical, but I don't mind trying, or taking the excuse to buy some tools!

DuggieFresh5

BobC said:

You could remove the pressuretrol (check the pigtail for a clog by blowing into it, there should just be a little resistance from water in the loop) and then add a T, a couple of nipples and some 90's. Put the pressuretrol back on one and a new gauge on the other.

Also as someone else mentioned look into the pressuretrols brass fitting, there is a small hole at the base of that fitting that has to be clear. They do get plugged from time to time.

Bob

I'm going to look into this. I put the gauge where I did, because I only needed a couple of fittings and it was quicker/easier then moving the pressuretrol; I'll have to rewire the thing to since whoever installed it didn't believe in leaving any slack in the wires.

Question: If I put a 90 on the valve before the pigtail, is that OK? Seems to me like it would take a helluva lot to get crud in the pigtail if it were vertical.

KC_Jones

DuggieFresh5 said:

I don't mind trying, or taking the excuse to buy some tools!

When I recently replaced my boiler I got to buy a few new tools...always nice to have an excuse! Your instincts on the pigtail are good. Vertical won't hurt, but I am not sure how well that pigtail you have will work in the vertical. I can't picture that in my head I am sometimes more hands on so I don't want to say for sure if that would work. You are lucky if Gerry is your local guy. Use him wisely!

BobC

You can buy straight pigtails (McMaster Carr if there isn't a plumbing wholesaler close by), just make sure it's brass, not steel. One nice feature about having both the ptrol and the gauge on the pigtail is you can just unscrew the gauge and blow into it if you suspect the pigtail is plugged.

Bob

David Nadle

McMaster's angle pigtail is nicer than the original, it does a full loop instead of one twist. By the way, if that pressuretrol is the old kind with a mercury switch, it may be that when the pigtail heats up and expands it gives gives the p-trol a slight tilt and throws off the accuracy. The pressuretrol should really be level and oriented so that the pigtail is parallel to its sides.

BobC

Also the ptrol should be level when hot because the pigtail shifts as it gets hot.

Bob

DuggieFresh5

I hadn't considered a mercury switch as part of the equation! I'll check that out. McMaster does have a nice full-loop pigtail. I might try that or the 90 bend. The existing pigtail appears to be copper. I think it might have been hand bent. The "run" is definitely pitched towards the angle bend, so whatever goes in, probably can't get out.

DuggieFresh5

KC_Jones said:

The pressure is basically a factor of steam production versus venting capacity and condensing speed. If the boiler is over sized or venting isn't the greatest it will build more pressure. If it is an over size situation you will only be able to keep the pressure so low and then the pressuretrol kicks the burner off. Have you done an EDR calculation and compared it to the boiler size?

I did my EDR calculation tonight. I've attached my work and used the #'s in The Lost Art of Steam Heating to guide me. It appears the boiler is somewhat over sized. I calculated a need for 123,000 BTU, the boiler's heating capacity (not input) is 151,000. That is around 20% over.

Should I expect issues with pressure cut-off based on that difference?

KC_Jones

Not horrible, but yes over sized. It could be that was the closest to your connected load. I don't think you are in bad shape with that. My new one is around 18% over sized, but was the closest match to my system without being under sized.

BobC

20% will cause the pressuretrol to act but I wouldn't worry about it. For 16 years I lived with a boiler rated for 596 sq ft of steam that was connected to a load of 210 sq ft. Once I got the venting straitened out and fixed a couple of radiator leaders that didn't have enough slope that boiler headed a 90 year old 1150 sq ft house (one block from the ocean just south of Boston) on 400 gallons of oil a year. There was nothing I could do about it so I lived with it till that boiler croaked.

You might be able to downfire that boiler a little bit, ask your service guy. BTW the best way to match the boiler ro the radiators is to have a boilers whose sq ft of steam equals the total EDR. The boiler rating assumes a 33% pickup factor so if all the piping is insulated you can get buy with a slightly smaller boiler.

Bob

DuggieFresh5

I think the saying, "it is what it is" applies then. I will ask Gerry about down firing the next time he services my system. Thanks!

Doug

nicholas bonham-carter

When you figure the EDR, compare the square feet value of the boiler with the square feet total of the radiators, and that will be more accurate.--NBC

DuggieFresh5

How do I calculate for the square feet value of the boiler? I noticed a couple of other posters were using that measurement.

Abracadabra

DuggieFresh5 said:

How do I calculate for the square feet value of the boiler? I noticed a couple of other posters were using that measurement.

It's stated by the manufacturer in the specs of the boiler.

DuggieFresh5

Thanks Abracadabra. I'm struggling to find that information. I don't have a manual for the boiler and while I can find a parts list online, I can't find a manual.

If anyone out there has a good resource for manuals, I have a Sears/Kenmore by Dunkirk, model #229-96526. If the resource I found online is correct, by serial # my boiler was built in December of 1986 (#508600197).

DuggieFresh5

BobC said:

Have you checked the pigtail to make sure it's clear? If the pigtail gets clogged the pressuretrol will never work because it can't sense the pressure in the boiler.

I removed the pressuretrol last night and ensured everything was clear. I blew out the pigtail and added some water to the loop. That was actually quite easy and I may pursue adding a tee to mount my pressure gauge in tandem with the control.

Abracadabra

Check the label on the boiler carefully. From one of the pics you posted, the rating plate looks like it's just left of the transformer and pressuretrol.

BobC

The boiler nameplate usually has the sq ft of steam rating on it.

Bob

nicholas bonham-carter

the specs for the boiler will include the sq ft figure.-NBC

KC_Jones

Definitely no manual available, but there are parts...lol

http://www.searspartsdirect.com/partsdirect/part-model/Kenmore-Parts/Kenmore-Parts/Model-229965260/0582/0912000?pathTaken=modelSearch&prst=0&shdMod=229965260

vaporvac

It should be on the boiler plate. If not, you could look it up under that boiler's specs.

DuggieFresh5

KC_Jones said:

Definitely no manual available, but there are parts...lol

http://www.searspartsdirect.com/partsdirect/part-model/Kenmore-Parts/Kenmore-Parts/Model-229965260/0582/0912000?pathTaken=modelSearch&prst=0&shdMod=229965260

That's what I found!

Vaporvac - I'm not able to find the boiler's specs. That is what is vexing me. Especially since Sears has parts...

DuggieFresh5

Abracadabra said:

Check the label on the boiler carefully. From one of the pics you posted, the rating plate looks like it's just left of the transformer and pressuretrol.

The only other spec (besides BTU output) that seemed related to output was the min. pressure relief valve rating. There isn't any other kind of information that I could find on the body of the boiler.