New Pressuretrol cuts out but not back in

k423

Hi I’m new to the site new home owner need some help with my boiler I just installed new pressuretrol it seam to work ok with the cutin off when boiler reach around 5 psi but the main problem I’m having is that when it does that it doesn’t turn back on after that it just stay like that. Also when it cuts out my best thermostat still says heating im not sure if it’s suppose to say heating if it cuts out? Also when it stays like if I bang the pressuretrol then it fires back up. Banging the pressuretrol seems to be the only way to get it to fireback up if it is cut out by the pressuretrol. Any help will be Appreciated thanks in advance 

Fred

First of all, The Pressuretrol Cut-out or "Main" depending on the Pressuretrol model you have should be set at about 1.5 PSI and the Cut-In set at about .5PSI. If you have the Model 404 Pressuretrol, set the Cut-in Scale on the front of the Pressuretrol to .5 and then remove the cover and you will see a white wheel, set that to "1" facing the front of the Pressuretrol. That will give you a cut-out of 1.5PSI. Setting the Pressuretrol to 5PSI is way to high. When you installed the new Pressuretrol, did you take the pigtail (looped pipe that the Pressuretrol is mounted on) off and clean it out? It sounds like the pigtail is clogged and once the pressure makes its way into the Pressuretrol side of the Pigtail, it is being held there because it can't get past the clog to drop back down to .5 PSI and re-fire the boiler.

k423

I took the pigtail off and cleaned it also full up boiler with water with pigtail off and cleaned out elbow. This is my current setting once it cuts out. It does not cut back in unless I bang the pressuretrol

EBEBRATT-Ed

Your pressure gauge is showing 4psi. The boiler won't start until the pressure drops (assuming the gauge is good)

Assuming the gauge is good,

Shut the boiler switch down until the gauge drops to 0. Set the "Main" scale on the pressure control to 4psi, set the "diff" at 2psi. Then start the boiler & turn the thermostat up if you have too. When the boiler pressure reaches 1.5-2 psi on the gauge lower the main setting until the burner shuts off. Dont touch the diff yet.

When the burner shuts off. Watch the pressure gauge. When the needle is the width of the needle above 0 lower the Diff setting until the boiler starts.

The "Main" setting always has to be more psi setting than the "diff " setting

Jamie Hall

Differential may be set high enough that it won't cut in. Try setting the differential to 0.5

That said, however, if you are depending on that 0 to 30 psi gauge to figure out what's happening, don't. They are very rarely accurate at the low pressure ranges steam heat works at. If you want to know what pressure the system is really running at, get a 0 to 3 psi gauge and some nipples, a T, and some elbows and mount it on the same pigtail as the pressuretrol (you need to keep that 0 to 30, though, for code and insurance compliance).

k423

Ok going to try the main 4 and the diff 2 suggestion. 

k423

This is my set up and I have a nest thermostat and boiler only cuts back in when I bang pressuretrol would not fire up if I adjust thermostat only if I bang pressuretrol

k423

Tried to do the main 4 diff 2 suggestion turned the main all the way down boiler did not shut off it still running as we speak any suggestions ?

k423

Also if the boiler cut off from the pressuretrol should the nest thermostat still be reading heating or should it it be grey in idle mode?

JUGHNE

The diff has to be less than the main. Try 2 on the main and .5 on diff.
Do not believe that gauge, they are almost worthless at 2 PSI or less.
And after this is figured out, you may have problems with the Nest.
Many people do....it is not good for steam or hot water heat.

Most tstat problems asked about here and another heating site are always concerning the Nest.

k423

My nest can cause the boiler not to cut back in ?

EdTheHeaterMan

Does the Nest show an error message when the system fails to respond?
When did the problem first present?
When did you install the Nest?

k423

No the nest does not show an error it just shows that orange heating even though it’s not.

problem started with new pressuretrol I purchased 2 days ago.

Nest was installed last Kano when I purchase the home.

Reason I purchased new pressuretrol is because my old one will allow the gauge to go all the way up to around 10-15 psi cause the boiler to start release steam. It would not cut boiler off even though I have it set to .5 diff 2 main. Pressure gauge goes all the way up pass 10 psi then starts blowing off steam. I was able to cut boiler off and on from nest app with my old pressuretrol. With the new pressuretrol it cuts my boiler off once the gauge reaches about 5 but once it does that it doesn’t cut back in after that and that’s my Main problem now. In order to get the boiler to fire back up I have to bang the pressuretrol then it fires back up. I can’t even fire it back up from nest app if it cuts out from the pressuretrol settings.

k423

Also made a little video of the issue I’m having is there any way for me to post it?

Jamie Hall

OK. If the old pressuretrol allowed the pressure to get to 10 psi, there was either something wrong with it -- or the pigtail and the opening into the boiler was clogged, more likely the latter. This will affect the new one as well.

I presume you have taken the pigtail off and cleaned it out, and also checked that the opening into the boiler is completely clear? If not, that's the first thing you should do.

The Nest will show a call for heat regardless of whether the boiler is firing or not. All it tells the boiler is that it wants hear; it does not control the boiler in any other way. In that regard it is no more useful for control as twiddling the dial on a 1920s bimetal thermostat, except that it's less reliable.

archibald tuttle

as has been adverted to many times on these pages, those pressuretrols are not remarkably more accurate and repeatable at low pressures than the 30 lbs. gauge. my preference is two stage fire with really accurate controls because building up enough pressure to create a differential where you don't short cycle, unless you have a really tight system, is difficult and tends to require cut out pressures that are higher than ideal, e.g. 4 psi.

( if you look closely, the initial settings of 4 cutout and 2 diff recommended by @EBEBRATT-Ed were not for operation but to be tuned in to below 2 psi cutout and fractional cut-in. pressure–better accomplished with a more accurate gauge or more accurate instrument attached to the manifold for test runs. If testing with very accurate pressure measurement demonstrates that the control is hitting its marks on repeated cycles without constant adjustment and your off cycles are in the range of 5 minutes or better then you maybe have the luckiest of all possible worlds. otherwise you should considered changing control or firing strategy or both.)

a less complicated, but less ideal alternative than two stage (where the firing rate drops when the cutout is reached rather than ceasing to fire altogether) is to regulate the gas pressure coming in within the allowable firing range for the boiler to lower the firing rate so that once warm the system fires at equilibrium maybe around .5 psi. This is a balancing act because as you downfire your cold or standing start is going to lengthen considerably, although that can be accommodated with anticipation either based in dropping indoor temps or with outdoor temp monitoring or some comparative control strategy.

you can establish this with much more accurate instruments temporarily attached and then the pressuretrols are just safety controls that don't trip during normal operation which is the way the vast majority of steam i've encountered operates, with pressuretrols even less capable than the one you've got.

Pretty much the only time I have ever seen most systems with 'standard' 10 or 15 lbs. pressuretrols set for '5' psi ever hit their mark is when the system is overfilled by accident and you get gravity pressure of water exceeding the mark (e.g. water up to the second floor and spitting out of the 1st floor air valves)

k423

Ok so just changed the pressuretrol and pigtail to this one and it’s working like a charm. 

What setting should I put it on? 

k423

I think the new pressuretrol I got was defective.

Erin Holohan Haskell

k423 said:

Also made a little video of the issue I’m having is there any way for me to post it?

We can't host videos, but you can post it to YouTube and share the url for it here. Thanks.

EdTheHeaterMan

If it is working like a charm. then leave it alone.

k423

Working like a charm meaning its cutin in and out with no problem. I think I’ll go with Fred recommendation of .5 cut in scale and white wheel set to 1? Thanks for all the help.

ethicalpaul

And if you ever have to replace that boiler make sure the installer re-does the near boiler piping to match the installation manual, and not that horrorshow that is there now. But if you have water getting shot out of your radiator vents or loud hammering waking you up at night that's the place to look.

SteamCrazy

Agree with EthicalPaul. Also shouldn't that pigtail be turn so that it's not tilting pressuretrol as it heats up and cools down, Good luck. 

ethicalpaul

Thanks @SteamCrazy you said my favorite words

That pressuretrol isn't a mercury type and doesn't care much about its orientation.

JUGHNE

The necessity of the pressure control remaining absolutelly level would only apply to older mercury type P-trol and other switches such as in older T-stat.

k423

Model 404 Pressuretrol, set the Cut-in Scale on the front of the Pressuretrol to .5 and then remove the cover and you will see a white wheel, set that to "1" facing the front of the Pressuretrol. That will give you a cut-out of 1.5PSI.   

that setting doesn’t work to will for my system house taking a very long time to heat up to set temp. Thermostat set to 75 about 6 hours ago and it’s now at 66 it was originally on 59 because I was away from home for a few days. What setting can I use to heat up house a little quicker? Will cut-in set to 1 and white wheel set to 2 be good?

LS123

@k423 good morning... i have seen on the web that some p-Trolls dont seem to work at .5 cut in (at least based on some youtube clips. try to increase cut in just a little bit. like you mentioned perhaps 1 0r .75. As you mention cut out seems to work) Depending on the size of the house, your system config. Running the boiler 6 hrs non stop probably generate a lot of heat and keeping components of P-trol hot... Perhaps you might benefit from programmable P stat, even remote control one so you can gradually increase the temp. Not sure your boiler capacity to produce heat at max. if the house been at low temp... I am guessing some of the heat generated by the boiler is taken by structure of the house. for example... if I keep the house at 63 over night (my wood floors and plaster walls are colder in the morning... when I gradually increase the temp by 2F as I wake up ... say 6:30 am... by 8 -10 am heat get settled in and house is comfortably worm... is your boiler right size set for max and efficient performance, is the system gets regular maintenance. is it gas or oil... mine is oil, has a .85 GPH nozelle and heat up about 2000 SQ comfortably ... but I have not drop my house temp below 60F nor have tried to increase temp by large number of Fahrenheit ( no more than 2 F at a time) sudden increase and amount of time it takes lot more fuels as I been told...but back to the Ptrol... cut in cut out... try increasing cut in and test it out... good luck!

Jamie Hall

k423 said:

Model 404 Pressuretrol, set the Cut-in Scale on the front of the Pressuretrol to .5 and then remove the cover and you will see a white wheel, set that to "1" facing the front of the Pressuretrol. That will give you a cut-out of 1.5PSI.   

that setting doesn’t work to will for my system house taking a very long time to heat up to set temp. Thermostat set to 75 about 6 hours ago and it’s now at 66 it was originally on 59 because I was away from home for a few days. What setting can I use to heat up house a little quicker? Will cut-in set to 1 and white wheel set to 2 be good?

No. Raising the pressure will be no help at all. If the boiler is running, it's running and is delivering all the steam that it can.

Assuming that the boiler is running properly (you have had it cleaned, and the burners properly adjusted this year, haven't you?) you are limited by one of two things: the boiler capacity and the radiator capacity. The radiator capacity is what it is, and is usually the limiting factor. If the boiler is cycling on and off on pressure, the radiator capacity is what is limiting it. However, if the boiler is not cycling on and off, but is running continuously, it is the boiler capacity that is limiting.

Now mind that is not to say that the boiler is running correctly. It's possible -- though rare -- that the boiler is simply too small for the job. It's also possible that the burners are out of adjustment, or that you have a significant steam leak.

LS123

@Jamie Hall ... I thought running a boiler for 6 hrs would produce access heat and preventing the P-toll functionality... now I stand corrected.... thank you! @K423 my boiler could run for couple of hours max and bring the temp to what I want... ( do not increase more than 2 or 3 F. ) I have not seen the P-trol (its an old mercury one) kick in at all (it has a old front mount 30 psi (3 psi on the pig tail... max I have since put the 3 psi is 1/2 pound of pressure and heat up the radiator and the house)... burner shuts down when temp on Tstat is met

Jamie Hall

Sounds to me as though you're good, @LS123 . Make sure that mercury pressuretrol is level -- and keep it. Those things are bulletproof.

Marc_18

It needs to be pointed out that the OP (K423) should insulate the near-boiler piping and the mains.