What Caused Steam Pressure to Raise

STvex

Hi, I have a gas weil eg-45 steam boiler, Honeywell grey pressuretrol box set at 2 and 1 for differential. I know it should be .5 and1. Mains about 25 to 30 feet are insulated and have 2 gorton #1 main vents. Pigtail was cleaned before heating season. Have the traditional 0 to 30 psi reader. After about 25 minutes of the burner on, going from 69 degrees to 71 degrees, the boiler reaches about 4 PSI then it shuts down. Most likely pressuretrol kicking in. After five minutes it kicks back on, then shuts off as the thermostat is satisfied Is this ok or normal? Now that spring will be here next month, I plan on adding a Gorton #2 and #1 at the main end. This should give me more than enough main venting. Other than cleaning out the pigtail and adding more main venting is there anything else I can do to ensure the pressure doesn't go above 3 psi? I plan on setting the thermostat to 71 all day next year so the boiler doesn't have to work that hard. Thanks in advance for the replies.

Fred

You can adjust the Pressuretrol down to where you know it should be. Aside from that, Main venting will help and making sure the pigtail is clean and open is also essential. If the Pressuretrol needs to be calibrated, we can provide instructions on how to do that but you first need to get a 0 - 3 PSI gauge on that boiler so you can actually see what the pressure is. 0 - 30 PSI gauges just are not accurate.

Mark N

Is the boiler oversized for your system? Is it piped properly? Do you know what the EDR of your radiators is? I would think the boiler is oversized if the pressure raises to 4 PSI in 25 minutes.

Abracadabra

pressuretrol should not be set for .5 cutout and 1 differential. You are asking it to cutout at .5 and cut-in at -.5psi (vacuum). set it for 1 cutout and .5 differential.

either:
1- gauge is wrong. install a 0-3 psi gauge.
2 - pressuretrol is failing. replace pressuretrol
3 - pigtail is clogged. clean the pigtail

vaporvac

So does the boiler shut-off on pressure or because it's reached temp? In any case something is wrong here as per the above posts.

STvex

The pressurtrol is brand new, replaced last October, boiler is 30 yrs old, other than replacing boiler what do I do with oversized boiler, I don't know the edr of my radiators but I have a 1600 square feet house with 9 radiators, I'll add a 0 to 3 psi and make sure pigtails is clean. What does calibrating a pressuretrol does, it's hard to tell what shuts of the boiler cause when it's a 4 psi the thermostat reaches it tempreture

Abracadabra

A pic of the controls/gauge/pressuretrol piping please?

Fred

You first need to calculate the EDR of each of your 9 radiators. That is a fairly easy task. Once you do that, look at the serial #/Rating plate on you boiler. It should have the "Net Sq. Ft. of Steam listed on it. If your boiler is sized correctly, that rating should be very close to your total radiator EDR. If the boiler rating is significantly more, the boiler is over sized. Most of us have radiators that are moderately to grossly over sized. You have to make sure you have as much Main venting as is necessary to vent the air out of the Mains without building pressure prematurely. The boiler can be down fired to some degree but that will take a Pro to do that.
Until you know if/how over sized the boiler is, I wouldn't worry to much about that. Get the venting on the Mains.
Calibrating the Pressuretrol is done to make sure that it is reasonably accurate at measuring pressure and shuting the boiler burner down when the pressure reaches the set range, .5PSI Cut-in and a Differential of 1 PSI for a Cut-out of about 1.5PSI . You must have a 0 - 3 PSI gauge on the boiler to do the calibration.
If, in fact you are running at 4 PSI, that's way to high. You want to stay at no more than 1.5PSI. Most of us run a normal heating cycle at anywhere from about 2 ounces to 12 ounces of pressure.

STvex

Can I take out the 0-30 PSI reader, put a T, two nipples and an elbow and have both readers side by side? And to confirm, the reader on the outside of the pressuretrol should be .5 and the inside dial 1? Can someone post a link to a good 0 to 3 psi guage. Thanks to everyone.

BobC

A lot of boilers are oversized, the best you can do is to make sure the venting is adequate and the pressure is kept low.

Newer pressuretrols are notoriously inaccurate, if it is a grey box with an adjustment wheel inside turn that wheel to "1" and set the front adjustment as low as it will go. Don't trust your 0-30 gauge, add a 0-3 PSI gauge so you will know what the pressure really is. You can T of the pigtail and add the gauge there.

Ig the pressure really is above 3, there is a procedure to calibrate the pressuretrol but see what you really have before we go through that,

Bob

Fred

STvex said:

Can I take out the 0-30 PSI reader, put a T, two nipples and an elbow and have both readers side by side? And to confirm, the reader on the outside of the pressuretrol should be .5 and the inside dial 1? Can someone post a link to a good 0 to 3 psi guage. Thanks to everyone.

Yes, On your Pressuretrol, the scale on the front should be set to .5 PSI and the white wheel inside should be set at 1 PSI.
Here is a link to the gauge most of us use:
http://www.valworx.com/product/low-pressure-gauge-25-0-3-psi
Make sure the gauge/gauges are on a pigtail as well.

vaporvac

NB: Add the 0-3 ptrol, NOT replace the 0-30. The latter needs to be there by code.

BobC

The pigtail has to be between the boiler and a 0-3 gauge, if the existing gauge is after the pigtai put the 0-3 next t the existing gauge to keep the insurance guys happy.

http://www.valworx.com/category/low-pressure-gauges-25-lower-mount

The 33020 is the 0-3 PSI lower mount gauge. Put it up on a nipple to keep it happy and you might wnt to have a 1/4" shutoff valve in series with it so you can isolate it if you have to.

Bob

Jamie Hall

And to go back to part of the original question -- 25 minutes is a little short for reaching pressure, but that may be because the boiler is well oversize. Otherwise that cutting out and cutting back in is more or less normal.

STvex

Thanks for the responses from all. About to order the 0 to 3 gauge rightnow