Pressuretrol

Jeremy Osner

We've been having problems for a while with leaking steam vents on our radiators -- I was looking at the boiler last night and saw that the pressuretrol on the side of the boiler is all the way at the top of its scale, about 9 psi. The boiler was running and its pressure gauge read about 5 psi. I confirmed today that this is indeed way too high and that a more appropriate setting would be 1 1/2 psi. I am going to reset it when I get home tonight. I am a bit worried about long-term damage to our boiler and our pipes -- it must have been set that way for a long time as no-one has (to our knowledge) changed that setting since we moved in a year and a half ago. If our system has been running at such high pressure for a year or more, is there a chance of permanent damage? Any advice? And, one other question: in an article I was just reading on this site, there were the phrases, "someone had set the pressuretrol to cut in at 2 psi and out at 6 psi", and "I cranked the pressuretrol down to where it belonged - cut in at 1/2 psi with a 1-psi differential." There is only one sliding switch on my pressuretrol; but these statements make it sound like there are two separate settings. Am I missing something?

Thanks,
Jeremy

Unknown

The other dial is inside the control

with the 115 volts AC in there with it. Be careful.

Noel

Jeremy Osner

Thanks Noel -- I will be careful. So the two controls are "cut-in" and "cut-out" -- I am assuming "cut-in" is the slider on the front of the box because it says "cut-in" above it -- and that the "cut-out", which is inside the box, should be set higher by about 1 psi. Is that correct?

Unknown

some controls are that way

The differential is either "additive" or "subtractive" relative to the front setting. It should say which on the control.

My guess is yours is additive.

Noel

Jeremy Osner

Thanks for your help -- just one more to make sure I have this straight: I will set the cut-in to 1 1/2 psi. If the control sys it is "additive" then I will set the cut-out to 2 1/2 psi; otherwise I will set it to 1/2 psi.

Unknown

nope

set the differential to 1. That "1" gets ADDED to your front setpoint, or SUBTRACTED from it, if it happens to be the other type. If you set the front to 2 and the differential to 2 1/2, the cut-out would be 5 1/2.

Noel

Jeremy Osner

I see -- thanks very much for the clarification.

David Efflandt

Should be set as low as it goes

A pressuretrol should more typically be set as low as it goes with the pointer on the front at 0.5 and inside dial at 1. Then it will cycle the burner off at 1.5 psi and on at 1/2 psi. Any higher slows down the steam (less efficient), may not allow air vents to work properly (Hoffman 1A instructions say maximum "operating" pressure 1.5 psig, and maximum pressure 10 psi), and may blow steam out of the valve packings.

Mine was cranked way up by previous owner due to faulty vent damper that would not reopen when hot. Replacing the vent damper allowed setting the pressuretrol as low as it goes, so the system operates quietly and efficiently.

Tom_22

How Low Does It Go?

> A pressuretrol should more typically be set as

> low as it goes with the pointer on the front at

> 0.5 and inside dial at 1. Then it will cycle the

> burner off at 1.5 psi and on at 1/2 psi. Any

> higher slows down the steam (less efficient), may

> not allow air vents to work properly (Hoffman 1A

> instructions say maximum "operating" pressure 1.5

> psig, and maximum pressure 10 psi), and may blow

> steam out of the valve packings.

>

> Mine was

> cranked way up by previous owner due to faulty

> vent damper that would not reopen when hot.

> Replacing the vent damper allowed setting the

> pressuretrol as low as it goes, so the system

> operates quietly and efficiently.



Dave, how low does a pressuretrol go? If you set it as low as it goes, isn't that zero, or is it some other minimum?

I checked the one in my house a few weeks ago and the cut in was set around 3 psi! Differential was 1 pound. I changed the cut in to about .75 at that time and it's been working good, better I think, and using less fuel I think, though I can't say for sure.

I just lowered it some more to what looks like about .3 and am waiting to see what happens now.

Tom_22

How Low Does It Go?

> A pressuretrol should more typically be set as

> low as it goes with the pointer on the front at

> 0.5 and inside dial at 1. Then it will cycle the

> burner off at 1.5 psi and on at 1/2 psi. Any

> higher slows down the steam (less efficient), may

> not allow air vents to work properly (Hoffman 1A

> instructions say maximum "operating" pressure 1.5

> psig, and maximum pressure 10 psi), and may blow

> steam out of the valve packings.

>

> Mine was

> cranked way up by previous owner due to faulty

> vent damper that would not reopen when hot.

> Replacing the vent damper allowed setting the

> pressuretrol as low as it goes, so the system

> operates quietly and efficiently.



Dave, how low does a pressuretrol go? If you set it as low as it goes, isn't that zero, or is it some other minimum?

I checked the one in my house a few weeks ago and the cut in was set around 3 psi! Differential was 1 pound. I changed the cut in to about .75 at that time and it's been working good, better I think, and using less fuel I think, though I can't say for sure.

I just lowered it some more to what looks like about .3 and am waiting to see what happens now.

Tom_22

How Low Does Pressuretrol Go?

Dave, how low does a pressuretrol go? If you set it as low as it goes, isn't that zero, or is it some other minimum?

I checked the one in my house a few weeks ago and the cut in was set around 3 psi! Differential was 1 pound. I changed the cut in to about .75 at that time and it's been working good, better I think, and using less fuel I think, though I can't say for sure.

I just lowered it some more to what looks like about .3 and am waiting to see what happens now.

TomBk

David Efflandt

mine bottoms out at 0.5

Maybe they changed them or there are different brands. My Honeywell PA404A bottoms out at 0.5 and will not go any lower even if the screw goes slack. So its minimal setting of 0.5 psi cut-in and 1 psi additive differential (1.5 psi cut-out) is ideal for operating at around 1 psi.

Vaporstats go lower, but could get down to a point where an oversize boiler pressure cycles too often.

Unknown

Not the vaporstat's fault,

and a vaporstat is STILL a good way to run it. Oversize is oversize, period.

Noel

Tom_22

Boiler wouldn't run with Pressuretrol at .3

The boiler didn't turn on. I moved it up to about .5 and now it seems to be working fine.