Pressuretrol Installed via Low Water Cutoff?

pkwastavich

Hi All!

I've been lurking here for a little while and had a question that I haven't been able to find an answer to yet.

First some backstory:

We've had some trouble with a few of our radiators leaking at the union between the water supply and the radiator themselves. From what I've been reading, some folks had luck stopping leaks by reducing the pressure in the system, so I decided to check the settings on my pressuretrol.

For reference I have a Honeywell P404A. From what I understand, and what the label says inside the pressuretrol, the cutout pressure = cut in + differential. Cut in was set around .5, however the differential was set somewhere around 3.5. Tonight, I lowered the differential down to 1, which hopefully reduce the pressure.

Unfortunately, I discovered that the existing pressure gauge is broken (the indicator on it is way past 30 psi & stuck there all the time, even without the boiler running). I'm planning to install a new pressure gauge this weekend, because that seems important .


Anyway, the actual question: I noticed that my pressuretrol is connected to the boiler via, what I think is, the low water cutoff. Based on pictures online, I haven't seen any pressuretrols connected in this way. Any idea if this is an acceptable place for the pressuretrol to live?

Here's a pic: https://imgur.com/a/vycr9ko The pigtail runs from the top of the low water cutof into the bottom of the pressuretrol.

Thanks!
Pete

Fred

That Pressuretrol is mounted on a McDonnell Miller #67 low water cut off. It is OK to mount it there but the pigtail should be taken off and cleaned at least twice each heating season. They get clogged easily when they are mounted there. If you replace the gauge, you can buy a couple nipples and a Tee and mount it on the same boiler tapping with the new gauge. That 0 - 30 PSI gauge is required by code but it is a wise investment to also buy a 0 - 3 PSI gauge and mount it on the boiler as well. That will be the gauge that will let you see the actual boiler operating pressure. The 0 - 30 PSI gauge will just sit there and do nothing, until and unless the Pressuretrol fails or the pigtail gets clogged and the pressure gets out of control.

pkwastavich

Thank you! Always nice to know what I'm working with.

I was actually planning on picking up a 0 - 5 rather than a 0 - 3. From what ive read, the pressuretrol we have can be somewhat inaccuate (i.e, some folks set theirs at 1.5 psi and itll trip at 3-4). Think that would he accurate enough? I suppose if im regularly seeing 5+ psi while set at 1.5, then that may be cause for concern.

I was thinking about putting the low pressure gauge off of the same pipe as pressuretrol, though i suppose it could mount it off the same tapping as the larger gauge - ill have that off anyway. Just need to figure out how to get the thing off since its pressed right against the boiler housing. Regardless ill make sure to clean the pigtail while im down there.

Good news is that lowering the pressure seemed to fix our leaks (so far). I feel like it also quieted down some of the more noisey vents (though they still arent completely silent and I could just be imagining things).

Thanks again for you help! Appriciate it!
Pete

Fred

A 0-5 PSI gauge is ok but I would not install a new gauge to accommodate a pressure that would still be way higher than it should be. The Pressuretrol can be recalibrated to be very accurate. Here is the 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.

ethicalpaul

> @Fred said:
> The 0 - 30 PSI gauge will just sit there and do nothing, until and unless the Pressuretrol fails or the pigtail gets clogged and the pressure gets out of control.

And then what will it do? 😅 Turn down the fire?

nicholas bonham-carter

Stick with the 0-3 psi gauge, as it will be easier to read the ounces of pressure, for testing the capacity of your main venting.—NBC

pkwastavich

0-3 it is! Ill let you guys know how it goes!

@ethicalpaul, i believe itll turn the basement into a nice sauna. Assuming the pressure relief valve is working

Thanks all!
Pete

Fred

ethicalpaul said:

> @Fred said:

> The 0 - 30 PSI gauge will just sit there and do nothing, until and unless the Pressuretrol fails or the pigtail gets clogged and the pressure gets out of control.



And then what will it do? 😅 Turn down the fire?

It still won't do anything but sit there. The gauge is not a control, just a visual representation of the system pressure. At about 15 PSI, a working PRV will relieve the pressure in the form of steam/water in the space around the boiler.

ethicalpaul

Thanks @Fred, I was attempting to demonstrate the ridiculous nature of that code requirement

Well I mean, it's not totally ridiculous...you need to know if your pressuretrol is failing...if you happen to be down there looking at the gauge.

I just have a picture in my head of a boiler shooting through a roof with a 0-30 psi gauge on it and no one reading it.

Fred

ethicalpaul said:

Thanks @Fred, I was attempting to demonstrate the ridiculous nature of that code requirement

Well I mean, it's not totally ridiculous...you need to know if your pressuretrol is failing...if you happen to be down there looking at the gauge.

I just have a picture in my head of a boiler shooting through a roof with a 0-30 psi gauge on it and no one reading it.

I agree totally!

pkwastavich

I suppose you could have a gauge that sends pressure stats to a computer and alert on them that way. Wonder how much those would run you