Boiler cuts out at pressure doesnt cut back in

Doone

I've read the wall for years but this is the first time I need to ask for help.

I have a 33 year old Repco TGC 220 on a one pipe system which I have owned for that many years, in a NYC 3 floor house that had steam heat installed prewar. I replaced the low water cutoff and auto feeder 2 years ago, it works fine. This year I am having issues with cut out and cut in. Specifically the honeywell temptrol ( replaced 3 years ago) cuts out at pressure but doesn't cut back in unless - a) the boiler cools, or b) I readjust the cut out screw (the differential is set 1 and a quarter). There is a brass pigtail from the LWC to the temptrol and the original built in (internal syphon) pressure valve has been kaput for about 15 years but that has never had any effect on anything in the past. There is proper heat at all radiators and none of the Gortons are clogged , including the ones on each main ( all properly sized per floor). I don't have water hammer and there has always been a cycling of cut out off 2 minutes, cut in 6 min. or so once pressure has been reached, but not so this year. I treat the system annually with Hercules liquid cleaner. Any suggestions would be extremely helpful. Thanks in advance.

BobC

Did you make sure that pigtail between the boiler and pressuretrol is clear? It sounds like it might be gunked up, sometimes you get a flap of crud where the pigtail screws into the cast iron. Also make sure the little hole inside the brass fitting that screws onto the pigtail is clean.

Bob

JUGHNE

A clean brass pigtail going into a clean boiler opening, a tee on the pigtail with your pressure control and a 0 to 5 psi pressure gauge so you can see what the control sees. IMHO

Jamie Hall

It does sort of sound as though the pressuretrol is misbehaving... could be clogged, either pigtail or the opening to the pressuretrol or the opening to the boiler.

Or it could just be... tired.

Doone

The pigtail is attached to the LWC and ITT McDonnel blowoff valve so its a little tight. Will have to have my plumber come to clean out and put an extension and maybe that tee on it so I can hook up a pressure gauge. Picture attached so you can see. Thanks for the answers so far.

BobC

Have him clean out the LWCO if it hasn't been done this year while he's there - that should be done every year.

Bob

JUGHNE

Your pigtail is low enough that it gets boiler water in and out of it. I sure would raise it up so the loop is well above the water line. Add a brass union for easy cleaning.

Or find another port on the boiler well above the water line, Old boiler may have plugs that won't come out. Where was the original gauge connected? That may be an access point, just get rid of any snubber fitting and use your pigtail. And prime the pigtail loop before using.

Doone

Ok, I am going to have the plumber raise the height of the pressuretrol and extend the loop of the pigtail above the height of the waterline and add a union for easy removal and cleanout. The original gauge isn't functioning and not leaking. Rather than create the possibility of a leak or other problem the plumber will put a tee on the pressuretrol pigtail and put a 15 lb pressure gauge on one leg of the tee. Also he will clean out the LWC at the same time. There is a lot of tiny rust scale this year, coming out of the blowdown but otherwise the boiler is functional and heating well. Thanks for all the suggestions. Doone

vaporvac

I believe you need a 0-30gauge to meet code, but I'd add a 0-3lb low-pressure gauge while you're at it so you can see what's actually happening with your boiler. Perhaps the current Ptrol is just clogged in some way.

Fred

I can almost assure you that the pigtail is clogged and probably the opening in the MM #67 LWCO that it is mounted on as well. I have a similar set up and if it's not cleaned a couple times a season, it gets clogged with gunk. Once that happens, the pressure at the Pressuretrol diaphram sometimes can not release and the boiler will not restart. I bet if you tap on the top of the Pressuretrol, it will fire.

Doone

And the winner is the clog at the bottom of the pigtail and the opening it goes into at the LWCO. Plumber extended the connection with a union so I can access in future to clean out any new clogs. He added a tee and code approved pressure gauge with wide spaces between lb. markers so I can see exactly what is going on. Fee was very reasonable too. Thanks all for your advice, see pic attached. Doone

nicholas bonham-carter

I don't see a union between the LWCO, and the pressuretrol.
A union would make it easier to take off the pressure trol, and run a zip-tie through the pigtail.
When you blow down your LWCO, you can see how much debris is in there potentially splashing up into the pigtail, and plugging it up. Adding a 0-3 psi gauge would still be a good choice, as the cheap standard 30 psi gauges are probably not accurate at the lower end of the scale, even when you can see the numbers.--NBC

Doone

NBC - sorry for the late reply, there is a union below the pressure gauge, I can spin it off to put the zip tie in and then spin it back on. It's reading well enough for me so that I can see my c/o is 1.6lbs and c/i is at 1.2 lb.

How much water should I be losing in this weather if I may ask your opinion? I am losing about a qt a day all the gortons seal properly there is no hissing or sputtering at the valves of any of the radiators and my returns are above the basement floor and not leaking. I hear no hissing at the boiler when it is pressurized. Thanks for your help, Doone