steam boiler short cycling

nytech28 · November 13

hay techs , I replaced a defective pressuretrol PA404A1033 on steam boiler ,add boiler treatment for service , all the radiaters are getting heat , but the pressuretrol short cycles boiler every few minutes i have it set just below 2psi , it was very late in evening so i didnt further check , will need to return back ,wanted to post the issue for solution .tnx

ethicalpaul · November 13

The boiler is oversized for the amount of radiation and so pressure is building.

You can verify that the main venting is sufficient and operational to help this issue, but short of disabling a burner (assuming it's a gas) or down firing it (if it's oil) that's about all you can do.

leave the thermostat at a single setting will also minimize the cycling, but don't worry about the cycling if it's gas.

nytech28 · November 13

sorry I didnt specify , its a gas fired steam boiler , gravity type, 175k btu serving 4 apartment with few radiators in each apt. also found few gate vavles leaking little steam by the stem nut ,but I dont think that would reduce pressure to fast.

ethicalpaul · November 13

Fix the valve leaks, but yes, that won't affect your pressure very much. But you don't want any steam leaks.

Do you know the EDR or total square feet of radiation in the building? Compare that to the "Net Square Feet of Steam" rating on the boiler and you will likely see the boiler is too large.

reggi · November 13

What boiler treatment and how much did you add ?

mattmia2 · November 13

and are all the radiators heatign more or less all the way acrross

and is it cycling on pressure or the low water cutoff or some other control?

nytech28 · November 13

used 1qt ,8 way treatment per instructions, its going off on pressure troll which i repalced & set just below 2psi ,with diff @1from factory,all the radiaters across were getting hot , before I left job, tanant mentioned that radiater were not very hot, but was heating , I did find few valves closed for radiaters in bldg & opened all radiaters in bldg to test full heat.

ethicalpaul · November 14

Don't follow the instructions on 8-way. This otherwise fine product (I use it and love it—it almost eliminates corrosion) wants you to use way too much of itself. You can use about 1/4 of what the instructions call for.

DanielDAY · November 18

I’ve had issues with these pressuretrols before and still do. Verify that the actuator is somewhat stiff at the setting you have it at and not super easy to click. Recently had one that was at the same setting as the other two but the first one was very sensitive. If your pressuretrol is sensitive, it’s probably defective. If you can sneeze on it and it clicks, that’s a bad one for sure.

also please send a picture of the settings on your pressuretrol. I have also noticed they can be less accurate when you lower the cut in too low.

mattmia2 · November 18

it is too late now, but if you had to replace it you might as well have sprung for a vaporstat.

what was wrong with the original pressuretrol?

109A_5 · November 18

An inexpensive Delay on Break timer can be added to minimize the cycling nonsense after the first trip on pressure. There are other ways to minimize the cycling, the Delay on Break timer is probably the least expensive and easiest to install.

nytech28 · November 18

https://forum.heatinghelp.com/discussion/comment/1872831#Comment_1872831

I dont have picture but the new pressuretroll cut in was set just below 2psi , with the diff @1 from factory ,i havent got a call back its ben 5days already .

nytech28 · November 18

the original pressuretroll was stock in open position, soon as I would touch it boiler would come on, as someone mentioned in comment as soon as u sneeze on the pressuretroll it would activate , even toke it out & cleaned it but still would not cut in ,so i had to repalce it.

nytech28 · November 18

https://forum.heatinghelp.com/discussion/comment/1872836#Comment_1872836

you mentioned delay on break timer , is this a time delay ,thats used on air conditioning compressor or its something specially for steam boilers ?

Jamie Hall · November 18

https://forum.heatinghelp.com/discussion/comment/1872866#Comment_1872866

Whatever else might have been wrong those settings are too high anyway for residential steam heat.

nytech28 · November 18

https://forum.heatinghelp.com/discussion/comment/1872870#Comment_1872870

so what setting your putting them just to be exact, & this is the pressuretroll I installed.

dabrakeman · November 18

Slide the slider down right to 0.5psi and the white wheel inside should be set on 1

nytech28 · November 18

ok so thats gona set the psi for the system to 1.5psi

dabrakeman · November 18

Assuming you have an accurate pressuretrol which would be unusual :) Most as set still seem to let the pressure creep closer to 2psi before cutting out.