How to loosen setscrews on scaleplate to recalibrate pressuretrol

rrwitherspoon

Pressuretrol not turning boiler off at 5 psi when set cut in 0.5 psi and cut out 1.5 psi.
Seems not functioning observed pressure up to 5psi I have to turn boiler off myself

BobC

Have you checked the pigtail is not blocked? While the pressuretrol is off check the little hole at the base of it's brass fitting to make sure that little hole is clear.

Also make sure the spring has not decoupled from the lever.

Bob

Jamie Hall

That's more than a calibration error. Follow Bob's advice -- and check the pigtail and where it goes into boiler, too.

Might make sure that it is wired properly, if that doesn't hep...

rrwitherspoon

The pigtail is clear.The little hole on bottom of pressuretrol is patent. How do you make sure not decoupled from lever?

rrwitherspoon

Wired as it always was when functioning .Pink wire at top.

BobC

On the left side of the lever there is a threaded ferrule that the top pressure adjustment screw threads into. That sometimes gets unscrewed, make sure it is engaged.

Sometimes the microswitch contacts get welded closed. To test that, remove one of the wires on the switch, if the boiler shuts down the pressuretrol is at fault. BE CAREFUL THOSE WIRES CAN HAVE 120V ON THEM - turn off the power before messing with them.

Bob

rrwitherspoon

Ok i will try when i get home

rrwitherspoon

Everything is engaged. No misaligned ferrules
or levers. Should the contact fork wires of pressuretrol be placed between metal nut and screw? Like a sandwich ? Maybe that is the problem.

BobC

As long as the wire is under the head of the screw or one of it's washers, the contact should be solid. Have you had a chance to turn off the power while the boiler is firing and delivering 5PSI, remove one wire, and see if the boiler starts up when you reapply power? If the boiler. If it does not it indicates something is wrong with the pressuretrol.

There is always the possibility that the gauge is not working right. At 5PSI I would expect the vents would be hissing a bit loud, any signs of increased noise?

Bob

rrwitherspoon

Yes, at 5 psi the last radiator supply valve hisses and a leak appears that otherwise you would not even detect

rrwitherspoon

I will get vapostat and low pressure gauge installed

rrwitherspoon

Shall I install vaporstat just like pressuretrol.
I noticed there 3 wires instead of 2

SWEI

SPDT terminals. You want break on rise.

rrwitherspoon

Does one use all 3 terminals?

SWEI

Just the common (R) and the break on rise (B). Leave the make on rise (W) alone.

David Nadle

No. You want to connect to the two terminals R and B that "break on rise." Don't buy a two terminal vaporstat.

rrwitherspoon

I hope instructions come with vaporstat for wire connections
L408 1017 model number