two pressuretrols?

Unknown

pressuretrols. They are as I explained above.

JM_2

Why do both of my steam boilers have two pressuretrols each.
On both units one is set at .5psi cut-in and the other is set a 6psi cut-in.
Domestic hot water is supplied from a separate gas HWH.
JM

Unknown

Is the 6 psi cut in

a manual reset pressuretrol ? It might have a button to reset if it hits the setting . Other than that , it might just be a backup to the main pressuretrol - we usually install 2 on our commercial steam jobs , as well as a manual reset .

Or , one of em could be a reverse acting pressuretrol , if you have some sort of heat timing device for the building . We see them on the bigger apartment buildings with steam heat and no indoor thermostats .

Unknown

Is your system Powerpile?

In the late 70's and 80's when redudndant gas valves (dual seated) became a requirement many boiler companies in order to keep using powerpile were allowed to use an auxiliary limit or second pressuretrol which was wired into the self genrating circuit as a safety in lieu of a dual seated gas valve. the second pressuretrol would be set at a higher shut down point usually 14 lbs off 9 lbs on. Pop safety on steam will open at 15 lbs.

The other pressuretrol was set usually at 2lbs off and .5 on. It depended on the systems and local codes as to the setting.

JM_2

Yes it is powerpile

I remember having to have one of these replaced two years ago.

JM