Differential Pressuretrol setting verification

bohemka

Hi. First post!

I'm the new owner of an old single-pipe steam system with a gas boiler. I've just finished reading Dan's book, and have a list of things to do to take care of the hammer and hissing. I have a quick question about setting a differential pressuretrol and hope that someone can help.

The MAIN on our system was set at almost 5 psi (!), while the DIFF is bottomed out or nearly bottomed out, but the problem is that I cannot tell, as the lowest number present is "2." It is lower than 2, though, and it looks like I'd guess it was at 1 based on the spacing between 2 and 3, 4, etc., but without fiddling with it it could be set as low as it goes. I don't know.

At any rate the MAIN seems to be set too high, and based on what I know now I'd guess the system is set somewhere between 3 psi and 4.5 psi, which is obviously too high. The MAIN gauge does not offer a setting lower than 2 either.

It's the same exact Honeywell differential pressuretrol that's pictured in the book.

What I was going to do (and I wanted to check this before I did it), was crank the MAIN down to 2 and leave the DIFF at its sub-2 setting. But perhaps this is still too high. I know I want the system at .5 psi with a maximum upper range to 1.5 psi, but this is difficult when the gauges don't offer settings below 2.

If anybody is familiar with this differential pressuretrol and can confirm that I'm on the right track or if I've got it all wrong, I'd really appreciate it.

Thanks!

bohemka

Sorry for such a basic question.

I cannot find the manual anywhere, and google searches pull up the additive Pressuretrol settings.

I suppose basic math is my friend. If readings lower than 2 aren't available, and I want to achieve a .5 psi system setting, I guess can set the MAIN to 5 psi and the Differential to 4.5 psi (rough estimate). Right?

Thanks a lot for any advice.

JStar

Set the Main to as low as it will go, typically 2psi, and the differential somewhere slightly lower than 2psi. The lower the better, but some Pressuretrols just can't get low enough.

Main minus Differential equals Cut-In. So, it will cycle between 0-2psi.

bohemka

Thanks a lot, JStar. That's what I've done, and it's heating fine and some hammer has left as a result. Still some insulating and venting to take care of now...

Thanks again.