low pressure gauge set up

Jamie Hall

is required by code; get it reinstalled as soon as you can.

A pigtail (preferably red brass) is always a good idea; helps to protect the gauge against damage.

Pressuretrols are not wildly accurate at low settings; I'd be on the gauge, not the pressuretrol, as being accurate.

And it doesn't matter how the pressuretrol is wired, though I always try to get the colours right. It's just an on-off switch, basically.

bob_114

Hi all.

i purchased a lower pressure gauge 1-5psi model and just installed in on the boiler as per many recommendations on the wall. i took out the existing 0-30 gauge just to test out the unit and will put in on a pigtail in a few days.
i have two questions.

the gauge is pretty accurate in that it cuts off at the set limit 2psi. I have a subractive honeywell pressuretrol so i set the differential to 1 psi as per dan's book.
however, instead of cycling back on at 1 psi, the unit is cycling back on at 1.5psi. is there suppose to be a difference b/w the pressure reading on the pressure gauge and pressuretrol? i would assume if the cutout is accurate, then the cut in should be accurate too? thoughts?

since the stock 0-30 gauge is plug directly into the tapping with no pigtail, how pertinent is it that i need to mount this low pressure gauge on a pigtail? what are the downsides if i dont?

lastly, does it matter how i wire the honeywell pressuretrol? black wire goes to terminal marked "b" and red wire goes to terminal marked "r"? this is a non mercury type switch, L404f1367. the installers had it reverved.


thank you in advance for your inputs.

I am very addicted to the Wall. This forum is like a narcotic!!

bob_114

Thanks Jamie.

I guess my last question would be how do i get the pressuretrol to cut back in at .5psi? as right not it cuts out and within a minute it cuts back in...


Much appreciated

Jamie Hall

You can try

setting the differential a bit higher, but I wouldn't set it too high. Pressuretrols, unlike vaporstats, get kind of squirrely down that low and what you don't want to have happen is to have the thing cut out and then refuse to cut back in! Actually, having it cut back in within a minute or two isn't bad; what's happening is that the steam is condensing which it does very fast. If you can get it so that there is at least a minute I'd settle for it, so long as everything else seems OK.

bob_114

Thanks Jamie!!