Pressusretrol replacement

mel rowe

Thanks Mark for your reply. You were right that I do have a PA404A Pressuretrol. You recommended as a replacement the L408A. Could you explain how this is different than the L608A-1046 vaporstat, and why would it be better for me? Thanks very much. Mel

mel rowe

When the boiler on my old one pipe system was replaced, the installer put in a gauge that read from 0-50 psi. Obviously that was useless to me. I finally replaced it this week with a 0-5 psi gage and now I have found that my old pressuretrol Honeywell 404B has been breaking at 2 1/2 and making at 1 1/2, about 1 psi above where it should. I'mk thinking of replacing it with a vaporstat, after reading Dan's book. There are several listed in the Honeywell L608A family. My question is which one is the correct one to use as a replacement? Thanks.

carol_3

I'll see what I can find out. Anyone else know?

superMARKet

Vaporstat

Are you sure you've got a "B" control (L404B or PA404B)? Those make a circuit when the pressure rises and aren't typically specified as controls on low-pressure steam boilers, where you want the burner to stop when the pressure rises. It sounds to me like you've probably got a PA404A instead. Could you take a closer look at your control and verify?

Assuming you've got a PA404A on there now, you'll want an L408A Vaporstat, specifically, L408A1157. This will give you 0-4psi cut-out and 2-16oz/sq.in. subtractive differential.

mel rowe

Pardon me Mark, I do have a PA404A. So you said that I would need a L408A1157. Could you please enlighten me as to why this version, rather than the L608A1046? I'm just trying to increase my understanding of these things. I looked at Honeywell's site and could find no info at all. Thanks for your help.

superMARKet

L608A has extra contacts

The L608A makes one circuit and breaks another on pressure rise (it's an spdt switch). Using the 404A/404B pressuretrol example from above, the 608A combines the features of both. You don't need the extra terminal, but other than the possibility of wiring confusion and about $15, it's the same thing.

Note that I specified L408A1157, which is 0-4psi. L608A1046, what you asked about, is 0-1psi. The 608 equivalent with the wider range is L608A1053. You get 16oz/sq.in. adjustable subtractive differential with any of these. Having a 4psi top end gives you a little bit more flexibility, in my opinion.