Right pressuretrol replacement (residential, steam)

Lev77

Hi all and thanks for reading,

We have this steam system.



I recently cleaned and tested this for winter (including the pigtail), and the pressure gauge was going nuts.
Time to replace and T off the pigtail.
I also wasn't sure I could trust the pressuretrol.

This pressuretrol is Honeywell L404A 1354, has mercury tube.
It was discontinued.


From what I've been reading, this pressuretrol might have been the wrong one in the first place because of the high PSI cut-out. But I wasn't sure if there was a reason for them to select that one, maybe due to boiler model or some other reason.

Any suggestions?
Thanks!

Jamie Hall

That is the old standard pressuretrol. The cutout is high -- but you can adjust it down to about 1.75 psi, which is OK except for vapour.

The mercury pressure switches last forever.

However. They are extremely sensitive to being level. Yours is anything but level, if the picture is any guide. To work properly, you must level it. You can probably swing the pigtail enough to get it right.

Lev77

Thanks Jamie. If I wanted to replace it, what model would you recommend?

Jamie Hall

Probably something in the PA404 series with the right range -- but why would you want to replace it? The newer ones don't work as well...

Lev77

Well I'm not sure how many years these components have been here but definitely more than 10. I thought it might be time to replace them. That's the only reason really - and that this model was discontinued.

KC_Jones

If it isn't broke don't fix it, I don't have any experience with that particular model, but many on here feel those are better than the new ones.

I can tell you the new ones are abysmal as far as accuracy goes. I have 2 vaporstats and a pressuretrol on mine and none of them are correct.

Jamie Hall

Lev77 said:

Well I'm not sure how many years these components have been here but definitely more than 10. I thought it might be time to replace them. That's the only reason really - and that this model was discontinued.

It was discontinued. Because of the mercury switch. Because of the mercury switch it will still be switching reliably long after either you or I care, unless someone does something evil to the diaphragm.

EBEBRATT-Ed

The L404A was a good commercial control seldom seen in houses. They last a long time. You must level it to be accurate as @Jamie Hall said. In fact if you look closely behind the mercury tube you will see on the back inside wall of the control Honeywell builds in a "plumb bob " out of a strip of aluminum to help level the control although a level is probably more accurate