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Pressuretrols and Gauges

SMRTK
SMRTK Member Posts: 41
in Strictly Steam

Good evening,

Below is a photo of my old boiler pressuretrol assembly. The boiler has since been replaced and all of the near boiler piping has been redone. As I am working through getting the new boiler up and running I have a couple of questions about the pressuretrol and gauge:

My old boiler had a Honeywell pressuretrol for cut in and cut out and another high limit pressuretrol with a manual reset. My new boiler has a Resideo that is identical to the Honeywell on the right for cut in and cut out. There is no second pressuretrol.

  • Do I need/want to add the second pressuretrol high limit switch?
  • If the answer is yes, is it advisable to use the one that came off of my old boiler?

For context, the old boiler was not installed correctly, maintained at all and our water is terrible. In fact, the entire assembly fell off one day when I bumped my head on a steam pipe. It was rusted through at the point of contact with the sight glass piping. That was a lot of weight on that one little connection.

For the gauge my question is sensitivity. The gauge that came with the unit is the same that was on the old one, 0-30 PSI. Since I have had my boiler up and running the gauge has not moved even a little bit. Should I get a lower pressure gauge? Is there a recommended brand/range? Part of me feels that I need to see something happening here to know that it is all working. Not very scientific, I know.

image.png

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 26,561

    On the pressuretrols. On larger boilers two are required — one for control and one for safety — the latter having a manual reset. It does no harm to have two on any boiler.

    On the pressure gauges. Code — and your insurance people — want one gauge which reads to twice the setting of the pressure relief valve. Not optional. However, also not of much use to seeing how the boiler is actually operating — so many people put another gauge, typically 0 to 3 or 0 to 5 psig — on. Very often smply teed off the pigtail carrying the control pressuretrol.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    SMRTK
  • mattmia2
    mattmia2 Member Posts: 14,705

    that red button is the manual reset on that secondary pressuretrol

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 18,893

    Usually, manual reset pressure control is installed on commercial jobs. In MA where I am they are required over 200,000btu.

    If in doubt put it on the new boiler. It should be on its own pigtail not doubled up like on the old boiler.

    No pressure on the gauge is a good thing not a bad thing. Put a LP gauge on if you want. You have to keep the 0-30 gauge and I would put a petcock on the LP gauge only. Keep it off when not checking pressure.

    SMRTKbburd
  • SMRTK
    SMRTK Member Posts: 41
    https://forum.heatinghelp.com/discussion/comment/1870931#Comment_1870931

    Are the pressuretrols pretty durable? Given that the system was not in great operating order would re-using the old one be a problem?

  • 109A_5
    109A_5 Member Posts: 3,085

    I too like to see the actual working pressure. I like this type of gauge (Dwyer Magnehelic), many on eBay, but you really need to know what pressure your system runs at since that would determine the type of gauge you purchase. They come in many pressure varieties.

    image.png
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
    SMRTK
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 18,893

    Yes the pressure controls are durable. Just make sure the pipe connection is clean.

  • dandub1960
    dandub1960 Member Posts: 32

    In a pinch you can make a water manometer from some vinyl tubing and a hose barb. Attach the barb to your low drain hose (get a hose if you don't have one) then suspend a sufficient length of vinyl from a high point (preferably near the sight glass) and connect the two pieces of hose with the barb. Careful open the drain valve (preferably with the boiler cold initially) and the water level should fill the vinyl right up to the waterline in the sight glass. During boiler operation you can watch the pressure gradually climb as the level in the vinyl moves above that in the sight glass.

    Voila! You now have a very sensitive pressure measurement in inches of WC. Just close off the boiler drain when you're done watching or if the boiler pressure is going to exceed the headspace you have. For most gravity systems this shouldn't be the case but you never know. You will also see clearly if you system is pushing water up in dry returns.

    You can tap on that 30# gauge all day long and register nothing.

    Steward to 1923 Spanish revival near Chicago - 2 pipe steam 650 EDR Burham 5B

    109A_5

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