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Running a water boiler with water supply off while away?

yhc Member Posts: 12
Good morning.  You have helped me troubleshoot my Embassy model 160 boiler.  Since it was last serviced a couple weeks ago, it’s been running well.  Thank you again, especially @kcopp and @109A_5

I have one unrelated question on the Embassy  boiler heating system.  Each zone is controlled with a thermostat.  Is it safe to leave the heating system running with water main supply to the house turned OFF for a few days to a week when I am away?  Or would there be enough evaporation loss in the system to lower the water pressure to negatively affect or shut off the boiler?


  • pecmsg
    pecmsg Member Posts: 4,838
    If water is needed, then there is a leak somewhere.
    Why are you turning the water off?
    STEAM DOCTOR Member Posts: 1,965
    Is there a functioning low water cut off? You should probably be okay. Presumably there are no leaks because if they were you would know about it by now. There are those who always leave the water feed to the boiler off. Where are you located? If you are away, do you need heat?
  • Jamie Hall
    Jamie Hall Member Posts: 23,275
    I can't seem to find any information on that boiler, but if this is a hot water system there should be no problem at all, assuming the pressure has been holding steady and you have a low water cutoff.

    If this is a steam boiler, then if you don't have two low water cutoffs, the lower manual reset, I couldn't recommend it.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • 109A_5
    109A_5 Member Posts: 1,385
    Hello @yhc,
    Looks like it has a Low water (pressure) safety switch. If no leaks and maybe if the safety switch functionality is verified.


    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
    Alan (California Radiant) Forbes
  • jumper
    jumper Member Posts: 2,245
    What happened to flow switch?
  • yhc
    yhc Member Posts: 12
    Thank you all for the replies. 

    I had Flo by Moen, smart water monitor and shut off system, installed a couple years ago.  At that time a plumber has suggested of either shutting off the well pump or the main line coming off of the well pump off when I am away IF I am concerned about possible freezing and flooding. 

    I have never tried that as an option but wanted to know if it is safe to do so to have it as an option

    And to answer Steam Doctor, the current outside temperature ranges from 20-40’F so yes I need to keep the heater/boiler on. 
  • yhc
    yhc Member Posts: 12
    jumper said:
    What happened to flow switch?
    Not sure what you mean, @jumper
  • hot_rod
    hot_rod Member Posts: 22,109
    A happy medium if you do not want a fill valve left on is to use a fill tank or expansion tank fill.
    This way you still have a few gallons of fill if some rogue air purges out and pressure drops below the low water cut off pressure switch.

    Mod cons commonly use a pressure switch as protection, a flow type or probe LWC can also be used.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream