Drained heating system to replace rad valve - can't refill

Discussion in 'Boiler Forum' started by 157, Dec 1, 2020.

  1. 157

    157 Member

    Mar 27, 2014
    • 3 story (2 main floors plus attic with two rads), 1920's house
    • 14 total hydronic radiators
    • Single zone
    • Gas-fired Crown boiler (see pic below)
    • Manual (?) cold water refill (see pic below)
    • Has expansion tank on return line (see pic below)
    I had a leaking rad valve on the first floor. I drained the system and replaced the valve. Now, I'm trying to refill the system and I cannot seem to get the heat past the first floor. By the time I get the last of the (5) first-floor radiators bleed and shooting water instead of air, the pressure in the system is so low that the next radiator I open starts sucking air (see gauge pic below).

    Here's the order of operations I'm following:
    1. Turn the system off (flipping off kill switch, but leaving pilot on), let it cool down
    2. Turn on the manual cold water refill to bring the PSI up to ~12 (the gauge half-works on the boiler, but the expansion tanks starts spitting water at some point)
    3. Open the bleeder on the first-floor radiator furthest away from the boiler and work towards the radiator closest to the boiler
    4. [Lost pressure]
    Is this where I should have more patience and just go back to step 2 and open the manual cold water to refill and start over? At this rate, it will take me like 5 hours to get all three floors bled — there's 10 more radiators to go on floor two and three!

    Full boiler setup:

    Expansion tank on return:

    Gauge after bleeding first-floor radiators:

    Cold water refill setup:
    Last edited: Dec 1, 2020
  2. fitter30

    fitter30 Well-Known Member

    Feb 2, 2020
    Retired service tech
    Peace valley missouri
    Your boiler is 160*? Your tridicator gauge is bad if it not. The water regulator is bad if system doesn't fill. Auto air bleed on ex tank needs to be replaced. Fill system to 20 lbs then bleed some radiators or use two people and your phones for communication. Check the ex tank air pressure while system is drained. Working on a system with a bad gauge makes diagnoses a lot harder especially if the person doesn't know it.
  3. Sponsor

    Sponsor Paid Advertisement

Similar Threads: Drained heating
Forum Title Date
Boiler Forum Mixing Valve For heating and domestic May 7, 2021
Boiler Forum Oversized boiler, extremely high heating bills Feb 21, 2021
Boiler Forum Hydronic heating. When should the pumps run? Feb 13, 2021
Boiler Forum Third Floor Radiator Not Heating (Steam Boiler) Jan 20, 2021
Boiler Forum Infloor heating Poly B Dec 24, 2020

Share This Page