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Filling at 10

michaeldonahuemichaeldonahue Member Posts: 4
How can I fill a hot water system at 10 degrees? House has been vacant for a few years. Have leak tested with air & fixed. Thanks


  • SteamheadSteamhead Member Posts: 13,998
    Set up enough portable heaters to get the house above freezing. Then fill one story at a time.
    All Steamed Up, Inc.
    "Reducing our country's energy consumption, one system at a time"
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Baltimore, MD (USA) and consulting anywhere.
  • Jamie HallJamie Hall Member Posts: 13,416
    Good luck. It can be done, but you're going to be walking a tightrope -- and the possibilities of real and serious damage are ample.

    If at all possible, my first choice would be to bring the house up to about 40 throughout using construction heaters. We used to call them salamanders; I'm not sure what the current term is. Propane or kerosene fired. Since they are fuel fired, there is some danger involved! Carbon monoxide, for one, as well as the obvious problem of setting things on fire.

    Assuming this is hydronic...

    If that is not possible, then in principle you can fill the boiler and the immediate piping, if it's primary secondary, with warm water and fire it up. When it hits its limit, open the valves to the lowest of the zones and start filling that zone; as soon as possible get the pump for that zone running and get hot water circulating (if there is a mixing valve, set it for as high a temperature as possible). Keep the boiler going! The whole thing is going to want to freeze on you, but keep pumping. You're not purging here, just trying to get it warm. Once you are getting a decent return temperature -- say 80 to 100 -- repeat with the next zone, and so on. Do not let the water stop flowing in any zone until the building is up to at least 40. Don't leave the operation unattended until the whole system is giving decent return temperatures and the building is up to 40. It may take a while. It may take quite a while, depending on the size of the boiler and the type of system (radiant floors, for instance, could take days).

    Note that you will need a water supply. You may find that you need a construction heater just to keep that from freezing in the intervals when you are not filling the boiler or a zone.

    If you can't fill the boiler and run it without also filling a zone at the same time, I can't recommend you try, unless you can bring in a portable boiler and use it for your hot water source. Very hot water...

    If it springs a nice new leak while it is warming up, which is quite possible, be prepared to shut it down and drain it completely, fast.

    Another possibility would be to prepare enough antifreeze/water solution to fill the system completely, and fill with that and fire it up. The problem with that, of course, is that then you are using antifreeze/water in your system, which has problems of its own to cope with.

    Or, of course, just wait until the house warms up above freezing. Spring is coming...
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • michaeldonahuemichaeldonahue Member Posts: 4
    Thanks Will give it try. But may not be Abe to get temp up & walk into house safety! Can I use R/V antifreeze then bleed off? Thanks Steamhead
  • ZmanZman Member Posts: 6,004
    edited January 2017
    Use propylene glycol. You can buy it at any supply house. Premix it at 30% concentration with warm water.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • hot_rodhot_rod Member Posts: 13,850
    How large of a system? I'd error on the safe side with hydronic glycol, probably 12 bucks a gallon for a premix solution.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • michaeldonahuemichaeldonahue Member Posts: 4
    Could I cut the glycol depends on temp? Do one zone get above 32 then feed the next zone with wash hose to next zone ect 1st floor 2end & so on House temp will going up? Thank you all for good info!
  • hot_rodhot_rod Member Posts: 13,850
    Yes you could go down to a 30% mix that would offer burst protection at those temperatures.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • michaeldonahuemichaeldonahue Member Posts: 4
    Thank you hot rod
  • ZmanZman Member Posts: 6,004
    I would not recommend trying to fill and dilute the mix one zone at a time.
    Murphy and his law's will be with you when you attempt this. What happens if you get a zone air locked with a partial fill of water?
    Fill the system with 30%, get it circulating, then fire the boiler.
    If you need to add water to top the system and you end up with 25% or so in the system that is not an issue.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
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