Click here to Find a Contractor in your area.
Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit

steam boiler makeup water

and was wondering what would be an average quantity of makeup water taken on in say a months time..assume the system is tight with no leaks there some industry chart for this? i know that no system is perfectly tight and some water gets taken on..i'm going to install a water meter as there are some doorway underground returns but need to be able to tell the homeowner something like,,"call me if the water meter clocks more than X amount in a month"..any thoughts would be helpful and appreciated..thanks


  • Have them keep a log that you start

    Let them track how much water they put in at blowdown times. Even a gallon or cu ft between blowdowns would be a leak, so there shouldn't be much at all. If a leak shows up, it'll eat GALLONS extra over a month of heating season. We have some customers with water meters on the boilers. If it doesn't leak when you begin tracking, they'll know if it begins to leak. If it leaks now, and they just get used to a big number, it's trouble for the boiler. Leaks above the waterline in the building will show up fast. Leaks up the chimney inside the boiler show up on the meter, as do underground leaks. I like metering makeup water, and logging the use.

  • Jacob Myron_11
    Jacob Myron_11 Member Posts: 3
    Make upwater usage

    depends on the the type of system.

    One pipe steam systems use more water than two pipe systems.

    One pipe steam systems lose water via vent valves. A vent valve can be operating perfectly and some of the vented air has water molecules attached to the venting air. Packing nuts on radiators might leak and the leak is not visable.

    Two pipe steam systems will exhaust some water vapors out of the master vent valve while venting air.

    Two pipe steam systems with condensate and or boiler feed pumps will leak water as air is released from the vent pipe on the receivers of the pump sets.

    If the piping is tight and no leaks are visisble it will take one season to establish what the normal water loss rate is for the building.

    You cannot apply a formula to determine water loss that will be correct for all buildings.

    I can tell you this, when I serviced large buildings with central plants the developments when they were new averaged between 1/2 - 1 gallon of water loss per apartment. As the buildings got older the water loss increased.

    Some of these develoments did not have leaking pipes they had leaking steam traps. The water left the system as steam via the vents on the condenste or vacuum pump sets. After the traps were rebuilt or replaced the water loss dropped.

    In these developments water meters were read daily. In a small house the meter should be read once a month.

    All blow down water loss must be recorded, if a boiler is drained for repair that water loss must be recorded. The total of all water used as blow down or water usage when a boiler is drained must be subtracted from the total water usage shown on the meter.

    Remember all buildings are different even if they have the same size boiler and equivelent radiation load.

    You need one operational season to determine what is amount of make up water is normal for a buildings steam heating season.

  • thanks for the info guys

    its helpfull information
  • Bob_19
    Bob_19 Member Posts: 94

    A good beginning is to have the numbers first.
    1lb of water will make 1lb of steam, 1gal of water weighs 8.3 lbs.
    If you know how many lbs/hr the boiler makes at full load, (small boilers normally run full tilt till shutdown) then you have a starting point.
    Install a meter to capture water makeup, a single count meter installed for the boiler will compliment the water meter telling you how many cycles ran, this helps to account for blowdowns, the only problem here is boiler on times. This gives you a more accurate leak detection system.
    Other than that there are no norms for water make-up.
This discussion has been closed.