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Boiler Water loss--How much is normal

Dave in QCADave in QCA Member Posts: 1,759
I feel a little bit silly in floating this out here, but I've change my boiler operating habits and I'm seeing something that causes me concern.

Back in December 2012, we installed a new Weil-Mclain 680 boiler. There was a very detailed post about that project on here at that time. The system is a 2-pipe Dunham and the venting is through a pair of Dunham Air Eliminators and both have air checks on them. After a steam cycle, the system goes into vacuum and it holds well. At 1 cycle per hour, there is not a discernable loss of vacuum. However, if there is not a call for heat, the vacuum will dissipate before 2 hours passes. So, the system is not 100% tight, but is pretty darned tight. There is no underground returning piping. All of the basement piping is visible with steam lines insulated. There are no leaking radiators, no leaking traps or inlet valves. There is no visible leaks in the boiler and there is no white smoke. So, this sounds like a very tight system, right?

A change in my LWCO blow-downs has caused me to question it. In the past, I have flushed the 2 MM LWCO devices and have also done a quick flush of the drain. The boiler has been treated with SteamMaster tablets from the beginning. I catch the blowdown water in a bucket and it is always very clean. When I flush the LWCOs, I always manually top the boiler off to the normal water lever, using the bypass on the autofill meter (VXT) Each fall, at the beginning of the heating system, I drain the boiler and wand out the bottom, refill, add Steammaster tablets, and bring it up to steaming for 15 minutes.

So, this year, rather flush out clean water and cause the treatment to be diluted, I cut back on the blowdown routine. I waited until Thanksgiving to for the first blowdown, and it was perfectly clean. So, I waited until February 1 for the next. What I noticed was that I was beginning to see water use on the VXT meter. I did one more blowdown at April 1, and again, the water was clear. However, now, at the end of the season, the VXT is showing 36 gallons used. The boiler holds around 50 gallons as I recall. The only place that I can identify that water is lost, is in the humid air that is expelled in the venting oz.

Your thoughts and insight would be greatly appreciated.
Dave in Quad Cities, America
Weil-McLain 680 with Riello 2-stage burner, December 2012. Firing rate=375MBH Low, 690MBH Hi.
System = Early Dunham 2-pipe Vacuo-Vapor (inlet and outlet both at bottom of radiators) Traps are Dunham #2 rebuilt w. Barnes-Jones Cage Units, Dunham-Bush 1E, Mepco 1E, and Armstrong TS-2. All valves haveTunstall orifices sized at 8 oz.
Current connected load EDR= 1,259 sq ft, Original system EDR = 2,100 sq ft Vaporstat, 13 oz cutout, 4 oz cutin - Temp. control Tekmar 279.
http://grandviewdavenport.com

Comments

  • EBEBRATT-EdEBEBRATT-Ed Member Posts: 6,935
    Not sure If I understand but in previous years you filled manually after blow down and this year you let the feeder do it??

    So now your seeing 36 gallons and wonder if that is too much??

    It's like 70% of what the boiler holds I don't think it's an issue. Probably lost through the vents
  • Dave in QCADave in QCA Member Posts: 1,759
    To Clarify, in previous years I blew down every 2 weeks and manually topped of the water level. THIS year, I only blew down 3 times total. As before, I manually topped off the water level.
    Dave in Quad Cities, America
    Weil-McLain 680 with Riello 2-stage burner, December 2012. Firing rate=375MBH Low, 690MBH Hi.
    System = Early Dunham 2-pipe Vacuo-Vapor (inlet and outlet both at bottom of radiators) Traps are Dunham #2 rebuilt w. Barnes-Jones Cage Units, Dunham-Bush 1E, Mepco 1E, and Armstrong TS-2. All valves haveTunstall orifices sized at 8 oz.
    Current connected load EDR= 1,259 sq ft, Original system EDR = 2,100 sq ft Vaporstat, 13 oz cutout, 4 oz cutin - Temp. control Tekmar 279.
    http://grandviewdavenport.com
  • Jamie HallJamie Hall Member Posts: 12,703
    Does that 36 gallons include the blowdown use? If the system still holds a vacuum -- and two hours isn't half bad for that! -- I'd not worry about a leak, and it may possibly be just humid air being lost. However, if it no longer holds the vacuum, I'd go looking for a tiny drip somewhere -- most likely spot is, oddly, in a dry return at or near a fitting.
    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
  • JUGHNEJUGHNE Member Posts: 6,790
    Previously when you manually topped off the boiler was that water recorded on the VXT using the switch?
    Or the valve bypass around the VXT?
  • Dave in QCADave in QCA Member Posts: 1,759
    Jamie, 36 gallons does not include the blowdown use.
    Dave in Quad Cities, America
    Weil-McLain 680 with Riello 2-stage burner, December 2012. Firing rate=375MBH Low, 690MBH Hi.
    System = Early Dunham 2-pipe Vacuo-Vapor (inlet and outlet both at bottom of radiators) Traps are Dunham #2 rebuilt w. Barnes-Jones Cage Units, Dunham-Bush 1E, Mepco 1E, and Armstrong TS-2. All valves haveTunstall orifices sized at 8 oz.
    Current connected load EDR= 1,259 sq ft, Original system EDR = 2,100 sq ft Vaporstat, 13 oz cutout, 4 oz cutin - Temp. control Tekmar 279.
    http://grandviewdavenport.com
  • Dave in QCADave in QCA Member Posts: 1,759
    JUGHNE said:

    Previously when you manually topped off the boiler was that water recorded on the VXT using the switch?
    Or the valve bypass around the VXT?

    It was done with the bypass, so that was never recorded in the past. I probably topped it off higher than the NWL and often enough to mask the normal water loss. However, because of that, I don't have a clue what the normal water loss is.
    Dave in Quad Cities, America
    Weil-McLain 680 with Riello 2-stage burner, December 2012. Firing rate=375MBH Low, 690MBH Hi.
    System = Early Dunham 2-pipe Vacuo-Vapor (inlet and outlet both at bottom of radiators) Traps are Dunham #2 rebuilt w. Barnes-Jones Cage Units, Dunham-Bush 1E, Mepco 1E, and Armstrong TS-2. All valves haveTunstall orifices sized at 8 oz.
    Current connected load EDR= 1,259 sq ft, Original system EDR = 2,100 sq ft Vaporstat, 13 oz cutout, 4 oz cutin - Temp. control Tekmar 279.
    http://grandviewdavenport.com
  • PMJPMJ Member Posts: 950
    36 gallons (on top of blow down water) escaping a natural vacuum system performing as you describe as humid air through vacuum vents which would be rarely be open is unlikely.

    If the system really holds vacuum like you say (mine is very similar) I would have to shut off the supply valve and observe for myself the sight glass and the VXT for every add to satisfy myself about the number it was coming up with.



    1926 1000EDR Mouat 2 pipe vapor system,1957 Bryant Boiler 463,000 BTU input, Natural vacuum operation with single solenoid vent, Custom PLC control
  • dopey27177dopey27177 Member Posts: 276
    In a new heating system a bout your size 1 gallon per month water loss is normal.

    In a system your age 3 gallons a month would be normal

    Because you lose all your vacuum in two hours your system is not as tight as it could be.

    My guess is you have slight leaks at packing glands of the radiator valves and other valves.

    As far as the as vacuum loss, check the air check or penny valve for dirt on the seats, this could be the vapor loss (water loss) and system vacuum loss.

    Jake
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