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Oil boiler turning on almost every time I use ~1Gal+ of hot water

agurkas
agurkas Member Posts: 238
in Domestic Hot Water
I have W-M WGO4 boiler for steam heat (QB180 series 2 oil burner gun) with indirect 60 gallon water heater. Water heater is set to 125F with 5 degree variation (I think that is the maximum setting). On the boiler, I think, the thermostat is set to 160F (Honeywell unit).

Seems like every time I use about 1 gallon plus of water, the boiler fires up for short period of time. I feel the boiler is cycling just way too much. Any tips what I can do to tune it a bit?

I know boiler is out of tune, since the last service person (before house was sold to us) just jacked up all the pressures etc. I dialed down the cut-in PSIs for the steam heat and immediately saw improvement in efficiency and speed of house warming up. So figured for water heating side there is something out of whack.

Comments

  • agurkas
    agurkas Member Posts: 238
    Unfortunately the Amtrol Boilermate Premier moderl WHS80 only had 5F or 10F degree diff. Do you know what controller and where I would get it to increase the diff?
  • Zman
    Zman Member Posts: 7,611
    I agree with what BC is saying about your aquastat. Another thing to consider is that the boilermate heat exchangers have a tendency to get plugged up on the domestic side. This causes the exchange rate to go down and the boiler to short cycle. I would look into the reason for the short cycle. Is the call from the indirect turning off and on or is the call steady and the boiler is cycling because it is hitting it's operating temp?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Zman
    Zman Member Posts: 7,611
    One a really good day that indirect will absorb about 50k btu/hr requiring the boiler to cycle some. Once they have been in service a while, they don't have many good days...
    First, narrow down the problem, then plan the fix. The aquastat placement should also be checked.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Zman
    Zman Member Posts: 7,611
    I was making the assumption it was around 4 gpm because of the 3/4" pipe. The loss curve on that coil gets really steep as it approaches 6gpm.
    I have timed the recovery on one with good coils and it verified the math.
    I think the trick is to figure out if it is a differential issue or a coil issue. No sense fixing one if the other is the problem.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Zman
    Zman Member Posts: 7,611
    BC,
    I may be able to find my notes on that one.
    I like to verify the boiler's performance by estimating the amount of time it should take for it to heat the indirect from the cold temp that it starts at to the setpoint. Once the boiler is fired, you just time it to see how long it takes.
    With the amtrol, even with oversized piping and a fairly robust circulator, I could not get the mod/con to come up to full fire.
    Because I am curious, I compared the delta T and flow rate to the boilers output and the time it took to heat the tank.
    All 3 of those numbers told me the indirect was taking about 50k+/-.
    Carl
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Steamhead
    Steamhead Member Posts: 17,337
    Does the boiler stay hot all the time? If so, when the circ to the indirect starts it will cool the boiler enough to start the burner.

    With an indirect, the boiler does not need to stay at maximum temperature all the time.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
    icesailor
  • agurkas
    agurkas Member Posts: 238
    So question: so if I were to not mess with water tank thermostat and leave it with built in 5 degree diff and 125F water temp setting, what should the boiler be set at? Max is at 160F now. Haven't opened it up yet to see what is the diff.
    What should the max and diff be?

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