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Hot Water Trouble

Hi - I have a Burnham steam boiler/gas fired with a tankless coil/Honeywell aquastat. Hot water has quit working. If I bump up the low temp control on the aquastat, normally set at 120, to 130, the furnace fires for a few minutes then shuts off. Again to 140, the same. Again to 150 the same.

Steam heat is off. Water temp problem persists, heat off or on. Unit is around 17 years old.

Bad aquastat control?

Thanks - Mark

Comments

  • lchmblchmb Member Posts: 2,985
    if the boiler is hot to the touch it could be the coil is plugged or the mixing valve has gone bad...
  • CTOilHeatCTOilHeat Member Posts: 54
    Probably the mixing valve. When you adjust the aquastat the boiler is responding as it should.

    When you run the hot water, check the pipes around the mixing (tempering) valve. Should be cool going into the coil. wicked hot coming out to the valve. If it's that way and cool after the valve, well, it's the valve.
  • MarkH10MarkH10 Member Posts: 4
    Thanks gents...no mixing valve, got rid of that and use standard valves. The furnace shuts down.
  • JohnNYJohnNY Member Posts: 2,432
    Are you saying you don't think the boiler is meeting the aquastat setting, or not so much?
    For installations, troubleshooting, and private consulting services, find John "JohnNY" Cataneo here at :
    "72°F Mechanical, LLC"
    Or email John at [email protected]
    John is the Boilers and Hydronic Heating Systems Course Instructor at NYC's Mechanics Institute, a professional Master Plumber, licensed by The Department of Buildings of The City of New York, and works extensively in NYC while consulting for clients in and out of state.
    John also oversees mechanical installations and maintenance for metro-area clients with his family's company, Gateway Plumbing and Heating along with his brother/business partner.
  • ZmanZman Member Posts: 5,753
    What temp does the boiler gauge read?
    If the boiler is coming up to temp and there is no mixing valve, it sure sounds like the coil is fouled.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • SuperTechSuperTech Member Posts: 1,304
    It kinda sounds like it's only firing to a low limit setting? I'd replace the aquastat. If this is a sudden problem where everything was perfect beforehand it has to be something electronic malfunctioning. Aquastat is the likely suspect based on your information. I'd look into a digital replacement, but a mechanical one is perfectly fine.
    Intplm.
  • MarkH10MarkH10 Member Posts: 4
    SuperTech said:

    It kinda sounds like it's only firing to a low limit setting? I'd replace the aquastat. If this is a sudden problem where everything was perfect beforehand it has to be something electronic malfunctioning. Aquastat is the likely suspect based on your information. I'd look into a digital replacement, but a mechanical one is perfectly fine.

    I think so...when it is off, it will not come on until I bump up the low level setting, runs a few minuits then shuts off, not restarting. I turn the low level up a bit, it starts, runs a few minuits and shuts off. And keeps on doing this as I turn up the low level a few degrees. It keeps shutting off.

    Thanks.
  • Intplm.Intplm. Member Posts: 1,135
    MarkH10 said:

    Thanks gents...no mixing valve, got rid of that and use standard valves. The furnace shuts down.

    @MarkH10 Why did you remove the mixing valve?

    While you are working on the boiler, you should install a thermostatic mixing valve. Not a tempering valve, but a thermostatic mixing valve. This will protect you from burns due to hot water settings from the boiler. And it will protect your faucets from prematurely burning out the parts inside that will, and do cause leaks.

    Do this to protect yourself and your plumbing system.
    "Standard valves," as you mentioned, do not protect.
  • MarkH10MarkH10 Member Posts: 4
    Intplm. said:

    MarkH10 said:

    Thanks gents...no mixing valve, got rid of that and use standard valves. The furnace shuts down.

    @MarkH10 Why did you remove the mixing valve?

    While you are working on the boiler, you should install a thermostatic mixing valve. Not a tempering valve, but a thermostatic mixing valve. This will protect you from burns due to hot water settings from the boiler. And it will protect your faucets from prematurely burning out the parts inside that will, and do cause leaks.

    Do this to protect yourself and your plumbing system.
    "Standard valves," as you mentioned, do not protect.
    I have had thermo mixing valves on this system over the years, needing to replace them maybe once every 10 - 12 years. Then, in the last 3 years I had had 4 valves fail. Nothing else in my system is failing or corroding...probably the valves today are not as durable as past. I been using Watts valves.

    I did put in ball valves this time around on the advice of the plumber that last installed the mixing valve. The hot is open and the cold is used to control the temp. Water is staying consistent at 120 - 125 degrees, randomly checked over a two week period. If anything, the hot valve may be subject to wear, time will tell. Water at all facets should be fine at the 120 temp.

    Today I swapped out the aquastat, original problem solved.

    Thanks for the help guys, I'm impressed at the assistance I received here as newbie.
  • SuperTechSuperTech Member Posts: 1,304
    I believe if you used something other than the Watts valve you wouldn't experience so much trouble. I've always views those valves as low end. I've had better luck with Taco and Honeywell. Caleffi makes some really nice mixing valves.
  • Intplm.Intplm. Member Posts: 1,135
    SuperTech said:

    I believe if you used something other than the Watts valve you wouldn't experience so much trouble. I've always views those valves as low end. I've had better luck with Taco and Honeywell. Caleffi makes some really nice mixing valves.

    @MarkH10

    What @SuperTech is referring to when he mentions the "Watts" valve. That Watts valve is what is called a "tempering" valve.

    He makes the suggestion as I have,that you need to install a "thermostatic mixing valve" like the brands he mentioned (Taco, Honeywell or Caleffi.)
    The Watts burns out prematurely as you have alluded to in one of your earlier posts.
    If you do not use a thermostatic mixing valve as suggested, you take the chance of causing high temperature water burns to yourself and others. Not to mention the damage you can cause to the faucets and valves in your home.
    I strongly suggest that you put one of those valves in as mentioned !
    SuperTech
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