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Bad zone valve or aquastat

Hello Everyone
I can only get hot water if I jump the aquastat at the water tank. I replaced the zone valve because when I manually pushed the lever, my furnace kicked on (could have been by chance...I don't know). Also, the zone valve that I purchased had an open box so I'm thinking maybe the valve was used and not good. The only time I can get the furnace to kick on and get hot water, is if I jump the aquastat. As soon as I take the jumper off, The furnace kicks off. I have an L4006 honeywell aquastat. Thanks in advance!

Comments

  • John RuhnkeJohn Ruhnke Posts: 797Member
    By jumping out the aquastat and it fires the boiler you are proving that the rest of the system works. You have isolated the problem. Now you need to look at the final three possibilities. The aquastat itself, its sensor or its well.
    John Ruhnke
    Hydronics Designer
    Hydronics is the most comfortable and energy efficient HVAC system.
  • AvasonsynAvasonsyn Posts: 10Member
    Thanks for the quick reply! I should probably just replace the aquastat correct? I don’t know squat about the sensor. Thanks again! That was FAST!
  • John RuhnkeJohn Ruhnke Posts: 797Member
    The sensor and the aquastat are sold together. In order to change the well you need to drain the heater. You could buy a well and first try things without the well. Most likely the well is fine. They make a heat transfer jell that comes with the aquastat. Just squirt it in the well before sticking in the sensor.
    John Ruhnke
    Hydronics Designer
    Hydronics is the most comfortable and energy efficient HVAC system.
  • AvasonsynAvasonsyn Posts: 10Member
    Great! I think I will return the zone valve that I just put in. The box was already open and I will tell them that. Put the old one in and buy an aquastat. Jeez! Those things are pricey. I will be sure to post after I replace aquastat. Thank you!!
  • AvasonsynAvasonsyn Posts: 10Member
    One more thing...is it dangerous to leave that jumper in for the night until I can get an aquastat?
  • Jamie HallJamie Hall Posts: 10,672Member
    Yes. It's supposed to shut off the system at a set high temperature. With the jumper in there, it won't -- and the best result will be water all over the floor when the temperature and pressure relief valve opens. If it opens... if not... well... not good.
    Jamie



    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
  • AvasonsynAvasonsyn Posts: 10Member
    That is great advice. I will just jump it tonight when hot showers are in order. I will get a new part tomorrow and go from there. Again, I will let everyone know the outcome. I returned the old/new zone valve today and asked the person not to put it back on the shelf because it did look used when I bought it. Thanks again HVACRs!
  • HVACNUTHVACNUT Posts: 2,330Member
    There are other numbers after L4006A that are important. Make sure you get the same or comparable. Things like well (bottom or back mount) or surface mount, temperature and differential settings.
  • AvasonsynAvasonsyn Posts: 10Member
    Picked up a new aquastat at the plumbing store today. Replaced it. After running the hot water for about 5 minutes, the furnace kicked on. I was happy. My furnace is set at 180 degrees and its taking some time to get to that temperature. It's probably been about 20 minutes or so. Any idea where to set the aquastat temperature and the the temperature differential setting? Should I set it at 10-15 degrees? Again...Thank you everyone!
  • AvasonsynAvasonsyn Posts: 10Member
    Furnace just turned off...I hate to get ahead of myself but it looks like things are in order. This is what the internet was supposed to be about. I will update in a few days. Thank you everyone! I'm sure I will post more questions about my outdoor woodburner in the next few weeks or so. :#
  • AvasonsynAvasonsyn Posts: 10Member
    I’ve searched this and other forums. It seems there is no definitive answer out there. I’m going to contact Honeywell and see if I can get a straight answer.
  • John RuhnkeJohn Ruhnke Posts: 797Member
    edited September 10
    @Avasonsyn

    According to the codes for dhw you should set the aquastat to 120 degrees. 20 degrees is a standard differential setting. To prevent legionaries disease the water needs to be set higher than 135 degrees. To compensate for the hotter water you should have a mixing valve installed on the hot water outlet leaving the heater to mix it down to 120 degrees.
    John Ruhnke
    Hydronics Designer
    Hydronics is the most comfortable and energy efficient HVAC system.
  • AvasonsynAvasonsyn Posts: 10Member
    That's sounds great. I appreciate the time everyone puts in to help out. I will make the changes.
  • AvasonsynAvasonsyn Posts: 10Member
    Hey guys...everything has been great up to last night. No hot water. Jumped the aquastat and furnace fired up. Any thoughts or suggestions? I’m going to the plumbing place to ask them to test the stat. I’m not sure if that’s even possible but I’ll ask any way. Any help would be appreciated. Thanks!
  • HVACNUTHVACNUT Posts: 2,330Member
    edited 2:43PM
    Jumping out the aquastat and making the burner fire doesn't necessarily mean the aquastat is the culprit.
    The indirect circulator was definitely NOT running when you first noticed no hot water?
    Was the boiler cold?
    Did you install another L4006A?
    Wire connections are good on the screw terminals?
    You made sure the aquastat capillary is seated all the way to the back of the well?
    Reading back it looks like temp is set to 120° and a 20° diff? As said, the tank should be kept at about 145°, 10° diff, and a thermostatic mixing valve set to 120° out to the house.
    Ever read Plum Island?
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