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how to adjust tap hot water

ivan_ Member Posts: 3

Preface.. just bought this home with an oil furnace. The tap hot water is provided by a tankless heating coil in the furnace. The hw system has an add on tank, which is the tan tank on the right.

My hot water is at 165 deg. and I can't figure out how to adjust lower temp. I'm thinking the aquastat near the tankless heater in the furnace is what I need to adjust but this was set to 70deg. So maybe not the case. If this is the aquastat then maybe it's busted or not wired incorrectly. I don't see an aquastat on the tank and I think the stat on the left is for the hydronic heating.

What I need help with is understanding how my system is designed and what all the parts are so I can troubleshoot it effectively, or at least be knowledgeable before calling in the pro. Fixing it myself is my primary objective.


    HVACNUT Member Posts: 5,023
    There are 2 vertical rectangle covers on the water heater.
    The lower cover has a thermostat behind it. Pull the insulation out.
    Grab a flashlight and small screwdriver.
    Its 120v there so be careful.
    It should be set to 120° or Medium depending on the brand.
    If its already set to 120°, then it could be a bad thermostat.
    You can get one at a box store. Electric water heater thermostat. Easy. Take a pic of the wiring. Snap out, snap in. Of course turn off the power first.

    Quid pro quo.
    Can you post some pics of the boiler and burner? I haven't seen a Paragon in forever and a day. Nassau county?
  • JohnNY
    JohnNY Member Posts: 3,145
    It looks like they're using that electric water heater as a storage tank. While the boiler is making heat, the hot water through the shuttle pump will be way hot...as stated.
    That whole setup should have a mixing valve on it before the water goes out to the fixtures.
    Contact John "JohnNY" Cataneo, NYC Master Plumber, Lic 1784
    Plumbing in NYC or in NJ.
    Take his class.
    CanuckerJean-David Beyer
  • Jamie Hall
    Jamie Hall Member Posts: 21,091
    What @JohnNY said. Definitely need a mixing valve set to something reasonable.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Jean-David Beyer
  • ivan_
    ivan_ Member Posts: 3
    @HVACNUT you called it, i'm in Nassau and here are the pics of my Paragon. I do have an electric water heater thats being used as a storage tank. I found the thermostat at the bottom of this tank and appears to be functional. When i increase the temp on it the shuttle pump activates. So i decreased the temp to see what effect it will have on the overall hot water temp.

    @JohnNY I'm also going to start looking into installing a mixer valve. Looks like the TACO is a popular one, model 5002-P3. Maybe i'll get the sweat on one, not sure yet.

    I'm still a little lost about the right thermostat. What is the purpose of this one? When i adjust the left one the burner activates. With the right one i don't think anything changes in the system.

  • Jamie Hall
    Jamie Hall Member Posts: 21,091
    There are two thermostats on most electric water heaters. Only one element runs at a time.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    HVACNUT Member Posts: 5,023
    Its being used as an Aquabooster but its piped incorrectly. Backwards actually.
    And there should be a swing check between the pump and the cold tee to prevent backflow through the coil when cold water is being drawn into the bottom of the tank.
    The upper thermostat should be manual reset.
  • ivan_
    ivan_ Member Posts: 3
    The upper thermostat, where the coil is, is set all the way down, around 70. Im using the lower thermostat to balance out the temperature depending on where I set the furnace temp to, which is currently at 160.

    I didnt think it was piped incorrectly because it's working as expected.

    This is what I think is going on and what needs to change. I found a aquabooster diagram for reference. Currently.. Cold water tees into the hot water which comes out of the base of the tank. This then goes through the pump and the coil. Hot water comes out of the coil and drops into the top of the tank.

    To correct, I need to pull water out of the connection on the top of the tank and not the bottom. The output from the coil need to go into the bottom.
    The Cold water feed needs to be removed and connected like in the diagram, between the pump and coil with a flow check.

    So my tank is not the tank in the diagram, will pull water out of the top connection work the same?

    Can the coil flow both way, or do I need to maintain in and out connections?
    HVACNUT Member Posts: 5,023
    The upper thermostat is was referring to in in the water heater. The upper cover.
    This diagram matches your tank better.
    Still need the check valve.