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Running Out of Hot Water With a Megastor -40

crc3 Member Posts: 2
Only during the winter months our first shower of the day runs out of hot water.  We have had this problem for years.  Our service company swears that the piping size is correct and the hot water is set up with priority over a call for heat.We have three separate zones HW is zone one.  Just today we ran out of hot water drawing a bath.  It was the first bath of the day.  It seems like the Megastor goes to sleep at night and does not maintain temperature  until it runs out of hot water from the first shower or bath of the day.  There are no problems with the hot water the rest of the day and we do not have this problem in the summer.

Any thoughts would be appreciated.


  • Ironman
    Ironman Member Posts: 6,365

    How about posting some pics of the indirect, the boiler, it's near piping and controls. What zone control are you using?
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • kcopp
    kcopp Member Posts: 3,715
    sounds like.....

    an aquastat issue. may need a cup of coffee!
  • Zman
    Zman Member Posts: 6,559

    You really need to post pictures of this one. Get one where you can see all the piping in the boiler room.

    My guess is that you are missing a check valve or two and the heat is stealing energy from the DHW

    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • hot_rod
    hot_rod Member Posts: 14,784
    got a thermometer?

    what is the temperature at the faucet when you first start a DHW flow? Does it have a 3 way thermostatic valve installed? Could be an aquastat out of wack, if it is not a piping or flow issue.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Weezbo
    Weezbo Member Posts: 6,232
    well, you probably

    might not use the hot water the rest of the day and in the summer...or the useage may not be as much ...

    there is one thing that helps somewhat , and it is most likely to become a requirement across the planet as macro economics drills down to the micro in search of hidden resources.. it is called a recirulation system that coupled with anti scald valves will somewhat decrease the wait time for domestic hot water . and ,... bring hot water out of the system for longer periods of time . because of that i think i would turn Grunfoss outside sales man for a momment and have you look into their recirc system with a timer and P/T differential bypass . the stainless steel circulator does not effect the existing system on non peak useage , what i mean by that is if it is not running your system works fine any way , however if you have the timer set for 1/2 hr or so before jumping up out of bed or when ever you chose to get the hot water to circulate , it will save a great deal of water and discomfort waiting for the temp to be what you expect.

    there is a temp . diverting by pass valve that you install under a vanity or sink that allows the water to bleed a small amount of hot water (which has cooled down) into the cold water line..

    and as the circulator must get the water from somewhere, it pulls it back through the cold water line so that hot water can be brought to the faucet. once that happens and the temp in the hot side is achieved...

    it quit bleeding into the cold side..

    the circ being a pressure differential circ, knows this as it were and slows to a halt burning very little power or electricity..

    . maybe you could look into that .


    *~//: )
  • crc3
    crc3 Member Posts: 2

    I'm not sure they will help but I have attached some pictures.
  • Matt_67
    Matt_67 Member Posts: 195
    temp of cold water

    Does the temperature of your incoming water change during the winter months?  Where I live the cold water temperature is 65 - 70 degrees during the summer and 35 degrees in the winter.  If that is the case you would have less recovery in the winter.
  • Ironman
    Ironman Member Posts: 6,365
    Taco Zone Panel

    You stated earlier that the indirect was connected to zone 1 for priority. This may be your problem.

    The last zone (highest number) on the right side of the terminals is the priority zone on the Taco panel. The internal switch must also be set to "priority".
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
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