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Shower Water Not Hot Enough

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db5683
db5683 Member Posts: 4
Hello all- new home owner here with a brand new Peerless Boiler with a Hydrostat 3250. I’ve noticed since installation- my water doesn’t get as hot as it used to and/or doesn’t remain hot while I shower. Just a quick run down on the system- it’s a 3 zone oil fired boiler which also supplies domestic hot water to the house. There’s also a taco thermostatic mixing valve on the system as well. I am curious if there is a way to remedy this? I’m not too familiar with plumbing systems.

Is this cooler water issue because of the low and hi limit settings on the hydrostat 3250 or is it because of the setting of the thermostatic mixing valve on the boiler? (My old boiler didn’t have one- it was from the early 90s) I’ve turned the mixing valve a bit counter clockwise which seems to have helped a bit? It’s hard to tell. Is this something that can be fixed in the settings on the hydrostat controls?

Simply put, I’m looking for my water to be a hotter and to maintain that temp while showering and not having these prolonged periods of cool water.We have a new baby at home and would like to be able to run warmer baths and maintain that temp to fill up the tub.

Any insight is appreciated. Thank you all!

Comments

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,852
    edited February 29
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    The mixing valve may be set too cold. try to increase the mixing valve temperature first.
    EDIT:
    The next thing to check is the low limit temperature. it must be set high enough to get the cold inlet water to the desired hot eater temperature in the time it takes from entering the coil until it exits the coil. It is basically an instant water heater. 58° water enters the boiler's coil and gets heated by the time it reaches the end of the coil. If the water in the boiler is 120°, then the 58° water might get to be about 90° by the time it gets the the outlet. If the boiler temperature is 140° then the 58° water may increase to 115° by the time it ets to the outlet. If you set the boiler water to be 160° then you may get 130° at the outlet. That is what you want.. then the mixing valve can add cold water to the 130° water leaving the coil and get the water temperature leaving the boiler room at 120°.

    So you want the low limit set at 160° and the high limit to 180° for starters.
    if you have enough hot water then your goo to go. if you still do not have enough hot water, then go to 165° low limit. Then 170° low limit.... until you get the amount of hot water you need. Always set the high limit at least 20° higher than the Low Limit.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • db5683
    db5683 Member Posts: 4
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    Thanks for the quick reply Ed- I will give that a go again- I’ve turned it some-was Just cautious of doing it too much. 
  • psb75
    psb75 Member Posts: 835
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    Full open mixing valve won't go any hotter than 120F.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,852
    edited February 29
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    psb75 said:

    Full open mixing valve won't go any hotter than 120F.

    Depending on the model number. That is true. What model number mixing valve do you have?
    I added to my original comment. Check out the edit above

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • bburd
    bburd Member Posts: 917
    edited February 29
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    If you have a tankless coil, you may also need to set the hydrostat for "DHW priority" so the space heating circulator will not run when the boiler is below the temperature needed to make hot tap water. On older controls this is what the low limit setting does. I'm not familiar with the hydrostat, but some modern controls have a separate setting for this.

    Edit:  DHW priority is for indirect hot water tanks with a separate aquastat, not for tankless coils.

    Bburd
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,540
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    I would set the high limit at 190. It's only going to get that hot if it needs too. It won't make the boiler maintain 190.

    Tankless heater GPMs are all rated at 200 degree boiler water if I am not mistaken.
  • db5683
    db5683 Member Posts: 4
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    Thank you everyone for your quick replies. This is all very helpful. The mixing valve is a “TACO 007 CIRCULATOR” according to my invoice. 
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,852
    edited February 29
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    The next thing to check is the low limit temperature. it must be set high enough to get the cold inlet water to the desired hot water temperature in the time it takes from entering the coil until it exits the coil. It is basically an instant water heater. 58° water enters the boiler's coil and gets heated by the time it reaches the end of the coil. If the water in the boiler is 120°, then the 58° water might get to be about 90° by the time it gets the the outlet. If the boiler temperature is 140° then the 58° water may increase to 115° by the time it ets to the outlet. If you set the boiler water to be 160° then you may get 130° at the outlet. That is what you want.. then the mixing valve can add cold water to the 130° water leaving the coil and get the water temperature leaving the boiler room at 120°.

    So you want the low limit set at 160° and the high limit to 180° for starters.
    if you have enough hot water then your goo to go. if you still do not have enough hot water, then go to 165° low limit. Then 170° low limit.... until you get the amount of hot water you need. Always set the high limit at least 20° higher than the Low Limit.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • pedmec
    pedmec Member Posts: 975
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    Do you have hot water everywhere else. It could be that they are supplying hot water that is cooler than the setting from the the old boiler. If that is the case then the shower valve will also supply cooler hot water. For example if you had 130 degree water supplying hot water to the shower valve and the shower valve is sending out 112 then if you lowered the supply from 130 to say 120 then the shower valve will deliver less than 112, maybe 102.
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,304
    edited March 1
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    Hi, Often a quick way to narrow down the problem is to run water and then go feel pipes. Touch the pipe exiting the boiler, and all three pipes at the mixing valve. See if cold is flowing into the mixer. If those are proper, it could be the shower valve setting or even a crossover somewhere else in the system.
    Yours, Larry
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,852
    edited March 1
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    db5683 said:

    Thank you everyone for your quick replies. This is all very helpful. The mixing valve is a “TACO 007 CIRCULATOR” according to my invoice. 

    Taco 007 circulator is not a mixing valve. Can you take a picture of your boiler from far enough back to see the connecting pipes from floor to ceiling form at least 2 different sides? you can post them by clicking on the Picture Icon at the top of each comment

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    Larry Weingarten
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,852
    edited March 1
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    It is possible that you can call a professional and they will not know how to solve your problem. You will need an experienced pro that understands how the Hydrostat control operates and how the boiler piping should be connected to an indirect coil.

    So you do not know if you have a mixing valve because the Taco 007 is not a mixing valve. Do you know how many heating thermostats you have in your home?

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • db5683
    db5683 Member Posts: 4
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    Thanks again to everyone’s help on here. After a more aggressive adjustment to the mixing valve- the water in the shower is hotter and staying hot for much longer.
    PC7060
  • RascalOrnery
    RascalOrnery Member Posts: 23
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    db5683 said:

    Thanks again to everyone’s help on here. After a more aggressive adjustment to the mixing valve- the water in the shower is hotter and staying hot for much longer.

    if you continue to have problems but your boiler temp is good and your hot tap is not hot your mixing valve may need replaced. Mine went bad, very slowly so we hardly noticed, then it was just only really giving lukewarm water if the boiler was below the low limit setting. I took it apart yesterday and the center o ring between the cold and hot intake ports had pretty much been shredded. 0.75$ at the hardware store and I'm back in business.

  • hot_rod
    hot_rod Member Posts: 22,158
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    If the mixing valve has an ASSE 1070 number on it, the highest it can be set us 120F. So you may need to crank it all the way up yo get the temperature you had in the old system without a mixing valve
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream