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Hydrostat 3250 Plus issues

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We recently moved into a home with Hydrostat 3250 Plus. Our hot water (particularly to the shower) is very inconsistent. The water will be turned all the way to hot and will be hot for a few minutes and then warm and then cool and then back to hot.

I thought adjusting the low temperature limit and high temperature limit may help. Does anyone have any other ideas?

I have been able to adjust the high temperature limit and have felt the hot water be even hotter (just not consistently). The low temperature limit will not allow me to go past 140. In the manual it says it should be able to go from 110-200. Does anyone know why it's stuck at 140?

Comments

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,844
    edited March 1
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    Does the tankless coil (that is your water heater) have a mixing valve that is connected to the hot and cold pipes do that you can control the water temperature leaving the boiler room?

    Also, How old is the boiler? More to the point.. How old is the tankless coil? It could be clogged.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    MaxMercy
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,844
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    How many thermostats (zones) are in your home. If there are more than one zone and each zone has a circulator, there could be a problem with the set up that can cause the problem you are experiencing.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • HVACNUT
    HVACNUT Member Posts: 5,841
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    @mckreed, what is making the domestic hot water? Coil in the boiler, or indirect?
    Remove Jumper and you'll be able to raise the Lo side. Keep it at least 20° below the Hi setting. And the Hi setting shouldn't need to exceed 180°.


    DJD775MaxMercy
  • mckreed
    mckreed Member Posts: 5
    edited March 3
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    @HVACNUT Thank you! When I removed the jumper, as suggested, it allowed me to change the low temp. When I put the jumper back in, it reverted back to the original temp of 140. Should I keep the jumper out?

    It's a coil in the boiler.
  • pedmec
    pedmec Member Posts: 975
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    Take a picture of the hydrostat with the cover off so your settings can be viewed.
    exqheat
  • mckreed
    mckreed Member Posts: 5
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  • mckreed
    mckreed Member Posts: 5
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    @EdTheHeaterMan just one zone
  • HVACNUT
    HVACNUT Member Posts: 5,841
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    The jumper is in. Remove it.
    You might need to turn the Lo down to OFF first, then raise it to the desired setting. 
    Just pressing the setting/test button will scroll through the settings. 
  • mckreed
    mckreed Member Posts: 5
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    @HVACNUT Okay! Is it safe to keep the jumper out? What is it's purpose?
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,844
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    mckreed said:

    @EdTheHeaterMan just one zone

    Thanks for that info. The symptoms you are describing fit with a dirty tankless coil. There is one point of concern though. The readout of 128°F is inconsistent with the 150ish° setting on the LOW dial. Not a fan of that particular control however everyone else seems to like it, and you are stuck with it. Try to set the LOW dial to 165° and see if you get better results. The 128° boiler temperature is the cause of the cooler water portion of your shower. Once the Hydrostat starts to operate the burner, then the cool shower water will gradually get hot again. Once the boiler temperature reaches the low limit temperature of 150° (your current setting) the Hydrostat will turn off the burner and the boiler temperature will begin to drop. If you are in the shower long enough, that temperature may drop to that 128° again and you will start to get a cooler shower again until the burner starts and the boiler temperature increases. .

    Try the higher temperature for now and if you can not get the hot water you desire, we can look at the tankless coil cleaning procedure.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • HVACNUT
    HVACNUT Member Posts: 5,841
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    mckreed said:
    @HVACNUT Okay! Is it safe to keep the jumper out? What is it's purpose?
    No idea what the purpose is other than to piss me off.
    MikeAmann