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Can you sufficiently heat up a 60 gallon superstore with high limit at 160 degrees?

MCarpenterMCarpenter Member Posts: 12
I have a customer with an old weil mclain 68. 3 zone valves. 8124A.

He INSISTS on his boiler limits to be 140 - 160 being sufficient to heat his house. He has a hot water coil which is pretty much done. He wants to add 60 gallon superstore.

He has told me other contractors who have come to his home to give him an estimate had told him there is a way to keep the settings at 140 -160 for the heat and make the boiler run to 180 only for the hot water heater.

I have been in the business for 10 years. Scratching my head......Is there something I am missing?.....I am pretty sure there is not. I think maybe his best bet is 8148 or even fuel smart hydrostat 160-180?? Any suggestions? Almost don't want this job.


  • MCarpenterMCarpenter Member Posts: 12
    Seperate loop

    Even with a separate loop is there a way to bypass 160 high limit to 180 just for the hot water.???

  • heatpro02920heatpro02920 Member Posts: 991
    edited February 2013
    Customer knows best, lol..

    You can and I am not a Superstore installer but most tanks show their gpm at certain temps... Normally when I am designing a medium temperature system I will oversize the indirect and the heat emmiters to compensate for the lowered high limit... At 160 with a 20 degree transfer loss you will still get 140, recovery suffers hence the larger tank...

    Now to hook the boiler to run the indirect at a higher temp would be a little tricky with an old boiler, you can do it with a seperate control, so one aquastat for the heating zones set to 160 and a another for the indirect set to 180.. But it is much easier and less complicated to oversize the indirect and show him the charts, let him pick his gpm...

    Also I recommend using a priority zone control when running indirects with low High limits, this will help...

    But to answer your question 160 will still give him hot water, I have systems out there with big smart tanks running 150 that work great...
  • ChrisChris Member Posts: 3,056
    edited February 2013
    Sure Why Not?

    Can it be done of course. Can it be done in your application we don't know because you haven't provided enough information.

    What is the btu/hr output of the boiler?

    What brand indirect model and how many gallons? SSC or SSU?

    Are we doing DHW zone priority? If not, What is the heat loss of the home? If you know that and measure the emitters and calculate whether they can over come each rooms loss

    then you can run 160 supply water temp. Also remember I only need that water temperature on the coldest day of the year.

    What size is the DHW zone piping?

    If zoned with a zone valve, what is install for a circulator? If zoned pump, size and make of pump?

    Answer these questions and you will find the answer as it pertains to your application.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • icesailoricesailor Member Posts: 7,265
    Give him what he wants.

    Give him what he wants. If they call you on the phone, they want to spend money.

    A SuperStor runs off the high limit. If he runs the High Limit at 160, it will heat the water just fine. It could be better but he's smart and we're not.

    He's smart enough to know that when he dumps the tankless and goes to a cold start with that aging "68 boiler, it will probably croak in two  years. Maybe you'll get to change it for a gas one. Weil-McLain WGO's are a nice replacement if you hang with oil.
  • MCarpenterMCarpenter Member Posts: 12

    Thank you guys. Very much appreciated. I have been beating myself thinking about this. I am going to do a priority.
  • Ron Jr.Ron Jr. Member Posts: 527

    and Hydrolevel reset aquastats do this automatically . And have LWCO functionality .

    I tried something like this last year . I had my high limit at 150 on the boiler and my Superstor set at 130 ( summer settings ) . It does work , but it takes a looooong time for the tank to hit 130 when the boiler temp is so close to the indirect's temp . It's always better to ramp the boiler temp up as high as possible for the heater to recover faster .
  • ChrisChris Member Posts: 3,056
    AquaSmart and HydroStat

    Basically pre/post purge the pump while keeping the burner off. They do not provide full reset unless you install the optional outdoor sensor.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • STEVEusaPASTEVEusaPA Member Posts: 1,499
    You can do it....

    easily with a Tekmar boiler control.  He would get outdoor reset, and when he gets a DHW call, the boiler temp will bump up to whatever temp you pick.  Keep in mind you're not bringing the water temp from ice cold to 160.  When I get a DHW call, my control resets the boiler target temp for 170, and usually doesnt even fire til I'm done my shower (TMI?), then only fires about 10 minutes to satisfy the indirect aquastat (not in priority mode).
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