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Superstor and Baxi


I have a question about a boiler hookup.  My current configuration has a Baxi boiler with tankless hot water capabilities in conjunction with a Superstor Indirect water heater. There are 3 zones of heat and the DHW. Currently the Superstor is heated with the direct hot water function of the boiler. This poses a problem for me because as soon as the Superstor calls for hot water, the boiler kicks over to heating the Superstor instead of the house. In the course of 3 consecutive showers in the morning, my house heat can be off for at least 30 minutes. The house then cools off pretty quickly.

My thought is that the Superstor should have been a seperate heat zone so that it would not interupt house heating. Am I right?



  • Charlie from wmass
    Charlie from wmass Member Posts: 4,322
    No, you have a priority set up

    The controls are configured to prioritize the domestic hot water production. If you removed the priority function, which maybe as simple as a switch moved over, then you would loose the full power of the boiler to produce hot water. This may not be an issue if the boiler is slightly or grossly over sized to heat the home. What is the boiler size, super stor size, and square footage of your home? Also what region are you located in?
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • Bosdub
    Bosdub Member Posts: 4
    Here's the specs

    Thanks for the reply Charlie.

    I have a Baxi HT 1.330

    Output? Not sure but inside the boiler it said Max output 112601 btu

    Boiler also has the outside sensor

    Superstor is a 65 gallon

    Living area is about 2200 sq feet.

    I am in the Boston area.

    I did look at adjusting the controls to "not allow domestic hot water" during a certain time, like when we take showers. I would think 65 gallons is enough for 3 showers. I would then have the domestic hot water kick in after we all leave for work. I wasn't quite sure how to make those changes work. The instructions I found for the controller indicated that the installer needed to "allow" the domestic hot water setting to be off. So I did set some hours for no DHW but not sure it's working. It just doesn't make sense to me for the heat to have to shut down to make hot water when I have 65 gallons of water available.
  • Henry
    Henry Member Posts: 998
    Hot water

    Even in our colder Canadian climate, we always maintain hot water priority. You should be able to make up 100 gallons at 100 Deg rise with your boiler. I think that you have a pump problem if you can't make up the hot water. Here, we use 4 BTU per cubic foot. Your setup should easily make hot water and keep the house warm.

    Something is definetly not right!

  • Bosdub
    Bosdub Member Posts: 4
    Not Clear

    I guess I wasn't clear what the issue I have is.

    The issue is..during our morning showers, the boiler is making hot water to satisfy the Superstor's need to get back to temp. During that time, the boiler does not supply the house with heat. It can't do both at the same time. As the Superstor is hooked up to the On-demand hot water portion of the boiler, it takes precedence over heating the house. The boiler is thinking "on-demand" gotta keep that hot water going even though I have 65 gallons of hot water available.

    That's why I am thinking the Superstor should have been just another heat zone as opposed to being hooked into the on-demand portion of the boiler. That's the way my old boiler was, although it had no on-demand option.

    I hope this makes sense. Sorry for the confusion
  • Robert_25
    Robert_25 Member Posts: 530
    Indirect size

    You probably don't want to hear this, but a 60 gallon indirect is a big load for a 110K btu boiler.  I looked at the manual for your boiler, and it appears that there is a three way valve that allows the DHW priority.  If it is only has "one or the other" functionality, it will be dedicated to heating that Superstor for quite a while...or as you have observed, long enough for the house to start cooling. 

    Plumbing the indirect as a regular heating zone would reduce the recovery of the DHW, but if the 60 gallon reserve is enough for your needs that might not be a problem. 
  • Bosdub
    Bosdub Member Posts: 4

    I appreciate everyones responses..thanks!

    60 gallons is plenty for my needs. The only reason I have the 60 gallon is for a large whirlpool tub which has been used twice in 8 years!

    I'm thinking I have the plumber who installed the system come back out and re-connect the Superstor as a heat zone. Only problem is he didn't build any growth into the system. The zone control only supports 3 zones and they are all in use. Should I be expected to foot the entire bill to upgrade the zone control and re-plumb the Superstor? I don't mind paying some of it but I'm kinda thinking he should be a bit responsible for not atking all this into consideration. Maybe I pay the supplies cost?

    Anyway, thanks again, all!
  • Gordan
    Gordan Member Posts: 891
    edited November 2010
    I don't know specifically about your boiler

    Most mod-cons with controls that have the DHW priority feature can set a time limit on that priority. So, if you've got a constant DHW call for over N minutes, and there's also a space heating call, it will go back to space heating.

    I just perused the manual for your boiler and, while I didn't see a mention of this specific feature, I did see that you can program the indirect temp setpoint by hour, in much the same way that you can do with space temperature. This is if you have the Siemens QA control with your boiler. I don't think that your notion of the plumber being responsible for some of the cost of upgrading your zone control is reasonable, even if making the indirect into just another zone were a good option, which in my opinion it is not.
  • Ironman
    Ironman Member Posts: 7,379
    You Should Be Able To...

    Keep your existing zone control and add another one for the domestic.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
This discussion has been closed.