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controls for a H/W oil fired upgrade

DuffDuff Member Posts: 60
Need to pick your brain..How can I change a 3 zone H/W Boiler with all relays to primary and secondary piping? The primary circulator I would want to run only when there is a call for heat  and not continuously. Older boilers are not set up for this and I'm not sure how to get that primary circulator to run  when any of the three zones are calling. Thanks in advance, Duff


  • Jean-David BeyerJean-David Beyer Member Posts: 2,663
    I am not a heating contractor.

    But what I would do is get a relay box like one of these,

     perhaps an SVR503-4 if you use zone valves or an SR403-4 if you use zone circulators. Hook up three thermostats to the thing, and three circulators to it. Each thermostat controls one circulator. If any thermostat calls for heat, it will also close the x-x contacts that go to the boiler; that should make it fire and turn on its (the boiler loop) circulator. Similarly for the zone valve model. These have a priority setup so if multiple thermostats calling for heat, you can arrange for one of them to get it all until it lets go.
  • Paul48Paul48 Member Posts: 4,492

    older boilers are set up so the circulator only runs on a call for heat.Need info on the boiler you have now and the controls being used now. Are you saying you a zone valve system now?
  • DuffDuff Member Posts: 60
    thanks Jean &Paul

    Jean , I'm gonna check out that taco relay box, Ive wired them in the past but not for what I need to do now.

    Paul, there are circulators in place for all the zones but I'm gonna change piping so I'm thinking of primary and secondary piping.
  • Paul48Paul48 Member Posts: 4,492

    Is there a specific problem or concern you are trying to address with a re-pipe? It's a good idea, just not one that is done with a properly functioning system.The more details, pictures, explainations you can provide here, the better. It'll save you time, money and bloody knuckles in the long run.
  • Dave H_2Dave H_2 Member Posts: 382
    Try this control

    Here is an example almost exactly for what you are doing.

    Primary pump will run whenever there is a call for heat. If needed, Zone 4 can be setup for DHW priority which depending upon piping can control the primary pump correctly.

    Add the PC-700 for boiler reset control, not needed immediately but easy to install if you have the 504 expandable controller

    Dave H
    Dave H
  • Paul48Paul48 Member Posts: 4,492

    is a  chance that you have everything there already to do what you want to do.Most basic boiler controls have the ability to control a single circulator.They may not have used that feature because they were adding zone circulators.I'd rather you didn't spend a lot of money, and then we find out that all you had to do was pipe in a low loss header and wire a primary circulator to your existing boiler control. Need info.
  • Dave H_2Dave H_2 Member Posts: 382

    Yes, most boilers to have a relay to control a pump, but that is not the same as controlling a primary pump.

    The controller on most oil fired boilers to turn on a pump only turns on when there is a call to the boiler. There are lots of times where the boiler may be hot enough to satisfy the zone calling for heat. In order to get those BTU's out of the boiler is to run the circulator through it without firing the boiler, especially helpful and economical when you have outdoor reset or low temp heating systems....keep the boiler off until you absolutely need it to fire.

    In controls that specifically control a primary pump, this pump runs whenever there is a zone calling for heat, not when the boiler fires.

    Dave H
    Dave H
  • Paul48Paul48 Member Posts: 4,492

    agree that post purge is a nice feature.Not knowing what he has, or how it has been utilized or under-utilized, I can't say what would be a good solution for him.
This discussion has been closed.


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