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primary secondary question

ffp20
ffp20 Member Posts: 2
In a previous life i was a service technician for an oil company many years ago and now i find myself replacing a boiler in one of my homes.

The home is 1300 sq ft home currently using an oil fired boiler with cast iron radiators on a single zone.

I will be replacing with a gas fired cast iron boiler and will be splitting off 2 bedrooms to its own zone and adding an indirect water heater, so, there will be a total of 3 zone run off of the new boiler.

I read Dans book, "pumping away" and found it incredibly educating. I wish i had it 25 years ago as i found explanations for issues i had back in my service days.

Anyway, is there any reason i cant use zone valves fed by a single circulator on the secondary circuit instead of circulators on each zone?

Comments

  • hot_rod
    hot_rod Member Posts: 21,975
    not sure you need primary/ secondary? Unless you want multiple temperatures or have pumping conflicts with high pressure drop heat exchanger type boiler.

    I do like to see boiler return protection on high mass or large water content systems, it assures the boiler always reaches a good operating condition.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Ironman
    Ironman Member Posts: 7,363
    ffp20 said:

    In a previous life i was a service technician for an oil company many years ago and now i find myself replacing a boiler in one of my homes.

    The home is 1300 sq ft home currently using an oil fired boiler with cast iron radiators on a single zone.

    I will be replacing with a gas fired cast iron boiler and will be splitting off 2 bedrooms to its own zone and adding an indirect water heater, so, there will be a total of 3 zone run off of the new boiler.

    I read Dans book, "pumping away" and found it incredibly educating. I wish i had it 25 years ago as i found explanations for issues i had back in my service days.

    Anyway, is there any reason i cant use zone valves fed by a single circulator on the secondary circuit instead of circulators on each zone?

    There's no reason you can't use zones valves as long as the smallest zone isn't over- pumped and all zones combined aren't under-pumped. I would use a Delta P pump like the Grundfos Alpha or Wilo Stratos if you use ZVs.

    I agree with HotRod about p/s and return temp protection.

    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    icesailor
  • SWEI
    SWEI Member Posts: 7,356
    What kind of emitters are installed? Have you done a room-by-room heat loss calculation?
  • ffp20
    ffp20 Member Posts: 2
    SWEI i have done the calculations. The rooms have cast iron radiators.
    Hotrod i thought of using primary/secondary because of return preotection. As i said the house has cast iron radiators with a short 2" reduced to 1-1/2" mains. Would a bypass suffice then and not do primary/secondary?
  • SWEI
    SWEI Member Posts: 7,356
    What water temp will you need on a design day to satisfy the load?

    With CI rads, I would look seriously at a fire-tube mod/con boiler. By the time you add a motorized mixing valve with ODR control, a second circulator, and the additional pipe and labor the cost will be very close. The mod/con will take up less space and give you additional control capabilities.
    RobGGordyBob Bona_4
  • ElvirMujahodzic
    ElvirMujahodzic Member Posts: 2
    Hello gentalmen , I will be replacing a similar system , currently I have 1 zone hydronic system with 2" supply and return lines they out the basement in a 3 family home, I wanted to slightly over size the boiler to make up for the volume of water in these pipes and it has big cast iron rads,, it will be a oil to gas conversion as well. I will keep the oringnal zone, had a additional new loop zone on 1st floor and also add a super store storage tank, so a total of 3 zones, I was thinking about doing primary secondary pumping on this project , the question I have is , SHOULD I pipe in the domestic tank before the primary pump to help the tank keep up at high demand? Or pipe it out on the secondary pumping like the other 2 zones, and no the owner does not want a condensing boiler lol, thank you, [email protected]
  • Rich_49
    Rich_49 Member Posts: 2,766
    Elvir , You may want to start a new discussion .
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    732-751-1560
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833