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Problems with shared return on new oil heating installation

melro
melro Member Posts: 2
I'm really hoping someone can offer some advice. I recently had installed a new oil heating system. Its a large installation with 3 zones and water. All the zones have a shared return due to lack of space for individual returns for each zone, therefore a shared return for all zones has been installed. It now seems that when an individual zone is on that the water returning from the heated zone migrates through the return to the other zones which are off, causing the radiators in the zones that are switched off to heat up. My question is how can this be resolved?

Comments

  • Robert O'Brien
    Robert O'Brien Member Posts: 3,540
    Flow check on return
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  • Jamie Hall
    Jamie Hall Member Posts: 23,160

    Flow check on return

    before they join together to create the shared return. Slightly less effective, but will also work, is a flow check on the feed.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Steamhead
    Steamhead Member Posts: 16,796

    Flow check on return

    This.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • Big Ed_4
    Big Ed_4 Member Posts: 2,761
    You have a missed place return pipe . The zone that is split needs to be rejoined back to single pipe before its connected to the mutual boiler return ... Or throw in checks
    I have enough experience to know , that I dont know it all
    Mike_Sheppard
  • Mike_Sheppard
    Mike_Sheppard Member Posts: 696
    edited April 2018
    @Big Ed is right. If you split one zone the returns need to connect back together before entering the common return. Otherwise you will need check valves. But eventually check valves will fail.

    Two pictures attached from B&G system design manual.
    Never stop learning.
  • melro
    melro Member Posts: 2
    Thanks very much for all your helpful replies. I would be interested to know why you think the check values will eventually fail?
  • Jamie Hall
    Jamie Hall Member Posts: 23,160
    sad experience..
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Mike_Sheppard
    Mike_Sheppard Member Posts: 696
    > @melro said:
    > Thanks very much for all your helpful replies. I would be interested to know why you think the check values will eventually fail?

    Because time is cruel and eventually everything fails. I’m sure they’d last a good long while though.
    Never stop learning.
  • Big Ed_4
    Big Ed_4 Member Posts: 2,761
    edited April 2018
    Adding a more complicated device to correct a simple solution just increases the odds of failure ....
    I have enough experience to know , that I dont know it all