Let me start by thanking you for looking at my question.

My oil burner has a 3/4 inch line from the circulator to the heating pipes that feed the downstairs. The 3/4 line splits into Zone A and Zone B which drops to 1/2. During a reno this summer, zone B was cut and capped as a project to come back to. Since the temp outside is near freezing now is as good a time as any.

Should I run the currently capped pipe back to where the junction was and do a 1/2 x 1/2 x 3/4 inch T (Idea B) or can I run the 1/2 inch into the 3/4 and because its reduced later down the line I'll have enough pressure to still feed Zone B (Idea A). Picture attached because I dont think I am explaining myself well. enter image description here

  • The way this is drawn, you do not have "zones" in the conventional sense. Usually, zones allow you to set different temps in the different zones, this appears to simply have a loop with a shortcut. Unless, of course, there are control valves present that you omitted from the drawing for simplicity...
    – FreeMan
    Commented Jan 16, 2023 at 16:46

1 Answer 1


If Zones A&B each have a zone valve or similar control, any of these works, so do the most convenient.

What you might need if they don't have individual zoning, or even if they do, for when both zones are calling for heat, would be balancing valves to adjust the relative flow in each zone. I assume that zone B is going "out of the picture;" if it has become much, much shorter than zone A, you might need a balancing valve you can adjust so it does not rob zone A whenever it wants heat, unless that's a behavior you desire.

If the relative change in overall pipe length is minor (there's a lot of B out of the picture) you might not need any balancing valve, or it might be needed in zone A, if that's shorter. Or perhaps there are already balancing valves in the existing piping. They are a bit non-obvious if you don't know what to look for.

e.g. this post has a balancing valve typical of the ones I know: Is this a bleeder? Why won't it close?

  • Hi, Thank you for your input so far. Zone A and B are controlled by 1 thermostat that controls the circulator at the burner. At one point Zone A and Zone B were comparable in size, but now B is heating roughly, 20 feet less. Commented Jan 15, 2023 at 23:42
  • I just ran around the basement. There are no balancing valves in the existing piping. If memory serves me correctly. the original t that we cut out had something that we assumed regulated the pressure equally but that has long been scrapped. Commented Jan 16, 2023 at 0:05
  • If you scrap parts you'll need later, you get to pay non-scrap prices to replace them. Live and learn. You could try it without and see if the balancing is a problem, if you can face cutting it open to put one in if needed, rather than putting one in when you connect it in the first place.
    – Ecnerwal
    Commented Jan 16, 2023 at 18:51

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.