Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

manifold building

Hi all,

I have a hot water boiler that provides heat to five zones, each controlled by a Honeywell V8043F zone valve. Each zone is comprised entirely of baseboard. I'm going to build a new manifold. The current manifold runs horizontally with each zone originating from the underside of the horizontal run. The valves are situated in a horizontal row. Here are my questions:

Is there any reason why I couldn't have the zones originate from the topside of the horizontal run? (Valves in the same horizontal row, but above this time.)

Is there any reason why I couldn't put the manifold on the vertical, with each zone and it's attendant valve running to the left or right?

Any input would be greatly appreciated.

Jim Glose


  • Constantin
    Constantin Member Posts: 3,796
    Some thoughts from a homeowner

    If every circuit on your manifold had its own pump, the orientation of the manifold and the take-offs would have little importance. Zone Valves are a bit different, because they merely restrict flow rather than create it.

    Here, the relative resistance to flow from each circuit comes into play. Otherwise, some circuits might heat faster than others. Manifold orientation can be a factor because the water will have a tendency to flow past a T rather than make a 90° turn, unless there is a good reason for it. Hence Monoflo T's and other means of creating a incentive for water to go where it otherwise wouldn't.

    Some installation diagrams I have seen featured globe valves on the returns to allow the installer to fine tune the resistance of each circuit and make the system respond evenly to heat calls. Installing different-sized or variable-speed pumps on individual secondary circuits ould achieve the same thing, naturally.

    IIRC, Dan mentioned in one of his books to put "U-traps" in the returns before they rejoin the manifold to prevent ghost flow. That is, if the pipes approach a horizontal return manifold from above, have them continue past it and then turn 180° back up to join the manifold. Naturally, check valves on the return do the same thing w/o the need for the U-bend.

    So I don't see a reason why your supply manifold couldn't go in any direction, as long as there is flow. A pump will ensure that, particulalry if you're using primary-secondary circuits.

    However, as I am a mere homeowner, you should probably wait and see what the pro's here think. After all, I am happy to be wrong, as the Wall is a form of an educational institution for me.
This discussion has been closed.