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balancing valves for a custom made hwh manifold construction


I took on a large heating renovation project for friends and ran into a problem I could use some help with. I built my own set of manifolds from scratch for a new hot water heating system for a large 3 story house with a renovated basement, and I left out the balancing valves and flow meters for each zoned manifold. I need to know how to balance the system, and install whatever I need to install on the manifolds I constructed.

I’m doing the job for a couple who live in this house which is mostly unoccupied since their children grew up and left the house. They have reached the point where the cost of oil was too much for them to sustain if they are going to keep the house, so the decision was made to replace the entire steam based heating system with a hot water heating system, where energy and money could be saved by controlling the floors of the house with zone valves.

I replaced the old oil fueled steam boiler with a 210 kbtu gas boiler and converted it into a hot water boiler. The size of the house was so large that multiple circuits were installed for each floor, so that the first floor and second floor each have their own manifold controlled by its own zone valve. The third floor and the basement share the third manifold controlled by a zone valve and the fourth manifold is connected to 3 kickspace heaters mounted inside the fireplaces of the house. The following diagram is the installation of the supply and return manifolds for the system, along with a photo of the actual construction of the supply manifold.

The piping that connects to each supply manifold is 1” which is smaller than the 1-1/4” piping that connects the return manifolds. Each manifold has a 1” trunk with four ½” pex connections and one ¾” pex connection. The zone valves have a ¾” opening, so I had to use 1” to ¾” adapters to fit the zone valves. I think this means that the supply manifold is smaller and therefore has more resistance than the return manifold.

After firing up the boiler and bleeding the air out of the system, I noticed that the kickspace heaters which were closest to the main supply line got most of heat but the baseboard heaters of the first and second floors at the top of the manifold construction got little or no heat. The return manifold is much hotter than the supply manifold, even after I reversed the flow of the circulation pump. I believe that the system is unbalanced since I never installed balancing valves and flow meters for each manifold. I plan to replace the 1” T fittings on the supply manifold with 1-1/4” T fittings to match the return manifold as much as possible. One plumber advised that I replace the T fittings on the manifold construction with monoflow T fittings but that won’t help me make the adjustments needed to make sure each manifold has the proper flow. Am I correct in my conclusion? If I am, do I need a ball valve with a temperature gauge or a flow meter for both the supply and return manifolds of each zone?

Uponor has a ball valve with a built in temperature gauge, but it has a special end connection for their model of manifolds. Since I need sweat connections on my valves, would it be feasible make my own balancing valves for this construction? Any information or links to information that could guide me through this would be greatly appreciated, so I thank you and look forward to hearing from you soon.




  • SWEI
    SWEI Member Posts: 7,356
    What are your flows

    in the various branches and overall?  How big is the new boiler?  What is the design day heat loss for the house?

    http://www.dahlvalve.com/products/balancing/mini-ball-balancing-valves.php are what we have been using.  They can be ordered with pretty much any style end you want.
  • heatseekr13
    heatseekr13 Member Posts: 2
    Re: balancing valves for hwh manifold construction

    Hello SWEI

    The boiler is 210 thousand btu input and 170 thousand btu output. I don't have the original day heat loss calculations available right now but I can contact you later in the day with that information.

    However, even with 2 of the four zones disconnected, I still had problems. For example the first floor zone would have both cast iron radiators and slant fin baseboard heaters, but only the radiators would heat up, leaving the baseboard heaters on the same manifold cold.

    Another problem that needs to be looked into is the lack of water pressure for the make up water to the boiler because the main valve for the house is defective.

    Again, thank you for the link to the site for balancing valves. I can get back to you later today or tomorrow about the heat loss calculations.
  • SWEI
    SWEI Member Posts: 7,356
    Is the boiler

    a conventional (non-modulating) type?  If so, you probably need some mixing controls to make this all work right.
  • Zman
    Zman Member Posts: 7,573
    Air lock

    Based on your description of the symptoms and the piping diagram I suspect that you have an air lock. Your circulator pumping into the expansion tank can make air removal difficult.

    Other contributing factors may be the configuration and sizing of the header. Are you unable to get pressurize the boiler piping?

    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Weezbo
    Weezbo Member Posts: 6,232
    You got enthusiasm : )

    And anyone that would help make the place easier on their pocket to own deserves a bit of help.

    It is best to start with what is so,

    1. did you purge each floor one at a time?

    2.do you have by passes in the field at the other stations on each floor?

    3. when you say baseboard ,...copper fin tube or iron?

    4. when you say radiators , existing or panel rads (new style low water temp) ?

    5.would you post a pic of the boiler piping , do not worry there is not much left field stuff we have not seen and dialed in ...Sherlock Holmes is no match for the guys around here when it comes to this stuff *~//: )

    i can tell that you are struggling and to reduce that for now soon as you can post the pic of the boiler piping and have either a pic of the rads and baseboard or answers , there are a few variables that might lead you and us further astray.one last question .

    do they have insulation ,to your knowledge, on the box and rim joist ? you can dial things in after that , the kick heaters are likely blasting away to meet the load . if you owned a heat gun that tells you the temps of floors or most objects that would be a handy tool for you to drag over to the job site.

    they are available these days in automotive parts stores and well worth the investment.
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