Balancing valves for PEX manifold (NOT radiant heating!!)

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by QueBall, Mar 1, 2013.

  1. QueBall

    QueBall New Member

    Messages:
    5
    Location:
    Edmonton, AB
    I'm trying to understand what kind of balancing valves are available for a hot water recirculation system operating on a PEX header system.

    I found lots of examples of headers and valves designed to balance a radiant heating system but none of those seem to apply to domestic hot water usage. Most of the manuals are silent on the topic or give dire warnings about the warranty being void if you are not using these headers for the intended purpose of radient heat.

    So any pointers on what is the best balancing solution for a hot water system like mine?
    The water only wants to flow to the shortest loops leaving the long loops cold and defeating the whole purpose if we don't put something in to balance the system and put some head pressure on those short loops.

    Do we just buy the radiant heat headers and use it for domestic hot water?
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,472
    Location:
    Cave Creek, Arizona
    you are trying to do the impossible. With a manifold system you can ONLY circulate through the manifold. The individual lines should be short enough so the hot water in the manifold arrives quickly, but NOT "instantaneously". "Radiant heat header/manifold" would be useless and completely ineffective for your purposes, because every one of those "circuits" loop back to the pump at the boiler. If you tried to use them for a hot water system you would create an IMMENSE can of worms for yourself, along with a lot of expense.
  3. DubbsDublin

    DubbsDublin New Member

    Messages:
    1
    Location:
    Wichita, KS
    Is this a hypothetical question about a system you're thinking about or are you trying to balance an existing system? If you use radiant valves, make sure they are compatible with potable water (chemistry of wetted surfaces).

    There are different types of balancing valves to consider: 1) manual throttle valves with pressure ports. 2) automatic pressure valves (think adjustable spring check valve that restricts flow based on pressure) 3) automatic thermal valves that work similar to the thermostat in a car (too cold, valve opens. too hot, valve shuts)

    I'm not sure if the plumbing is metric or NPS in Alberta. If your piping is metric, there are many European companies that make different types of balancing valves for hot water recirculation (Viega, Danfoss, Kempfer, etc.). I am not sure if anyone makes balancing valves with PEX connections.

    The type of valve should be based on the complexity of the system.

    I also agree with HJ as far as I understand. If you are designing this system recirculating a PEX manifold system you will end up with an expensive can of worms.
  4. QueBall

    QueBall New Member

    Messages:
    5
    Location:
    Edmonton, AB
    Not hypothetical

    Actual system in house recently installed new lines to the sinks replacing old polybutylene lines on the hot side to add the recirculating feature. (PB not recommended for continuously recirculating hot water so just replacing hot lines)

    Existing Navien tankless water heater with built in recirculation pump provides the push.

    The longest loop doesn't seem to recirculate much and is luke warm water in the pipe compared to the short ones that stay nice and hot.

    So for now, we are researching what options are to balance the recirculation flows. I'm pretty sure it doesn't need to be absolutely perfect to function for our needs. There is one loop that is much shorter than the other 3 (under 10ft) and our current thinking is that we might do a little hack where we change the return piping over from 1/2" to 3/8" on that short loop to give it more flow resistance on the return line and force more water to take the longer paths. Going to insulate the pipes to maintain as much heat in the system as possible. So even if the flow rate is lower on some loops as long as there is enough to maintain an adequate temperature then the system works.

    It just seems like the options for flow valves or headers we could use if we wanted to do a perfectly balanced system are lacking for this application. The vast majority of balancing and flow valves seem to be either for heating or for larger commercial or MDU situations where you would be balancing an entire floor of units. Not much on the low end for 1/2" domestic piping.

    So just looking for options, and opinions, or experience.

    One that might work:
    http://www.wattscanada.ca/pages/_products_details.asp?pid=539

    Oh as for Metric, Canada uses the exact same plumbing sizes as the USA. Things in building trades are still on the old system of measurement here so it's rarely any different between Canada and USA. If we were to import plumbing fixtures from Europe or Japan it would be the same nightmare finding ISO thread sizing adapters as you would have. The biggest problem is with distributors who still think our Dollar is valued at $0.70US and they overcharge like it was still 10 years ago. But in general plumbing for USA and Canada are identical.
  5. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,472
    Location:
    Cave Creek, Arizona
    Trying to "balance" the flow from ALL the lines off the manifold, it that is what you are trying to do, will be almost impossible, AND to control backflow EVERY one of them would need a check valve to maintain flow in the direction of the water heater.
  6. QueBall

    QueBall New Member

    Messages:
    5
    Location:
    Edmonton, AB
    Well on one side of the equation I'm curious to know what the optimal solution would look like. This is the do not care what it costs, just make it perfect option.
    So to do that we have:
    Put a check valve and a flow valve on every return line (Perhaps something that does both functions). There doesn't seem to be a product designed specifically for this application so it would be a mixture of fittings in front of the manifold.

    Any tips on the best products for this optimal solution are appreciated.

    On the practical side, I am pretty sure some simple steps will get us to the point of having things "adequately" balanced so the hot water circulates well enough to provide warm water on all the taps.
    So far this looks like, down sizing the return loop piping from the shortest run and making sure there is insulation on the pipes where possible. There is already a check valve integrated into the recirculation pump system of the water heater.
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