Recommendations for variable speed/pressure pump for radiant system

Discussion in 'Boiler Forum' started by alternety, Nov 14, 2017.

  1. alternety

    alternety Like an engineer

    Joined:
    Apr 2, 2006
    Location:
    Washington
    The system was originally designed for a circualtor that would adjust to demand from individual loop flows in the system.

    The system is for a fairly large square footage. A good part of the area that can be heated is not. Only about 40% is actually heated (excludes basement, garage, and a potential greenhouse).

    The solution was to be a pump smart enough to deal with this situation. I tried a brand name pump. It was the same basic pump, but "variable". For whatever reason the pump with the variable speed controller was hideously noisy (vs silent for the fixed speed). I bought equipment to control a pump, but it was also an expensive disaster. My fault. I thought the contractor understood what I was saying. Turned out the implementation was above his pay grade.

    There was a very interesting pump that appeared to be perfect for the application, but they only came in "REALLY BIG".

    What I need is a pump in the loop feeding the various zones that adjusts the pressure across the loop on a real time basis. This will cause a stable pressure to be presented to each of the zone valves. This would minimize noises and stabilize flow rated in each zone circuit.

    This approach would also require a device between the input and return of the loop piping to constrain the pressure across the loop to allow the pump to control it.

    If anyone has suggestions for products to implement this, I would appreciate some ideas for components. Or discussions of why it will or will not work.
     
  2. Dana

    Dana In the trades

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    Jan 14, 2009
    Location:
    01609
    This is sort of like asking for a recommendation on what car to buy, without knowing how many people it has to carry, at what speed, and for what distances.

    The answer is "a blue car", of course! So you might as well make it a blue pump too... :)

    Design-by-web-forum can be a pretty sketchy approach even when some of the necessary information is being provided, but it takes a crystal ball to figure this one out.
     
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  4. alternety

    alternety Like an engineer

    Joined:
    Apr 2, 2006
    Location:
    Washington
    Sorry about that. Should have included the existing pump info. I was rushing through posts. I still do not have a functioning heating system. DHW is fine. Heating; not so much. And using a mechanical flow bypass on the loop does not seem reasonable. Still trying to figure out how things are wired in the existing system. Minimal labels. No documentation. Lots of wires currently hanging out of several wire boxes.

    The blue car is a Grundfos UP26-64F. A fixed speed pump. My crystal ball seems to have expired on the nifty replacement.

    I believe the pump I referenced was a Taco smart pump. I could not find it in their current product list. It was just what I needed. Continuously variable speed pump that senses in/out pressure differential and adjusted flow. Apparently it did not work out for them. I looked at the specs and had conversations with the development people. It was a super product. But the sizing made it impractical for moderate size residential and commercial use. Unfortunate. It was a very cool device.

    This would seem to be a very desirable product. Fixed speed loop pumps feeding multiple zone valves are really are not a reasonable approach to a quite, energy efficient system.
     
    Last edited: Nov 18, 2017
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Joined:
    Sep 2, 2004
    Occupation:
    Retired Systems engineer for defense industry.
    Location:
    New England
    The alternative would be to have bypass valve(s) to keep the pressure constant when not all zones are operating. The pump would probably end up using a bit more power than a variable one.
     
  6. alternety

    alternety Like an engineer

    Joined:
    Apr 2, 2006
    Location:
    Washington
    I have the alternative installed. It is behind an assortment of tanks, pipes, and an air handler. I am barely able to touch it to see who the manufacturer is or a model number. Nor read anything on the device for how to set it up, or is there is some nice markings that tell me something useful about the pressure. I tried one of those cameras on a flex tubing; just could not get a useful angle. No documentation from installer.

    I have a moderate amount of knocking from time to time. The manifolds are in or close to bedrooms. What Taco was going to build would, I believe, would have helped that. I talked to them several times and went through their online course on the pump. I suggested that a more suitable (or additional) marketing target would be residential and small business. The ones they were building were very large. But very smart.

    If I got a nice brushless quiet pump I could probably build something similar. Grundfos made a variable version of the pump I have, but their "smart" control used a simple TRIAC (or maybe only an SCR) for speed control. The resulting pump was extremely noisy, so I did not use it. You could hear it upstairs from the equipment room with doors closed.

    Ah ha. A thread below on "recommendations variable" is for the Taco pumps I was talking about. They did/do make them. I spent a while on their site a few weeks ago and I just could not find them. So much for my search skills. I shall peruse the product.
     
  7. alternety

    alternety Like an engineer

    Joined:
    Apr 2, 2006
    Location:
    Washington
    Taco does have the variable speed pressure/flow controlled pumps. I just had problems using their web site and missed them.
     
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