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Thread: Looking for a bi-directional electrically actuated valve

  1. #1
    Aspiring Old Fart, EE, computer & networking geek Mikey's Avatar
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    Default Looking for a bi-directional electrically actuated valve

    I've installed a Watts circulating pump under a bathroom sink at the far end of the plumbing lines to replace an older "Chili Pepper" appliance whose pump motor crapped out. I still use the control circuitry from the Chili Pepper, allowing on-demand operation of the Watts. Everything works great, and the dead-quiet Watts is a welcome change from the very loud Chili Pepper.

    However... the Watts pump is a centrifugal pump, whereas the Chili Pepper pump was a geared pump. The geared (aka "positive displacement") pump also served as a valve, isolating the hot line from the cold line when the pump was off. The Watts pump, however, allows water to transfer between the two sides when the pump is off, leading to a couple of problems:

    1) Water circulates constantly, due to convection in the loop; and
    2) When you use water in the shower you always get an indeterminate mixture, regardless of the mixing valve setting.

    The easiest way to solve this seems to be to place a valve in-line with the pump, which would open when the pump was on. A simple check valve comes to mind, but I'm not sure the Watts will generate enough pressure to open a check valve strong enough to resist unwanted flow. Since I'm operating on a limited budget, I first thought of a simple irrigation valve, or a washing-machine valve, which can be had for about $10, with a few bucks more for a 24VAC transformer for the irrigation valve. But it turns out that most of these are solenoid-operated diaphragm valves, which only work in one direction, whereas I have to stop flow both ways.

    So... any suggestions? I've found some from industrial suppliers for big bucks, but I'd rather use something more commonplace (and cheaper) that some of the experts on this forum might have come across. Thanks for any help.

    I see that somebody else was trying to solve a similar problem in March, but got no responses.
    Last edited by Mikey; 11-15-2011 at 05:01 AM.

  2. #2
    Moderator & Master Plumber hj's Avatar
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    Default valve

    The pump will open a check valve, but you need a "thermostatic" valve which closes down when the temperature increases. The "'bypass valve" from a Grundfoss "Comfort", or Laing sysem should work depending on HOW you have the pump installed. ANd since you had to buy a new pump, either of those companies have a "ready made" unit that does the whole job.
    Licensed residential and commercial plumber

  3. #3
    Aspiring Old Fart, EE, computer & networking geek Mikey's Avatar
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    Me, "buy" a new $240 pump? No way. Anyway, the Watts pump is just connected between the hot and cold water risers at the sink. The control circuitry from the old Chili Pepper appliance starts the pump at the push of a button, and keeps it running until the water it's pumping reaches the setpoint, so all the valve has to do is open when the motor turns on, and close when it goes off. If this pump does indeed have the cojones to overcome a check valve, I'll give it a try, but the real open/shut valve is more appealing.

    The Grundfos and Watts (the pumps look suspiciously similar) recirculators are intended to be installed at the water heater, and run at timed intervals; if you don't get around to using hot water during one of those intervals, you've wasted some energy. Or, if you need hot water unexpectedly during a normally "off" period, you've got to manually turn the pump on, which means a trip to the water heater. In my case, that's a big deal. Also, in our house we've got a center-fed water distribution system, with the kitchen and laundry at one end and the bedrooms and bathrooms at the other. Each of these areas uses hot water at different times, so the point-of use control is much more appropriate for us. I've got another Chili Pepper appliance at the kitchen end which is still working; it's noisy, but tolerable in the kitchen, unlike in the master bath.
    Last edited by Mikey; 11-15-2011 at 07:12 AM.

  4. #4
    General Engineering Contractor ballvalve's Avatar
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    Check valve, maybe a swing type. Put it on a flex line and you can adjust its angle and thus the opening or 'keep closed' pressure.

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    In the Trades Tom Sawyer's Avatar
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    That's not too savage is it? LOL
    [B]No, plumbing ain't rocket science. Unlike rocket science, plumbing requires a license[B]

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    Aspiring Old Fart, EE, computer & networking geek Mikey's Avatar
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    I'm going to need some enlightening on the savage remark, I'm afraid. As for the swinging check valve, you may be on to something. The problem will be finding a) how much pressure the Watts pump can comfortably maintain to keep the hot->cold flow going through the valve, and b) how much suction can be generated by someone drawing cold water (which will also tend to open the valve). If (a) is greater than (b), we can adjust the check valve to open under (a) but stay closed under (b), and we're in good shape. Talk about Rube Goldberg. I've still got to believe there's a simple valve out there somewhere that will work, but diaphragm valves are so popular that they're used just about everywhere -- where they work just fine, because the application is usually one-sided.

  7. #7
    Retired Defense Industry Engineer jadnashua's Avatar
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    You need to be careful of the materials design of anything you insert into the water line. Normally, this would require something made of either SS or bronze, and those can get expensive. The unit I have uses a check valve made of Deldrin, rated at over 1-million cycles, but whose counting...
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  8. #8
    Aspiring Old Fart, EE, computer & networking geek Mikey's Avatar
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    Thanks, Jim. The supply lines are copper and CPVC, stop valves are brass, old Chili Pepper component is a thermoplastic of some kind, interconnecting tubing is Nylon I think, so it's a bastard system so far. All the valves I've found so far are either brass, bronze, or SS, so price is no object for those guys (but it is for me). The cheaper solenoid diaphragm valves are Nylon, PVC, or Delrin for the most part. I'm going to head over to a huge surplus store in Orlando one of these days to see if the military has a gazillion-dollar valve that could be adapted somehow, but for now I've got a manually-operated 1/4-turn valve doing the job. I have faith that there's a commodity product somewhere out there that will work, but I just haven't found it yet.

  9. #9
    Moderator & Master Plumber hj's Avatar
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    quote; If this pump does indeed have the cojones to overcome a check valve, I'll give it a try,

    The pump has enough cojones to operate a check valve when it is installed in a conventional circulation system. There is NO SUCTION when a cold faucet is opened, (and check valves are NOT adjustable). EVERYTHING is still under pressure. IF there were a pressure drop in the cold line when you used the faucet, then you have an undersized water system and THAT is a more serious problem than a bad check valve, AND if you had a defective single handle faucet that would cause the same problem. How much did the pump cost, assuming you purchased the correct one, add to that the cost of whatever "fix" you perform to make it work "right" and you may be close to the cost of the "already developed" system. Add in the time you spend doing it and you would have lost money on the makeshift system. BOTH companies make pumps which install AT the sink, JUST LIKE your pump, but they have the thermostatic control to stop circulation when the hot water arrives at the sink, at which time the pump goes into "idle" mode using very little power. You set the timers to shut down the system when NO ONE would be using hot water, such as the middle of the night and when everyone is at work. When you have a "split system" like yours, you install the pump at the heater and then install a "controller valve" at one of the sinks at both ends.
    Last edited by hj; 11-16-2011 at 05:33 AM.
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  10. #10
    Aspiring Old Fart, EE, computer & networking geek Mikey's Avatar
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    Well, it seems to me that if you have a hot and a cold line connected together (which, logically, is what I have) then any faucet opened will draw more-or-less equally from each line. This shows up most dramatically in the shower, where the (pressure-compensated) valve makes no difference in the temperature seen at the showerhead. If you close off the interconnect, the shower is normal.

    I have a check valve that is adjustable via a screw-and-spring arrangement, but have no idea what the range is.

    My pump, a Watts 500800, cost $80, as I remember, from that well-known auction site.

    My time is free these days, and as a retired engineer I'm a tinkerer by nature, so there's a net gain for me when I experiment like this.

    And, ultimately, if I can't find a valve, I can buy the undersink Watts valve (really the Grudnfos valve, I think, for about $40) and do it their way. However, their way wastes energy. In my case, the water is heated by a solar system, so it's arguable that energy is free, but it even gets cloudy in Florida...

  11. #11
    General Engineering Contractor ballvalve's Avatar
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    Quote Originally Posted by Tom Sawyer View Post
    That's not too savage is it? LOL
    He has an adjustable check valve so thats the ticket with tinkering.

    A swing check valve on a swing joint or 45 at the outler of a hydraulic ram water pump is a common and respected method of adjusting its operation. About the only use for a swing check outside of tiny flows.

  12. #12
    Aspiring Old Fart, EE, computer & networking geek Mikey's Avatar
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    Well, I loosened up the adjustable check valve to where I could blow it open, and installed it pointing from H to C. I have no idea what that is in psi, but it ain't much. In any event, the system is working as intended. I installed a 110VAC neon pilot light which plugs into the same duplex receptacle the pump is, so if the pump is on, the light is on. You push the button, occupy your time for a couple of minutes until the light goes out, and Viola! hot water. The cold side stays cold. Well, as cold as it gets in Florida, anyway.
    Last edited by Mikey; 04-11-2012 at 02:36 PM.

  13. #13
    Moderator & Master Plumber hj's Avatar
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    quote; I can buy the undersink Watts valve (really the Grudnfos valve, I think, for about $40) and do it their way.

    Their way does NOT "waste energy" because it just controls the flow of water created by your pump. In fact they COULD save energy, since they would close when the hot water arrives even if the pump were still running. YOUR way will inject hot water into the cold system IF the hot water arrives too quickly. Leave it to an engineer to try to invent a better wheel.
    Licensed residential and commercial plumber

  14. #14
    Aspiring Old Fart, EE, computer & networking geek Mikey's Avatar
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    Quote Originally Posted by hj View Post
    ...they would close when the hot water arrives even if the pump were still running. YOUR way will inject hot water into the cold system IF the hot water arrives too quickly.
    You apparently don't understand my way... The hot water will only arrive because the pump is running. And there's no such thing as the hot water arriving "too quickly" -- in fact, the sooner the better. The pump is turned off as soon as the hot water arrives. Their system wastes energy in that the pump is running for the entire period the timer is set for; my pump runs only long enough to bring the hot water to the point of use at the time it's wanted, and then immediately shuts off. In my case, the pump runs for approximately 2 minutes for every request, or for less time, if at all, if the hot water is already close by.

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