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Thread: Recirculation pump problems?

  1. #1

    Default Recirculation pump problems?

    Hello,

    We have dual water heaters (parallel) in the basement with a separate hot water return line and a recirculation pump. When the pump is on, there is instant hot water and everything works fine. When the pump is off, there is an acceptable delay of 30-60 seconds on most faucets in the morning. The kitchen faucet and two other faucets, however, can take upwards of 7 minutes to get hot water. This can happen both in the morning and also later in the day.

    We looked for a malfunctioning check valve or cross-connection, but my plumber states everything is working fine. He said to just keep the pump on as the kitchen and other slow faucets may just be at the end of the return loop.

    He may be right, but I don't understand why almost all the other faucets would get hot water in under a minute, and the others (one upstairs, one in kitchen and one in the basement) all take such an exceptionally long period of time to get hot. I don't have a problem with having the pump on (there is a timer), but I just want to make sure that the pump isn't covering up some other problem.

    Anything else we can check?

    thanks,
    nishan

  2. #2
    In the Trades Gary Swart's Avatar
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    Default

    Is there a recirculating line from the kitchen supply line? I have a recirculating pump too, and there is no return line from the kitchen supply. I knew when I installed that there would be a little more delay to this area and I am considering putting a return line in. My bathroom basin and shower at the far end of the line have virtually instant hot water, but that's where the return line begins.

  3. #3
    Moderator & Master Plumber hj's Avatar
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    Default circulation

    A properly designed circulation loop, assuming the structure's layout allows it, would have all the hot water using appliances in a continuous loop from the heater back to the pump at the heater. Any fixtures not on that loop will not have "instant" hot water, but will still have to evacuate the cooled water from the pipe back to the nearest "hot" water pipe. That is apparently your situation with those faucets and correcting the problem may be costly, again depending on how your building is constructed.

  4. #4

    Default

    HJ/Gary,

    Thanks for your replies, but I think I may have been a bit unclear. There is a return line from the kitchen and the hot water works fine when the recirculation pump is turned ON. My question was why just a few faucets take an extremely long time (5-7 minutes) for hot water when the pump is off. All the other faucets work fine when the pump is off (<1 minute).

    My general understanding is that the return line should run from the furthest fixture back to the heater. Looking at my system last night, I saw that a fixture in a room adjacent to the water heater is plumbed to the return line instead of the outgoing hot water line. This is one of the three fixtures that has the long wait for hot water. So instead of a return line running from the furthest fixture, everything is run in a true loop. The last fixture is only a few feet from the water heater but is being fed via all the other copper in the house. Now it makes sense why the wait is so long without the pump, and I suspect the other two faucets are plumbed the same way (I can't check though). Is this a standard way of plumbing a return line, or some creative solution.

  5. #5
    Moderator & Master Plumber hj's Avatar
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    Default pump

    Now that you have explained it better, the cause is clear. You either have or should have a check valve at the pump. If you have one it is defective so the cold water in the line and from the bottom of the tank is flowing back through the circulation pipe and since the sink and probably those other faucets are near the point where that pipe starts, they get the cold water. And it will continue until such time as the regular hot water can fill the normal piping. But since you are getting a lot of backflow, the hot water takes a lot longer to get to the faucet. Replace or install a check valve and everything will be back to normal.

  6. #6

    Default

    HJ,

    That's exactly what I thought, but the plumber said the check valves are fine.

    Also, in addition to the check valves, there are shut off valves on both sides of the pump on the return line. Closing those valves should prevent any backflow, but it didn't make a difference.

    Any ideas?

    thanks,
    nishan

  7. #7
    Moderator & Master Plumber hj's Avatar
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    Default pump

    Not without seeing the actual system, but I still think it is some variation of what I said, unless the sink is just so far away that it actually takes that long for the hot water to arrive.

  8. #8
    DIY Junior Member cfgenie's Avatar
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    Default did you ever figure it out?

    Quote Originally Posted by nishanf View Post
    HJ,

    That's exactly what I thought, but the plumber said the check valves are fine.

    Also, in addition to the check valves, there are shut off valves on both sides of the pump on the return line. Closing those valves should prevent any backflow, but it didn't make a difference.

    Any ideas?

    thanks,
    nishan
    Nishan, did you ever figure out what was up with your hot water wait times for the 3 fixtures?

  9. #9
    DIYer, not in the trades LLigetfa's Avatar
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    You dredged up a 6 year old thread asking a question that the OP already answered? As the OP stated, they were improperly plumbed into the return line.

  10. #10
    DIY Junior Member cfgenie's Avatar
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    the OP didn't read the guys original question clearly (nishan clearly said in his original question "We looked for a malfunctioning check valve or cross-connection, but my plumber states everything is working fine", yet the OP said "You either have or should have a check valve at the pump."

    Nishan added "Also, in addition to the check valves, there are shut off valves on both sides of the pump on the return line. Closing those valves should prevent any backflow, but it didn't make a difference". This was his last post to this subject. the OP added his last post which did not answer any questions, just some pompous ramble ("I still think it is some variation of what I said, unless the sink is just so far away...") that was again, not taking into account what nishan had stated - of the 3 fixtures taking so long, "The last fixture is only a few feet from the water heater".

    I am curious because I have a similar problem and I would like to know what nishan figured out, if anything.

  11. #11
    DIYer, not in the trades LLigetfa's Avatar
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    Quote Originally Posted by cfgenie View Post
    ...that was again, not taking into account what nishan had stated - of the 3 fixtures taking so long, "The last fixture is only a few feet from the water heater".
    Again, it is a reading comprehension issue. The last fixture may in fact be merely a few feet from the water heater but since it was incorrectly plumbed into the return line, it effectively was twice as far as the furthest fixture since that is how far the water had to travel.

  12. #12
    DIYer, not in the trades LLigetfa's Avatar
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    Anyway, all that is moot since the thread is 6 years old, I doubt the OP is still looking for an answer.

  13. #13
    DIY Junior Member cfgenie's Avatar
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    Default ...

    I guess OP must stand for something like original poster. my bad...I figured it was operator or some other reference to the guy answering nishanf's question.

    back to the point...nishanf is probably not looking for an answer, I agree. I AM. I asked NISHANF what he did about it, and the fact that he asked 6 years ago is great! That means he has probably done something about it by now. perhaps he figured out more regarding the two fixtures he was not able to see.

  14. #14
    DIYer, not in the trades LLigetfa's Avatar
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    Well then, in that case you would probably be much better off startiing a new thread asking for help. I doubt your house was built exactly like the OP's with the same plumbing into a return line. Also, since the OP has a total post count of 3, I very much doubt he is still hanging out on this forum.

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