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  • Hot Water pump

    Hello,
    I live in a house built in 1990 that has a hot water circulator pump installed for potable hot water. We have a normal 50 gallon natural gas water tank. The piping is as follows:
    cold into tank, hot out of tank to all faucets. Then, at the far end of the house the hot water line continues back where there is a grunfos (forget how to spell it) pump, a 3/4 check valve and then it tees back into the cold line right above the tank.

    Here is the problem:
    The system does circulate hot water. It is awesome. I have noticed though it is hard to get really hot water (not scalding hot, but really hot) without turning the tempature on the water heater up. The tank is only four years old and is set to the very hot setting. Well, this past week, my blue main water line broke. For the week that I temporarily patched the pipe and installed the new copper line, I had the pump turned off. When the pump is off, i seem to get hotter water, but as a result, it takes forever to get to the faucet.

    The Question:
    On many homes that have a similar system, the line that returns to the tank is pumped back into the bottom of the talk where the hose faucet sits. Could my problem be the fact that the pump line is returning the water though the top of the tank using the cold water inlet?

    Any other ideas of what might cause this? Thanks for any help!
    Jacob

  • #2
    1 st are the pipes insulated , this will help to keep the return water from cooling down to much.

    2 nd the tube on the cold water inlet of the water heater may not be good . this tube needs to go to the bottom of the heater . this keeps the cold water from taking a short cut to the hot outlet .
    Charlie

    My seek the peek fundraiser page
    http://observatory.mountwashington.o...nal&fr_id=1040


    http://www.mountwashington.org/weather/conditions.php

    new work pictures 12/09
    http://public.fotki.com/hvachawk/

    Comment


    • #3
      I think you should list your occupation before posting. I thought this was now a rule?
      the dog

      Comment


      • #4
        i would pipe it to the bottom wher the hose bibb is. remove the bibb and install a brass nipple and tee with a ball valve. then also the hose bibb on 1 end of the tee.

        i would also install a timer on the pump and shut it off at at non use times.

        the return line at the top of the heater, cold inlet would require a check valve on the cold inlet. i'm not a fan of this type of installation. plus it would also require an expansion tank.

        rick.
        phoebe it is

        Comment


        • #5
          Thanks everyone. For those interested, I am a general contractor for large high end custom home remodels. Sorry, i did not see where that was required.

          Alright, well, i guess i ought to change the configuration. Last night i tested my theory about the pump causing the water temperature to decrease, and i was correct. The water is dramatically hotter with the pump turned off. Thanks again for your help.

          Comment


          • #6
            Originally posted by Jacob S
            Thanks everyone. For those interested, I am a general contractor for large high end custom home remodels. Sorry, i did not see where that was required.

            Alright, well, i guess i ought to change the configuration. Last night i tested my theory about the pump causing the water temperature to decrease, and i was correct. The water is dramatically hotter with the pump turned off. Thanks again for your help.
            You are a contractor of "high end homes", but you don't have a plumbing contractor you can depend on? Hummmmmmmmm?
            the dog

            Comment


            • #7
              Well, i do appreciate your help, but i do not understand being questioned as far as my competence. If you want the whole story, I do what a normal GC does as well as a lot of the millwork and cabinetry. My plumber had never seen a pump plumbed back into the cold line like mine and was not sure if it would make a difference. He Always installs them at the bottom of the tank and he suggested I do the same. I figured i would get some other opinions from those who might have seen an install like this before instead of replumbing it for no reason without the facts. I do not see anything wrong with that.
              For the info, i did replumb the pump tonight and so far it seems that it fixed the problem. The longest part of the job was draining the tank, but once that was done, it was a piece of cake to install the brass pipe, tee, boiler drain and additional piping required for the pump.

              Comment


              • #8
                Id say the flow rate through the return loop is too high. The water is passing too quickly through the heater to reach maximum temp, thus is not real hot at furthest points. Some kind of flow control valve may help.

                Comment


                • #9
                  Jacob S....I am curious..what is the purpose of the piping you mentioned? Is it to recirculate the cold water in a hot water line so as to avoid having to run the hot water down the drain until the standing water in the hot water line is flushed and replenished from the hot water heater? Also, as you will learn, there are some posters to this forum who have next to nothing constructive to say.
                  there's a solution to every problem.....you just have to be willing to find it.

                  Comment


                  • #10
                    finner, the purpose of a hot water circulating line is to keep the water moving/ circulating in the hot water piping so that it stays warm. this way when you turn on the water at the far end of the house, the water in the hot pipe will already be hot. this will keep from wasting the water and from wasting your time waiting.

                    the drawback in return is the extra cost for the piping back to the heater, the cost of the pump, electricty, re-heating cost, and wear and tear on the piping.

                    a better fix would to install the heater as central to the hot water fixtures or to install a non electric circulating loop.

                    when all this hacked up forum gets back to normal, i will post a detalied installation guide to a non pumped circulating loop.

                    rick.
                    phoebe it is

                    Comment


                    • #11
                      Originally posted by FINER9998
                      Jacob S....I am curious..what is the purpose of the piping you mentioned? Is it to recirculate the cold water in a hot water line so as to avoid having to run the hot water down the drain until the standing water in the hot water line is flushed and replenished from the hot water heater? Also, as you will learn, there are some posters to this forum who have next to nothing constructive to say.
                      The system you are discribing is a Metlund system which is only used when a circulating system was not install and the homeowner does not want to tear the house up to add it. It is better than no system at all but does not work as well as a true circulating system. By the way Metlund was the original system but there are several knock-off systems now.
                      "Somewhere a Village is Missing Twelve Idiots!" - Casey Anthony

                      I never lost a cent on the jobs I didn't get!

                      Comment


                      • #12
                        Originally posted by PLUMBER RICK
                        finner, the purpose of a hot water circulating line is to keep the water moving/ circulating in the hot water piping so that it stays warm. this way when you turn on the water at the far end of the house, the water in the hot pipe will already be hot. this will keep from wasting the water and from wasting your time waiting.

                        the drawback in return is the extra cost for the piping back to the heater, the cost of the pump, electricty, re-heating cost, and wear and tear on the piping.

                        a better fix would to install the heater as central to the hot water fixtures or to install a non electric circulating loop.

                        when all this hacked up forum gets back to normal, i will post a detalied installation guide to a non pumped circulating loop.
                        rick.
                        rick i will be looking forward to seeing this detalalied installation .

                        hawk
                        Charlie

                        My seek the peek fundraiser page
                        http://observatory.mountwashington.o...nal&fr_id=1040


                        http://www.mountwashington.org/weather/conditions.php

                        new work pictures 12/09
                        http://public.fotki.com/hvachawk/

                        Comment


                        • #13
                          Originally posted by PLUMBER RICK
                          finner, the purpose of a hot water circulating line is to keep the water moving/ circulating in the hot water piping so that it stays warm. this way when you turn on the water at the far end of the house, the water in the hot pipe will already be hot. this will keep from wasting the water and from wasting your time waiting.

                          the drawback in return is the extra cost for the piping back to the heater, the cost of the pump, electricty, re-heating cost, and wear and tear on the piping.

                          a better fix would to install the heater as central to the hot water fixtures or to install a non electric circulating loop.

                          when all this hacked up forum gets back to normal, i will post a detalied installation guide to a non pumped circulating loop.

                          rick.
                          Many many years ago I reburbished all of the plumbing on on the McDonald Douglas home in Santa Monica during a renovation. One of the only things we left untouched was the self-circulating copper hot water system which had been in place since the 30s. It was a very neat system and still in great shape.
                          "Somewhere a Village is Missing Twelve Idiots!" - Casey Anthony

                          I never lost a cent on the jobs I didn't get!

                          Comment


                          • #14
                            PLUMBER RICK...I believe I've seen a system that is supposed to accomplish this task at a Home Depot. It had a timer that activated a pump on the hot water heater outlet pipe. The interesting part of the system was a fitting that was supposed to be placed at the sink furthest from the hot water heater. This fitting, which was placed between the hot and cold lines at the sink and the sink faucet, provided some kind of a bypass so that, when the pump was activated, the tepid hot water that had been sitting and cooling would be circulated back to the hot water heater rather than let run down the drain. While it sounded good, the idea of being tied to a timer didn't seem to provide sufficient flexibility. If there was some way to wire a switch to activate the pump from any sink or tub/shower so that tepid water was saved, it could probably provide for a considerable water saving. Also, i'd be very interested in how a non-pumped system such as you mentioned would work.
                            Last edited by FINER9998; 06-21-2006, 10:25 PM.
                            there's a solution to every problem.....you just have to be willing to find it.

                            Comment


                            • #15
                              Originally posted by FINER9998
                              PLUMBER RICK...I believe I've seen a system that is supposed to accomplish this task at a Home Depot. It had a timer that activated a pump on the hot water heater outlet pipe. The interesting part of the system was a fitting that was supposed to be placed at the sink furthest from the hot water heater. This fitting, which was placed between the hot and cold lines at the sink and the sink faucet, provided some kind of a bypass so that, when the pump was activated, the tepid hot water that had been sitting and cooling would be circulated back to the hot water heater rather than let run down the drain. While it sounded good, the idea of being tied to a timer didn't seem to provide sufficient flexibility. If there was some way to wire a switch to activate the pump from any sink or tub/shower so that tepid water was saved, it could probably provide for a considerable water saving. Also, i'd be very interested in how a non-pumped system such as you mentioned would work.
                              the system that you're talking is made by grundfos. originally about 7 years ago when it first came out, the pump and bypass tee was located together in a sink cabinet farthest from the heater. in the last few years they reworked the system to allow for the pump to be installed on the hot water outlet and the bypass tee at the far sink.

                              this system actually works pretty well. i've installed a hand full with good results and feedback from the customers. the purpose of the timer is so that you don't operate at odd hours. the bypass tee also incorporates a thermal bypass valve. when the water temperature rises to a preset level the bypass valve will shut and the system is up to temperature. just a little bit of warm water in the cold side and the hot side is warm, with hot to follow in seconds.

                              the mutland system that utah/ mark mentioned was an earlier system that does use a push button door bell switch. the real issue that i disliked is that you have to push the button, wait for the water to warm up, then turn on the faucet. you might as well run the water and accomplish the same thing without all the bells and whistles. just a little wasted water

                              i prefer the grundfos system. although if you are interested in the mutlund system, i have 4 of them in stock for sale

                              rick.
                              phoebe it is

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