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  • H.W. heater recirculation mix up?

    I was at a house today with two water heaters piped in paralell. They Also had a gravity fed 1/2 copper line set up for a return, it fed into only one heater. They were complaining that it took forever to get hot water to the furthest fixture.

    I had them turn on the furthest hot faucet, and felt the 1/2 return line. Slowly it got very hot, along with the main 3/4 hot line...at the same time. I then checked the return line hook up and noticed the install in this order:

    1. check valve
    2. gate valve

    Ok, no big deal. I looked at the flow of the check valve and noticed the arrow was pointing the flow going AWAY from the water heater. So instead of a retun line, they have two, dedicated hot lines, correct?

  • #2
    Re: H.W. heater recirculation mix up?

    Thats what they had, so did you change the check valve direction? I like to put in a drain port to help bleed the air from the return line.
    Ron Hasil Lic #058-160417
    A-Archer Sewer & Plumbing specializing in:
    Tankless Water Heaters | Drain and Sewer Cleaning
    Sump and Ejector Pumps | Backflow RPZ Testing

    Comment


    • #3
      Re: H.W. heater recirculation mix up?

      Originally posted by SewerRatz View Post
      Thats what they had, so did you change the check valve direction? I like to put in a drain port to help bleed the air from the return line.
      No, I that was the least of their problems. I have to go back. The whole line was uninsulated as well...

      Comment


      • #4
        Re: H.W. heater recirculation mix up?

        Ah one of those jobs, good luck with it.
        Ron Hasil Lic #058-160417
        A-Archer Sewer & Plumbing specializing in:
        Tankless Water Heaters | Drain and Sewer Cleaning
        Sump and Ejector Pumps | Backflow RPZ Testing

        Comment


        • #5
          Re: H.W. heater recirculation mix up?

          I had a similar one today...

          i'm not sure if it was originally intended to warm up the cold incoming water, or what.

          It was a 1/2" cross connection from the hot water supply going straight back to the water main

          Apparently, they had been having hot water issues for years and had multiple plumbers change every part of the water heater (some more than once).

          Sometimes, it's nice to feel smart.

          --------------

          Help me support children’s cancer research CLICK HERE!

          Comment


          • #6
            Re: H.W. heater recirculation mix up?

            I have had this same discussion over the years with other plumbers, water heater manufacturers and inspectors. When you pipe a "passive return" line into the bottom of one of two heaters piped in parallel, you negate the balanced piping arrangement. Therefore, you've diminished the heating efficiency of the entire system; the heater piped with the return will end up doing the bulk of the heating, as the return line has already created a flow through that heater.

            The way I pipe is this: Take the passive return piping back down between the two heaters, then tee off to BOTH drain fittings, making certain that the piping from the tee to each drain is exactly the same dimension. I valve off both drain connections, but I only install one check valve, on the drop piping before the tee. I like the previous poster's comment about insulation, too. I hardly EVER see these return lines insulated, which is another source of heat loss. We sell these great heaters, designed for efficiency, then we let the heat wick out into the basement.

            (Don't get me started on the last fifty times I quoted re-piping a SERIES piped dual water heater. Sheesh!)

            Comment


            • #7
              Re: H.W. heater recirculation mix up?

              Originally posted by radar_40 View Post
              I had a similar one today...

              i'm not sure if it was originally intended to warm up the cold incoming water, or what.

              It was a 1/2" cross connection from the hot water supply going straight back to the water main

              Apparently, they had been having hot water issues for years and had multiple plumbers change every part of the water heater (some more than once).

              Sometimes, it's nice to feel smart.

              --------------

              Help me support children’s cancer research CLICK HERE!
              I had one where a few guys where there trying to figure out why the whole apartment complex was only getting warm water. They went around changing Moen cartridges, another changed the water heater, and the last guy wanted to do a repipe since the place is all galvanized pipe.

              I get there and open the boiler drain on the water heater and I was getting 125º water. Then I used an inferred thermometer and followed the hot water pipe about 25' from the water heater. Once I got to that spot the temperature of the pipe dropped down to 105º it was shortly after a tee fitting. So I followed the tee'ed off pipe to the laundry area. I looked behind the washing machines (there where two). one was hooked up just fine but the other was not. What happened was the washing machine stopped working so they disconnected the water lines the the machine. But one of the shut offs did not shut all the way off. So their solution was to jumper the washing machine hose from the cold line to the hot. This did not present the problem at first since the other valve did shut off, but someone bored one day opened both valves full blast causing the cross connection.

              I agree with you 100% it is nice to feel smart once in a while.
              Ron Hasil Lic #058-160417
              A-Archer Sewer & Plumbing specializing in:
              Tankless Water Heaters | Drain and Sewer Cleaning
              Sump and Ejector Pumps | Backflow RPZ Testing

              Comment


              • #8
                Re: H.W. heater recirculation mix up?

                Originally posted by Western Reserve View Post
                I have had this same discussion over the years with other plumbers, water heater manufacturers and inspectors. When you pipe a "passive return" line into the bottom of one of two heaters piped in parallel, you negate the balanced piping arrangement. Therefore, you've diminished the heating efficiency of the entire system; the heater piped with the return will end up doing the bulk of the heating, as the return line has already created a flow through that heater.

                The way I pipe is this: Take the passive return piping back down between the two heaters, then tee off to BOTH drain fittings, making certain that the piping from the tee to each drain is exactly the same dimension. I valve off both drain connections, but I only install one check valve, on the drop piping before the tee. I like the previous poster's comment about insulation, too. I hardly EVER see these return lines insulated, which is another source of heat loss. We sell these great heaters, designed for efficiency, then we let the heat wick out into the basement.

                (Don't get me started on the last fifty times I quoted re-piping a SERIES piped dual water heater. Sheesh!)
                When I plumb parallel heaters I use the first in last out method for piping. So in this arrangement you would run the return to cold water inlet. Not 100% sure if this would work with a passive system. All the ones I had done has a recirculation pump installed.


                Attached Files
                Ron Hasil Lic #058-160417
                A-Archer Sewer & Plumbing specializing in:
                Tankless Water Heaters | Drain and Sewer Cleaning
                Sump and Ejector Pumps | Backflow RPZ Testing

                Comment


                • #9
                  Re: H.W. heater recirculation mix up?

                  Ratz: That's a great drawing, and a good way to pipe IF you use a circ pump. For a passive return, there has to be a heat loss on the return that will be enough to set up a convection loop, moving the hot water out of the heater and around the piping, leading back to the bottom of the heater or heaters. Getting the inlet piping, outlet piping and the split return piping dimensions exactly the same for both heaters is crucial, as is making certain that both (or all) heaters are the same size and preferably the same exact heaters.

                  Years ago, I had a guy tell me you also had to pitch the piping back to the heaters, which isn't really necessary, but won't hurt. One other thing to watch for is creating a "heat trap" in the return piping: You don't want to make a bunch of vertical changes in the piping. The convective loop is kinda sensitive and, like an air-locked line, a "trap" can impede the return flow.

                  Comment


                  • #10
                    Re: H.W. heater recirculation mix up?

                    I appreciate you guys discussing this, you learn something new every day!

                    Comment


                    • #11
                      Re: H.W. heater recirculation mix up?

                      My Buddy Steve/Rookie,
                      Sound Familiar?

                      Comment


                      • #12
                        Re: H.W. heater recirculation mix up?

                        Sometimes passive loops will get a little noisy when you turn the hot water on and off, I was able to solve this by putting an air chamber vertically on the highest possible point in the attic along with a water hammer arrestor horizontally. This would closely resemble a cross. Another thing I would do was drill a 1/4'' hole on the swinging portion of the check valve.
                        Last edited by rookie plumber; 03-12-2010, 06:03 PM.

                        Comment


                        • #13
                          Re: H.W. heater recirculation mix up?

                          I swear it's water heater craziness week!

                          I was on a boiler clean & tune today as a "sub" to a handydoof (WTF???). He turned the boiler aquastat down to 130deg F (several degrees below the condensing point of light oil) because "it was getting WAY too hot, it was ridiculous, so, I turned it down... BTW, can you look at the hot water system, it doesn't work right"

                          I'd have to attach about 25 pics to show it all.... convection loop through domestic coil on the boiler, fixed that..... upper aquastat was miswired... caught and corrected that.... explained to homeowner who I was and why I was still there at 7PM.... checked water temp at a sink.... 170deg F there are several kids home now....

                          started over and thought it all through.... realized that I missed the fact that the circ pump was backwards... which explained why the lower aquastat couldn't get to 105deg and the water at the tap was way hotter than I could leave it.

                          while I was correcting the pump issue, along with the multiple check valves in the way.... the HO comes out and starts asking 400 questions about the boiler and hot water system.,... apparently, the handydork who is doing all this work for her told her she needed a new boiler, and hot water tank

                          Finally got outta there at about 9PM... can't charge OT because nobody was makin me stay.... but I couldn't leave the hot water as hot as it was, and by the time I found out that it had been a problem for over a year, I already had figured out how to fix it.

                          I'm curious to see what we're gonna actually bill for.

                          i'm also tryin to figure out which inspector to call to get this guy's BS operation shut down.

                          --------- Help me support children’s cancer research CLICK HERE!

                          Comment


                          • #14
                            Re: H.W. heater recirculation mix up?

                            Originally posted by SewerRatz View Post
                            I had one where a few guys where there trying to figure out why the whole apartment complex was only getting warm water. They went around changing Moen cartridges, another changed the water heater, and the last guy wanted to do a repipe since the place is all galvanized pipe.

                            I get there and open the boiler drain on the water heater and I was getting 125º water. Then I used an inferred thermometer and followed the hot water pipe about 25' from the water heater. Once I got to that spot the temperature of the pipe dropped down to 105º it was shortly after a tee fitting. So I followed the tee'ed off pipe to the laundry area. I looked behind the washing machines (there where two). one was hooked up just fine but the other was not. What happened was the washing machine stopped working so they disconnected the water lines the the machine. But one of the shut offs did not shut all the way off. So their solution was to jumper the washing machine hose from the cold line to the hot. This did not present the problem at first since the other valve did shut off, but someone bored one day opened both valves full blast causing the cross connection.

                            I agree with you 100% it is nice to feel smart once in a while.


                            I did a new home that the new home owners complained they were only getting hot water to their master bath ( which was on 2nd floor directly above the laundry room. Ended up being the hot was leaking thu the washing machine in to the cold line. The second I shut off the laundry box the problem was over.......... For me any way.

                            Comment


                            • #15
                              Re: H.W. heater recirculation mix up?

                              In a sub division we have started to work in we have had a rash of clients calling in to say that they have debris in their shower faucets and many of them have had the original plumbing company come back and replace pressure balancing cartridges. Many Grohe shower valves have an issue with volume and temperature changes. The clients have complained that they were not receiving instant hot water with the recirculation lines and a drop in hot water.
                              I started to look at the recirculation pumps and noticed they are plumbed with the check valves, ball valves that are wide open and check valves with the drain valve. They look great and they are installed neatly. The issue the check valves and pumps are installed backwards drawing the sediment out of the water heaters and into their plumbing fixtures. This is the very first thing I check now. I have reinstalled six in the last two months and have sent letters to the sub division owners to call us to service their units.

                              I have also found a few swing check valves soldered in the closed position.

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