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Thread: Strange plumbing of two water tank system

  1. #1
    DIY Junior Member RunaboutDYI's Avatar
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    Default Strange plumbing of two water tank system

    We just purchased a home with two 60 gal water tanks with the input cold water and output hot water hooked up in parallel (to the tanks, lines not crossed). That is no big deal but what is strange is what they have done with the tank drains. The drains on the tanks are connected in parallel, coming off with a T. This now single drain line goes through some type of regulator or one way valve. The line then goes through a box shaped pipe arrangement with three valves from that point the line goes to a pipe in the dry wall. I have not checked to check for sure if the drain line eventually ends up being dumped or is sent to a basement bathroom. Because I have all the valves open and I don't hear water running it looks like the drains are run to one of the bathrooms. I attached a diagram of the the plumbing arrangement and a picture.

    It is the strange arrangement of the valves in the pipe box arrangement I can figure out. Any ideas of why they did what they did? What are the problems in using the water from the drain for heating?
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    Last edited by RunaboutDYI; 12-05-2009 at 02:59 PM.

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    Plumber krow's Avatar
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    I suspect they may be trying to use the bottom connection as a gravity fed return line.

    See if you can look at the check valve where the 2 drains meet. Which direction is the flow?

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    DIY Junior Member RunaboutDYI's Avatar
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    It could be part of a recirculation system. That "pipe box" could have been added to allow the addition of a recirculation pump? I will check the direction of the check valve. I was wondering why they had the HW heater at one end of a very long house. If the HW system has a recirculation pump installed would you expect it to be located by the HW heaters or at the other end of the house? I haven't seen a pump near the HW heaters.

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    Plumber jay_wat's Avatar
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    first thing i notice is the T & P drain lines,,wow!

    also no earthquake straps,, do notice the thermal expansion tank.

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    Plumber krow's Avatar
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    Quote Originally Posted by RunaboutDYI View Post
    If the HW system has a recirculation pump installed would you expect it to be located by the HW heaters or at the other end of the house? I haven't seen a pump near the HW heaters.
    AS I said in my earlier post. They could be relying on the recirculating line to be fed by gravity. As the water gets cold, it will drop to the lowest point allowing the hot water to rise to the highest point on its own

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    DIY Junior Member RunaboutDYI's Avatar
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    I understand what you meant by gravity feed (after I looked it up). My comment about not finding a recirculating pump had to do with the odd arrangement of valves on the recirculation line (circled in orange on drawing). The house is very long and there must be at least 250' of HW line just in the recirculation path. The loop, circled in orange, does not seem to serve a purpose. My thought was that it may be there in case someone wanted to add a recirculating pump. If that is the case maybe they did add one some where else, I just have not found it.
    No matter.
    I think you were right on about it being a gravity recirculation setup.
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    DIY Member Lightwave's Avatar
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    Quote Originally Posted by jay_wat View Post
    first thing i notice is the T & P drain lines,,wow
    Out of curiosity, what's wrong? Not acceptable to run T&P drains upward?

    I notice the lack of isolating valves on the piping attached to the WH drain connections. Can't completely isolate one tank for repairs.


    The air conditioning lineset doesn't look too hot either.

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    Plumber jimbo's Avatar
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    Quote Originally Posted by Lightwave View Post
    Out of curiosity, what's wrong? Not acceptable to run T&P drains upward?

    .
    I can't really tell in the pic what is up with the TP valves. Yes it is against ALL codes and very dangerous to run the discharge up. Condensation in the line, over time, would cause buildup of crud at the discharge and possibly prevent the valve from operating.

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    Nuclear Engineer nukeman's Avatar
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    Regarding the T&P, I know that GA does have a local amendment to the plumbing codes that does allow the T&P to run uphill, as strange as that sounds. I'll have to see if I can find that for you. I'm not a plumber, and don't live in GA, but that is something that I have come across in searching for possibilities for relocating my T&P. It seems like many places want you to run the T&P outside, so running uphill (in case of a basement installation) is the only way it they don't allow discharge to the floor or to an indirect waste receptor.

    Here is something that I also came across from the city of Palo Alto, CA regarding basement WH installations. Here, a coil drip tube alerts you to a leaking T&P and would allow condensation to drain.

    Where I live, you cannot run uphill, but are allowed to go outside, indirect waste receptor, or to the floor (if in a area where no damage would occur).

    Edit: Found it for GA. Section 504.6.1.

    http://www.dca.state.ga.us/developme...amendments.pdf
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    Last edited by nukeman; 12-07-2009 at 05:06 AM.

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    Plumber Cass's Avatar
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    I would rip it all out and start over...

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    DIY Senior Member Runs with bison's Avatar
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    Looks like that is a gas furnace...so why the electric water heaters? Seems like a money losing proposition to me.

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    DIY Junior Member RunaboutDYI's Avatar
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    I see the problem, I did not include the pressure release plumbing on my diagram. Both tanks have pressure release valves plumbed to drain up and vent outside the basement. They also have a valve on the vent lines so that you can drain the lines. The lines go up rather than down from the pressure release valves. To have the pressure vent drain down all I would have to do is open the valve on the drain line and go into a bucket or something to evaporate. I attached a drawing of one of the tanks showing how the vents are plumbed.




    Quote Originally Posted by nukeman View Post
    Regarding the T&P, I know that GA does have a local amendment to the plumbing codes that does allow the T&P to run uphill, as strange as that sounds. I'll have to see if I can find that for you. I'm not a plumber, and don't live in GA, but that is something that I have come across in searching for possibilities for relocating my T&P. It seems like many places want you to run the T&P outside, so running uphill (in case of a basement installation) is the only way it they don't allow discharge to the floor or to an indirect waste receptor.

    Here is something that I also came across from the city of Palo Alto, CA regarding basement WH installations. Here, a coil drip tube alerts you to a leaking T&P and would allow condensation to drain.

    Where I live, you cannot run uphill, but are allowed to go outside, indirect waste receptor, or to the floor (if in a area where no damage would occur).

    Edit: Found it for GA. Section 504.6.1.

    http://www.dca.state.ga.us/developme...amendments.pdf
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    Last edited by RunaboutDYI; 12-07-2009 at 07:28 AM.

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    DIY Junior Member RunaboutDYI's Avatar
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    The house has propane not natural gas. I am not sure if you get as much of a savings using propane instead of electric like you do with natural gas. If I built the house I think I would have gone with propane HW heater also. The only other possibility could have to do with venting . They would have had to run 3 stories of vent pipe for the HW heater. The gas furnaces is a high efficiency and vents out the side of the house with a PVC pipe. Lets not forget the builder put in what he could get away with, lowest cost. Don't ask me about the roof and how much I have to spend to fix the flashing that was not put in properly.


    Quote Originally Posted by Runs with bison View Post
    Looks like that is a gas furnace...so why the electric water heaters? Seems like a money losing proposition to me.

  14. #14
    DIY Junior Member RunaboutDYI's Avatar
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    Someone already did. They took one heat pump compressor and exchanger system and the condenser cooling fans off of two other heat pumps. In short I have enough to replace. Maybe when the electric tanks fail I will take a look at installing propane HW tanks.


    Quote Originally Posted by Cass View Post
    I would rip it all out and start over...

  15. #15
    Nuclear Engineer nukeman's Avatar
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    Regarding the two tanks, is this a large house with a large family? It doesn't seem like you would need 120 gallons of hot water. I guess an exception would be if you were using them as storage tanks for a solar hot water heating or something like that. If you do replace them, I'm sure a single 80 gallon gas WH would take care of your needs and simplify things a lot. I'm sure it will lower your cost as well.

    Edit: Didn't see your latest posts while typing this.
    Last edited by nukeman; 12-07-2009 at 07:32 AM.

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