Strange plumbing of two water tank system

Discussion in 'Water Heater Forum, Tanks' started by RunaboutDYI, Dec 5, 2009.

  1. RunaboutDYI

    RunaboutDYI New Member

    Messages:
    8
    Location:
    GEORGIA
    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?

    Attached Files:

    Last edited: Dec 5, 2009
  2. krow

    krow Plumber

    Messages:
    906
    Location:
    Ontario, Canada
    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?
  3. RunaboutDYI

    RunaboutDYI New Member

    Messages:
    8
    Location:
    GEORGIA
    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.
  4. jay_wat

    jay_wat Plumber

    Messages:
    24
    Location:
    Skagit Valley
    first thing i notice is the T & P drain lines,,wow!

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

    krow Plumber

    Messages:
    906
    Location:
    Ontario, Canada
    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
  6. RunaboutDYI

    RunaboutDYI New Member

    Messages:
    8
    Location:
    GEORGIA
    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.

    Attached Files:

  7. Lightwave

    Lightwave New Member

    Messages:
    98
    Location:
    Vancouver, BC
    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.
  8. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    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.
  9. nukeman

    nukeman Nuclear Engineer

    Messages:
    709
    Location:
    VA
    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/developm...programs/downloads/codespdf/IPCamendments.pdf

    Attached Files:

    • WH.jpg
      WH.jpg
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    Last edited: Dec 7, 2009
  10. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    I would rip it all out and start over...
  11. Runs with bison

    Runs with bison Member

    Messages:
    892
    Location:
    Midwest
    Looks like that is a gas furnace...so why the electric water heaters? Seems like a money losing proposition to me.
  12. RunaboutDYI

    RunaboutDYI New Member

    Messages:
    8
    Location:
    GEORGIA
    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.




    Attached Files:

    Last edited: Dec 7, 2009
  13. RunaboutDYI

    RunaboutDYI New Member

    Messages:
    8
    Location:
    GEORGIA
    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.


  14. RunaboutDYI

    RunaboutDYI New Member

    Messages:
    8
    Location:
    GEORGIA
    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.


  15. nukeman

    nukeman Nuclear Engineer

    Messages:
    709
    Location:
    VA
    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: Dec 7, 2009
  16. RunaboutDYI

    RunaboutDYI New Member

    Messages:
    8
    Location:
    GEORGIA
    The house is huge about 4x larger than we need and using one 80 gal tank when a replacement is need is a great idea. For the most part our hot water needs are going to be limited to the master bath, kitchen and powder room.


  17. Runs with bison

    Runs with bison Member

    Messages:
    892
    Location:
    Midwest
    Ahhhh, With it being propane all bets are off. Propane pricing is not that great.

    At least with electric the storage losses aren't that great--important when you have two large tanks. Is there a large tub in the home? A single 50 gallon hot water tank is insufficient for one of those.

    I don't understand why they did the T&P vent run with a high vertical leg. They probably should just dropped straight down, then out. Are the relief vents tied together or separate? They should be separate. I'm not sure what the legality would be of tying the relief vents together but engineering wise one would need to double the cross sectional area of the piping where they merge onward.
  18. nukeman

    nukeman Nuclear Engineer

    Messages:
    709
    Location:
    VA
    Good point. Per code, the T&P is supposed to run full size all the way to the discharge point. Installation of tees or valves on the line is also a no-no. If they merge together, that violates codes. It looks like they don't merge in the pic, but that is something that should be checked.
  19. RunaboutDYI

    RunaboutDYI New Member

    Messages:
    8
    Location:
    GEORGIA
    The T&P are run separately. The is a jacuzzi tub in the master. It has been my experience that you will empty and 80 gal tank filling one of these. We had one before and I think we used it about 5 time in 10 years. I guess that is the main reason for the two tanks.

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