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water heaters piping

....series piping, myself. I have seen parallel jobs where the installer did not set the piping up for equal pressure drop, resulting in one tank getting the majority of the flow. It's much easier and simpler to do a series configuration, and it's pretty hard to screw up!

How big are the existing tanks, and are you sure they are both working??

Edit: Oops - just reread, and see that they are 40 gallon tanks. I will repeat, though, that you should verify they are both working properly. Check burners, dip tubes, etc.

If they are indeed functioning properly, perhaps upgrade to a pair of 50s??

Also, I'm assuming these are gas?? If electric, you could upgrade the elements to high wattage ones for faster recovery.

Comments

  • to series or not to series?

    Came across this at customer's home.. Have two 40 gals water heaters piped in series, she complaining about running out of hot water for her growing 7 kids and never ending washing machine cycles. Told her that I always piped double heaters in parallel pipings for even temp outlet from heaters. Other plumbers say its make no differnce since the capitcity is still the same. Who's right? Happy holidays to u alll.
  • Rich Kontny_3
    Rich Kontny_3 Member Posts: 562
    Reverse return

    Is the only way to assure even flow and full capacity. Course of the least resistance can interupt series type piping if one is hot and the other is stone cold. I learned this quite afew years ago while sitting down with AO Smith engineers.

    No different than hydronic flow. If you take the time to reverse return and valve properly you have even flow and redundancy should one heater drop out!

    Series and even like piped manifolds do not stop thermal stratification and relative flow conditions.

    Rich K
  • Plumdog_2
    Plumdog_2 Member Posts: 873
    If I may,

    Do you mean parallel when you say series? Just wondering, as the flow issues crop up when parallel piping is used, slight differences in friction loss causing havoc with balancing the two tanks.
  • Big Ed_4
    Big Ed_4 Member Posts: 2,684
    Twin Tanks

    You pipe hot water heaters is series for hotter water like in a comerical aplacations.You stage the temperture to step up the temperture.


    And in parallel for quanity which would be residental . You may want to pipe that job in pararllel first. Then set it hotter but install a auto mix valve to temper the supply down .This would put more BTU in storage for a longer supply. Don't forget the heat trap before the auto mix. Or you may want more BTU input for recovery ...

    Like mentioned in a pararllel system you want to reverese return the supply piping for a more balance pressure drop.Reverse return - pipe inlet to first tank and supply to second tank then cross over conections to pararllel. This would give equal water paths between the tanks .
    I have enough experience to know , that I dont know it all
  • steveex
    steveex Member Posts: 95


    Always parallel.
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,226
    viewpoints

    Hello: I've seen lots of trouble with parallel piping as it can change over time. A little plug of rust in one fitting totally throws off the best balanced system. Piping in series can work nicely if the added flow restriction is not a problem. One advantage is you can shut off or turn down the upstream heater until you need to fill that big tub or deal with a house full of guests. Both systems are nice if you valve heaters individually so each heater can be bypassed if needed.

    Yours, Larry

    ps. I'll add that you likely get more undiluted hot water from a series system as you only dilute one tank with cold water. The original system likely has some other problem, with dip tubes, recirc line or cross connection.
  • Big Ed_4
    Big Ed_4 Member Posts: 2,684
    Think about this for a moment

    You have two 40k hot water heaters in pararllel piped reverse return. Both set for 120* and there is a draw for hot water. As the tanks cool both burners turn on at the same time , now you have a full 80k input for recovery.

    With a series piped system on a call for hot water the down stream burner will not turn on until the up stream tank is fully drained . So you you loose 40k input in the begining of the cycle.

    Which system will produce the highest quanity of hot water in the same time frame ?
    I have enough experience to know , that I dont know it all
  • Dave Stroman
    Dave Stroman Member Posts: 763


    I agree with Larry. Have you ever seen what happens to the dialectic unions after a few years? I have seen a parallel installation where there was no flow through one of the heaters because of rust build up in one union. The tank sat for years with no flow. All that time they were operating on one tank. When I corrected the condition, it took weeks for the rusty colored water to finally disappear. I say never parallel.

    Dave Stroman
    Dave Stroman
  • bob young
    bob young Member Posts: 2,177
    brass

    i say never use di-electric fittings. brass nipples are the preffered fitting
  • Big Ed_4
    Big Ed_4 Member Posts: 2,684
    Brass is best......

    ......or add back flush valves ???

    Better yet install a single proper tank if you can......

    You have this job and a father family has six daughers...... Good Luck!!! I don't think there is a big enough tank. You know the drill. They run the hot water for 20 min. Until the bathroom heats up. Then another 20 min. In. While the sister is banging on the door.

    Then Dad redo the bath and wants the full shower with body sprays. Now we have a 15 gallon draw.

    Hot water is the biggest load in the house. You have to do it right......

    Good Luck. Hope I helped....

    I have enough experience to know , that I dont know it all
  • GCW
    GCW Member Posts: 3
    Question on copper sweating and flux

    Started to add a water heater... reverse return parallel seemed to be the suggested method by most. So i drew it up, measured, cut and dry fit everything. Followed all the hints i could find on sweating copper. After finishing i had a tee right in the middle that leaked. Had water laying in it during sweat, I think.



    So i cut it all out and started over. Ran out of time before the AFC championship game. I had to stop... Before stopping I had thoroughly cleaned all the fittings and pipe and applied flux to EVERYTHING. It is now the next day. I



    Can I pick up where i left off and just sweat the cleaned and fluxed joints assembled in place from yesterday or do i need to re clean and reflux everything?
  • GCW
    GCW Member Posts: 3
    Question on copper sweating and flux

    Started to add a water heater... reverse return parallel seemed to be the suggested method by most. So i drew it up, measured, cut and dry fit everything. Followed all the hints i could find on sweating copper. After finishing i had a tee right in the middle that leaked. Had water laying in it during sweat, I think.



    So i cut it all out and started over. Ran out of time before the AFC championship game. I had to stop... Before stopping I had thoroughly cleaned all the fittings and pipe and applied flux to EVERYTHING. It is now the next day. I



    Can I pick up where i left off and just sweat the cleaned and fluxed joints assembled in place from yesterday or do i need to re clean and reflux everything?
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
    I'd pull it and redo it...

    In the GOOD OL' Days, when petroleum based flux was the norm, you could go for up to 24 hours between application and soldering.



    But with todays water soluble flux, I wouldn't take a chance.



    Better safe than sorry.



    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
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