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hwr piping questioned

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i have a 50gal electric tank w/stats set @ 120degf. and completely rebuilt last winter with all new internals. tank is
blown-down every month or so. (it is circa 2006, hence the rebuild). oem internals looked surprisingly good .
this year the bath on the opposite end of the house began running out of hw even with short showers. my bath directly
above the tank never seemed to duplicate any hw shortage. i suspected a corrupted hwr check valve which is tee'd into the cw make-up line going to the electric tank. the check was a swing-type. upstream of that is a laing circulator with internal aquastat. hwr line is 1/2". all piping is insulated copper. although not 8 pipe dia. seperating check and circulator, the hwr has been trouble-free until this year.
when i removed the swing check from the hwr i found it frozen partially open. AHA!! i sourced a new S.S. spring check
@1psi cracking pressure. cleaned up the laing also. installed new check in the former location of the swing check.
after putting the hwr back on line, i noticed the hw discharge rose to 130degf ! way above setpoint! i bled off the extra
hw to get back near set point.
monitoring temps. after this, i found the hw discharge stayed around 125degf. with a long shower it would drop to 100
or so. the laing setpt. is about 115degf. hw discharge languishes, but eventually climbs back to 120degf. after a few hrs.

my question: would moving the hwr return connection to the drain tapping at the bottom of the tank be the preferred
location, or can it be left where it is? also could the new check be allowing a back-flow of cw into the hwr? this is a
very robust Strataflo billeted stainless valve ( soft seat?) and not cheap. what am i missing here?


Comments

  • bill_brooks
    bill_brooks Member Posts: 50
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    BTW: if the hwr is valved off from the dhw, once hw has arrived
    at any fixture, it'll run all day just like a 50gal.should!
  • hot_rod
    hot_rod Member Posts: 22,260
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    Did you check the dip tube on the tank? It should take the recirculating to the bottom, just like connecting to the drain valve.
    A single handle tub shower valve can cause a cross over if hot and cold.

    Does the home have a Backflow preventer on the main?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Zmanrick in Alaska
  • bill_brooks
    bill_brooks Member Posts: 50
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    thanks hot rod.
    i changed the dip tube with an oem b w. dip tube. old one ok.
    yes all water services in this area must have a back flo on the main. i also have a CW expansion tank near my dhw tank.
    understand, in 15yrs. living here, this problem only came up this winter.
    what about returning HW to the bottom tank drain? i haven't
    relocated just yet as i wanted to see effects of new spring check.
  • bill_brooks
    bill_brooks Member Posts: 50
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    p.s: at this juncture, the 20degf temp drop after long showers, is still a puzzle. i suppose the over-set point issue is another. those
    showers both have anti-scald internals per code. they are identical newport brass variety.
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,336
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    Hello @bill_brooks , Have you tried doing a cross connection test? I do this by shutting off the cold supply to the tank and then open a hot tap. If water stops flowing after a few seconds, the system is tight. If it keeps running, there is a cross connection (between hot and cold) somewhere in the piping that wants to be found.

    Yours, Larry
    kcopp
  • bill_brooks
    bill_brooks Member Posts: 50
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    that was next on the list. old retiree, too many irons in the fire. you know the drill.
    thanks!
  • bill_brooks
    bill_brooks Member Posts: 50
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    shut OFF service stops to both showers. have a slight stream of cw from the basement laundry faucet even with both showers valved OFF. laundry faucet OPEN to hot side only.
    the only faucets remaining are sink faucets. i don't see how they
    could be leaking- by unless cold cw is leaking past the hw valve
    stem. there are no other true mixing arrangements in the system. the main cw to the tank remained closed for the test.
    any other ideas?
  • Alan (California Radiant) Forbes
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    Do the same thing again and this time, turn the valve off to your hwr and see if you still get cw coming out of the hot water side of your laundry faucet.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • mattmia2
    mattmia2 Member Posts: 9,747
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    did you turn off the stops to the washing machine?
    rick in Alaska
  • Alan (California Radiant) Forbes
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    mattmia2 said:

    did you turn off the stops to the washing machine?

    I've never seen a cross-connection at a washing machine, but I'm sure it's happened before. Good call.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • bill_brooks
    bill_brooks Member Posts: 50
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    thanks gents. i will perform the hwr shut-off and/or shutting wash machine service stops. i could see a leak-by from the
    washer if a solenoid was hanging up. otherwise it should be the
    same as a lav faucet, correct?
  • mattmia2
    mattmia2 Member Posts: 9,747
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    I would think it would leak in to the washer before it leaked in to the supply on the other side, but unless there is a tempering valve somewhere, that is the only other place where hot and cold come together. You investigated any single handle faucets, right? I guess it could be a stop that isn't holding wherever the cross connection is as well. Did you check that the new dip tube is still intact? Maybe that combined with the stop for the water heater not holding completely?
  • mattmia2
    mattmia2 Member Posts: 9,747
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    Oh, and here's another idea, if you get the system nice and full of hot water before you do your test, you should be able to tell by the temp of the pipes where the cold water is flowing from.
  • bill_brooks
    bill_brooks Member Posts: 50
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    more things to ponder.
    thanks all
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,624
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    remember the old washing machines with the rubber Y hose and only 1 inlet to the washer
  • bill_brooks
    bill_brooks Member Posts: 50
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    so far the washer feed has not revealed anything. it's the "one armed bandit" variety. shuts off all water w/1 pull.
    i've shut off the service stops to the lav faucets also. nothing.
    no tempering valve in system.
    btw: my hwr is tee'd into the cw make-up to the hw tank ABOVE
    the cw control valve to the tank. i'm not sure why it would have
    any affect. if it did, wouldn't the cw circuit get warm eventually?
    thanks
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,336
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    Hello, Good chance I'm misunderstanding things, but my approach to testing for cross connection is to shut off only cold supply to the heater and open a hot tap anywhere. I'd leave everything else open or in normal position. Then you trace down where the cross connection is. Closing stops before opening that hot tap makes it basically impossible to know where the leak is as it could have been at a fixture that got shut off. That make sense? :p

    Yours, Larry
  • bill_brooks
    bill_brooks Member Posts: 50
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    i know this is frustrating! everything was aok until old flapper check corroded partially open. (or at least it never showed up).
    my cross checking procedure is exactly as yours. i shut cw to hw tank, closed both service stops to furthest shower that suffers the tell-tale hw cooling on a regular basis.
    open the hw ONLY on the basement laundry faucet and get a fine stream of cw that persists.
    so far, i've been unable to track down the cw infiltrator. even after shutting the remaining faucets 1 at a time. that's it!
    thanks for the think on this.
  • bill_brooks
    bill_brooks Member Posts: 50
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    clarification: or at least the cw problem never showed up until the new spring check was installed.
  • bill_brooks
    bill_brooks Member Posts: 50
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    sorry for the confusion.
    please re-read my very first entry. disregard my latest clarification. i didn't say what i meant.
    thanks
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,336
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    Hi @bill_brooks , Have you tried the test I suggested? I'm thinking it could add some useful information. B)

    Yours, Larry
  • bill_brooks
    bill_brooks Member Posts: 50
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    pardon me. i thought i was using your cross-connection test
    larry.
    thanks
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,336
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    Hi, All good, but closing the service stops to showers or other fixtures removes them from the test, when they could be the problem. :o

    Yours, Larry
  • bill_brooks
    bill_brooks Member Posts: 50
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    understood. i was merely trying process of elimination. if the stream stops after finding the offending fixture, that should be
    the culprit. other fixtures back on if they don't cause stream.
    yes?
    thanks larry
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,336
    edited June 2020
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    You win!!! :p

    ps. There IS the possibility that two fixtures leak. I'd start with everything open and close down one fixture at a time to find the leak. Also, you just might hear water running at the cross connection.

    Yours, Larry
  • bill_brooks
    bill_brooks Member Posts: 50
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    10-4!
    thanks for your patience and help!
    one thought. is there a fix for a 2-handled faucet leak? based on
    your instruction, i'm going back thru all faucets again, especially the single handled kitchen faucet. i blew it off perhaps too quickly. the 2 handled are probably not at fault. but i'll check
    again.

    best regards, bill
  • bill_brooks
    bill_brooks Member Posts: 50
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    my builder insisted on placing the hwr tee'd into the cw make-up
    to the hw tank when i built my house. (it was convenient)
    its always been my observation that hwr should be piped into the bottom of the hw tank in conjunction with the tank drain and the circulator and check valve close by.
    does anyone agree with this practice and could it be contributing
    to my gradual tepid hw supply particularly at my far shower?
  • Alan (California Radiant) Forbes
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    hwr teed into the cw feed is normal practice.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,336
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    Hi, I agree with Alan, (as long as the dip tube is in good shape) but either way should work. A two handle fixture cannot create a cross connection unless there is a shut off valve downstream, like on a shower arm. ;)

    Yours, Larry
  • rick in Alaska
    rick in Alaska Member Posts: 1,457
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    Around here they install tempering valves on the supply line to toilets. Because of my experience with them, they are very high on my most hated product list. Beacon makes them and they are designed to mix a little hot water with cold to make the water going to the toilets a little warmer to keep them from sweating. I have found that around here that with our humidity level, if a toilet is sweating, I will guarantee it is leaking internally. However, by putting the tempering valve on, now you don't know it is leaking. I remove them as fast as I find them, first because they mask any problems, and second and most important, a very tiny amount of debris in them makes the check valves stick, and causes either straight hot water to go to the toilet, or the hot and the cold to cross in to each other.
    I would double check the piping to the toilets and make sure you do not have one of them.
    Rick
  • dopey27177
    dopey27177 Member Posts: 887
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    Your electric heater is 220 volts.
    If the unit has two electric coils.

    Is it possible that one coil is defective?
    Is it possible that a fuse or circuit breaker is blown?

    Is the circulating pump, pumping water? Possible the impeller is worn out, not afixed to the shaft or shaft disconnected from the stator.

    Jake
  • bill_brooks
    bill_brooks Member Posts: 50
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    okie dokie boys. now we're putting rubber to the road! if i read
    yunz (pittsburghese) correctly, i only need concern myself with my 2, 1 handle shower fixtures, and my 1 handle fixture in the kitchen.
    shutting service valves to all 3 (1 at a time) really tested neg. for
    cross-connection. the cw very slight stream was unchanged after
    testing each. i even checked each fixture by observing their
    output while closing a service valve eliminating a leaky ball valve
    as a possibility.
    i can feel each fixture's riser up to the actual fixture. i could use
    my infrared camera to look for temp. change in the risers when
    testing them again.
    i agree, there has to be a fixture leaking thru. finding it is quite
    a challenge! there are no tempering valves in the system.
    on to "page 2", as paul harvey used to say.
  • bill_brooks
    bill_brooks Member Posts: 50
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    hi jake,
    i replaced ALL tank internals last fall. both elements, dip tube, anode, heat sink nipples, dialectric unions, and relief valve. before installing the new s.s. spring check, i pulled the circulator
    and cleaned the impeller and its volute. all existing components
    looked ok, but i replaced all except for the laing circ. the orig.
    flapper check was the only defective part of the entire hw system. both new elements are working fine as are their new
    thermostats. i've always had a lab-grade thermometer installed
    on the hw tank discharge. when this problem occurs, a 20-25deg drop in temp. is observed on the discharge temp. curiously,
    when the hwr is valved off, the problem does not occur! this problem displays all the classic cross-connection symptoms. it
    should be much easier to find.
  • bill_brooks
    bill_brooks Member Posts: 50
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    gents, here's an oddity. in re-testing each fixture, i now get a
    fine stream of tepid water coming from the laundry faucet. i then
    decided to leave all the faucets valved OFF except the hwr at the
    check valve / circulator tie-in to the cw make-up tee.
    when i shut off the hwr, i got a loud SLAM at the laundry faucet.
    the stream turned into a greater flow! it was tepid water! where
    would the back-flo be coming from? all fixtures are still valved
    CLOSED as well as the hwr return.
    i noticed the laundry fixture hw valve must now be opened all the way to get any flow. could the SLAM have been the hw valve stem washer becoming unseated by the backflow? before i
    tear into that, i wanted an opinion on whether the cross-conn.
    could be coming from the laundry fixture all this time? it is a cheap builders faucet which has been the ugly step-child in the
    system for years. what does this group think?
    thanks much, bill
  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,050
    edited June 2020
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    Yes, the SLAM could have been a loose bibb washing slamming against a seat.

    As far as the laundry faucet, it would not be the culprit if the cw side is turned off during testing which I'm sure it is.

    Have you tried what @Larry Weingarten suggested?
    "ps. There IS the possibility that two fixtures leak. I'd start with everything open and close down one fixture at a time to find the leak. Also, you just might hear water running at the cross connection."

    I'm being lazy and not reading through all the posts, but when the temperature drops, have you checked the water temp. at the laundry faucet? Oh, now I remember that you have a thermometer on the water heater outlet and there was a 20F drop.

    Check the dip tube again. That's all I got.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • bill_brooks
    bill_brooks Member Posts: 50
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    "the game is afoot", as sherlock holmes used to say. i'm trashing
    the cheapo laundry faucet in exchange for a delta. hopefully it'll last longer and people won't reef on the handles. i hate washers!
    i've followed larry's instruction since the beginning. i agree with his methodology.
    however, this problem only shows up when the farthest shower is in use. i can't duplicate it with the other fixtures.
    that the drop in tank temp, seemingly all by itself, is another matter entirely i think. or part of the same problem, as yet,
    unexplained. i've even noted a lower temp than setpt. without
    any hw use for a long period. once again, this suggests hw/cw
    mixing in the hwr. why the stats don't catch the drop, i can't explain.
    i'm going to leave the suspect shower at the far end of the house
    OFF for a while just to see what happens.
    thanks again, bill
  • neilc
    neilc Member Posts: 2,708
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    faulty new springcheck ?
    or something on its seat ?
    known to beat dead horses
  • bill_brooks
    bill_brooks Member Posts: 50
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    neil,
    i guess anything is possible. that's why i asked above if the hwr should be plumbed into the bottom of the hw tank. but pressures in the cw make-up to the tank should be no different than if the hwr is
    piped to the bottom . the system should be balanced.
    leaving the farthest shower valved OFF for the last 24hrs. hasn't
    really revealed too much. the discharge temp of the tank is still
    hanging about 10degf below setpt. thankfully i haven't seen any
    superheating that i noticed before. just about 110degf.
    maybe i should turn the suspect shower back OPEN and go to
    my shower next which is directly over the hw tank,etc. to see if
    anything suspicious occurs. as far as the check is concerned, i tend
    not to suspect fault there. it is a solid billet of stainless machined
    to accept the ball,spring and seat.
    the far shower never runs out of hw if i valve OFF the hwr entirely. but everyone is ready to mutiny because of the long
    hw travel time to that shower.
    except for the 2 shower fixtures, the others are all 2-handle type.
    i'm at a loss.
    my thanks to everyone for trying to help.
    bill