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what to do for an expansion tank for domestic coil in boiler

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leonz
leonz Member Posts: 1,127
With the heating season a few weeks away, I want to fix the domestic coil connection on my coal stoker boiler.

The propress fittings they installed blew apart and the well ran dry that night and I want to fix the mess they made the right way.

Is there a small cylindrical type bladder tank on the market that I can use for this so I can attach it to the outlet side of the domestic coil? Otherwise I would have to pipe it to a tank on the floor or a small amtrol bladder tank on the water heater as the domestic coil in the coal stoker normally feeds the blended/tempered warmer water into the cold side of the water heater?

They used soft copper tubing when they installed the propain fired water heater and I would need to thread in bronze/brass nipples to the tank inlet(cold side) to make a Tee to attach the hot water bladder tank.

The other issue is the concrete floor under the water heater; the person that had this house before did not use good concrete for the floor and it is turning to dust and I think the water heater should be placed on concrete blocks to get it off the floor. if this is done the propain people could plumb in the expansion tank at the water heater and it would be done and over with and I could fix the domestic coil piping later.

Thanks for any help in advance.

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  • pecmsg
    pecmsg Member Posts: 4,847
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    leonz said:



    The propress fittings they installed blew apart and the well ran dry that night and I want to fix the mess they made the right way.


    Why or How did they blow apart?
  • Jamie Hall
    Jamie Hall Member Posts: 23,289
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    You can use pretty much any small domestic water expansion tank meant for protecting well pumps. Even Lowe's has two little ones meant for the job (depends on the size of the water heater). If you are moderately handy, you can do the job yourself, though you'll need to get a few fittings.

    Of slightly more concern, the T&P valve on the water heater should have opened before any pipe fittings failed. So I would be very much inclined to check and possibly replace that.

    As to putting the water heater up on blocks... why not? The propane people may indeed need to be called in to change the gas line connection -- but unless they are also plumbers, it's unlikely that they will redo the plumbing for you. Take the opportunity to install the expansion tank and a tempering valve at the same time.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • leonz
    leonz Member Posts: 1,127
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    pecmsg said:

    leonz said:



    The propress fittings they installed blew apart and the well ran dry that night and I want to fix the mess they made the right way.


    Why or How did they blow apart?
    =================================================================

    They did not install 2 long bronze nipples and threaded to solder copper elbows to the female N.P.T. ports of the domestic coil with one nipple being shorter than the other to allow the eventual removal of the coil and the heat from coils mounting weldment melted the o-ring is the reason I believe the fittings blew apart and flooded the boiler room and laundry room and ran the well dry.

    The way they left it the piping has to be cut back to fix it with 2 sets of soldered unions and the tempering valve is not at the water heater but at the hot water out line to the piping that was connected to the old
    electric water heater.



  • leonz
    leonz Member Posts: 1,127
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    You can use pretty much any small domestic water expansion tank meant for protecting well pumps. Even Lowe's has two little ones meant for the job (depends on the size of the water heater). If you are moderately handy, you can do the job yourself, though you'll need to get a few fittings.

    Of slightly more concern, the T&P valve on the water heater should have opened before any pipe fittings failed. So I would be very much inclined to check and possibly replace that.

    As to putting the water heater up on blocks... why not? The propane people may indeed need to be called in to change the gas line connection -- but unless they are also plumbers, it's unlikely that they will redo the plumbing for you. Take the opportunity to install the expansion tank and a tempering valve at the same time.

    =================================================================

    Hello Jamie,

    The propain folks do plumbing so no worries there. Thanks much for the help, the water heater is a Bradford White 40 gallon propain gas unit and I think its 10 years old.

    When they cleaned it last year it was first time it had been cleaned by the installing dealer and they found that it was very clean and looked brand new when they disassembled it to inspect and clean the burner.

    When I call them to arrange a time to raise it up, I will ask them to bring along a new relief valve too and I will have the concrete block and an assortment of fittings-nipples, elbows etc., and the bladder tank on hand for them to install.



  • pecmsg
    pecmsg Member Posts: 4,847
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    leonz said:
    The propress fittings they installed blew apart and the well ran dry that night and I want to fix the mess they made the right way.
    Why or How did they blow apart?
    ================================================================= They did not install 2 long bronze nipples and threaded to solder copper elbows to the female N.P.T. ports of the domestic coil with one nipple being shorter than the other to allow the eventual removal of the coil and the heat from coils mounting weldment melted the o-ring is the reason I believe the fittings blew apart and flooded the boiler room and laundry room and ran the well dry. The way they left it the piping has to be cut back to fix it with 2 sets of soldered unions and the tempering valve is not at the water heater but at the hot water out line to the piping that was connected to the old electric water heater.
    That sounds like a installer issue and not pro press fittings. As stated the PT Relief should have opened long before the fittings let go. 
  • JUGHNE
    JUGHNE Member Posts: 11,061
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    Do you have a check valve or back flow preventer between your cold water supply and cold inlet of the water heater.....or any such device in the plumbing anywhere.

    The water well would have a check valve somewhere between the exp tank and water suction point.
    But your tank should be free to respond to your house piping.

    And I assume you have an expansion/bladder tank for your well system.
    If no BFP/check valve, I doubt if you need any additional expansion tank.
    But you must be certain that your T&P relief valve is able to open and release water.

    Here water heater expansion is not a problem as the hot water will push some cold water back thru CW supply into city mains or into the domestic well water expansion tank.

    Only when a check valve is in the CW supply and the WH tank cannot expand back to the main or tank is there a problem.

    Many years ago our water company added new meters with back flow preventers at the main entrance.
    This caused multiple problems..... A 60 year old electric water heater tank started to leak.... other creative people found a 3/4" plug for their T&P valves....etc.
    We have since had the BFP's removed.
  • pecmsg
    pecmsg Member Posts: 4,847
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    JUGHNE said:
    Do you have a check valve or back flow preventer between your cold water supply and cold inlet of the water heater.....or any such device in the plumbing anywhere. The water well would have a check valve somewhere between the exp tank and water suction point. But your tank should be free to respond to your house piping. And I assume you have an expansion/bladder tank for your well system. If no BFP/check valve, I doubt if you need any additional expansion tank. But you must be certain that your T&P relief valve is able to open and release water. Here water heater expansion is not a problem as the hot water will push some cold water back thru CW supply into city mains or into the domestic well water expansion tank. Only when a check valve is in the CW supply and the WH tank cannot expand back to the main or tank is there a problem. Many years ago our water company added new meters with back flow preventers at the main entrance. This caused multiple problems..... A 60 year old electric water heater tank started to leak.... other creative people found a 3/4" plug for their T&P valves....etc. We have since had the BFP's removed.
    That’s not a solution. That back flow serves a purpose. 
    A small x tank solves the problem. 
  • JUGHNE
    JUGHNE Member Posts: 11,061
    edited August 2022
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    But does the OP have a BFP / check valve?
  • leonz
    leonz Member Posts: 1,127
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    I do have a back flow preventer but the fill valve for the boiler is shut off as the boiler uses a steel compression tank.

    If I remember correctly the propain water heater has an internal check valve on the cold water inlet to prevent hot water from heating the cold water feed line.

    Adding the expansion tank is the obvious solution when I fix the connections to the domestic coil.


  • JUGHNE
    JUGHNE Member Posts: 11,061
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    Yes, I recall now that there may be a check in the WH tank inlet.

    So the small bladder tank sounds in line.

    It needs to be one for domestic raw water....not the standard hydronic type....there is a difference.
  • hot_rod
    hot_rod Member Posts: 22,143
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    Add the tank, why not? Some water heaters have heat trapper nipples. I don’t think they are considered bubble type checks, just a bit of resistance to prevent thermal induced flow out of the tank. Some use a thin rubber flapper, some have a plastic ball, the ones where the anode and dip tube are all one.

    IF you have just a tankless coil, the softball type expansion tanks used on tankless water heaters would be adequate. If another tank or preheat tank is downstream of any BFD, the exp tank would need to be larger, a #15, or spend a few bucks more for a # 30 ThermTrol tank

    I think all the current plumbing codes call for an expansion device, the T&P is not a thermal expansion device😗
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • leonz
    leonz Member Posts: 1,127
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    OK, I will plan on a number 15 tank for the job as we will have to finagle some extra room at the water heater. I would like to move the mixing valve too.