Replacing supply lines

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by citykid, Jul 12, 2006.

  1. citykid

    citykid New Member

    Messages:
    41
    Hello all,
    I am replacing a washing machine in the basement and am unable to shut off the hot water line. The valve by the WM just will not stop the flow. But there is no other shutoff between here and the hot water tank.

    Now I obviously need to shut off the water to cut into the lines (hot and cold) to install new shutoffs and install some extra pipe for a water hammer problem. How do I do this? Shut off the main going into the hot water heater seems like I have to. Would I need to drain the heater to keep the hot water from coming out and down the line to where I need to work?
  2. speedball1

    speedball1 Retired plumber

    Messages:
    43
    Location:
    Sarasota Fl.
    Hey Kid,

    Turn the water off at the hot water heater. Open the farthest hot water faucet in the system to prevent a vacuum lock and drain off a few gallons from the water heater boiler drain, you do not need to drain it completely.
    You may now replace the hot water shut off to the washer and after that you may install your new washer. After everything's installed turn the water back on and let the air bleed of out of the faucet you opened. When water comes out of the faucet the system's pressured up readyto use.
    Good luck, Tom
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,324
    Location:
    New England
    Normally, when you shut off the water to your water heater, it won't drain - you'd create a vacuum fairly quickly (like a finger over a soda straw pulled out of the glass). That being said, to be on the safe side, you could shut it off. If it is gas, the valve is right there - you'll probably have to relight the pilot when you are done since few don't have a pilot. If it is electric, shut off the circuit breaker.

    Several companies make shutoffs specifically designed for clothes washers...this might be a good thing. One of the most frequent sources of floods is from a burst hose to a washer. It really is best to shut off th esupply each time you finish with th ewash, and a dedicated valve designed for this makes it easy.

    Note, too, that most newer washers really need a 2" drain line - they pump mucho water very quickly; often much more and faster than an old one. It can overwhelm a 1.5" line (the much more common size previously). Don't be surprised if you have problems if it isn't 2".
  4. citykid

    citykid New Member

    Messages:
    41
    So turn off the cold water supply to the heater, drain some water out of it, open up a hot water faucet soemwhere in the house (for pressure), and that will stop the hot water from coming out of the hot water tank? I was also thinking of installing a hot water shut off a little after the hot water heater (just so I wouldn't have to do this again)
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,324
    Location:
    New England
    The only reason you need to open a faucet is to relieve the pressure and, if you are going to solder on a valve (better in this case than a compression fitting IMHO), you have to get the water out of the line so you can solder. You won't get much water out from the hot side at all.

    Highly recommend a special washing machine valve.
  6. citykid

    citykid New Member

    Messages:
    41
    Well, that is my question. How to keep water out of the hot water lines. Do I need to completely empty the hot water heater?

    Thanks for the responses.
  7. plumber1

    plumber1 Plumber

    Messages:
    1,423
    Location:
    Florida
    If you use the w/h drain valve be prepared to deal with a dripping drain valve.
  8. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,324
    Location:
    New England
    If you open one up upstairs, then open the one down where the washer is, all of the water in the pipe between will drain out...since the supply is off, you won't get any more in it until you turn it back on. Now, some single handle faucets can have a cross-over, so if you only shut off the supply to the HWH, you might still get water under pressure out. Put the handle all the way to hot, or shut off the main supply. In either case, the HWH won't drain.
  9. coach606

    coach606 New Member

    Messages:
    144
    Location:
    Illinois
    Just to understand...

    So if you turn off the cold water feeding your water heater it will basically stop hot water coming out, correct?

    Opening the faucets is just to drain the water in the supply lines so you can sweat the pipe, correct?

    I'm going to tap some water lines for a new bathroom in my attic. They are right off the water heater, cold going in and hot coming out. I figured that if I shut off the cold going in, when I cut that pipe to tee in any water in it would just come out.

    Is that correct? Hope I didn't hijack your thread. I was just clarifying the advice and checking on my plan.
  10. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,324
    Location:
    New England
    Is your HWH in the attic? Regardless, if you shut off the supply, you can't siphon it out, and since the pipe comes out of the top, gravity keeps it there. You'll get some spurts when you turn it back on then open up a faucet, but that is normal until all of the air is out of the lines.
  11. coach606

    coach606 New Member

    Messages:
    144
    Location:
    Illinois
    Not in the attic.

    HWH is in the basement. New bathroom is in the attic.
  12. prashster

    prashster New Member

    Messages:
    941
    Citykid: The hot water heater is just a resevoir. It requires pressure to be able to send water out. It gets that pressure from the incoming cold water line. Once you turn the cold water supply to the heater off, there is no pressure available to push the hot water out of the line.

    That being said, there will be hot water downstream of the heater that must be drained. A small amount of hot water may be 'sucked' out of the heater when you open the tap, but since the heater is usually in the basement, the force of gravity is sufficient to counter any siphon that might occur.
  13. coach606

    coach606 New Member

    Messages:
    144
    Location:
    Illinois
    The line I'm tapping into is in the basement...

    Since I'm teeing into the basement line, I figure it should drain enough to be soldered. Correct?
  14. prashster

    prashster New Member

    Messages:
    941
    Yes. Just drain the excess that's in the outgoing supply line and you'll be fine.
    You might find that it's hard to drain the water in the line quickly. This happens because there is no air inlet upstream to displace the draining water; it's like holding yr finger on a straw full of water.

    I usually turn on a downstream faucet, then cut the pipe at the tee, loosen some straps and pull the pipe down gently to get some slope which'll assist the drainage. If it doesn't stop after like 10 minutes, I'll use white bread. THen you should be able to solder just fine.

    IMHO, a stop valve on the outgoing side of the water heater isn't necessary. You'd be better off putting one just before your next anticipated junction.
    1 person likes this.
  15. citykid

    citykid New Member

    Messages:
    41
    Ahh, to finally understand. You guys are the best, thank you.
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