# Replacing Dishwasher, No water shutoff



## AandPDan (Mar 27, 2011)

While you have the water off, can you put a shut-off valve in the line, so you don't ever have to go through this again OR if the dishwasher ever leaks, OR needs replacing again?


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## sustorm (Apr 4, 2011)

That certainly can be done, good thought, thanks. Other than that, safe plan?


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## Rehabber (Dec 29, 2005)

#1,2, and 3 arejust fine, but add a shutoff valve at the beginning of the supply line.


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## sustorm (Apr 4, 2011)

okay thanks will do


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## LateralConcepts (Jun 6, 2010)

The water supply for your HWH is most likely 3/4". I'm guessing copper? How is the existing transition made to the dishwasher supply? If it's a saddle valve (needle valve), get rid of it! Install a 3/4" x 1/2" Tee, a 1/2" x 3/8" compression stop, then a stainless steel braided supply line for your dishwasher.


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## sustorm (Apr 4, 2011)

there is a T off of the main HW outlet that goes to a pvc line down the wall. That goes to an elbow where the copper line runs straight to the dishwasher inlet.


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## md2lgyk (Jan 6, 2009)

sustorm said:


> there is a T off of the main HW outlet that goes to a pvc line down the wall. That goes to an elbow where the copper line runs straight to the dishwasher inlet.


I hope you meant CPVC. Regular PVC is not for use with hot water.


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## LateralConcepts (Jun 6, 2010)

> I hope you meant CPVC. Regular PVC is not for use with hot water.


PVC is used all the time.


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## sustorm (Apr 4, 2011)

do i have to completely drain the hot water tank, or just shut off the inlet and run some water out to releave the pressure? When I disconnect the dishwasher line, is it going to run like a hose?


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## LateralConcepts (Jun 6, 2010)

sustorm said:


> do i have to completely drain the hot water tank, or just shut off the inlet and run some water out to releave the pressure? When I disconnect the dishwasher line, is it going to run like a hose?


No. Just shut off the valve to the cold water inlet, open up a faucet. If possible, open one that's lower than the dishwasher connection.


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## Jackofall1 (Dec 5, 2010)

Just turning the HW supply off is fine, with all valves closed it will be air locked, you may get a bit of water out of the line to the DW, when you disconnect it.

Mark


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## sustorm (Apr 4, 2011)

the dishwasher inlet is probably the lowest hot water line and the home is on a slab. Do I open a faucet and leave it open, or do i just disconnect the dishwasher line, catch that water and due to the air lock, and put my valve/pipe plug on the line until I install the new dishwasher

thanks for the help


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## Jackofall1 (Dec 5, 2010)

You should be fine as long as no one opens a valve when you have to DW disconnected and there isn't a leaky hot water tap.

Being that is the lowest point even if you drained the piping you would still have water in the line. 

As long as your system is air/liquid tight you should be fine. Make sure you install a shut off valve to the DW when you have it apart.

Mark


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## LateralConcepts (Jun 6, 2010)

sustorm said:


> the dishwasher inlet is probably the lowest hot water line and the home is on a slab. Do I open a faucet and leave it open, or do i just disconnect the dishwasher line, catch that water and due to the air lock, and put my valve/pipe plug on the line until I install the new dishwasher
> 
> thanks for the help


In that case, just open the kitchen faucet (burp it) then shut it back off. It'll air lock as long as there are no leaky valve in the house. You might get a little water. Just work quick. What kind of valve did you end up getting? How do you plan to connect it to the PVC? or CPVC? Whatever it is..


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## sustorm (Apr 4, 2011)

the "pvc" goes to an elbow where 3/8 copper is run to the dishwasher inlet, i havent purchased the valve yet, any recommendations?


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## LateralConcepts (Jun 6, 2010)

sustorm said:


> the "pvc" goes to an elbow where 3/8 copper is run to the dishwasher inlet, i havent purchased the valve yet, any recommendations?


Can you take a picture of the existing connection and transition from PVC to copper. I'm having a hard time visualizing how it's set-up now.

You'd actually be better off just T'ing off the water supply for the kitchen faucet. Use a 3-way valve. 1/2"x3/8"x3/8" compression angle stop. Then of course you'd have to cap off the connection at the water heater.


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## sustorm (Apr 4, 2011)

sorry, I cant, I wish i could. the pvc just comes down the inside of the wall to a 90 and at the 90 the pipe is copper, i believe there might be a fitting similar to this at the 90, then the copper is run through the wall and under the dishwasher straight to the inlet and that looks similar to the other picture.

FYI the below pictures are not mine and were retrieved from google images


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## rjniles (Feb 5, 2007)

LateralConcepts said:


> PVC is used all the time.


I have to question this statement. My understanding that if PVC is used with hot water it will soften and bulge. And over time it will burst. Have I been misled?


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## WillK (Aug 29, 2010)

LateralConcepts said:


> In that case, just open the kitchen faucet (burp it) then shut it back off. It'll air lock as long as there are no leaky valve in the house. You might get a little water. Just work quick. What kind of valve did you end up getting? How do you plan to connect it to the PVC? or CPVC? Whatever it is..


Funny story... In my crawl space I had to cut a copper line feeding the toilet upstairs, I was soldering on a threaded fitting so I could put in a shutoff valve and do a CPVC jog where the pipe was route through where I'm going to install a beam. I made my cut in the copper pipe having shut off the house water supply and went to the store to get my CPVC fittings.

When I came back, water was still coming out. I had left faucets openning, so the whole thing was siphoning water out of the hot water heater. When I shut off the faucets, the water stopped and I was able to solder my fitting on.


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## LateralConcepts (Jun 6, 2010)

rjniles said:


> I have to question this statement. My understanding that if PVC is used with hot water it will soften and bulge. And over time it will burst. Have I been misled?


Yes, I think you've been mislead. PVC is perfectly acceptable unless the AHJ (inspector/code) says otherwise. Personally I think CPVC is far more prone to becoming brittle over time. And PEX.. IMO is far superior to both.

http://www.ppfahome.org/pvc/index.html
*"What are the temperature limitations of PVC pipe?*
The maximum use temperature for PVC pressure pipe is 140 degrees F. PVC DWV piping readily withstands the hot and cold water discharges that are normally associated with plumbing fixtures."


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## WillK (Aug 29, 2010)

PVC is fine for DWV at hot water temperatures because DWV is not presurized.

Using your same source, here is their page on CPVC:
http://www.ppfahome.org/cpvc/index.html

They rate CPVC for 400 psi at room temperature and 100psi at 180 degrees F. 

http://www.ppfahome.org/cpvc/faqcpvc.html


> CPVC systems conforming to ASTM D2846 are rated for continuous service at 100 psi and 180 degrees F and are marked accordingly. The model codes recognize CPVC's capability to handle short-term pressure/temperature excursions beyond these levels. Therefore, CPVC is well suited for usage as T/P relief valve discharge lines, evidenced by its faultless service history over the past two decades in this application.




You were also quoting from their FAQ page:
http://www.ppfahome.org/pvc/faqpvc.html

Further down on that page they show a chart for converting pressure ratings by tempeature. The pressure rating for PVC is half of its room temperature presure rating when it carries water at 130 degrees F.

Looking on Home Depot Schedule 40 PVC is rated at 480 PSI. Typical city water pressure operates around a 50 psi ballpark, but you have to consider that water hammering can result in pressure spikes of 250 to 400 psi.

http://www.siouxchief.com/Resource_/ProductMedia/133/Water Hammer FAQ 4-04.pdf


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## LateralConcepts (Jun 6, 2010)

WillK said:


> PVC is fine for DWV at hot water temperatures because DWV is not presurized.
> 
> Using your same source, here is their page on CPVC:
> http://www.ppfahome.org/cpvc/index.html
> ...


Not really sure what you're trying to prove. Again, PVC is perfectly acceptable for water piping (hot & cold). I've seen miles and miles of the stuff over the years. Obviously we all know that different areas have different codes. 

If water is spiking to 200+psi, you will have far bigger problems than what kind of pipe is installed. Water pressure shouldn't exceed 80psi. 75 is about ideal. Regardless of what the pressure from the city is; if excessive, it's the responsibility of the homeowner to regulate the pressure with a PRV.


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## WillK (Aug 29, 2010)

I guess I'm speaking to theory and you're speaking to practice and the reader can take the info and decide for themselves, within the range of what is acceptable to their particular AHJ.


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## sustorm (Apr 4, 2011)

just to clarify, the pipe was CPVC, and thanks for all of your help, i turned off the hot water inlet, ran the kitchen sink until HW stopped coming out and then disconnected the old dishwasher and only lost a small bit of water, thanks again!


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