Dishwasher Hot tap in old Galvanized pipe under sink. Which adapters?

[Robert C.]

Need new Hot Water Valve under sink for new dishwasher. Very limited access, I would replace whole line but don't want to blow out the outside wall. Any help on getting this valve spliced into 5/8 GAVANIZED pipe would be much appreciated. Sharkbite? PEX?

 

[breplum]

Only good way is to replace the galv. pipe.
Galv pipe is obsolete, builds and throws off rust and not worth a penny's worth of time to touch unless it is to throw it into the steel recycling bin.
WE stopped using galv. steel before 1950. It was a poor choice but it got us through until better came along.

 

[Jeff Handy]

Your picture is not showing enough of what is going on under there.

Where do the faucet supply lines attach?
Show that also.

Where are the existing shutoff valves for the sink?

I see none in your picture.

Are they down below in a basement or crawlspace?

There is no way to splice in a valve in the middle of a galvanized pipe, all connections are threaded.

You might be able to attach a tee fitting to feed the dishwasher, where the hot pipe ends and where the sink faucet supply attaches.

Or if there is access from a basement or crawl, tie in somewhere down there, and run a separate new line up for the dishwasher

 

[Riickk]

That looks like a ? scan ? of an actual photograph, notice the bent / curled paper in upper left corner.

 

[Jeff Handy]

And I think it is sitting on a laptop.

Meanwhile it is a lousy view, does not show enough of the whole shebang.

 

[Robert C.]

@Jeff Handy Yes this is a 1930s home, so I should R/R the old galvanized pipe to the threads at each end. No way to successfully tap the hot (left pipe) in the middle of run?

 

[Robert C.]

Should I use threaded brass to copper where the galvanized pipe starts?

 

[Jeff Handy]

Many questions un-answered, others vaguely.

But there is no proper way to tap the pipe in the middle of a run.
Not in a pipe always under pressure.

If you are adding copper to galvanized, I have always used a brass transition piece.
A valve, coupling, nipple, etc.
To reduce corrosion from galvanic action.
Using teflon tape also might help slightly with that, as some think, but not really a factor.

 

[Robert C.]

Many questions un-answered, others vaguely.

But there is no proper way to tap the pipe in the middle of a run.
Not in a pipe always under pressure.

If you are adding copper to galvanized, I have always used a brass transition piece.
A valve, coupling, nipple, etc.
To reduce corrosion from galvanic action.
Using teflon tape also might help slightly with that, as some think, but not really a factor.

Thank you Jeff much appreciated. - Robert

 

[House Doc]

Can you take a picture of the supply lines that supply the sink faucet? That alone would answer a number of questions.

 

[Robert C.]

Can you take a picture of the supply lines that supply the sink faucet? That alone would answer a number of questions.

Hi Doc, The hot pipe closest to to drain on left is supply coming from crawl space under house. Feeds up to sink above. The sink and surrounding tile are 1930's vintage so irreplaceable. I was trying to avoid having to demo the kitchen sink. I think i have a solution as to feed 2 separate copper pipes (in-line) up to sink and connect half way with hot valve in center. That way i don't have to demo the outside wall as one contractor suggested. Jeff advised me to use brass at thread connects from source galvanized pipe. Space is tight in this old construction. Cabinets were the last thing added in those days.

 

[Helper Dave]

Why would you have to demo the wall if you have the access you've shown us, plus access in a crawl space?

Seems to me like you could just cut the galvi out in the crawl space somewhere, find a spot to thread in some brass adapters, and get yourself transitioned to copper or Pex, or whatever you want, and get all new lines up to the sink where the existing ones are.

As others have pointed out, we're not seeing the whole picture, though.

 

[Jeff Handy]

This is another one of those threads where something seems fishy.

 

[frodo]

click this link use 2 dressor couplings 2- nipples and a tee

 

[Jeff Handy]

I would never use a Dresser coupling for a line under constant pressure.
Legal or not.

I used one exactly one time, to repair a rotted galvanized shower riser with terrible access from the back side, where I could not safely unscrew the upper pipe from the shower arm ell.
There is only pressure during a shower, of course.

And the ends of the pipe were restrained, so they could not push apart.

But it is similar to a Sharkbite connection, but so much iffier.

I had a house with that same style of coupling on pvc sump pump discharge lines, and had several floods when they failed to hold.

 

[Riickk]

When we re-plumbed the hot water heat, to break out each apartment,
for separate heat, we used copper pipe, and this type of union to avoid
galvanic action rotting the old iron pipe.

 

[Jeff Handy]

I defer to the pros on here who certainly know better than I do.

So if any of my statements in above posts were bad advice, I apologize and will let others give better guidance.

 

[frodo]

I have used 1000's of dressers as long as the pipe is restrained they will last a long time

of course. the ''correct'' fix would be to remove the galvi pipe and replace with new pipe

i do believe that a dresser tee [middle threaded] can be found on a goggle search.

note.. do not use a pvc dresser only use a gavli dresser

a dresser is a repair fitting. and the correct position of the fitting is in a pipe run that does not move
it can not be used on a end of the line

 

[frodo]

I would never use a Dresser coupling for a line under constant pressure.
Legal or not.

I used one exactly one time, to repair a rotted galvanized shower riser with terrible access from the back side, where I could not safely unscrew the upper pipe from the shower arm ell.
There is only pressure during a shower, of course.

And the ends of the pipe were restrained, so they could not push apart.

But it is similar to a Sharkbite connection, but so much iffier.

I had a house with that same style of coupling on pvc sump pump discharge lines, and had several floods when they failed to hold.

he he he
you can not use a galvi dresser on pvc. it does not fit
you have to screw a galvi nipple into a female then use the dresser on the nipple

 

[Jeff Handy]

I realize you can not use galvanized dressers on pvc.

The fittings that I had which failed on my pvc sump lines were pvc compression couplings, of that same dresser style, but in pvc.

They were already installed when I bought my old house, but I removed them after they failed and I replaced with shielded no hubs.