[Plumbing Question] Low Hot Water Pressure.

CYEATHAWK

Well-Known Member
Aug 26, 2007
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This is what I think the problem is. I’m not complete sure on how to remove it.


I see someone put the proper dielectric union between the galvanized and copper on the cold. Can't tell on the hot with all that scale but the shape looks to be the remnants of a union. Wow!

That is definitely a DYI job.

Cut both copper pipes, and see if you then turn the rotted galvanized elbow off the galvanized straight. Use a little heat on the elbow if you need it. If it breaks off the galvanized straight, or once off the threads on the straight are really bad you have two choices.

The hard, cut back about 5 inches on the straight galvanized line and re thread....or the "easy" find where that straight ends and go ahead and take it off and that junction if you can. A couple of good pipe wrenches, some WD40 and some heat will do the trick if it's tough.

Then, wrench on a pex transition fitting to the galvanize pipe and solder two pex transition fittings on the copper pipes.

Then it looks like about 10 feet of pex, one pex "T" and about six crimp rings and you are ready to go. Hopefully that was the problem. If not.....would hate to see what is. Good luck.
 

cjclone

Active Member
Nov 22, 2006
487
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28
We had a problem when we had a tankless water heater put in. They used the old piping and the calcium broke loose and clogged the pipe. No pressure and no hot water since the flow was so slow. The old water heater weighed a ton with all of the calcium in it. We had a water softener put in before that, but too many years without one. Sounds like some new plumbing and a water softener may be needed. Good luck.
 

cyclone4L

Well-Known Member
Jun 30, 2013
3,631
7,157
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I see someone put the proper dielectric union between the galvanized and copper on the cold. Can't tell on the hot with all that scale but the shape looks to be the remnants of a union. Wow!

That is definitely a DYI job.

Cut both copper pipes, and see if you then turn the rotted galvanized elbow off the galvanized straight. Use a little heat on the elbow if you need it. If it breaks off the galvanized straight, or once off the threads on the straight are really bad you have two choices.

The hard, cut back about 5 inches on the straight galvanized line and re thread....or the "easy" find where that straight ends and go ahead and take it off and that junction if you can. A couple of good pipe wrenches, some WD40 and some heat will do the trick if it's tough.

Then, wrench on a pex transition fitting to the galvanize pipe and solder two pex transition fittings on the copper pipes.

Then it looks like about 10 feet of pex, one pex "T" and about six crimp rings and you are ready to go. Hopefully that was the problem. If not.....would hate to see what is. Good luck.
Wow man! Thank you so much for your help!
I should also tell you that both those lines that you see in the second attachment and fed into the top of the water heater. I figured the one of the valve was the outlet, but I could be wrong?
 

CYEATHAWK

Well-Known Member
Aug 26, 2007
6,005
4,179
113
Wow man! Thank you so much for your help!
I should also tell you that both those lines that you see in the second attachment and fed into the top of the water heater. I figured the one of the valve was the outlet, but I could be wrong?


Usually the line with the shut off valve is the inlet(cold)...........usually. You can tell after someone runs the hot water to just touch which line is hot and which is cold.
 

CyclonesRock

Well-Known Member
Jan 1, 2018
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Iowa
The galvanized piping has probably experienced some heavy electrolysis, especially if no electrolysis isolators are installed on the top of the inlet/outlet of the water tank. Prior to replacement, the old tank probably used up/lost its anode and resulted in the galvanized pipe contributing ions to the system, causing extreme oxidation in your galvanized piping (clogging it). I'd pull the galvanized pipe out as far as I could easily on the hot water/supply/discharge and replace with plex. If you use copper, make sure you isolate the tank with isolation connectors to keep further electrolysis from happening throughout your system, and then make sure your tank anode is in good shape (it supplies ions to the water and keeps them from seeking those ions from the tank/galvanized piping!
 

charlie_B

Active Member
Mar 21, 2017
138
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Just make sure you don't get pex too close to the water heater. Probably follow manufacturing specs but some codes say at least 18 inches away.

The Uniform Plumbing Code (UPC 604.13) states that “PEX tubing shall not be installed within the first 18 inches of piping connected to a water heater."
 

Donqluione

Active Member
Feb 5, 2017
209
215
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DM Metro
Wow man! Thank you so much for your help!
I should also tell you that both those lines that you see in the second attachment and fed into the top of the water heater. I figured the one of the valve was the outlet, but I could be wrong?
Or you could hire a plumber to ensure it's done correctly, once and for all. How much is your time and safety worth?

It IS possible to blow the place up with a messed up water heater, doubtful that it could get messed up that badly, but it's possible. More likely that you'll spend a lot of time and money and it might still be messed up. But sometimes it's better to hire a professional rather than DIY, which the prior owner obviously should have done.

Once the plumber has straightened out the water heater mess and made a pex connection somewhere down the line, take it from there if you want, continue from that junction downstream until you're thoroughly tired of plumbing.