[Plumbing Question] Low Hot Water Pressure.

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Donqluione

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Feb 5, 2017
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Hey guys,
Need some help. Just bought a house that is over 100 years old and there is one problem: the hot water pressure is low.

Some other important information:
  • Cold water pressure is normal
  • Galvanized piping in the house
  • New water heater
  • There’s “jerry rigged” piping right in before or after the hot water heater.
What would guy recommend I try to get the water pressure back to normal?
Is the cold water piping also all galvanized, or has some of it been replaced? Old galvanized pipes that I've seen has generally had lots of scale build up, some where the water was hard had been reduced to almost half the original diameter.

If it's all galvanized that wouldn't explain why only the hot water pressure is low. So, assuming that the valves are fully open, the messed up plumbing feeding into/out of the heater would be a good first effort. I'm not a big fan of pex, only from the standpoint of questioning how well it will hold up LT. It is very easy to work with and cheap, replace the messed up stuff and see if the problem is solved. If not, I'd continue replacement to the first faucet, see if that takes care of it.

Might ultimately save a lot of money by having a plumber advise you and do it, rather than doing it yourself. Plumbing was created and given to mankind by Satan: his gift mandates that plumbing always has a problem of some sort, so if one is fixed another problem always seems to pop up. But you do you.
 
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clone34

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Mar 29, 2009
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My first house was an old home. Galvanized pipe builds up scale/rust inside. The hot water side builds up faster than cold water. When I started replacing the galvanized I couldn't even see through a 12" section of pipe. Lots of peaks and valleys that water would creep through. Like someone else said start at the water heater and go as far as necessary.
 
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EvilBetty

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Sep 7, 2012
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Is the hot water pressure low at every release point or just certain ones? Every single faucet and shower/tub is low, or just specific ones?
 

exCYtable

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Apr 15, 2010
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We had this happen once. Turned out there was a leak in the pipe that ran from the street into the house that was the culprit.
 

SCNCY

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We had this happen once. Turned out there was a leak in the pipe that ran from the street into the house that was the culprit.

But that'd be the case if water pressure was low everywhere. The cold water pressure is fine, its just the hot water pressure.
 
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CYEATHAWK

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Aug 26, 2007
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Hey guys,
Need some help. Just bought a house that is over 100 years old and there is one problem: the hot water pressure is low.

Some other important information:
  • Cold water pressure is normal
  • Galvanized piping in the house
  • New water heater
  • There’s “jerry rigged” piping right in before or after the hot water heater.
What would guy recommend I try to get the water pressure back to normal?


Others said it and I will second..........probably hot lines getting plugged with crap. Do a lot of work in older apartments and homes with original galvanized pipe and the hot having less pressure than the cold is pretty much the rule.

Have taken apart the old galvanized and the turns are where it's the worst. Some of the straights are so gunked up with calcium you can't fit a pencil through 3/4" ID line. The nature of the beast with certain water types. It's why in certain areas hot water heaters don't last very long.

So with it being okay on the cold side........start from your new heater and just run new hot line throughout. They have a pre-made 3/4 copper starter line from the heater at any box store with a pex fitting soldered on the end. Use that straight off your heater because you want at least 18" of hard line to start. Then just branch it off into where you need it i.e. kitchen or bath.
 
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cyclone4L

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Jun 30, 2013
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Others said it and I will second..........probably hot lines getting plugged with crap. Do a lot of work in older apartments and homes with original galvanized pipe and the hot having less pressure than the cold is pretty much the rule.

Have taken apart the old galvanized and the turns are where it's the worst. Some of the straights are so gunked up with calcium you can't fit a pencil through 3/4" ID line. The nature of the beast with certain water types. It's why in certain areas hot water heaters don't last very long.

So with it being okay on the cold side........start from your new heater and just run new hot line throughout. They have a pre-made 3/4 copper starter line from the heater at any box store with a pex fitting soldered on the end. Use that straight off your heater because you want at least 18" of hard line to start. Then just branch it off into where you need it i.e. kitchen or bath.
This is what I think the problem is. I’m not complete sure on how to remove it.
 

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Pat

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Oct 20, 2011
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Yea… I was thinking about doing it myself with pex, but on second thought with all the tight spaces and rusted joints, it may be tough.
I would find out who installed it and have them make it right. Then possibly executed.
 

cysmiley

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Looks like some copper/galvanized reaction.
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!
 
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