How To Troubleshoot Low Hot Water Pressure

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    In this How To we will look at some of the ways to track down low pressure on the hot water side of your supply lines.

    A Writer Asks:

    I have a problem getting hot water from my shower. Cold water tap works all the time, hot water tap works but the pressure is very bad. Bathroom and kitchen sinks have no trouble getting hot water. Thanks for any help on this.

    Whats the Answer?

    The first thing you have to understand is how your hot and cold water are plumbed throughout your home.

    When water enters your home it is on a service line from the water company. It then attaches to a Water Meter so they can charge you for your use.

    After the water meter the home owner is responsible for interior plumbing and it is at this point that a splitter is installed to divert water to a hot water heater. One line is sent to the hot water heater and the other is plumbed into the cold water lines in your house.

    From the splitter fitting cold water is fed to the hot water heater where it circulates and is heated and then exits and is plumbed into the pipe that supplies hot water to each appliance in the home.

    If you have good cold water pressure then the problem is somewhere between the splitter fitting to the hot water heater all the way up to the appliance where hot water should exit.

    If you find that the entire home has low hot water pressure then the problem is between the splitter fitting .. through the hot water heater.. up to the point the exiting hot water is plumbed into the rest of the house.

    If you have different levels of hot water pressure at each faucet then the problem is between the exit of the hot water heater and each fixture in the home.

    In this home only a few fixtures are having problems so the clog is probably limited to that part of the home. However when you have calcification of pipes at the level it restricts flow you can bet the problem is also beginning in other parts of the house.

    What type of problems can lower water pressure?

    Normally if the home is receiving good pressure then the pipes inside the home are probably clogged. This can happen from calcium deposits building up in pipes overtime.

    Additionally if low pressure is on the hot water side then there could be a clog in your hot water heater that is causing a problem.

    Clogs in hot water heaters can be from a variety of things from calcium buildup to breakdown of a exit pipe that is serves double purpose as an anode rod. It could also be from sediment buildup.

    How do you test where the problem is?

    Some homes have been plumbed with drain valves but this is pretty rare. About the only chance you will have to test is at the water heater. There is both a drain valve and there could be a test valve right after the water heater to test for line pressure and heat.

    Other than those two places if you do not have access valves you will need to remove a connector from a hot water line and check it for corrosion. If you do not see it at the fixture you will need to cut into a line midspan and I would suggest you install a drain valve and test the pressure if you don’t see corrosion.

    It really comes down to a lot of hunting but once this amount of corrosion is present in your system it often means total replacement of your plumbing lines. At that point you want to move away from metallic and use cPVC or Pex to re-plumb the whole home. Expect to do the cold water lines at the same time.

    On the other hand you might just get lucky and it could be corrosion at a point where galvanized pipe meets with copper such as at your water heater and the rest of the house could be fine.

    It takes a bit of hunting.


    Final Note

    Corrosion in water lines is a common problem and it will occur in most parts of the country but it can be accelerated by hard water with high calcium levels. Calcium in your diet is a good thing but you don’t want this calcium in your pipes and it could also cause health problems.

    You may need to install filtration systems as the calcium may not be the only element found in your water.

    Talk with your water company and a local plumber about what they see in your area. Then take the steps you need to repair and prevent this if possible.


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