Gas Hot Water Tank Is 6 Yrs Old. Very Low Hot Water Pressure - Plumbing - DIY Home Improvement | DIYChatroom

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Old 04-14-2012, 10:46 AM   #1
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Gas hot water tank is 6 yrs old. Very low hot water pressure

Throughout the whole house there is little hot water pressure, the cold is strong. What to do or check before I go to the expense of replacing the tank. Thank you.


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Old 04-14-2012, 10:53 AM   #2
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Get a garden hose spigot cap (one typically comes with a lawn sprinkler that allows daisy chaining, such caps are also sold separately.

With a pot or bucket to catch the water, and with the main water still turned on, open the drain valve at the bottom of the water heater. If you get a strong flow here then the hot water tank is not at fault for the low pressure.

While you are at it, drain more water out until any sand or discoloration disappears; may take more than one bucketful.

Use the garden hose cap if the water heater drain valve doesn't close completely.

Arteriosclerosis in the water pipes is a common reason for low water pressure, particularly in homes more than 50 years old. It is possible for the hot water line to clog sooner than the cold water line.

A 6 year old water heater is rarely if ever responsible for low water pressure.


The good conscientious technician or serviceperson will carry extra oils and lubricants in case the new pump did not come with oil or the oil was accidentally spilled, so the service call can be completed without an extra visit.

Last edited by AllanJ; 04-14-2012 at 10:56 AM.
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Old 04-14-2012, 10:53 AM   #3
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What type of pipes do you have? Steel, CPVC, copper?
There has to be a 3/4 supply line in and out of that tank, if someone used 1/2" instead that could be the whole problum.

The 3/4" needs to run all the way to the end of the lines, and can then be steped down to 1/2 for the supplys to the fixtures.

If you have a globe or or gate valve as a shut off on the tank it could not be opened all the way or the shaft could be broke off inside the valve. Really needs to be a ball valve instead.
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Old 04-14-2012, 11:28 AM   #4
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Is supply valve open to water heater?
"facts" have no relevance to this discusion
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Old 04-14-2012, 02:05 PM   #5
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Originally Posted by sucarty View Post
Throughout the whole house there is little hot water pressure, the cold is strong. What to do or check before I go to the expense of replacing the tank. Thank you.
You could have a defective heat trap valve in the hot water output line of your water heater. Heat trap valves can be internal or external to the water heater. Here's a picture of external heat trap valves:

Sediment from the tank can clog the hot water heat trap valve causing low hot water flow.

External heat trap valves can be replaced. As far as I know, heat trap valves internal to the water heater cannot be replaced.

If you do have a defective or clogged external heat trap valve on the hot water output line, I suggest replacing it (and the one on the cold line) using heat trap pipes instead of valves. Heat trap pipes will never clog and will allow maximum hot water flow.

EDIT: If you do have heat trap valves on your water heater and the one on the hot water line is clogged by sediment, I have an idea on how you could unclog it without doing any plumbing work. Never tried it personally but I believe it might work.

BTW, have you drained/flushed your water heater in the 6 years you've had it? If so, how often?


Last edited by Homerepairguy; 04-14-2012 at 02:29 PM.
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