I recently bought a home in Florida where the electric water heater is located in the garage. I seem to have felt some odd water temperature fluctuations where one day it felt much cooler than normal and the next much warmer than usual. I know the water heater is at least 19 years old, and the last inspection tags on it show July 2004. My question is regarding the placement of the temperature and pressure relief valve. It seems to be plumbed back into the cold water line. Is this correct?? I attached a picture of the top and the T&P valve connects to the cold pipe which also comes from the rear of the heater. I know the hot water line is on top on the left, and the cold water lines on the top right and in the rear. Let me know if the plumbing is incorrect, either way I plan to replace the whole thing soon anyway! Thanks, Ryan

Water Heater

  • 1
    I can't comment on the cold side plumbing connection, however the pressure relief valve is top center. If the tank is electric and has dual elements and the complaint is fluctuations in temp then likely one of the elements is burnt out.
    – Tyson
    Commented Nov 13, 2016 at 3:44
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    What is the valve on top of the vertical line on the cold side? It seems that the T&P drain was manifolded with the line off of it -- a closeup photo of it would be quite helpful. Commented Nov 13, 2016 at 4:02
  • 1
    The tee on the left and behind the water heater; what does its bottom end connect to? Commented Nov 13, 2016 at 12:49

4 Answers 4


The temperature relief valve should never be connected to any water line. This is a safety that keeps the water heater from becoming a bomb. If there is any question about relief valve not working properly, replace it. The piping from the t/r valve should be run towards the floor with no plugs or reduction in size so it can do as its name - relieve pressure if the water heater thermostat should stick on and keep heating water.

If your relief valve leaks water it's either defective or your water temp is too high. Most people are afraid to test relief valves but you should open it at least 1 time per year to make sure it opens properly and reseats. Most valves are 3/4 inch output and should run down to within 4 inches from floor. To test, put a can or container under and lift lever for 2 to 3 seconds and watch for water to escape then stop. This insures your valve is opening and closing as it should.


The plumbing is not "incorrect" per se. The only thing we try to have is the bottom end of the piping from the TPR valve exposed vs plumbed to a drain so you can see if something is awry with the TPR valve.

It is a curious thing what is coming off the cold water line. What ever is coming off your cold water line is surely designed to release and drain like the TPR valve in its own way for its own reasons.

You TPR valve plumbing that is visible (which is in question) is fine though.


This is a siphon valve prevents water from being siphoned back Into the water heater probably because the water heaters location is lower in the house for at least one fixture('s) And the tnp will function normal because that siphon valve has a spring loaded valve in it that only operates one way


On the cold water pipe is a second relief valve. Its discharge is plumbed together with the discharge of the tpr valve. That should go down to your pan.

  • How can you tell from this image that this a relief valve?
    – FreeMan
    Commented Feb 10 at 15:54

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