Wtare heater relief discharge

[MasterPlumbersKeymaster]

Today my water heater began discharging hot water from the relief valve. When I saw it, it had probably relieved a gallon or two of water outside. I am on a well and pressure tank, the water heater is propane fueled. I turned the temperature down on the heater as it was turned up high. For some reason I turned on the hot water in the sink too. It stopped discharging soon after.

This is the 1st time this happened. It is fairly new. What is the most likely reason for this.

Thanks in advance.

[Retired plbg1Participant]

Sometimes when water is heated fast it has to expan and builds up pressure so it goes out the valve, thats for saftey.

[robertgfParticipant]

unless the water was heated to 210 degrees the relief valve would not go off on temp. you probably have a pressure problem due to thermal expansion that needs to be addressed turning the temp down might lessen the problem but will not eliminate

[oscarParticipant]

No wonder you are retired,Mr retired plbg.,some of your replies are just plain stupid.

[Retired plbg1Participant]

Oscar
If you dont like my replies then dont read them and keep your mouth shut.

[oscarParticipant]

I didnt say a word.I type with my fingers,not my mouth

[mikeinpaParticipant]

Do you two know each other

[SelgasParticipant]

Ok you lot it’s my turn to try and assist this fellow so here we go.
Firstly the valve you are referring to is called a TPR valve (temperature and pressure relief) it is designed so that is the water rose to a temperature greater than 99 degrees C, or the water pressure exceeded the valves rated specifications then it will open and discharge or release the pressure via the valve to waste.
However, with over 35 years experience with gas fired water heaters it is commonplace for this to happen on ocassion due to the extreemly rapid heat up capability of the gas burner used in the water heater.
To overcome this problem install a pressure limiting valve on the inlet to the cylinder and a cold water releif valve on the same line rated at 70% of the maximum setting of the hot water relief valve. This will allow the expansion to discharge cold water when the main burner is firing and keep your gas operating costs to a minimum.
Hope this helps.

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Selgas Services Ltd
Craftsman Gasfitters, Plumbers, Electrical Service Technicians

[oscarParticipant]

Alright peter,see tired plbg,thats an intelligent answer.

[Author]

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