- This topic has 8 replies, 7 voices, and was last updated 20 years, 7 months ago by
DUNBAR.
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Dan Stout
I notice water dripping from a pipe from the relief valve, do I have to replace my Temperature relief valve?
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It could be the valve are the pressure could be building up for some reason and expanding. Is your tank old are is it new, sometimes the valves get weak, try blowing the TP valve off and see if it stops. The washer gets old and the spring gets weak, if it dont stop try a new one and if it still drips then you have a press. are expanding problem which can be solved with and expansion tank on heater.
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Gus
If it is gas fired the makers advise that it is quite normal for small amounts of up to 5 litres of water per day to discharge through a pressure relief valve when the main gas burner is firing.
As the water is heated it expands and releases excessive pressures through the TPR valve which is a safety valve.
If the discharge continues after the main gas burner has switched off then it is likely you have a faulty TPR valve that will have to be replaced.
A mains pressure cylinder should be fitted with a pressure limiting valve on the cold water inlet to ensure that the incomming cold water pressure does not “creep” up above that which the valves have been set for.
We often install a cold water relief valve here to minimise the discharge of heated water to waste – if you follow this course then the cold water RV MUST be set to discharge at 70% of the pressure set on the Hot Water TPR valve.
Selgas Services Ltd
Craftsman Gasfitters, Plumbers, Electrical Service Technicians -
Click on products, then thermal expansion.
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Thank you Dunbar for the webb site, I have order the pressure gage should be here next week.
Peter I do like when people speak my language so I can understand thank you -
In reply to message posted by Peter:
GusIf it is gas fired the makers advise that it is quite normal for small amounts of up to 5 litres of water per day to discharge through a pressure relief valve when the main gas burner is firing.
As the water is heated it expands and releases excessive pressures through the TPR valve which is a safety valve.
Peter,
The makers may say that, but I must say that I don’t think it’s normal for a TPR valve to discharge 5 or even 1/2 liter of water daily during the heating cycle of a properly installed and functioning gas water heater. Unless something is amiss, the tank should heat up just fine without its contents exceeding the T&P set points of the valve. If there is too much pressure, you need to find out why, and fix the problem. Sometimes an expansion tank must be added above the heater tank.
NtP
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Nick
We don’t use expansion tanks on mains pressure water heaters down here so what we do is to install a cold water relief valve on the inlet supply just after the pressure limiting valve. The cold water relief is set to 70% of that to which the hot water one is so when the water heats and expands it releases cooler water which equates to an energy saving to the user.
I understand the principal of using an expansion tank but like I said we don’t use them down here.
Selgas Services Ltd
Craftsman Gasfitters, Plumbers, Electrical Service Technicians -
When a hot water system heats up 4-7% of the volume is expected to be released via the T&P valve. If it doesnt the you get a bloody big explosion.
http://www.safteng.net/Accident%20Photos/Hot%20Water%20heater%20explosion.htm
DISCLAIMERAll advice is given with-out seeing the job, and hence all advice MUST be taken as advice with limited knowledge on the exact situation. NO responsibility can or will be taken. And yes, I am a licensed Plumber and Drainer with my own business in Brisbane Australia.
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In the United States, if a T&P is releasing, it is considered malfunctioning and the appropriate means to fix it is necessary.
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