Cold water relief valve question
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Smooky
In the Trades
Sometimes a pressure relief valve is added instead of installing a thermal expansion tank.
It would be set at 125 PSI
The water heater T&P is set at 150 PSI, so in this case, you want the incoming cold to release before the water heater T&P would. It may be that the water heater in the home has no way of draining it's T&P outside. This is a common fix for that.
The water heater T&P is set at 150 PSI, so in this case, you want the incoming cold to release before the water heater T&P would. It may be that the water heater in the home has no way of draining it's T&P outside. This is a common fix for that.
Jsmallberries
Member
Municipal water supply
There must be a back-flow preventer, so any excess pressure can't flow back to the main supply. So that is what it's for? The water heater is in the garage, no expansion tank. So if we don't mind water in the garage, this isn't really needed, or is it?
There must be a back-flow preventer, so any excess pressure can't flow back to the main supply. So that is what it's for? The water heater is in the garage, no expansion tank. So if we don't mind water in the garage, this isn't really needed, or is it?
Jadnashua
Retired Defense Industry Engineer xxx
The T&P valve is not designed to be turned on/off frequently. So, weeping water regularly might mean that either the spring gets weaker or the minerals build up and freeze up the valve so that it can't turn on when it really should. Plus, consider that the T&P valve won't open until the pressure gets to 150psi and plumbing systems are designed for a maximum of 80psi on a regular basis...it's best to prevent that from happening, and for that, you need an ET. Where I live, they are code and are prudent, everywhere. Your washing machine hoses, maybe the supply to your frig water dispenser, the hoses to your toilets, none of them like that high pressure, either.
Jsmallberries
Member
Thank Jim,
One more thing, then I'll move on. Hot water rise in pressure I get, what would cause a substantial pressure rise on the cold water side?
One more thing, then I'll move on. Hot water rise in pressure I get, what would cause a substantial pressure rise on the cold water side?
Smooky
In the Trades
The hot water heater is feed from the cold water. When the water heats up it pushes back on the cold water.
Themp
Active Member
From the picture it looks like the stucco wall has a stain from the pressure release valve dumping? In any case do you know what the setting is for this valve? If it is 125 psi then I would think this is to high to really provide any protection over time for your plumbing. If it has been dumping then you are wasting water to relieve the pressure.
What is your city water supply pressure to the house and is it being reduced by a pressure reducing valve(PRV)? You want to have around 60psi for the house, so the question is what do you have now? You will need a pressure gauge to hook to that outside faucet to see what the pressure is. Here is a nice one:
http://www.homedepot.com/p/3-4-in-Plastic-Water-Pressure-Test-Gauge-DP-IWTG/100175467
You can let it monitor the pressure for a few hours and see what the max pressure you have over time with that red needle. Meaning you are using hot water and the water heater is being used to cause the increase in pressure in your house. Then again all this is based on:
1.) What is the city water pressure to your house?
2.) What is the pressure relief valve set to on the hose bib?
3.) Do you have a pressure reducing valve? If not then it will be the city pressure and the water heater when it heats water will dump the increase pressure back to the city. But does the city have a back valve in the meter? Then water will not be released back to the city and the pressure relief valve at the hose bib comes into play.
Based on your posts it would seem that right now you have city water pressure in the house and the city does have a back flow valve in the meter. The pressure relief valve at the hose bib is to dump pressure that is greater than what it is set to. This setup works, except you have no control over your water pressure(city pressure) and it wastes water when it relieves the pressure. The best setup is to have a pressure reducing valve and thermal expansion tank and then you can control your house pressure and set it to what you want.
http://www.watts.com/pages/learnabout/thermalExpansion.asp
But, if the city is providing 60 psi and the relief valve at the hose bib is set at 70-80 psi then you can leave as is and the only down side is the wasting of water to relieve that pressure above 60 psi.
What is your city water supply pressure to the house and is it being reduced by a pressure reducing valve(PRV)? You want to have around 60psi for the house, so the question is what do you have now? You will need a pressure gauge to hook to that outside faucet to see what the pressure is. Here is a nice one:
http://www.homedepot.com/p/3-4-in-Plastic-Water-Pressure-Test-Gauge-DP-IWTG/100175467
You can let it monitor the pressure for a few hours and see what the max pressure you have over time with that red needle. Meaning you are using hot water and the water heater is being used to cause the increase in pressure in your house. Then again all this is based on:
1.) What is the city water pressure to your house?
2.) What is the pressure relief valve set to on the hose bib?
3.) Do you have a pressure reducing valve? If not then it will be the city pressure and the water heater when it heats water will dump the increase pressure back to the city. But does the city have a back valve in the meter? Then water will not be released back to the city and the pressure relief valve at the hose bib comes into play.
Based on your posts it would seem that right now you have city water pressure in the house and the city does have a back flow valve in the meter. The pressure relief valve at the hose bib is to dump pressure that is greater than what it is set to. This setup works, except you have no control over your water pressure(city pressure) and it wastes water when it relieves the pressure. The best setup is to have a pressure reducing valve and thermal expansion tank and then you can control your house pressure and set it to what you want.
http://www.watts.com/pages/learnabout/thermalExpansion.asp
But, if the city is providing 60 psi and the relief valve at the hose bib is set at 70-80 psi then you can leave as is and the only down side is the wasting of water to relieve that pressure above 60 psi.
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