PRV / PR valve questions

1. Do PRV's installed on the outside of homes typically go bad w/in 10 yrs?
2. Is it code to install a pressure relief valve after the PRV on the outside of homes in Southern California?
3. @ what pressure does a factory installed TP valve open on a water heater?
4. @ what pressure would a PR valve on the ouside of the home be set?
5. If the PRV went bad and I had 150 lbs of pressure go into my home, wouldn't the TP valve on the water heater open before damage in my home?

One of the pros may have some more specific data, but yes, a PRV can go bad within that timeframe; could last longer.

The T&P valve one the WH is probably set for somewhere around that pressure. Numerous things could fail prior to the internal pressure reaching 150# - washing machine hoses, flexible supply lines going to faucets or toilets and numerous other things. Normal high pressure in a house is in the order of 80#, and while there is often a margin of safety on fixtures, it's not good to have higher pressure. Nasty things can happen.

WHen a PRV is installed on a system, you always need an expansion tank. WIthout one, the internal pressure can go high even though the PRV is working perfectly...the cold water replacing the hot in the WH expands when heated and the PRV will prevent it from being relieved by backing out into the system.

Some locales install a check valve on the incoming supply which also requires an expansion tank in the dwelling.

1. Do PRV's installed on the outside of homes typically go bad w/in 10 yrs?
Typically?, Don't know about typical, but they can.

2. Is it code to install a pressure relief valve after the PRV on the outside of homes in Southern California?

There needs to be a pressure relief for the water heater.

3. @ what pressure does a factory installed TP valve open on a water heater?
150 PSI

4. @ what pressure would a PR valve on the ouside of the home be set?

I've seen some that come set for 125 PSI that are not for the water heater but are on the cold water side.

5. If the PRV went bad and I had 150 lbs of pressure go into my home, wouldn't the TP valve on the water heater open before damage in my home?

Damage to faucets?
Damage to the water heater?
UPC code in California requires a pressure reducing valve if it's over 80 PSI
And an expansion tank.
It's overly high water pressure that causes water heaters to fail.
Faucet seals to go bad, Toilets to continue to run.

As for a pressue relief valve outside the house: It is fairly common here in San Diego, in condos and apartments, to have a water heater located in an inside closet somewhere, where it is not convenient to pipe the TP overflow outside. In that case, they install a Watts 210 on the water heater in the place of a regular TP. It is a temperature activated gas shut-off. That's the "T". Now, for the "P", you are required to have a pressure relief valve outside the dwelling. It must be located downstream ( towards the house) from any shut off valve.

usckww said:

1. Do PRV's installed on the outside of homes typically go bad w/in 10 yrs? yes, and sometimes sooner
2. Is it code to install a pressure relief valve after the PRV on the outside of homes in Southern California?Yes, the pressure only needs to be installed after the prv because with the new prv installed it makes the potable system a closed system, meaning during a high pressure incident, the water is unable to exit back out the water meter back to the city
3. @ what pressure does a factory installed TP valve open on a water heater?
150 LBS
4. @ what pressure would a PR valve on the ouside of the home be set? 150 LBS
5. If the PRV went bad and I had 150 lbs of pressure go into my home, wouldn't the TP valve on the water heater open before damage in my home?

Click to expand...

Maybe, but it is code to have one on the cold side water service, at the prv install location.

jimbo said:

As for a pressue relief valve outside the house: It is fairly common here in San Diego, in condos and apartments, to have a water heater located in an inside closet somewhere, where it is not convenient to pipe the TP overflow outside. In that case, they install a Watts 210 on the water heater in the place of a regular TP. It is a temperature activated gas shut-off. That's the "T". Now, for the "P", you are required to have a pressure relief valve outside the dwelling. It must be located downstream ( towards the house) from any shut off valve.

Click to expand...

The city of los angeles has stopped approving watts 210, they say the valve is malfunctioning and allowing water to go into the gas.

Have you heard anything down there??

The city now wants you to get a letter from them for $100.00, releasing you and the city from liability.

Wow, haven't heard about problems, and I have a Watts 210 on my own water heater! It's new, about 4 years old, but the original one ran for 16 years. If water gets in the gas line, doesn't that cause immediate issues with firing the WH burner?

jimbo said:

Wow, haven't heard about problems, and I have a Watts 210 on my own water heater! It's new, about 4 years old, but the original one ran for 16 years. If water gets in the gas line, doesn't that cause immediate issues with firing the WH burner?

Click to expand...

For sure, I have heard of one suspected case of this happening, but I have personally not run into this, but I did call the head inspector, and he stated what I had posted, so he confirmed it.

Thanks, great knowledge, and a few more questions

Thanks to all who provide me some guidance on this.

?-on the plumbing manafold, out side the house, after the PRV, on the stub out where the Pressure valve should have been installed, is a plug, all rusted out. I believe the plumber simply installed a steel plug, rather than a brass one and now it is corroded the stub out and coroding the manafold. Could it have done additional damage in my house? How would I know? and I recently had a water filter rupture and flood my kitchen, could the bi-metalic issue have caused additional corosion in the filter causing it to fail?