Watts 25aubz3 - prv question
#1
01-22-23, 11:35 AM
Watts 25aubz3 - prv question
I understand that this valve doesn,t have a built in check valve thus allowing water to back up upstream in the system. If this is the case does that eliminate the need for an expansion tank.
#2
01-22-23, 05:27 PM
Group Moderator
Welcome to the forms.
Yes.... you are correct BUT an hydronic pressure tank is set to roughly 12-15 psi. If you didn't have that pressure tank.... your boiler would have to increase pressure to over 40 psi to be able to get pushed back into the water supply. Your boiler T & P valve releases at 30 psi. Way before the system pressure would get pushed back into the water supply line.
In other words... a pressure tank is still needed.
Watts 25AUB specs - pdf
Yes.... you are correct BUT an hydronic pressure tank is set to roughly 12-15 psi. If you didn't have that pressure tank.... your boiler would have to increase pressure to over 40 psi to be able to get pushed back into the water supply. Your boiler T & P valve releases at 30 psi. Way before the system pressure would get pushed back into the water supply line.
In other words... a pressure tank is still needed.
Watts 25AUB specs - pdf
#3
01-22-23, 06:29 PM
Pressure reducing valves are "one way" and do now allow reverse flow so check valves are generally not used. They supply water pressure at typically 12 psi and automatically replenish any that is lost.
https://www.supplyhouse.com/Watts-00...eaded-F-Outlet
In a closed hot water heating system, as temperature of “non compressible” water changes, flexible bladders in expansion tanks maintain set pressure. https://www.youtube.com/watch?v=S2HVSogYELM
Without expansion tanks pressure relief valve may open to release water: https://www.supplyhouse.com/Pressure...alves-17144000
https://www.supplyhouse.com/Watts-00...eaded-F-Outlet
In a closed hot water heating system, as temperature of “non compressible” water changes, flexible bladders in expansion tanks maintain set pressure. https://www.youtube.com/watch?v=S2HVSogYELM
Without expansion tanks pressure relief valve may open to release water: https://www.supplyhouse.com/Pressure...alves-17144000
#4
01-22-23, 06:33 PM
There may be a little confusion here with this PRV. This one is used to reduce house water pressure and not a hot water heating system. This particular valve has a range of 25-75 psi to reduce street pressure in the home if you happen to live in a home with excessively high pressure of 100 lbs or more which could damage your fixtures.
An expansion tank in most cases is not necessary but if you find your T&P dripping due to thermal expansion after a while when everything is off an expansion tank could help, but not the same tank that would be required on a heating system. A tank maid for potable water and can handle street pressure water would be needed.
Hope this helps a little.
An expansion tank in most cases is not necessary but if you find your T&P dripping due to thermal expansion after a while when everything is off an expansion tank could help, but not the same tank that would be required on a heating system. A tank maid for potable water and can handle street pressure water would be needed.
Hope this helps a little.
#5
01-22-23, 09:43 PM
Regardless of application PRV " Pressure Reducing Valves are "one way" and do now allow reverse flow so check valves are generally not used.
The most common PRV failure is leaking valve seats that results in pressure rising above setting., so a check valve to prevent back flow is useless
The most common PRV failure is leaking valve seats that results in pressure rising above setting., so a check valve to prevent back flow is useless
