what is a vacuum relief valve for?

Users who are viewing this thread

northman

Member
Messages
35
Reaction score
0
Points
6
Location
Washington
on a water heater/expansion tank installation?

Looking at the Watts site to size an expansion tank, they show a vacuum relief valve installed at the water heater. What is the purpose? Is it necessary or are they just trying to sell parts?


Greg
 

Peanut9199

Customer Service Manager Plumbing Wholesale
Messages
869
Reaction score
2
Points
0
Location
Ontario, Canada
"Vacuum Relief Valves are used in water heater/tank applications to automatically allow air to enter into the piping system to prevent vacuum conditions that could siphon the water from the system and damage water heater/tank equipment." and no you don't need it.
 

Jadnashua

Retired Defense Industry Engineer xxx
Messages
32,770
Reaction score
1,190
Points
113
Location
New England
My city requires them on new installs along with a tempering valve. My guess is to prevent what may be heated water that has sat for awhile in the water heater from being sucked back into the rest of the potable water. Since all of the water is supposed to be potable, not sure why, but as I said, it is code in my city.
 

hj

Master Plumber
Messages
33,602
Reaction score
1,040
Points
113
Location
Cave Creek, Arizona
Website
www.terrylove.com
vacuum vent

If the heater is in an upper floor level or attic, then the negative pressure created by a broken pipe draining the heater could collapse the walls of the heater. In this case, the installation requires a vacuum vent to relieve the negative pressure. It is not required if the heater is in a basement or first floor because those installations cannot create high negative pressures.
 

hj

Master Plumber
Messages
33,602
Reaction score
1,040
Points
113
Location
Cave Creek, Arizona
Website
www.terrylove.com
valve

Those applications do not require a vacuum relief valve, they require backflow prevention devices, and the higher the possible contamination level, the more sophisiticated the device has to be.
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks