Backflow preventer vs Check valve

[James Ascherl]

Can anyone tell me the difference between a backflow preventer and a check valve? Don't they both do the same thing? A check valve is a lot cheaper though. I need a backflow preventer on my supply line, and thought I could just use a check valve instead.

Also does anyone have recommendations on what size circulators to use. I need one for the EKO 40 and one for the 4 zones. I'm using Taco ECV zone valves for the zones. My start-up kit came with a Taco 007-F5.

 

[Hunderliggur]

A backflow preventer protects your potable water. A check valve controls flow but it is not absolute. A check valve is not an appropriate substitute for a backflow preventer.

 

[bigburner]

If you don't have nasty stuff in the boiler they make a DOUBLE CHECK VALVE that's approved for this use, but a watts 70 ? isn't that expensive and has a drain to atmosphere. your best bet!!

 

[benjamin]

How sure do you want to be that you don't get crap in your drinking water?

Simple check valves have been used for years, but a backflow preventer is much better. Especially if you're going to add any chemicals to your boiler (mercaptan?) or if you are on an unreliable water system (a well that loses pressure whenever the power goes out).

Another possibility is not having a connection. Either fill the system with a pump, or have an elevated open expansion tank that you can fill with a hose, just don't leave a hose hooked up or in the tank to back siphon.

 

[James Ascherl]

Thanks for the clarification folks. I just broke down and added a BFP to my ever growing list for Santa aka: Pex Supply! Hope everyone has a great Christmas. I hope you all get lots of loot!