Swing Check vs. dual check vs. double check valve

Yes, it's true I'll let the inspector win in the end. However, I'd like to know the correct thing to do.

The unit does say install according to manufacturers instructions, however it doesn't mention valves in the autoflush line at all. It leaves all the plumbing up to a licensed plumber. I have two licensed plumbers who disagree on the best way to handle this. What is at stake is the operation of the somewhat expensive steam unit. Yes it's covered under warranty, but not if it is installed incorrectly. I'm also not one of those people who says, "oh I'll just sue somebody later if it's done wrong."

It seems that both these valves will prevent DWV water from backing up into the generator, which is what everyone is worried about. One valve does it with a swinging arm that is forced to close under flow in the wrong direction. No problems with water flowing in the line in the correct direction. As I understand it, the dual check is spring operated, by what looks like a drop in pressure in the autoflush line. However, the autoflush line is not ever under pressure as the potable supply line is. The air pressure in the autoflush is that of whatever vents the line. The water pressure, when water is allowed to drain, is rho*g*h + ambient pressure. What plumber #1 is worried about is that the dual check might close and stay closed causing the unit not to drain or start to drain and then close. Is that even possible?

Can anybody explain the dual check better or enlighten me on the pressure that causes the dual check to operate or what might cause my steam unit to malfunction? If I'm totally missing the point, I'd appreciate an explanation of the correct thinking.

Thanks!

For more information, please visit BSTV.

Before the BFP or after it?

<A HREF="http://www.heatinghelp.com/getListed.cfm?id=449&Step=30">To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"</A>

Are you interested in learning more about Industrial Swing Check Valve? Contact us today to secure an expert consultation!

There was an error rendering this rich post.

0