Backflow Preventer Sizing

Greetings all! I had a backflow device (Zurn 975 XL) installed for an irrigation line. The line is 3/4" and the backflow device is 1". Is there any problems with this setup?

Thanks much.

No problems.

Would there be any advantage to it? I.E. better pressure or maybe he only had a 1" on hand?

I can't see any advantage, but it certainly won't be a problem with pressure or volume.

Hi am new to this site and have a question about a flood guard preventer for the sewer in my basement. I purchased a new 3 inch to replace the existing old 3 inch one; however, I was about to install it and found that it is about 1/2 inch too narrow and will fall through the drain pipe. There are four screws but they do not seem to do anything (i.e. thought they might enlarge the rubber ring to fit snugly against the pipe wall but nope. A 4 inch would likely be too big - any suggestions are there actual adjustable flood guards available (am in Manitoba Canada)? Thanks