Using Brass Unions

luna12

I'm installing a Weil-McLain CGa-6 cast iron boiler. The piping system is a monoflo from the 1950s. I will be using black pipe for the near-boiler piping. A certain area of my setup is close quarters, and I want to use a male by male union. I wasn't able to track down a 1-1/4" one made from black malleable iron, so I got the only one I could find and it's made from brass. However instead of being a ground joint union, metal to metal, it has a washer that I think is teflon. The union is rated at 250 degrees. Here's the link: https://www.amazon.com/dp/B0GCCYBMLH?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1

Can I still use this in my piping system? When I saw that it had a washer, I thought it seemed kind of iffy.

mattmia2

kinda weird but should be fine, teflon is fine at hydronic heating temps.

Jamie Hall

I can't think of a good reason why it shouldn't be fine. I suspect, though, that even more than the ground joint type you will have to observe the usual cautions — as close to perfect alignment, both linear and angular, as you can manage, and go easy with the wrench. Be a gorilla and the washer will fail.