“If you're in the business zoning with pumps ,here’s a piece of advice—grab yourself a Taco SR504-4 Switching Relay. This little gizmo is the heavyweight champ of zoning solutions. It comes with these nifty PowerPort Cards and has external lights to tell you what's what at a glance. And the layout on the PC board? It's like they designed it with the contractor in mind—straightforward and no fuss. Hook it up with the old reliable 00 family of circulators and thermostats”
“Same part number, but completely different physical size/layout. It works, but I had to re-route wires. I do mostly repairs, so it's a bit of a pain. They should use a different part number. But can't complain about it's a mfg issue.”
