Orifice Plates

[fwdixon]

So reading again and came across something called an "Orifice Plate" that the old-timers installed in the upper story hot water rads to ensure flow to the lower floors. The article also said that when converting to force flow, the plates needed to be moved to the first floor rads.

I understand having the plates on the top floor in a gravity system, but why move them for force flow? Also, how did the old timers know how big to make the orifice, trial and error or something more scientific?

[skippedover]

I've worked on a lot of systems including many designs of gravity systems but never encountered what you describe. All the systems on which I've worked have radiator valves that can be used to regulate the speed of flow through the radiator and hence the output. This would negate the need for any restrictors in the pipes. Naturally it wouldn't matter if the system was being operated as a gravity system or a forced water system, the radiator valves would still operate the same way. I'd recommend you stop reading if these issues vex you.

[billygoat22]

restrictor plates can only reduce flow. Would have to hit the hydronic site that mirrors this one for techs. Not sue can say the site name but Dan Holohan and other wetheads hang there.they have more a feel for this.

some restrictor plates were simply hand fabricated from sheet metal.

[fwdixon]

Skip...i appreciate the feedback but I am reading to educate myself, and part of that is asking questions about those things I'm not confident I understand fully.

Billy, from what I have read so far they were generally hand made by the installer out of sheet lead or steel, and were intended to reduce flow so that the hot water went to the lower floor rads. Will keep at it, thx for the tip.