Mixing 1/2-inch and 3/4-inch pipe

Wilson

My house has four zones of 3/4" coppper finned radiators all served by Taco 007 pumps. My wife is encouraging me to take out the copper radiators that serve the bedroom zone in favor of the Myson radiators, which I have told her might be more quieter than copper finned radiators and which she thinks are more stylish.

I cannot get a straight answer from any of the bidders about whether the different pipe size and material will cause circulation and/or corrosion problems even though they are isolated in their own zone. Also wonder whether all the 3/4" pipe needs to be ripped out and replaced with 1/2", as one bidder on the job claims or whether a 3/4 to 1/2 reducer can be used at each radiator?

Mike T., Swampeast MO

Lots going on in that post...

Panel radiators (like Myson and others) are steel--not cast iron. The connections to/from them are generally brass which makes a reasonable "galvanic transition" from copper to steel so corrosion because of the dissimilar metals shouldn't be a problem. Of course wacko water chemistries can mess up any system...

Fin baseboard is generally connected in series (one right after the other on the same pipe) in each zone. Panel radiators generally aren't connected in this way--personally I say it's because fin baseboard is highly convective and quite predictable while panels are highly radiative and unpredictable, but that's my "quirk"....

If in a one-pipe system like baseboard, panels usually use special diverters to direct a given amount of water into each panel in the loop. Diverter systems MUST be VERY carefully engineered!!!!!

It's hard to guess what is going on with your different bidders, but I'm guessing that the one who wants to "rip out the ¾" and replace with ½"" is going to to pipe each panel with ½" pipe INTO a ¾" manifold. The second may be using a diverter system. What you DON'T want to do is:

1) Mix panels/fin baseboard in the same zone without VERY careful planning/engineering.

2) Hook panels up in simple series to a ¾" single-pipe loop with ½" reducers to the panels.