Double Pumping

Tony Wilson

Recently I have been seeing radiant heat installations with a copper fin tube boiler, where the installer has piped the system in parallel, no primary secondary, the supply from the boiler terminates at the supply manifold, there is no tempering valve. An undersized bypass has been installed, the boiler has been turned down to 140 degrees and for some reason there are two pumps in series, one on the return and one on the supply at the boiler. Besides the lower boiler temp with an undersized bypass possibly causing a condensation problem in the future, what on earth is the installer thinking putting two pumps in series?? The answer from the installer is that "it's more efficient that way.".
First of all, is he right? and second, is there any supporting documentation either way?

Mark Wolff

A picture is worth a thousand words.

Post one and lets see.