"Phil Again" wrote in message
...
On Wed, 05 Mar 2008 17:55:54 -0800, freeacs wrote:


That's a primary loop. Often that circulator is controlled by an
outdoor temperature sensor working through a controller like Tekmar to
determine the optimal temperature for the system


Well, I don't know if there are check valves as I am not a plumber. I
will check if the return is cool from each return. I would think not
having check valves (and having reverse flow) would be quite bad, is
this common? Is it a good/bad idea? Would a check valve make a
difference in how things should perform? ACS

I don't know about outdoor sensor controlling a circulator.

I don't know how common not having a flow valve (check valve?) is. The
system I lived with didn't have them. Yes, it was not a good idea not
having them. I was told expensive (Labor cost mostly) and they fail.
Experts can comment on that statement.

What I was thinking, and it is only my thinking, a zone circulator pump
will draw hot water from the manifold. The pump will draw from the
manifold the least resistance source of hot water. If there is a primary
loop with a pump, wouldn't the source of least resistance flow of hot
water be from the boiler? Thus the reverse flow should be minimized,
yes? But then again, maybe even in this plan, a reverse flow inhibitor
might still be needed.

On any hydronic system there is either going to be flow checks or zone
valves to prevent reverse flow. Today, you can get the flow check built into
the circulator