Balancing valves....

[kuribo]

I am planning a 4 zone system, fed from storage, with a modulating temp. control valve to supply a constant temp. Also will have a variable speed circulator supplying the 4 zones. They will be piped in parallel. I understand that without balancing valves, some zones will get more flow than others. I am wondering if this matters much since it will just mean that the zone valve will stay open longer for oversupplied zones and close sooner on oversupplied zones, won't it?

Would using modulation valves instead of on/off zone valves on each zone be another way to do this instead of a balancing valve and on/off zone valve?

Thanks.

 

[kuribo]

Found this study on the topic interesting...

(broken link removed)

 

[DaveBP]

If you're planning on using isolation valves on each end of each zone loop, so you can repair or modify a zone without shutting down and draining the entire system (and easier air flushing), why not use one of them to tweak flow rates if it becomes a problem. (Yes I know ball valves are not the best way to adjust flow).

If you use an outdoor reset type controller to manage everything, with your temp modulating valve the system would vary the water temp ( to the zones ) to meet the load and in the colder parts of the heating season the zone valves might not close very often. The cost of modulating valves on each zone might pay for a very nice controller. I'm thinking of the Tekmar stuff but there are others.

 

[kuribo]

Based on the research done on the above linked paper, I think I will skip the balancing valves. I might go with the reverse return plumbing though as that won't cost me much extra....The way I installed the pex, each of the 4 1/2" loops at the 6 supply and return manifolds are 300 feet long, so each of the 6 s&r manifolds will have a very similar resistance. The main difference is the leg from the from supply to the manifolds, but again, those shouldn't be all that different in number of fittings, though some legs will have slightly longer straight runs. I doubt that difference will cause any major problems.