[Mobile Master Tech]

BBP, I agree about traditional circulators and zone valves. I read of some systems in a typical house that were too noisy to sleep and the electrical draw is 800-1200W! At what point is that considered a "hybrid" hydronic plus electric resistance heating system....

Those sentry valves look great for systems where valves make sense. The advertised wattage for conventional ones is 5-22W per valve any time it is on, plus the pump draw. The Alpha pumps are great too, especially how they self regulate for current demand. A system designed with these is another good way to do it.

I used spherical Bell & Gossett pumps designed by Laing is so makeup water can flow through them and the oneway flapper valves, allowing an open system-no corrosion issues, and all my plumbing is always flushed! The smaller ones take 9W for 0.5gpm through 250-300ft loops and the large one takes 23W to move 2gpm, 0.5gpm for each of 4 300ft loops. They have no bearings, no seals and the only moving part is the magnetic impeller which stays sealed inside the drive can. The impeller is free to pivot so they will probably never jam. They can't leak and will probably never fail. They are adjustable speed for finetuning. You are right, there isn't need for high flows and the power required to produce them.

The other reason to use individual pumps rather than one pump plus valves is eliminating points of failure. If the only pump fails, no heat. If one pump fails in a multipump system, only one zone is down. If the controls fail, both system types are down but I can just plug my pumps into an electrical outlet and I have heat. 3 items are required for a zone to function in a single pump system-controls, pump and valve. In mine, you only have 2 items-controls and pump. Fewer points of failure and fewer single points of failure.