3-way valve zone control?

Teemok

I am looking at a problem hydronic system. No flow in many zones. This is likely due to a failed air separator letting micro bubbles collect in cold low flow areas. Repetitive air lock. It never worked great. P/S piped. It has a single 26-99 pump with many (over ten haven't counted yet) 3way zone/diverter valves serving Myson decor style steel flat 3 bar radiators. Each zone has two flow setters. 3-way valves/diverters are on the return. Supply Tee's off to the first flow setter that is a by-pass to the normally open valve port. The bypass water then has to go through a second flow setter to get back to the return. Once the valve activates water goes through the radiators and must pass trough the single flow setter on the return. Is there any logic to this? The only justification I can make for this design is constant flow rates and the by-passes keep the run outs warm. This is a not that big of a structure or cold enough a climate to need that. The setters are seized and many have broken handles. I am thinking an ECM pump, remove by-pass flow setter and cap by-pass. Make the remaining flow setter on the return work or replace it. What say you's guys.

Alan (California Radiant) Forbes

Crazy to use a high head, high volume circulator on the system and then buffer it down with flow setters. It's like pushing on the brake and throttle at the same time.

I like your re-do.

Teemok

The whole design counts on good balancing. I'm being generous to imagine it was once balanced well. I can see it working well enough but with clogs and well meaning service techs or maintenance guys "fixing things" balance is easily lost. The installer put twin Munchkins on a vision board under a deck with no rain protection. I don't think I'm dealing with the work of the sharpest designers here. Belimo valves and dual 3/4" flow setters on 1/2" run outs. More money than sense. Probably an off site cookie cutter designer who draws up hydronic plans for boiler/chiller office buildings multi air handler systems or a rookie supply sales guy with ideas.

hot_rod

Looks like a commercial engineered design with 3 way valves and multiple balance valves?
A standard 2 way zone valve and manual balance vale should work.

If you knew the flow rate required at each radiator a PIV works great with delta P circs.

Or a Quicksetter at each would allow you to balance and see flow rate.

Teemok

Haven't been there live yet, just acted as phone support. I'll see it tomorrow. Quicksetter is a good tip. Thanks. Capping the by-pass effectively makes a 2-way valve. Clean up add mag-filter, fix air sep., Ecm's. If I find the remaining flow setters are clogged or can't be adjusted, I'll look at the Quicksetters.
There are three floors worth of this. Each with it's own pump, maybe 30+ of these setups.
Air vent off a T on the return and a purge port on the supply with no isolation. Shakes head, every zone, all in a crawl, ugh. This guy had problems he tried to solve but failed.

Teemok

Trouble is there's no zone mapping. No zvc controllers. No end switches. Rats nest low voltage wiring. I don't know how much emitter is on each zone. I'm thinking with a good guess at the right sized constant pressure pump I'll be able to set zone flow by measuring delta T with the zone spaces at/near design temperature.

hot_rod

Those auto vents probably are not doing much either.

Alan (California Radiant) Forbes

Trouble is there's no zone mapping. No zvc controllers. No end switches. Rats nest low voltage wiring.

By this time, the owners should be able to recognize your skill and experience. Tell them that you want to document and correct the piping and wiring shortcomings to make the system work and make troubleshooting easier. That is, if you don't mind spending time in that crawlspace.

Teemok

Went there today. Beautiful 10ksqft Victorian with a chapel in it. Building management dysfunctional, Vision 3 board burnt, every 26-99 motor is facing up. Multiple dead pumps littering the soaked boiler room that's under an open gap board deck in the rain. System pressure at 35psi with 50# reliefs. 20 leaking (maybe 3-4 gallons an hour) flow setters improperly set. All pumps wired un-switched constant circulation. Expansion tank at 5 psi. 27 thermostats un-mapped. Air sep. clogged. F13 on the only "was working" boiler. Got them heat today at all good zone valves. First time in 4 years. DHW will take another day. Expensive assessment and emergency make-it-work hacks in the rain. I doubt they'll do anything. They'll just run it as is till it goes down again. Continuous leaking and all. Ghetto wealthy. They rolled their eyes when I tried to explain what's up. Maintenance guys have the replacement pumps sitting there like a pile of consumables. Maintenance head explains to his helpers: "You see, this system burns natural gas, electricity, circ. pumps and wastes 100 gallon of water a day. It works great. Ha Ha Ha, climbs into a golf cart."