Water balance

Ed Parisi

Ed Parisi

Water Balance

I would like to purchase a read out tool for balancing domestic hot water recirculating sytems with circuit setters. Looking for feedback on what tool your using and what to look for when buying.

don_50

Have

you check bell&gossett.I have the b&g ro-5 fluid meter.I
got my over 20 years ago still going strong.

It will do 0 to 25 ft of head.Also you can check the dwyer
site,they have meters for everything you would want to tweak.

Jerry Boulanger_2

Save yourself the trouble

and use automatic flow control valves. You can get a bronze body valve, sweat or threaded, for flow rates as low as 0.33 USgpm. Get the lowest control range, usually 1-14 psid. They are ideal for balancing DHWR systems. Go to griswoldcontrols.com for more info.

Brad White_2

Griswolds are OK only if

you are sure you want a constant volume system. More and more systems are going to varibable speed and Griswold valves defeat the principle. I use Griswolds where I need a definite flow such as a water source heat pump or where I cannot tolerate fluctuations in an otherwise variable flow system.

Jerry Boulanger_2

I have to disagree.

Automatic flow control valves are particularly applicable to variable speed/variable flow systems, especially if they are direct return, as most large systems are. They are the only device that can provide variable balancing head loss. The only thing better is pressure-independent control valves.

Brad White_2

Maybe we are using different terms, Jerry

Automatic flow control valves as I define the term consists of an orifice cartridge and a spring which guarantees constant flow plus or minus 5 percent when it is in its operating range. Below operating range you get less flow and above it you have a restriction that can also give you less flow.

There ARE balancing valves that incorporate some of these characteristics and those I believe are termed "pressure independent balancing valves". In these, the Delta-P remains constant so that the Cv of the adjustable orifice can do its job without fluctuations.

I had a hard time grasping that at first, thinking that a constant delta-p means constant flow, but what helped me was that the orifice is adjustable (like any balancing valve) and the flow is held steady at whatever setting.


But if we are talking standard Griswold valves without adjustments, I would stand by my "constant volume" statement. If you have a constant volume system with so-many circuits, and you back off the pump, all you would do is reduce the flow rate while the valves open to allow the same flow they are designed for. This would continue until some if not all Griswold valves fall below their operating range. At this point, the path of least resistance once again takes over and the system is out of balance. Does that make sense?

Agreed balancing valves are more critical on direct return systems, and even reverse return systems because emitters rarely have the same pressure drop.

Jerry Boulanger_2

Automatic flow limiting valves

work as you describe them, except that if the delta P across the cartridge exceeds the high end of the control range, the flow will be higher than the rated value.

I think we may be struggling with terminology here. You refer to 'constant volume', which to me means constant flow, in which case the pump would be constant speed.

I still disagree with you, but this is a complex topic. If you'd like to continue the discussion, e-mail me direct with a phone number and I'll call you. I've used automatic flow limiting valves in systems up to several thousand gpm.