Circuit setters generally are installed at the end of a heating hot water loop to allow there to be continuous flow through the piping system. It is a minimum flow device, they are generally not needed if your system involves 3-way valves. I typically design reheat coil heating hot water loops with 2 way valves, and install a circuit setter at the end of the loop, and set it for ten percent flow.
NCPE, you couldn't be any more incorrect in your statement. Circuit setters are used to balance hydronic systems, and they are required at every terminal in the system, even when there is a control valve present. The only exception to this rule is when the control valve is a pressure independent type, which involves a significant cost increase. Contact your local testing and balancing firm for details on the importance of balancing valves(circuit setters).
But if you have the option, go with the pressure independant control valve. This eliminates the need for the circuit setter, and you dont have to rely on the balancer for a balanced system. (I am not sure what the upcharge is, but by not having to rely on the balancer, I think it would be worth it)
I think it may depend on your pumping. If you have variable primary pumping, then I would suggest going to the PICV and losing the balance valve. If its a small system, say under 5 HP pumping then variable pumping may not offset cost.
Rebalance is a significant issue, especially when the ABCV's age. Last two I had to have cut out because they would no longer budge from their set positions. Trying to find the ABCV's can be a task by itself.
KLPE, "at every terminal in the system? Different systems call for different components, first off. Chilled water primary loops for example, can be balanced with the triple duty valve after the pump discharge. 2way valve hot water recirculation piping typically needs a circuit setter at each end of the loop. Heating hot water piping could be balanced with any flow control device, VFD on the pump, bypass valve, flow control valve, etc. I don't know exacty what you mean when you say
"they are required at every terminal in the system, even when there is a control valve present. The only exception to this rule is when the control valve is a pressure independent type"
You must not design chilled/heating hot water systems. Stick to plumbing buddy. Be sure to install your water hammer arrestor.
"Chilled water primary loops for example, can be balanced with the triple duty valve after the pump discharge"
Do you mean you dump some percentage of the pump's output right at the pump head? Seems a bit wasteful, esp. in a system that's running at 20-30% of max design load. Would seem to make more sense to put PICV's at each terminal and back the system up the pump curve, lowering energy costs due to pumping. Yeah, the first cost might be high, but it pays off to the building owner in lower energy costs over time.
That would seem to be pretty much the idea behind going to variable primary pumping. I'm in the middle of converting a constant primary/constant secondary into a variable primary. The LCCA has it as the best cost over 25 years, lower first cost than variable primary/secondary, and it means geting rid of a buttload (an engineering estimation term) of ABCV's and 3-ways.
Variable primary AND variable secondary would seem the way to go, especially if you have large swings in demand which you normally do. Put a VFD on the chiller compressor and cooling tower fan as well and now your talkin energy savings.
This is an incorrect statement, which KLPE2B noted. There is really no call for you to tell them to go 'back to plumbing'. KLPE2B's description of circuit setters was accurate and concise.
Ok Cris, so like KLPE noted, they are REQUIRED AT EVERY TERMINAL IN THE SYSTEM???? What about at a 3-way valve heating coil? And he didn't say what kind of system either...
"Circuit setters generally are installed at the end of a heating hot water loop to allow there to be continuous flow through the piping system"
I think he means this to be a Griswald valve, which will provide a minimum flow through the hot water system that would be equal to the minimum flow of the pumps on VFD's lowest speed, as to not over pressurize the system.
I thought that the balance valves would satisfy part load conditions by pumping full volume whether needed or not-where the energy savings are. Where I've usually seen them is for maximum flow independent of pressure on multiple loops off the same pump.
NCPE-you only need one balance valve if you have only one device on the loop. Two of the heating loops I've been working are constant volume with Griswald's. On one, the design flow was 837 gpm for 840 gpm pumps. The valve choked flow down from 840 to 837. The other choked flow from 440 down to 437 gpm. I lost both griswald's. Valves are not always needed on the return, sometimes you luck out. Also was a chance to bypass the VFD's some meathead had put on a constant volume system.
FYI, the larger chillers are IGV's. The small unit is VFD; cooling towers are pony motor plus VFD motor. The LCCA bore it out, with electrical escalation factor being the most sensitive-depending on kw costs for 25 years, either one could be lowest cost.
"I thought that the balance valves would satisfy part load conditions by pumping full volume whether needed or not-where the energy savings are."
Pump energy (in terms of input energy to a centrifugal pump) is best minimized by minimizing flow, not by allowing full volume flow.
Pumping at full volume returns "partially used" chilled water or hot water back to the chiller or boiler. Neither result gives best efficiency for the chller or boiler.
I think you've got the point, but in reverse. The offset for not having to run the pump is the payoff goal of the PICV's. If you can wait 25 years, I'll tell you how it came out as compared to the estimated life cycle cost analysis. First year data will be available about 1 year from now.
