Water Balance Fun

[Poodle Head Mikey]

I don't know anything about those valves but my first thought would the difficulty of obtaining anything like stability in the operation. With valves that (relatively) large the tendency to overshoot the control point will be substantial. And an overshoot soon leads to undershoot. <g>. And as all the valves may be doing it at the same time it seems like a big bag of worms to untangle.

Are the valves two position or modulating? Can you limit their full-opening to a percentage? Or control the modulating rate to dead-slow? <g>

Oh wait; "circuit setters" I now see you wrote. Are there also individual control valves or is the flow always constant through the coils?

With the balancing valves oversized will there be any tendency towards noise?

PHM
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I'm doing TAB on a job that has been interesting from start to finish. I thought you guys might like to hear about some of the fun.
The building has a history of not heating or cooling properly. For this reason the redesign is over kill of the highest order. Every space has a fan powered box and every space has a design airflow and heating design that considerably exceeds the need.
The present problem is that most of the FPB water heating coils were downsized at the last minute but they forgot to down size the circuit setters and control valves. A few coils were up sized. The circuit setters are Nexus Orturi and the design orifice DP'S vary from 0.81 inches of water to 129 inches of water to provide design GPM. The control valves were provided the same size as the circuit setters.
I'll give my take on this after getting some of your comments but thought you guys would like to add your two cents.

[Poodle Head Mikey]

After reading through all of what everybody else had to say; maybe the above was my one cent. <g>

[WAYNE3298]

The system won't be stable Poodle but it will heat the building flawlessly. That's why this is difficult to explain. Moet engineers don't really understand what they have designed on water systems like this. The only thing circuit setters in series with equal percentage two way control valves are good for is to prevent excess flow when the control valve is full open. When the valves first open on a call for heat they may go full open but immediately close some to control flow to meet the load. The bottom line is it was a waste of money to install them in this system.
Yes Poodle if I try to set the oversized circuit setters to design flow there will be noise. Believe it or not it would also be more difficult for the control valve to control flow since the valves are in series.

BBeerme your advice about telling them what steps have been taken to assure the system functions with minimum hunting sounds like a winner to me. That made me think that explaining what I did and why in laymen terms might be the best approach.
Laying the foundation now and leaving the door open to a more technical explanation just may be the right approach. Getting more technical can be done later if they choose to challenge the report.

[bradluke0]

True brad we could discuss it to death if nothing else. To do what you said about return temperature it would require balance of the individual circuit setters. There are so many miss-sized I don't want to do that. I don't disagree with the theory but in this application it isn't feasible.
I finally decided to not balance any of the system except DP set point. The control valves will take care of heating the building with no problem even though some of them will hunt. The control guy reset the PID to 180 seconds. That should help some. He also said the valves would go full open upon a call for heat then throttle back. That will keep debris from collecting on the valve seat of the oversized valves. I don't know how to explain all this in the balance summary without getting technical and losing everybody. Nobody on this job has a good technical understanding of hydronics so how do I communicate? If you have words that will help I'm interested.
On the FPB fan airflow the minimum airflow is too high but the outlet temperature is good because the coils are also oversized. The only way to get the airflows lower is to reset the manufacturer's SCR minimum adjustment. I can set the minimums down to 60% of the motor input voltage without damaging the motor but don't want to do that unless there are complaints.

What I meant about setting each floor by return temperature was using the main valves to each floor , one adjustment only to get the return water from each floor the same temperature . ( glad this job is yours and not mine ...lol )

[WAYNE3298]

There are no such valves to set. I agree with your suggested approach but can't do it. It is going to be hard to explain in understandable terms why water balance shouldn't be done. Nobody in the loop even knows what an equal percentage control valve does. Without them knowing that I'm afraid a technical explanation would make them think I'm trying to baffle them with BS.
How would you approach explaining this Brad?
It looks like at this point the technical explanation is my only choice. They will probably muter among themselves but act like they understand.

[bradluke0]

I will pm you with my number later on ….give me a shout .

[WAYNE3298]

Will do Brad. Feel free to email me also. I enjoy talking to all you guys.

[bradluke0]

I guess I am dumb , I cant figure out how to pm you . PM me your # and I'll call you .

[WAYNE3298]

That's funny I have trouble with trying to PM or even answer a PM. My email address is in my profile. If you email me we can get around the PM.

[pecmsg]

I guess I am dumb , I cant figure out how to pm you . PM me your # and I'll call you .

Only Pro Members can PM!

[WAYNE3298]

I didn't know that pecmsr. Brad is probably eligible now for pro membership. Looks qualified to me.

[crazzycajun]

I didn't know that pecmsr. Brad is probably eligible now for pro membership. Looks qualified to me.

Yup he has the posts just needs to fill out the application and send whiskey to twilli

[WAYNE3298]

Finally got to the bottom of the problem. Early on I found some errors in the heat coil calcs and the circuit setters. I sent them to the engineer. Him and the vender got together and made the corrections. There was no official resubmittal so I thought my comments had been ignored. The engineer sent me their hand marked up corrections. They revised the heat coils, control valves and circuit setters. Calcs associated with the mark-ups are all good. The system can be balanced.

[bradluke0]

Its good to see they followed though . I am a bit disappointed in one respect though , I still think its better off wide open and let the 2-way control valves do their thing . BTW.....Many years ago we used to balance HCA hospitals all over the country . All of their heating was hot water reheat with 2-way control valves . We cleared it through HCA to not balance them . We checked the operation on them by checking the leaving air temp . Balance them or not , it just shows there is more than one way to skin a cat .

[WAYNE3298]

I totally agree Brad and have made that clear to the engineer. Two-way equal percentage valves will do the job and all circuit setters do is add resistance to the water system. Three-way valves are a different story.
This engineer is my favorite but I am disappointed he didn't send me an official resubmittal. It would have saved me a lot of grief. The final circuit setter picks are great. The valves are Nexus and some of the original picks had pressure drops from below one inch to seven inches water. Those pressure drops do not allow balancing.