circuit setter

Keith_8

A couple of weeks ago I posted regarding how effective reverse return piping would be on commercial boilers.

We are going to be repiping the boilers in the next couple weeks, using reverse return piping. I am going to include a 4" circuit setter on each boiler to fine tune the flow rate.

It would seem to make sense to install the circuit setters on the return piping back into each boiler(2). But then again maybe not. What do you guy's think?

Keith

Larry_45

Cuircut Setter

Keith:

It Depends? To try and balance your cuircits you need them on your coils that cause a pressure drop. If your boiler cause the greatest pressure drop and you are pumping through both of them at the same time then you may need a curcut setter on those lines. But if the greatest pressure drop is on a coil out in your system then you may need them out on your system at every coil and radiator. To do it right you need to find out your total pressure drop and find out which aera or coil, radiator has your graetest pressure drop put that at zero and then figue your gpm requirements for each cuircut (coil; radiator) and set each cuircut setter to each one.


Larry

Keith_8

Circuit setters

Larry,
In my situation the terminal devices do have circuit setters and in theory they are receiving the appropriate flows rates.

My problem lies back in the boiler room. The boilers were piped incorrectly and the majority of the flow goes thru 1 boiler.

Keith

Nick S

Why not just install the circuit setters? Yea, reverse returns are better, but I bet you could even the flow out with just the balancing valves. Assuming you use a manometer and the charts of course. Keep in mind, you may affect the total flow through the system, so that should be rechecked also.

Paul_11

repiping the boilers

If you are going to repipe these boilers as you say, then you would not need any circuit setters. If you do your boiler room piping correctly, you will only have flow through each boiler when you want to have flow. Each boiler will have it's own pump.

I would not waste the money on circuit setter controls, in this instance. They can help get you out of a problem when the system piping was not done correctly to begin with.

Primary/secondary piping with cross over mains works great on fan coils. Each fan coil has it owns pump and it's own closely spaced tees.


Just pipe the boilers primary/ seconday and use a mixing valve or injection system and it will work great.

I don't know much about the rest of the system.
Are you planning on repiping the lines to your heating units?


BTW:
I find your use of the term reverse return piping in referring to boiler piping only, confusing.
Reverse return piping has to do with the system piping, not the boiler piping.

Good Luck.

Respectfully,

Paul B. Shay
pshay@arealgoodplumber.com
LMP 1307
LMFS 654B
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Ted_5

No re piping needed

Yes, you could balance each boiler for its proper flow rate with a pressure independent flow control valve. A circuit setter is a fixed orifice devise and the flow rate changes as pressure changes in the system. Spend the money on adding pressure independent valves not re piping the boilers. How is it piped now? I can help with getting the proper size valve. My cell number is 651-895-6627.

Keith_8

Repiping

The only repiping taking place is going to be in the boiler room. This school was built 2 or 3 years ago and in relation to the hot water system the only issue I know about is lack of flow thru one of the boilers.

The thought of decoupling the boilers from the main loop did enter my mind but the boiler room is extremely tight and major repiping would be a major challenge and expense. Obviuosly the benefits would be no flow thru an offline boiler and the energy savings/boiler performance greatly increased.

I have a meeting on Wednesday with the facility people. I recently heard that they also have an issue with access to the clean out plates and breeching adaptor. Maybe a complete repipe will be in order.

I agree that many times the phrase reverse return is a term usually refrenced in regards to the total system piping. However may times I have seen it used refrenced to how boilers, hot water heaters or chillers are piped.

" A proportional valve", that is something I hadn't heard or thought of. I'm assuming the valve actuator takes in differential pressure between the boilers and adjusts flow accordingly?

Thanks for the input guy's.

Keith

Keith_8

Pressure independent valves

Ted,
Sorry Ted, my brain read proportional valves not pressure independent. Tough getting old. What makes P.I.V. function?

The boilers are (2) HB Smith 28A-11 boilers. They are piped so that the #1 boiler is the 1st supply into the system and the 1st return connection back from the system. The #2 boiler just pretty much sits there satisfied on it's limit controls with little flow going thru it.

If you are going to email me a reply directly use my work email, kohara@championenergy.com.

Thanks, Keith

RJ_4

Agree with Paul, Save the grief. repipe using primary secondary loop with a primary pump and a pump for each boiler, top it off with a HEATTIMER logic control, this type of control will automatically rotate boilers.