Which valves to replace 70 y/o gate valves on monoflo used for minor balancing?
My monoflo has a single 2" supply and two 1-1/4 returns; returns have a gate valves that are completely shot and need replacement.
Can anyone suggest the highest flowing specific model 1-1/4 valve with rough balancing capabilities I can get?
Requirements
- highest CV possible in 1-1/4 to minimize potential monoflo issues and allow for better flushing / air purging
- minor balancing capabilities (the two returns seem balanced by design, but unlikely 100% which is why they likely had gate valves on there originally which broke off)
- longest lasting, my system is all steel pipe, replacing stuff isn't easy
The following looks good, a ball valve would be great because it's easiest to close/open to purge air / flush magnetite from the system. Don't ball valves create turbulence and cavitation if used for balancing?
Macon:
MBP-MB-125F125F
https://www.supplyhouse.com/Macon-Balancing-MBP-MB-125F125F-1-1-4-FNPT-MB-Venturi-Style-Manual-Balancing-Valve-29-Cv
I also considered getting a large common "balancing valve" i.e. 1-1/2 or 2" that is still rated for the minor balancing i may need to do on the 2 returns.
Any problems with that idea?
I've seen people suggest butterfly and plug valves, i haven't been able to find specific models in 1-1/4 NTP, those don't seem very common in residential.
Comments
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Bal valves are ok if you only throttle a little bit. Gate valves can never be used for balancing. You can use butterfly but as you said they are not usually used in residential.
The best thing would be an i 1/4" full port ball valve with a Balancing valve
But you can use a B & G circuit setter that will do both jobs. See the attached
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You can't use gate valves for balancing, it will destroy the gate and the thread, they have to be fully open or closed.
Full port ball valves will allow the best flow but are not linear if used for balancing. Globe valves are more precise for balancing but are more restrictive.
Unless you are using needles and gauges to measure flow there is no reason to buy the special balancing ball valve unless it has a special linear shaped ball and seat but I don't think those do.
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What is the CV on a 1-1/4 B and G circuit setter ?
I agreed full port ball valve + balancing valve is best, but what HIGH CV balancing valve is there for monoflo?
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What are these? Do they not allow linear control ?
Many manufacturers have them, they are called venturi balancing valves, this particular one from macon has a cv of 29 in 1-1/4" which is great.
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The "venturi" is to create the pressure drop so you can measure flow with a differential pressure gauge or 2 pressure gauges. The venturi is between the 2 pete's ports with the caps on them. It is going to reduce flow over a full port ball valve alone and isn't likely to be helpful in a small system. Unless you can find somewhere in the documentation where it uses a special shaped opening in the ball to produce linear response, it is not going to be anywhere near linear.
The circuit setter looks like it just has a nonlinear scale drawn on it.
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B & G Curve attached
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Thank's mattmia2.
EBEBRATT-Ed, so what is the Cv rating for the 1-1/4 circuit setter? Not great at reading graphs.
For example the regular Victaulic 1-1/4" blanacing valve is 16.4CV which may create problems for my monoflo system especially if i use zone valves which are under ~10CV
You guys see any problems with using a 2" balancing valve on a 1-1/4" pipe?
2" has a very high CV, and can throttle quite a bit, i would only need to throttle maybe 10%.
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The lines are the settings on the dial so at fully open the Cv is about 13 for a 1.25" circuit setter
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I would just use a ball valve instead of spending $300 on a circuit setter and plumb it in such a way I could substitute or add a globe valve for the ball valve for one of them once I figured out which half needed to be throttled.
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That's what those lines mean haha. Ok, 13 is pretty low though.
Putting a regular full port ball valve on the side that doesn't need throttling is a great idea.
Does it make sense to put the throttler only on the return whose return temperature is
higher? Labour is expensive to make changes afterwards, i'd rather "do it right" first time around.
Not sure about the ball valve for the other one though. Memory feature on the balancers is quite useful, among other things. Globe valves are also about as restrictive as balancing valves, that's why the original system had gate valves everywhere. Which still leaves the question if it is reasonable to put in a bigger valve than the pipe.
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you can use a bigger valve and reduce it but if you are using it for balancing the range where it is closed enough to provide flow control may be small. I would do it with a union and treaded valves and some threaded fittings, probably black nipples so I could disassemble it and change the valve or add a globe valve. Might put a globe and ball valve in series so you can leave the globe valve where it is balanced and use the ball valve for service.
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a Cv of 13 is about 130,000 btu at a delta t of 20f assuming 13 gpm and 1 psi drop at the valve.
you could even parallel 2 or more globe valves if you're really worried about it. real balancing valves are really for commercial systems and pretty expensive.
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if you want or need to know the flow, the Quicksetter is a ball type balance valve, like a Circuit Setter, and has a readout instead of PT ports. Unless you have a Dp meter, the pressure ports don’t help you much.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
My 70-yr-old monoflo system works very well - it's all on one zone with one thermostat for the whole house.. There are 4 loops, and each as a plug valve for balancing. We run with all 4 plug valves wide open, and things work fine. However, our bedrooms have old Crane cast-iron baseboards - they have built-in sliding flow adjusters. Most of the bedroom flow adjusters are set for about 50% of full on - except for one bedroom that is set for 100% full on.
If there weren't adjusting valves on the bedroom baseboard units, I would install a ball valve for each bedroom.
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My common supply is 2", the split returns are 1-1/4". Gate valves. No restrictions anywhere by design.
Each of the two returns serves 11 rads and 100"+ feet cast iron baseboard. The first 6 rads valves are throttled down to less 1/4 of a rad valve turn (a lot of restriction / head)
On top of that returns pump towards to expansion tank, air entrapment issues, i want to add
2 zone valves which max out out 10 CV for something like Taco Sentry.
Will my monoflo work the same if it all has to go through a ~1/2 opening of a modern "balancing valve" and another ~1/2 opening in the zone valve in a system with a 2" supply and 1-1/4 returns?
I had an issue where 1 rad was connected wrong (monoflo tees reversed) in the middle of the loop, essential the 1-1/4 pipe was reduced to 1/2" - 3/4", all other rads past that rad were noticeably cold.
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The only way to know is to do the math and i don't quite know how to do it. The curve of the circulator is just as important as the resistance of the loop. It may be that a Cv of 10 is insignificant compared to the resistance of the monoflo tees. You can parallel 2 or more of anything to increase the Cv. Full port ball valves will have a Cv pretty close to that of the pipe. It might make more sense to use a circulator with a flatter curve than to try to get the lowest resistance possible.
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Most mono systems used convectors , adjustment of convection is used to balance ..
There was an error rendering this rich post.
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