Measuring flow in a hydronic system

DCContrarian

Hi --
Is there a gauge you can put on a hydronic system to measure water flow? If possible I'd like to measure individual zones to get an idea of heat output.

delcrossv

Yep. https://supplyhouse.com/Caleffi-132552A-3-4-NPT-QuickSetter-Balancing-Valve-w-Flow-Meter

GroundUp

Those Quicksetters are not very accurate. An ultrasonic is probably best, but out of the budget for most people. What kind of system are we talking here? Is it possible maybe to time the boiler cycle while measuring temp delta and doing it that way?

hot_rod

Actually the Quicksetters are + or - 1%. I have compared them to certified lab quality test meters.

Inside the Quicksetter is a piston with a magnet attached. The magnet moves the indicator ball. If you have crappy water with ferrous particles or magnetite it can stick to the magnet and hamper movement. This only happens when the ring is pulled.
It's good to have a magnetic separator on hydronic systems. It protects ECM circs and Quicksetters.

Any accurate device, mix valves, balance valves, PIC valves, etc need to be protected by a separator or Y strainer.

It's the ultrasonic flowmeters either Doppler or time transit type that can be finicky, they depend on the attachment to the pipe and condition of the inside of the pipe. Any rust or scale inside or outside the pipe affects them.
Any air, even micro bubbles in the piping throw them for a loop also. Dirty fluids and thick glycol confuses them. If the fluid cannot pass ultrasonic energy, it cannot be measured.

I've connected our portable ultrasonic to hydronic systems and have gotten no reading.

The rotary type meters are what are used on BTU meters and residential water metering, I find them to be very accurate.

With the Quicksetter you can both observe and adjust flow if you find you need to do some balancing to improve the systems performance.

ScottSecor

We have used the Caleffi Quicksetter a few times and had excellent results. I strongly recommend them.

GroundUp

hot_rod said:

Actually the Quicksetters are + or - 1%. I have compared them to certified lab quality test meters.

Perhaps the ~60 of them that I bought were defective. Compared to ultrasonic, the dozen or so that I tested were up to 40% off in both directions. Darn odd that a 300ft loop of 1/2" PEX can flow anywhere from .4 GPM to 1.2 GPM in the same system at 80* AWT under a 15-58 according to the Quicksetter when every manifold ever has dictated that the same loop is always .7-.8 GPM which coincides with the head loss and has been verified with countless ultrasonic meters.

hot_rod

You seem to run in to a lot of unusual, un-explainable situations

It's a chunk of brass with 3 holes in it, really not much to go out of tolerance.

Other than the passage way being plugged or compromised. Which isn't the valves fault.

If Ultrasonic work best for you, I'd stick with them.

GroundUp

I no longer have access to ultrasonic equipment nor do I do commercial work anymore, so in my case, the manifold flowmeters are close enough for my liking 99% of the time. That was one particular job about 4-5 years ago where we had a 52 unit condo with all radiant floors and the engineer spec'd redundant flowmeters/balancing valves. I had heard great things about the Quicksetter so that's what I installed. The balancing guy lost his mind and it took weeks to convince them that we didn't have to replace them all, and could just use the manifolds instead. Unusual, sure. Unexplainable, hardly. I'd be happy to show you how the one in my shop varies by 10+% with each pull of the ring sometimes only seconds apart. Not throwing any shade at the product, merely sharing that it's not very precise.

hot_rod

If you have any that are off the 10- 40% you indicated we would sure like to get some back to test. That is way out of spec.

jumper

Tap to read pressure drop across device you have a system curve for?

GroundUp

@hot_rod maybe I'm just really bad at math, but this sure seems to be a little over 1% worth of variation. It won't let me post the video but here are some screenshots of said video indicating the wild variations between 2 and 4 GPM while the manifold flowmeters remain constant at approximately 3. This is the 5 loop radiant slab in my shop.

hot_rod

I know if you don't pull the ring/ valve out completely, you will get erratic readings like that.

Pull the ring out the put a wrench on the square valve stem and turn to see if adjusting makes the reading change.

Release and pull the pin as you make flow adjustments.

GroundUp

10 full pulls with 9 different readings- it's not a faulty pull (see the discolored finger, it's being pulled all the way). Yes the reading changes with the balancing function, but the fact remains that less than 10% of the pulls are alike without an actual change in flow. If we want to take an average of several dozen readings, sure it'll be pretty close. The average person who's going to give it 1 yank and call that correct because the MFG says so, may very well be disappointed. I will continue to buy these because I do like them (actually have a few on my shelf), I just wanted to illustrate that they are not as precise with any given pull of the ring as we're led to believe. A precaution, if you will.

DCContrarian

OP here -- I don't need the balancing function, the gauge would just be for informational purposes. So is something like that available without the balancing valve? They're kind of pricey, that's all.

EdTheHeaterMan

DCContrarian said:

OP here -- I don't need the balancing function, the gauge would just be for informational purposes. So is something like that available without the balancing valve? They're kind of pricey, that's all.

What will you do with that information?

Are you experiencing a problem that needs diagnosing? Or are you just one of those folks that just needs to know stuff. @ethicalpaul is one of our Steam Boiler DIY guys that likes to know stuff. He put Glass Pipes on his steam boiler, just so he can see what is happening inside there. Not because it needs to be there. Not to solve a problem. Just so he knows what all those books are saying is true.

GroundUp

DCContrarian said:

OP here -- I don't need the balancing function, the gauge would just be for informational purposes. So is something like that available without the balancing valve? They're kind of pricey, that's all.

There are other types of flowmeters that can be purchased without the balancing function, but anything hydronic specific is going to cost quite a bit more than the QuickSetter. As I had asked earlier- is it possible to calculate it based on run time and BTU output rather than actually trying to measure the flow rate?

DCContrarian

EdTheHeaterMan said:

DCContrarian said:

OP here -- I don't need the balancing function, the gauge would just be for informational purposes. So is something like that available without the balancing valve? They're kind of pricey, that's all.

What will you do with that information?

Are you experiencing a problem that needs diagnosing? Or are you just one of those folks that just needs to know stuff.

Definitely someone who just wants to know stuff. Somewhere between a tinkerer and a mad scientist.

Zman

The Calleffi valves work great unless they get plugged up. Magnetite is usually the culprit as it sticks to the internal magnet.
I have only used the cheaper ultrasonic meter and they are not very accurate as compared to city water meters.
Just measuring the difference in temperature (even with your hands) can give you some good information about the flow rate in a heating pipe. The bigger the difference, the lower the flow (unless there is no flow at all).

ethicalpaul

> Just so he knows what all those books are saying is true.

Sometimes true

DCContrarian

ethicalpaul said:

> Just so he knows what all those books are saying is true.

Sometimes true

Exactly. Trying to figure out which parts are the true parts.

hot_rod

If you want the best accuracy, and if you also want energy info, a certified BTU meter is the way to go. Find the Onicon on e-bay from time to time.

EdTheHeaterMan

hot_rod said:

If you want the best accuracy, and if you also want energy info, a certified BTU meter is the way to go. Find the Onicon on e-bay from time to time.

Now this guy NEEDS to know what is happening inside those pipes. He works for a manufacturer of the Stuff we use... and he has some pretty cool toys to play with. If you want the real deal, to have the inside scoop, to be in the know... Bob has probably already tested it, and he helps to wright the book that tell us what in going on inside those pipes. Not a Hobby. It's his job to know.

JohnNY

@hot_rod
The mechanical drawings I get on projects routinely include balancing valves on all secondary circuits. Once installed, they are rarely looked at a second time. 
Caleffi’s Quicksetter is my go-to balancing valve when I actually need to know my flow rates but I’ve learned not to automatically line-size them. Rather, I drop down a size or try to calculate my expected flow rate and size for the valve that indicates within range. 

In other words, there’s a learning curve to using the Quicksetter. Just like everything else. Great product though. Clients love the optics of having them. 

I also have this stupid thing but it feels archaic to me. 

https://www.dpgaugestore.com/product/820/

pecmsg

DCContrarian said:

Hi --
Is there a gauge you can put on a hydronic system to measure water flow? If possible I'd like to measure individual zones to get an idea of heat output.

How accurate do you want to be?

For a simple home system just measure the supply water temperature and return temperature. Get them all roughly the same. In my house I'm running 20°F Delta.

hot_rod

The Quicksetter is and foremost  a balancing valve as @JohnNY mentioned. Intended to add additional functionality to the ever popular B&G  Circuit Setter. You set the flow to the engineered design or equipment spec. It eliminates the need to connect a meter every valve in a building to make the initial setting. In many cases it is a one time use valve.

For ongoing visuals of flow, a flowmeter, a constantly  spinning type is a better choice, they more accurately read down to 1/10 of a gallon resolution. There is a standard for energy meters now that they test and  certify to. So it is accurate when it leaves the factory

I would not put 100% confidence in the  flowmeters on the manifold either. I consider them flow indicators, not precise flow measuring devices. Notice how they bounce around if you don’t have a completely air free system. Dirty fluid renders them useless after time also.

There is no 100% perfect way to measure hydronic flows  in my experience. The people that do this for a living, Badger Meter, Onicon, etc are clear on the pros and cons of each type of meter.

Wait until you try to meter sewage water😯

hot_rod

Vortex shedding is another flow measuring method. You'll see these sensors used in some circulators, solar pump stations, etc. Inserted right into the pump body.
This little paddle looking device can also sense temperature or pressure. It is what is giving information to the control to modulate pump speed, for example.

I've found with high glycol % they can drift a bit.

Jamie Hall

So many ways to measure flow... I get a bit of a chuckle out of the comment on sewage, though -- or storm water. My go-to device for those applications was and remains a Parshall flume, but they only work for open channel flow. Otherwise, venturi meters or the very similar in principle rising float meters (gravity return, not spring) are pretty bulletproof...

rbeck53

Can't he just use the hydronic formula for simplicity?

hot_rod

500 X flow X delta t
So you would need to measure or know two numbers

Delta tee is easy to measure, accurate flow needs to be used for the formula to be accurate

with a pressure gauge you could measure across the pump, then use a pump curve to get a flow number

rbeck53

Flow=BTU/(Delta-T*500)

GroundUp

rbeck53 said:

Flow=BTU/(Delta-T*500)

I suggested this twice and was ignored both times. It doesn't appear that simplicity is an option here....

hot_rod

What BTU number would you use, input, IBR, DOE/CSA, steady state, cycle efficiency, altitude derate?
Seems like the BTU would be the most inaccurate number to pin down.
Unless you have a BTU meter, which is a rotary meter and delta T reading.

GroundUp

Whichever number fits the application. This isn't rocket science. Simple delta T and run time data will easily get within 5%. OP expressed their disinterest in spending QuickSetter money, so this simple formula is a free way to get very close.

DCContrarian

OP here. I know delta T. I'm trying to measure BTU output. The heat source is an air-to-water heat pump with a variable speed compressor so measuring input isn't a simple matter.

pecmsg

Thats almost impossible. The compressor speed, ambient temperature are always changing trying to match the load. Bet you can do is go by the manufacture's performance data.

hot_rod

Back to your original question, here is an assortment of flowmeters I have used. Anything with a window gets to be useless after a few years unless you keep the fluid very clean.

If you want to do multiple zones inexpensively, maybe try some of these imports from Amazon. Hard to find much of any meter at that price. 56 bucks for 2!

Voyager

hot_rod said:

Actually the Quicksetters are + or - 1%. I have compared them to certified lab quality test meters.

Inside the Quicksetter is a piston with a magnet attached. The magnet moves the indicator ball. If you have crappy water with ferrous particles or magnetite it can stick to the magnet and hamper movement. This only happens when the ring is pulled.
It's good to have a magnetic separator on hydronic systems. It protects ECM circs and Quicksetters.

Any accurate device, mix valves, balance valves, PIC valves, etc need to be protected by a separator or Y strainer.

It's the ultrasonic flowmeters either Doppler or time transit type that can be finicky, they depend on the attachment to the pipe and condition of the inside of the pipe. Any rust or scale inside or outside the pipe affects them.
Any air, even micro bubbles in the piping throw them for a loop also. Dirty fluids and thick glycol confuses them. If the fluid cannot pass ultrasonic energy, it cannot be measured.

I've connected our portable ultrasonic to hydronic systems and have gotten no reading.

The rotary type meters are what are used on BTU meters and residential water metering, I find them to be very accurate.

With the Quicksetter you can both observe and adjust flow if you find you need to do some balancing to improve the systems performance.

I doubt most people could read the scale to 1% on those. 1% of the minimum reading of 2 GPM is 0.02 GPM. Trying to interpolate that on the scale provided is impossible. Even the 0.07 value for 1% of full scale would be a challenge with marks only every 1 GPM that are both close together and logarithmic. Even if the device is inherently that accurate and repeatable, I doubt the reading of the scale is. But it certainly is better than nothing and much less expensive than most other nonintrusive flow measurement devices.

lkstdl

https://forum.heatinghelp.com/discussion/comment/1798447#Comment_1798447

I use the Baylan pulse-output water meters, sold by ThermAtlantic.

https://thermatlantic.com/controls-metering/meters/

The tailpieces provided were straight thread rather than tapered, so I recut them on my pipe threader to NPT.

They also sell a full heat meter kit but I haven't used it. In my case I need both metering and control so I made something myself.

I use the Raspberry Pi Pico microcontroller to count the pulses, and to take temperature readings from a pair of DS18B20 sensors. The data is stored locally and sent over WiFi to a PostgreSQL database. To physically connect everything together more easily, I made little printed circuit boards that sit on top of the Pico and have JST PH 3-pin connectors and the resistor needed for the 1-Wire protocol.

Luke

Kaos

I've been looking at this as well recently. The simplest I have found is something like bellow. Reasonable cost from your favorite overseas seller.

This does flow through the pipe without needing to cut in plus with the clamp on PT100, it can do heat directly. Modbus interface, so easy to read if you are into PLCs.

https://www.tultrasonicflowmeter.com/Content/upload/pdf/202113087/TUF-2000M-Modul-Ultrasonic-Flow-Meter.pdf

fentonc

I needed to solve a nearly identical problem (estimate BTU output per zone) for a similar reason (just curious about my heating system performance). I did it strictly based off of the supply and return temp on each zone and the specs for the type and amount of radiation in each zone (and the air temps for that zone).

The supply and return temps just tell me the average temperature of the radiation in that zone at any given moment, the datasheet tells me the heat output based on air temp and water temp per foot, and then I measured how many feet of baseboard for each zone. With a low-mass, zoned system and a cast iron boiler, the water temps (and in practice, the flow to any given zone) are pretty dynamic properties, so I just track estimated BTUs every second and integrate over time. This seems to give pretty good agreement with my overall system measurements.

jumper

I'm surprised that nobody weighed in on what I posted months ago.

»Tap to read pressure drop across device you have a system curve for?«

Easy and inexpensive. But I don't think even AssocAirBalance handbook mentions it.

BTW how do you guys calibrate your fancy instruments?