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Author Topic: Electronic Flowmeter  (Read 31652 times)
Nicedad
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« on: January 27, 2008, 04:19:32 PM »

Good afternoon all,

I will be soon starting phase 2 of my installation which is data logging. Have brought a 6 channel data logger and temp probes but am thinking that I also need to record the amount of hot water used.

Does anyone know of a flowmeter that I can connect to the the output of the hot water cylinder to record amount of water used as a digital output?

As I only have limited hot water pressure, the less restriction that the meter offfers the better.   
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KenB
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« Reply #1 on: January 27, 2008, 05:37:17 PM »

NiceDad,

There are several flowmeters available from Farnell Electronics - most have a pulse output.

Try these, but note the 65C maximum water temperature

http://uk.farnell.com/jsp/Industrial+Controls+&+Automation/Flow+&+Level/DIGMESA/932-8506/displayProduct.jsp?sku=8544700&_requestid=170181

Or there are these ones with standard brass pipe fittings from RS Components

http://uk.rs-online.com/web/search/searchBrowseAction.html?method=retrieveTfg&binCount=2&Ne=4294957561&Ntt=flowmeters&Ntk=I18NAll&Nr=AND%28avl%3auk%2csearchDiscon_uk%3aN%29&Ntx=mode%2bmatchallpartial&N=4294955544&Nty=1


Hope this helps,

Ken
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wyleu
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« Reply #2 on: January 28, 2008, 12:45:35 PM »

I have used a low pressure non return valve with a very strong magnet of the flapper and sensed with a ratiomatic hall effect probe epoxied to the valve body, to good effect. It would require a local calibration of some sort, but if your sensing voltage this is a pretty simple way of doing it and the non return valve is a component of the solar system anyway. In fact you can get variances with just the valve but its no where near as emphatic as the magnet.
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dhaslam
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« Reply #3 on: January 28, 2008, 12:59:35 PM »


Have brought a 6 channel data logger and temp probes


I am interested in a similar setup, can you give some details? 
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Nicedad
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« Reply #4 on: January 28, 2008, 08:39:35 PM »

Thanks Ken and Wyleu for your suggestions, I'm favouring the RS Components item at teh moments due to its ability to handle high temps and the good flow rate. I'm afraid my electronics ability its up to the standard to consider Wyleu's suggestion.

dhaslam:  I brought the items on ebay. I've checked this evening and although the guy I brought from is selling something similar its not the same as the one I have which has an analogue output daughter board and storage capability.
May I suggest you email him. His user name is pandavilla and if you enter data logger on ebay's search you will find the similar 6 channal product that his is selling.
The probes I have are standard PT100.


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wyleu
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« Reply #5 on: January 29, 2008, 09:35:09 AM »

How about putting in both suggestions? Then we could calibrate one with the other?

Obviously not an entirely realistic suggestion but, do beware of just assuming that a measurement is accurate. Flow is a quite difficult to measure accurately and cheaply and some fairly novel methods have been used over the years.
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wookey
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« Reply #6 on: February 12, 2008, 01:19:39 AM »

These people do a good selection of devices and their 800-series suits solar loops reasonably well: http://www.flowmeters.co.uk/pd_800series.htm and are not too expensive at 39 each. The biggest one of those does up to 15l/m which is just about enough for DHW but has 0.7bar pressure drop at that rate, which is too high I suspect, so a bigger device is really needed.

I expect they have something suitable (I've just mailed to ask)

Much cheaper (13.90+VAT) and with more useful fittings is this:
http://abcotuk.co.uk/Product.asp?ProductId=P158&Catid=C2

Very few details about that but it's used in boilers so may well be ideal. I'm intending to buy one and try it at some point.

Honeywell make some nice flowmeters too, designed for combi-boiler DHW monitoring, but I haven't found a source yet for pricing: C7195A2/B/Chttp://europe.hbc.honeywell.com/oem/combustion/residential_heating/boilers/sensor_hydronic_controls.htm

We should probably start a wiki page on monitoring tech, to collect useful links like this, as it's not trivial finding good value suitable kit.


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Wookey
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« Reply #7 on: February 12, 2008, 01:09:50 PM »

I bought a mechanical water meter on ebay for 10. It counts in cubic metres down to 1 litre, so all I had to do was take readings every few weeks to find out our average water consumption.

It also has a pulse output to record electronically, but I did not see the point in spending more time and effort. Plenty of other jobs to do!


cheers
Paul
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Nicedad
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« Reply #8 on: February 14, 2008, 08:04:32 PM »

Thanks for your input chaps, but I still don't think I've found the right item: low restriction and an electronic output.

I'm after real time monitoring so that I can then best assess performance. I would see that when up and running I would even give a rating to when water was drawn from the system (ie water taken at 07.00 would score higher that water taken at 13.00).

I'll keep looking

Thanks again
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Paulh_Boats
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« Reply #9 on: February 14, 2008, 08:32:49 PM »

Mine is a Brita model with very low restriction..you can blow gently through the pipe and dials spin round. I put it temporarily in the cold feed to the header tank and it worked very well.

There is one pulse per 10L, is that enough?
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« Reply #10 on: April 30, 2008, 10:38:53 PM »

I've done some more flowmeter research (for monitoring my solar loop, not the DHW output).

I've found these items:
Swissflow SF800
http://www.swissflow.com/en/SF800/Flow_Meter_Specifications
Nice bit of kit. Popular with PC Gamers who do water-cooling. Not sure of pricing (when I asked they offered me a sample in excahnge for some results :-), but I've seen 20-40 euro quoted. Flow restriction is quite high though as it's small (3/8" fittings), so 2bar at 20l/m, which is far too high for DHW output, but may be just OK for solar loop (I'll find out soon). Temp spec is nominally only 90C, but the materials should be fine up to about 250C for low pressure, and the company said it used to be specced for 123C but they've got more conservative, so expect it'll be OK.

Remag vision 2000:
http://www.remag.ch/documents/bulletin_vision_2000_en.pdf
100C for this one due to metal body. 0.9 bar pressure drop at 30l/m for largest model: 46500-164-4F16,5. About 30 euro, also 3/8 BSP

And finally:
As well as the 800 series I looked at originally (with temp spec of 125C and acceptable (for solar loop) pressure drop of 1 bar at 15 l/m but deeply inconvenient 8/12mm barbs), Titan do a transducer with 15mm compression fittings:  http://www.flowmeters.co.uk/pdf/turbine_meters/Flow_Transducer/Flow_Transducer.PDF
This is only specced for 70C, 15bar, but again at 1-2bar the acetal+nylon are probably OK up to solar loop stagnation temps (one may be pushing one's luck a bit here - only one way to find out). 0.7 bar drop at 30l/m, so that's the lowest of the bunch. The 15mm compression is just what we want, and GBP 21+VAT is a reasonble price. I'm probably going to get one of these and try it too. (flowmeters.co.uk have been very helpful in discussing tech specs).

I mentioned the Caleffi 316 from abcotuk in an earlier post. This is very cheap at GBP 13.90 from Abcotuk but turns out to be hard to get data on, because it is an OEM device for a boiler manufacturer. (If I knew which one I could ask them for details). It also has a temp limit of 30C accordin to caleffi's website, but then there are several models of this, so that may not apply. I've boiled it for 20 mins or so in a pan and it doesn't seem to have come to any pysical harm. What I don't know is which pin is which, and what voltage it wants. Looks like I'm just going to have to guess/experiment. Nice solid brass body with 1/2" BSP fittings

Just thought it worth summarising this lot as I've spent a while this week finding it out. Relevant for anyone wanting to electronically monitor flow rates. Next I get to find out what the limits of 1-wire pulse-counters are.
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Wookey
wyleu
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« Reply #11 on: May 01, 2008, 01:28:44 PM »

Excellent stuff.
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sealo0
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« Reply #12 on: May 03, 2008, 06:23:31 PM »

I mentioned the Caleffi 316 from abcotuk in an earlier post. This is very cheap at GBP 13.90 from Abcotuk but turns out to be hard to get data on, because it is an OEM device for a boiler manufacturer. (If I knew which one I could ask them for details). It also has a temp limit of 30C accordin to caleffi's website, but then there are several models of this, so that may not apply. I've boiled it for 20 mins or so in a pan and it doesn't seem to have come to any pysical harm. What I don't know is which pin is which, and what voltage it wants. Looks like I'm just going to have to guess/experiment. Nice solid brass body with 1/2" BSP fittings

Just thought it worth summarising this lot as I've spent a while this week finding it out. Relevant for anyone wanting to electronically monitor flow rates. Next I get to find out what the limits of 1-wire pulse-counters are.


Wookey

Not too sure if this helps

This is from thr WRAS ~ Flow control List 

Listing Number: 0605130

Installation Requirements: R001               

316 range of plastic and brass bodied flow switches. The flow of water through the valve causes the flow sensor to operate which connects the electrical circuit. Maximum working pressure 10.0 bar.

Size: 

Designation: 316000, 316402, 316403, 316404, 316405, 316406, 316407, 316408.

Marking: `Caleffi`, 316 and flow arrow cast into body (brass body). `116170` moulded into body (plastic body).

Note: 

Proviso: 

Manufacturer: Caleffi & Co Spa

Factor: Altecnic Limited


Regards

Mike
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wookey
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« Reply #13 on: May 04, 2008, 01:27:08 AM »

MIke, yes, thanx for that - that's the device(s). I phoned Altecnic for info which is where I found that it was an OEM part and they don't have info. I did find that the one abcotuk are selling is the 316406 model.
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Wookey
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« Reply #14 on: November 02, 2008, 11:25:39 PM »

OK. I finally got my flowmeter attached to the logging setup. It's a swissflow SF800 and it's survived in the system for 6 months or so, including one stagnation day. Having finally realised that my counter was actually working already and all I had to do was connect things up I got some data today.

1311506 pulses counted today, which at 6100 pulses/litre suggests that about 215l were pumped round the loop. The pump was on for approx 130mins today, so that a flow-rate of about 1.6 litres/min. Now that's intersting, because my original out-of-loop pump test suggests that it would do 15 l/m at 9W so we appear to have a factor of 10 there. That may be entirely reasonable once you allow for the 11m of 10mm pipe, 2 manifolds, a check valve and a plate heat exchanger to push the water through.

It is possible that the counter is missing pulses as it can only count up to about 2kHz (it's a hobby-boards DS2423-based widget), and that happens around 20l/m. I'll check with a scope that it really is getting about the right numbers.

The swissflow was provided as a sample to determine it's suitablity for this application. The evidence so far is that it's fine. I did have a bit of trouble getting the threads to seal completely but _lots_ of PTFE tape did it in the end. I was a bit concerned about damaging the plastic threads by screwing brass adaptors on with massive spanners (and then off, and on and off and on adding more tape each time) but it's been fine. It uses a 5V supply, which is handy when using 1-wire for counting. Power consumption is about 0.1W (20mA @5V).

I'll set up some graphing now and we'll get some idea of repeatability and variance.
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Wookey
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