# What is the best flow meter? **URL:** \ **Category:** Heatpump\ **Created:** [29 January 2021 20:24 UTC](https://community.openenergymonitor.org/t/what-is-the-best-flow-meter/16700 "2021-01-29T20:24:22Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![gck303](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/gck303/32/9889_2.png) [@gck303](https://community.openenergymonitor.org/u/gck303)\ **Post date:** [29 January 2021 20:24 UTC](https://community.openenergymonitor.org/t/what-is-the-best-flow-meter/16700/1 "2021-01-29T20:24:22Z")
I am really struggling to get a decent reading from the Sika VVX20 flow meter that is part of our Ecodan installation. I think it would be best to get a dedicated flow meter that provides a digital reading and not an analogue voltage. I have a couple of questions… I am aware of John Cantor’s blog post and will ensure that he meter is over sized. - it seems to me that the best (most reliable, accurate and easiest to interface with; though not the cheapest) is the Kamstrup when read via m-bus. Am I correct in this conclusion? - the documentation mentions the Kamstrup 402 and 403. Given that they all use the same communication method (mbus), can I in fact use any Kamstrup mbus meter? Thank you, George ---
**Author:** ![dlmpryor](https://community.openenergymonitor.org/letter_avatar_proxy/v4/letter/d/51bf81/32.png) [@dlmpryor](https://community.openenergymonitor.org/u/dlmpryor)\ **Post date:** [29 January 2021 21:12 UTC](https://community.openenergymonitor.org/t/what-is-the-best-flow-meter/16700/2 "2021-01-29T21:12:50Z")
How about a pulse output meter for $75 USD? > **[3/4](https://www.ekmmetering.com/collections/water-meters/products/3-4-water-meter-stainless-steel-pulse-output)** > > 3/4" Stainless Steel Pulse Output Water Meter - SPWM-075-CF. This is a great stainless steel water meter that can be read locally, or can be set up to be read remotely when paired with an Omnimeter Pulse v.4 and an EKM Push3 gateway. The complete... ---
**Author:** ![Bill.Thomson](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/bill.thomson/32/1834_2.png) [@Bill.Thomson](https://community.openenergymonitor.org/u/Bill.Thomson)\ **Post date:** [29 January 2021 21:40 UTC](https://community.openenergymonitor.org/t/what-is-the-best-flow-meter/16700/3 "2021-01-29T21:40:26Z")
> [@dlmpryor](#): > > How about a pulse output meter for $75 USD? Looks/sounds like a good deal, except for the size. (Imperial vice Metric) Strictly a guess, but I’m thinking he’d need one with metric threads. ---
**Author:** ![Robert.Wall](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/robert.wall/32/38246_2.png) [@Robert.Wall](https://community.openenergymonitor.org/u/Robert.Wall)\ **Post date:** [29 January 2021 22:03 UTC](https://community.openenergymonitor.org/t/what-is-the-best-flow-meter/16700/4 "2021-01-29T22:03:23Z")
Maybe not. My old pipework (where it isn’t lead) is ½" copper, yet the modern metric compression fittings work just fine. The reason is, 15 mm is the pipe outside diameter, whereas ½" is the inside. The threads are still the same. ---
**Author:** ![Bill.Thomson](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/bill.thomson/32/1834_2.png) [@Bill.Thomson](https://community.openenergymonitor.org/u/Bill.Thomson)\ **Post date:** [29 January 2021 22:06 UTC](https://community.openenergymonitor.org/t/what-is-the-best-flow-meter/16700/5 "2021-01-29T22:06:40Z")
That’s what makes me think it _might_ not work. E.g. over here with ½ inch copper tubing, ½ inch is the OD, vice the ID. Pipe is another story altogether. As you’ve often alluded to, _standards, many to choose from!_ (we make a distinction between _tubing_ and _pipe_) ---
**Author:** ![gck303](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/gck303/32/9889_2.png) [@gck303](https://community.openenergymonitor.org/u/gck303)\ **Post date:** [29 January 2021 22:22 UTC](https://community.openenergymonitor.org/t/what-is-the-best-flow-meter/16700/6 "2021-01-29T22:22:02Z")
It is for the UK, needs to fit to 22mm pipe. Is there any reason it is _better_ than the Kamstrup one? ---
**Author:** ![Bill.Thomson](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/bill.thomson/32/1834_2.png) [@Bill.Thomson](https://community.openenergymonitor.org/u/Bill.Thomson)\ **Post date:** [29 January 2021 22:23 UTC](https://community.openenergymonitor.org/t/what-is-the-best-flow-meter/16700/7 "2021-01-29T22:23:42Z")
> [@gck303](#): > > needs to fit to 22mm pipe. With 3/4 inch threads (~19mm) it wouldn’t be of any use to you anyway, would it? ---
**Author:** ![Robert.Wall](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/robert.wall/32/38246_2.png) [@Robert.Wall](https://community.openenergymonitor.org/u/Robert.Wall)\ **Post date:** [29 January 2021 22:52 UTC](https://community.openenergymonitor.org/t/what-is-the-best-flow-meter/16700/8 "2021-01-29T22:52:42Z")
22 mm is the old ¾" size (¾" inside, 22 mm outside, ≈1.5 mm wall thickness). If that meter is for ¾" pipe, it’s probably OK. If it’s ¾" BSP **thread** , that’s for 15mm (½") pipe fittings. ---
**Author:** ![Bill.Thomson](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/bill.thomson/32/1834_2.png) [@Bill.Thomson](https://community.openenergymonitor.org/u/Bill.Thomson)\ **Post date:** [30 January 2021 05:43 UTC](https://community.openenergymonitor.org/t/what-is-the-best-flow-meter/16700/9 "2021-01-30T05:43:57Z")
¾ inch pipe threads (US NPT, which that item has) have an OD of 1.05 inches. (26.67mm) The thread pitch is 14 turns per inch. [ANSI B1.20.1 - NPT - American National Standard Taper Pipe Threads](https://www.engineeringtoolbox.com/npt-national-pipe-taper-threads-d_750.html) About 4 years ago, forum user Jon Murphy acquired some gear via a forum member in the UK who “liquidated” (for lack of a better term) several “emonTH/flow meter” setups because the project fell apart. (Ref: [Free: EmonDHW setups for monitoring hot water use - #17 by markocoheat](https://community.openenergymonitor.org/t/free-emondhw-setups-for-monitoring-hot-water-use/1421/17)) I bought one of them from Jon. When I saw the flow meter, my first thought was the threaded ends appeared like they might fit a standard US garden hose. (¾ inch fittings/11.5 TPI) They didn’t. The _size_ was very close, if not the same, but the _thread pitch_ was not. So even if the size were to match what the OP needs, the thread pitch might be a show stopper. ![image](https://community.openenergymonitor.org/uploads/default/original/3X/3/e/3ec49ca4fa764dc0a258d451c477a1eff4f55d2a.png)