Valve box flow meter install feedback


#1

Reporting back in for those of you considering a valve box for an underground flow meter install… today I noticed that flow meter signal strength had reduced from excellent to poor. This resulted in incorrect flow readings and low-flow warnings this morning during my tests compared to the baseline I took yesterday.

After further tests, I wasn’t able to get the signal strength back up to excellent, but did notice that flow seemed accurate compared to the baseline when I took the lid of the valve box off. Since I recorded the baseline yesterday with the valve box lid off, this makes sense.

When I replaced the lid, the low-flow warnings started again.

Rachio team (@franz, @emil, @mckynzee, etc), is there any way to get more granular on the signal strength than just “excellent” and “low”? Would be nice to see the decibels to confirm that the lid is causing interference. I’m guessing you guys can read this from your end at least.

Any ideas on improving signal strength? Can anything be done with the LoRa on the controller side? I won’t be able to get the flow meter any closer than this without digging up my yard - not an option.

FYI, The flow meter is buried about 10 inches and is about 120-130 ft from the controller.

TL;DR - if you’re considering an underground install, you might want to wait for the Rachio team to weigh in.

:palm_tree::palm_tree:


Flow Meter (Gen 3) – What were you thinking?!
#2

@johnny2678 - I’m not a RF or Electrical engineer so take this all with a grain of salt. Radio waves typically go in a straight line (yes, there are reflections, etc.). Get a Pringles ™ can (empty after eating or disposing of the chips), remove the bottom and place it over the flow meter (may have to may some vertical cuts up the side of the can to get the can to go over the flow meter) and orient the top of the can towards the Rachio controller as best as you can - debating of where actual straight line or straight line that ends at the top of the valve box. This may help by acting as a directional antennae (don’t laugh hackers use this trick when war-driving trying to find open WiFi networks). Another option may be to wrap a wire around the flow meter and bring it to the top of the valve box (taped down at both ends on the outside top of the valve box) to see if the signal will propagate better above ground. Another option would be to get something that is less dense to the radio waves than the existing top - maybe plywood (and paint it green of course).


#4

All great ideas @DLane! Got a kick out of trying to explain to my wife that I was only scarfing down a whole can of Pringles to increase the signal strength in my new lawn gadget :laughing:

In all seriousness - an engineering diagram on the flow meter might be nice to see which side the radio is on if I try the wire trick. Rachio team, any input?


#5

Good idea, I had thought of staking down some thick gage plastic sheets over the top, but plywood sounds more durable, plus you can paint it green like you said.


#6

Hi @johnny2678, you are definitely at the far reaches of distance the system is capable of to an underground install. We are targeting 100ft, however, I think yours should work. We’ve seen 300ft to an underground install pretty easily and are giving ourselves some margin.

I suspect there may be something else going on with your low flow measurements, but I won’t be sure until I look at the logs. It shouldn’t give you a low flow or incorrect reading when you’re out of range. All the communication is error checked so you’ll either get a good value or nothing. Can you DM me your serial number (either controller or flow meter) and I may want to try some real time testing over the phone if you’re up for it.


#7

Also, is your controller above ground or is it in a basement? This makes a big difference.


#8

@brad, thanks for the response. Happy to do testing over the phone any time. Just let me know when.

Sent my controller serial in a DM.

My controller is mounted outdoors about 4.5 feet above ground on a cinder block wall, which could also be adding some interference.


#9

@johnny2678 if the cinder block wall is between the Rachio and the flow meter, I’d change the could to would. Along with any other structure (walls, fence (brick is deadly to radio waves), stucco has metal lathe behind it - ever heard of a Faraday cage?


#10

:googles faraday cage:

of course I’ve heard of it, who hasn’t?

:laughing:


#11

I’ll be doing some more radio tests tomorrow - hopefully I can lock it down.


#12

Quick update on @johnny2678’s flow meter:

First off, huge thank you to @johnny2678 for being a tester and taking an hour with me to try a bunch of different things. TLDR, 120ft to a buried flow meter with obstructions is on the hairy edge of the flow meter’s range.

We can see SNR (signal to noise ratio) of the radio which can be anywhere from -10 (worst) to +10 (best). John’s flow meter is sitting at -9 or -10 and intermittently dropping out. We did some testing and found 1. valve box cover had no impact 2. rotating 90 degrees had no impact and 3. upside down (batteries up) made the flow meter drop out.

I’ll see if there’s anything we can do to improve performance based on channel selection in this case and we’ll hopefully be back testing soon.

Again, big shout out to @johnny2678. Have a happy rest of your father’s day!


#13

@brad , @johnny2678,
Thanks for the work and info.

@brad,
Does the app or web interface offer this SNR info or were you looking at signal data reported to cloud that only Rachio can see? I’m wondering for other users that may want/need to run experiments on their setup.

Also, did you happen to determine that @johnny2678 low flow notification messages were from low signal strength?

From the photos published on the FCC website for flow sensor cert, it appears that the antenna is close to being under the printed Rachio logo on the sensor faceplate. https://fccid.io/2AOTBRFLOW/Internal-Photos/InternalPhotos-3847588. I believe the photo shows the top down view rotated 180 degrees as you would normally look at controller with connection LED towards top. (i.e. in this photo the led is shown towards bottom. I also believe the flow direction arrow in this photo points from right to left). That’s my interpretation anyway. Is that right?

The corresponding 900 Mhz antenna on controller is upper left as viewed on Rachio 3 FCC cert photo…https://fccid.io/2AOTB-ZULWC/Internal-Photos/InternalPhoto-w-antennas-3815931

@johnny2678
Which side of your valve box is closest to Rachio 3 controller? I’m just wondering if earth needs to be cleared out further close to sensor and/or on the valve box side closest to the antenna (outside box)…not that I know what could be filled in in place of dirt that would cause less RF impact than dirt or rock.


#14

@corfam - nice sleuthing on the FCC website. Your assessment of the 900Mhz radio location on the flow meter lines up with what @brad told me. If you’re looking at the flow meter and the flow arrow is pointing to the right, the radio antenna is on the top left side.

For now, there isn’t any SNR or RSSI signal strength data in the app, but Rachio can see SNR on their end. The app does report if the signal is Excellent or Poor (there may be more signal strength states but those are the only 2 i’ve seen).

@corfam - since you asked, my controller is physically located to the right side of the pic below. I suppose I could clear out some dirt to the right of the valve box just to see if that opens things up.
IMG_1560

Here’s a google maps pic for better reference, flow meter is by the street, controller is on the backside of my garage.
image

Thanks all, especially @brad for digging into this with me. And Happy Fathers Day to the Dads out there.


#15

At 112 ft. in 900 MHz with milliwatts + obstructions ( underground installation, garage, etc… ) you will never archive good signal level / reliability. You probably can install the controller in the other side of the garage an consider install it in a plastic box outdoor. Other factor is that in 900 MHz there is multiple equipments like telemetry, etc… system that basically have an impact in the SNR.


#16

I should clarify that the controller is already outdoors in an outdoor enclosure.


#17

@johnny2678 Great. Thanks for photos. I’m no expert on RF, but the pictures should help the community provide additional ideas. It sounds like @fpuig knows RF. The distance of your controller to sensor is certainly well within the Rachio advertised distance, so hopefully @brad has other ideas. My current thoughts are below. Some suggestions may sound dumb. :slight_smile:

  • At least for a trial, it seems you could move the sensor above ground by adding vertical sections of PVC…assuming you have water pressure to spare. If it worked, a support frame could be added and plants could help hide the setup.

  • Maybe Rachio controller and/or flow sensor antenna power is being currently being managed lower than FCC certified limits and can be tweaked by software change. Higher power would mean lower sensor battery life, but that could be trade-off for in ground sensor setups. Again, hopefully RF power isn’t already maxed out. Only Rachio team would know possibility there.

  • I wonder if any powered active 900 Mhz LoRa repeaters exist…and cheap ones at that.

  • I wonder, similar to what @DLane suggested if some type of passive RF director like the suggested “Pringles can” to surround sensor and direct RF towards controller would help…or maybe even a wire cut to specific length and placed near sensor to outside of enclosure to act as passive radiator.

Lastly…when you stated…

I’m wondering if you did have “excellent” RF signal strength initially was the sensor already in the ground at that point. ?? If so, it would be good to still figure out what changed. i.e Maybe the ground around valve box was initially dry during initial testing and significantly more moisture was there in later tests. …or maybe car wasn’t parked in garage when signal was excellent and has been in all other tests. Whatever caused the difference may lead to other possible solutions.


#18

Thanks again for the feedback @corfam. Always helps to talk/type it out when troubleshooting. There are no dumb suggestions :wink:

I should have enough system pressure to support this, but I would probably save this as a last resort. I could also drill through my block wall, extend my zone wires, and run them inside the garage so I could get the controller closer.

It’s my hope as well that Rachio can find a software solution that would extend the range for users that understand the tradeoff in battery life. I’m ok with changing the battery every year.

I wondered this as well.

I finished my can of pringles yesterday :wink: I have some work to do today but look forward to running some more tests. In the meantime, I did try and coil up some wire and place it over the antenna on the flow meter to see if signal strength was boosted.

Could be poor technique on my end but this doesn’t seem to have much of an effect.

When I measured excellent signal strength, I had just paired the flow meter to the device but it wasn’t installed yet. It was at ground level at the exact install spot - so it seems that the signal degradation is less from the garage/block wall and more from being buried ~10 inches or so and placed in the valve box.

Thanks again for the comments/suggestions.


#19

@johnny2678 I hope you don’t have to go through the trouble but it’s good controller antenna would then also face sensor in this configuration.

Again, I’m no RF guy, but wire length would matter to act as antenna tuned to somewhere close to 900 Mhz. FCC cert for Rachio’s flow sensor says transmit & receive is in the range of 903.8-922.2 MHz. Did you happen to cut your wire to a specific length? Just over 1 foot length would be good.

(https://www.digikey.com/en/articles/techzone/2012/nov/selecting-antennas-for-embedded-designs).

For this frequency range my calculations say wire length in the range of 12.8 inches to 13.1 inches would be appropriate. I would make it one continuous piece without the splice and probably also test leaving wire straight (no coil) where it rests on sensor.


#20

Good call on the antenna length. I’ll have some more time this afternoon to test some more configurations. thx again.


#21

great. When I said to test leaving wire straight I meant to say to align wire so that it’s parallel to PCB antenna as shown in FCC photo. That would put the wire sitting across short side of sensor like this:

image