Flow Meter Cement not comptatible?

I used Christy’s Red Hot Blue Glue and primer to attach my flow meter to my system. I was very careful to prime the fittings and let them dry before gluing them together. I them glued the fittings and allowed them to dry overnight before pressurizing the system. TWICE now - the fittings have blown apart. It looks like part of the PVC on the flow meter was ripped from the flow meter.

@Malibupacific - why not use the recommended Orbit PVC-lock fittings? I haven’t seen in any documentation where Rachio says one use glue to connect the flow meter to piping. I have seen where Rachio says that glue can mess up the readings, i.e. excess glue from the back of the joint hanging down into the water stream.

I believe the plastic is ABS, not PVC. @brad mentioned the flow meter materials in another thread and listed ABS, not PVC.

There is your problem. PVC primer is almost more of what bonds the joint together more so than the glue…you want the primer to be wet when you apply the glue. It is what softens the PVC and creates the chemical bond. The glue more or less fills the voids…also, with the red hot, primer isn’t really necessary.

Now…if the flow meter is made out of nylon or something other than PVC, disregard. PVC primers and cements may not work…

Just found this in the tech specs. And this would make sense as to wye it chewed up the ABS flow sensor. The chemicals in the primer and cements are way to aggressive for ABS.


You could possibly get by with utilizing transition glue…I’d have to do some research to see if the transition cements are rated for pressure, as they would typically be used for transitioning from ABS to PVC in drainage applications…

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Thanks for all the input! I called Rachio and they couldn’t help me. I’ll get some ABS glue and use that.

That won’t work with the PVC though…If it will work, which I’m not sure it will, you would need transition cement at the very least. The spec on the manufacturer I work with doesn’t recommend for pressure…

Then transition cement it is. I don’t know why Rachio didn’t make the meter out of PVC. I’m certain most home based systems use PVC…

Being that you probably aren’t much over 50-60 psi, you might be ok, but again, transition cement is designed for drainage, non-pressure applications…it may blow apart again.

@Malibupacific, please use the recommended fittings as outlined at rachio.com/flow

We DO NOT recommend using glue.

Correct, the Flow Meter is made of ABS and requires a special solvent to connect ABS to PVC; additionally, the solvent needs to be rated for high pressure. For this and flow disruption risks, we DO NOT recommend using glue.

@Malibupacific, I’ve confirmed your ticket(s) are in queue for review. We’re here to help!


PVC cement actually melts the PVC and literally bonds it together.

Transition cement doesn’t form a structural bond. ABS drain pipes are not under pressure and aren’t rated for pressure and neither is the transition cement.

If you do this, make sure to sand the parts of the fittings that contact the cement to give it more area to grab on to.

The Shark Bite PVC fittings are still cheaper than risking the damage to the sensor. I even use the Sharkbite PVC to Copper transition fittings on some of my installs.

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International Plumbing Code does not allow PVC pipe to be glued to ABS. Use a Orbit or other loc fitting. Christy’s hot glue is the absolute worst possible choice you could have made. It is only for fast setting repairs with PVC pipe and fittings.

Are there any special precautions that may now need to be taken if the OP chooses to use push-on type fittings instead of the unsupported glue option? I have no experience with transition glues, but am wondering the condition of the flowmeter outer ABS after the application of glue and subsequent blowout failure - might this impact the o-ring’s ability to properly seal?

It will be important to clean off any glue that has built up by using the least aggresive method possible to avoid damaging the outside diameter of the flow meter. Since the PVC glue didn’t have much of a chance of sticking in the first place, a small plastic scraper could do the trick of getting the glue off…

I can’t image that too much PVC glue can even stick to the ABS. In the event that some is still there, I would carefully cover the ends of the sensor and use some rubbing alcohol on a sightly dampened rag to carefully remove any small glue spots.