Both of these are labeled 1". The T on the left fits the little bit of grey pipe. The valve on the right is too small. What am I missing?

Close up of T, pipe and valve

3 Answers 3


That valve is for a different type of piping system called CPVC and the sizes and fittings are different. The difference is deliberate because CPVC is rated for hot water whereas regular PVC is not; they don't want people to accidentally (or deliberately, to save money) install regular PVC pipe or fittings on a hot water system.

Look at the valve label.

  • 3
    Would be worthwhile to refer them to the correct product :) homedepot.com/p/…
    – MonkeyZeus
    Jul 1, 2020 at 15:06
  • 1
    I would refer them to a plumbing shop, where the clerk would have been very likely to point out the odd fitting, rather than a "big box" store like Home Cheapo... Jul 1, 2020 at 18:41
  • 2
    Sure, that works too but I don't know where they live nor whether they have a local plumbing shop with a website catalogue of fittings to look at which I could reference.
    – MonkeyZeus
    Jul 1, 2020 at 18:44
  • @MonkeyZeus You should know that homedepot links can only be reached from the US. Maybe you could use a different reference?
    – AndreKR
    Jul 1, 2020 at 19:01
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    @AndreKR "1 inch PVC ball valve" in your local language should do the trick. I'm not sure how to satisfy the other 194 countries given that this website itself is targeted for an English audience.
    – MonkeyZeus
    Jul 1, 2020 at 19:07

When plastic piping systems were first introduce to the market, the manufacturers tried to make them similar to metalic piping systems so "pipers" would accept them. So they adopted similar wall thicknesses to schedule 40 and sch. 80. Piping systems have to be checked against the pressure and temperature of the process fluid. Here in was the problem. Adopting sch. 40 an 80 wall thickness caused inconsistant P-T rates for different sizes of plastic pipe. The solution was to create plastic pipe with a SDR, which stands for Standard Dimensional Ratio. SDR piping has the same P-T ratings regardless of pipe size.

Could one of you pipe and valve components be for a scheduled piping system and the other for a SDR piping systems?


Cpvc and pvc have the same od(outside diameter) and the fittings are interchangeable. The valve is probably just labeled wrong I bet a piece of 3/4 fits the valve just fine

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