I have been told that it is not advisable to use pex pipe between the valve and the tub spout, as it may result in pressure that sends the water to the shower. If the pipe is the same inside dimension as copper, then why would this be the case - unless the pex elbow being smaller might cause this ? I would like to plumb this without resorting to solder, and am trying to find out if it is possible. I also wonder if different brands/quality of valves might address this problem - I am using a new Moen posi-temp valve.

Also I have heard that the distance from the valve to the tub spout should be at least 11 inches and up to 18 inches. Does it matter ? Is it only about esthetics, or are there technical reasons for limits on this distance ?

Thanks.

Mike

I have been told that it is not advisable to use pex pipe between the valve and the tub spout, as it may result in pressure that sends the water to the shower.
It shouldn't cause backpressure but using Pex pipe as a spout stubout is a really dumb idea. You want your tub spout to be tight and secure, not flopping aroung because you connected it with flexible Pex tubing.

I have heard that the distance from the valve to the tub spout should be at least 11 inches and up to 18 inches. Does it matter ? Is it only about esthetics, or are there technical reasons for limits on this distance ?
We make our distance between tub valve and spout anywhere between 6 and 8 inches. If you raise the tub valve 18" above the spout you stand a very good chance of having the shower head leak water every time your made a tub draw. The shower raiser wants to be kept as long as possible so it can apply back pressure to prevent water from leaking out the shower head when drawing the tub. Keep the spout stubout ridged and the shower raiser as long as possible, We set ours at 76" above the floor line. Good luck, Tom

Thanks for the advice. The manufacturer suggests (just suggestions, not recommendations) the spout at 25", valve at 44" and shower at 77" - for their 3 piece tub shower (tub is quite tall, pushing spout up, and putting everything closer to the shower). I'll bring the valve down quite a bit which should help in these pressure factors.

Mike