PEX size for tub filler

[BruceL]

I'm redoing my bathroom and using a Kohler "Hi-flo valve" K-438 for the tub filler. My wife's ask is that the tub not take too long to fill up (our current tub is one of the huge ones that does take forever, thus her request). Every reference I see says 1/2" PEX is fine if it's serving only a tub. But my understanding is that 30' of 1/2 PEX won't come close to the 5.5 gpm per side this valve can deliver, so I should run 3/4 PEX instead, which is at least close.

It's a bit simpler to put a 1/2" off the manifold, so I wanted to make sure the extra work is worth it before running the extra 3/4" line with valve.

Since we have kids the water temperature is fairly low, so most of the fill has to come from the hot supply.

Thanks for any advice.
Bruce

 

[Terry]

That tub filler is rated for 11 gallons. I would use 3/4" to that valve.

 

[Sponsor]

 

[BruceL]

Thanks for confirming. No manifold for this one...

Bruce

 

[Jadnashua]

PEX allows a higher velocity for the water than say copper, but it comes at a price - the higher the velocity, the greater the friction and thus induced pressure loss. Bigger is better when you want to maximize flow.