How many valves are you going to use to operate this shower head? I ask because most shower valves I'm familiar with are restricted to 2.5 gpm.

This is the valve I'm using and it can push 21 gpm http://amzn.to/1XENYbG.

Regardless of valve, question remains, should I get the version with 2 or 4 inlets? For reasons unrelated to plumbing I prefer the 2 inlet product but will get the 4 inlet version if it will operate better.

Anyone?

I know I'm not answering your question, but I just want you to consider that you will need to run at least two 3/4" lines IN to that valve. And also a rating 21 gpm is not for each Out connection but for all six. You'll also need a tankless heater since you'll drain any reasonable size tank in one or two minutes.

And to maybe answer your later question, this unit is rated at over 4gpm so you will need to run at least two lines from that valve, assuming that each is just a bit over 3 gpm.

A week or so ago - you wanted to save $50 on hydronic towel warmer fittings - now you want to spend $900 on a shower valve and $600 on a shower head. This all doesn't make sense.

So much wrong. Why do people give advice about things they aren't familiar with.

This valve can supply up to 10 gpm per port. With 1 or 2 simultaneous ports the valve can supply the maximum of 10 gpm to each. If running more than 2 ports the formula is 21/X. So with three ports it's 7 gpm each (21/3=7). This is straight from Kohler.

At 4 gpm one line will be fine and it would be fine even if I was running five ports simultaneously (21/5=4.2). Assuming 70% hot water, my 85 gallon water heater can keep this shower head pumping for 30 minutes which is much longer than I'd ever need it.

So back to my question. I'm going to split one of the valves into 2 or 4 lines (depending on which shower head I buy) to feed the shower head and that will easily supply enough water. The question is if the 4 inlet version of the shower head has has an inherent performance advantage or if the performance of both can be expected to be the same.

Geoffrey, don't try to understand my purchasing habits. Whatever I buy, cheap or high-end, I pinch every last possible penny. Because I'm trying to save money doesn't mean I'm buying cheap stuff and it doesn't mean I don't buy quality products. My kitchen is filled with Miele and Sub Zero appliances -- purchased as cheaply as possible.

Wherever money can be saved I try to save it. Makes perfect sense to me :-)

Ack! I got my specs all mixed up. Been looking at too many shower heads. Before I start a new thread I thought I'd see if I can get an answer here.

The two shower heads I am considering both have two inlets. The difference is one is 2.5gpm and the other is 3.7gpm.

I like the finish of the 2.5gpm better and like that it is more water thrifty. My question is with a shower head this size is the difference in water pressure between these tow models going to be perceptible? And if so, will 2.5gpm be disappointing?

Thanks!