How to increase water pressure/flow in showerheads

[CindyJ]

The specs for that model say it has a 5.0 GPM flow rate. Most modern shower heads are 2.5 GPM.

My plumber is here now and I've been discussing the pressure problem with him. He removed the Kohler Pressure Balancing Valve, took a close look at it and told me he doesn't see how an adequate supply of water could possibly flow through such small holes. I told him that that model has a 5.0 GPM flow rate and he's baffled. Could it really be that this valve is the source of the water flow problem? He does agree, BTW, that the 1/2" CPVC could be problematic, especially since it branches into two showers.

[CindyJ]

FWIW, both CPVC and PEX have a lower flow capacity verses copper based on the same nominal size. This is because the outside of the pipe is what is controlled, not the inside, so because the plastic pipes need more strength, their walls are thicker, thus, the ID is smaller.

So when I asked the plumber (who is here right now) specifically about the reduced flow rate with CPVC, he said yes, it's less, but not so much that it would be noticeable. It's his assertion that it's the design of the showerhead, itself, even with the flow restrictor removed, that is responsible for the reduced pressure. And now I'm beginning to think that I don't really understand the distinction between reduced pressure and reduced water flow insofar as my experience with the shower is concerned. That is, I don't really know if it's that I'm feeling less water or less water pressure than I felt with the old showerhead and the old pipes.

I also don't want to sound like I'm telling the plumber how to do his job, but hey, I'm paying for it and I want it done right.

[Hackneyplumbing]

Increase the system pressure at the well pump. No more than 80psi. Problem solved.

[LLigetfa]

Increase the system pressure at the well pump. No more than 80psi. Problem solved.

+1 But you may need to consult a professional to ensure the system is capable of producing the higher pressure without deadheading the pump, that the bladder tank precharge is adjusted, and that the pump switch doesn't have a low pressure cutoff that could nuisance trip. Also, pump cycling should be evaluated and perhaps mitigated.

[LLigetfa]

When you say "static pressure," does that mean a consistent water pressure as opposed to water pressure that fluctuates when the pump turns on and off?

Static pressure is simply the pressure that exists in the absence of flow. Resistance in the lines, valves, aerators, showerheads, etc., will all conspire to reduce the pressure under varying flow conditions.

[LLigetfa]

I went down to the basement and the good news is that there is 3/4" pipe running from the filter to various places in the house...

Is this the first mention of a filter?

Filters can be flow restrictors so they too must be factored in. When there are disruptions to the plumbing system due to work that requires the system to be shutoff and drained, the subsequent in-rush can disturb sediment that used to lay dormant and this sediment can clog the filter and restrict flow with in turn restricts pressure.

[jadnashua]

Ever notice the difference in the flow out of a hose when you offer a restriction? The water speeds up when you put your thumb over the end and sprays further. A showerhead does the same thing. But, now partially shut the valve, and while the pressure is exactly the same feeding things, the spray is no longer as intense. A valve that is flowing it's max and the shower head able to take all of that, isn't creating that speedup because there's no restriction. To get decent speedup, you have to be able to supply more water than the showerheads are designed for, otherewise, you'll get a feeble spray. that doesn't mean the showerheads will spray more, but that they will spray harder - there must be a restriction for the water to accellerate in the showerhead, and 5gpm in with (essentially) 5gpm out, there's no restriction in the line, thus no accelleration.

[CindyJ]

Increase the system pressure at the well pump. No more than 80psi. Problem solved.

When I asked the plumber about increasing the system pressure from 40-60 PSI to 50-70 PSI he told me that the system would "blow" at 75, so increasing it wouldn't be a good idea. Part of what I'm up against is that I have no way of knowing if what he's telling me is correct and accurate.

[CindyJ]

Ever notice the difference in the flow out of a hose when you offer a restriction? The water speeds up when you put your thumb over the end and sprays further. A showerhead does the same thing. But, now partially shut the valve, and while the pressure is exactly the same feeding things, the spray is no longer as intense. A valve that is flowing it's max and the shower head able to take all of that, isn't creating that speedup because there's no restriction. To get decent speedup, you have to be able to supply more water than the showerheads are designed for, otherewise, you'll get a feeble spray. that doesn't mean the showerheads will spray more, but that they will spray harder - there must be a restriction for the water to accellerate in the showerhead, and 5gpm in with (essentially) 5gpm out, there's no restriction in the line, thus no accelleration.

Is the restriction you're referring to in the valve, or is it in the showerhead? I don't think there's anything that can be modified in the valve, and even with the restriction removed from the showerhead, the flow rate is still only about 2.5 GPM. Are you saying that that flow rate is okay because, as LLigetfa stated earlier, the valve is rated at 5 GPM? Or am I thoroughly confused?

The reality is, what I really want is a "hard spray" -- I don't think it matters if it is the result of increased flow or increased pressure.

[LLigetfa]

...the flow rate is still only about 2.5 GPM.

Is that the flow through the showerhead? If you remove the showerhead how much flow do you get? If about the same, then the combined flow restriction of the valve and upstream piping is to blame.

Ask you plumber what part of the system would "blow" at 75 PSI? It is not unusual for city pressure to be higher than that and most places code only call for a pressure regulator above 80 PSI.

[CindyJ]

Is that the flow through the showerhead? If you remove the showerhead how much flow do you get? If about the same, then the combined flow restriction of the valve and upstream piping is to blame.

Ask you plumber what part of the system would "blow" at 75 PSI? It is not unusual for city pressure to be higher than that and most places code only call for a pressure regulator above 80 PSI.

Yes, that was the flow through the showerhead. I'll have to wait until the weekend to test the flow without it.

I'll have to get clarification regarding what would blow at 75 PSI. He said something about water spraying out. I'll find out.

[jadnashua]

The outlet of the valve must supply more water than the showerheads can use, or their output will be like a hose with no nozzle on it - weak.

[Hackneyplumbing]

That valve has a flow rate of 5 gpm but at what pressure? Kohler is keeping that a secret I guess. Hey Kohler......how many flappers and flushvalve seals are you guys making now???? 15?? 20? You guys need to start drug testing your engineers. LOL

[jadnashua]

As I've said before, Kohler is infected with NIH (not invented here). They like to come up with their own ideas, and when the first one doesn't work, they come up with another, and seem to refuse to use the long-term wisdom of what is known to work...this is the reason their parts book looks more like a telephone book...it's huge because they keep few designs around for long. Others use a more universal guts that they know works, and can be built on large scale, and then just play with changing the trim to update the look or adjust to newer technology; not Kohler.