Yet another 3/4 vs 1/2 inch PEX question - Pump vs Municipal

[Glenn Stowe]

I recently did a bathroom reno in my 4-season cottage. While I was at it, I thought I'd swap out all the old 1/2 inch copper and PEX in the crawlspace with 3/4 PEX for the main supply lines to the bathroom fixtures. The thinking being I'd get the best water volume at the shower fixtures.

But..

The opposite seems to have happened. Water volume is poor, there are no strong flows coming from any of the shower fixtures.

I know normally the swap shouldn't make that much difference, but I am not on municipal supply, I'm on a pump that comes uphill quite a ways from a lake.

So my current theory is that the extra volume in the supply lines is too much for the pump to push and I should swap everything back to 1/2 inch to reduce the load/head. Between the hot and the cold there are probably 50-60 feet or so of 3/4 PEX in the system.

Before I try that, does this theory make any sense?

To add to the complexity, the pressure tank is also currently out of commission (blown membrane). While still in the system. But my understanding is that the only difference that makes is that the pump has to kick in more often. True?

 

[Reach4]

So my current theory is that the extra volume in the supply lines is too much for the pump to push and I should swap everything back to 1/2 inch to reduce the load/head. Between the hot and the cold there are probably 50-60 feet or so of 3/4 PEX in the system.

Switching to smaller pipe will not help with having better flow in the house. It could make priming easier, but during operation it would mean a little less flow to the house, and lower pressures at the house fixtures during flow conditions.

Where is the pump?

 

[Sponsor]

 

[Reach4]

Switching from 3/4 to 1/2 from the water heater to the bathroom could make hot water arrive a little sooner.

 

[Glenn Stowe]

It's a jet pump in the lake. Been doing more reading and I'm starting to think it's the shower diverter. The old system was just a basic two way at the tub spout. The new one uses a Delta multichoice 6-way (set up as three way). This guy drilled out the cartridge to fix it, but that seems kind of drastic.

 

[Reach4]

Get a pressure gauge. You can attach a garden hose pressure gauge at a laundry tap, garden hose spigot, or the drain on a water heater. Check the water pressure while a shower is running.

If available pressure is way down, even during no-flow, the jet may be clogged.

 

[Glenn Stowe]

It's just the shower fixtures actually. Everything else in the house seems fine. (Although you don't expect as much out of most other fixtures, so it may just be less noticeable.) Which again kind of points to this mixer. I'll know more when I install the new bathroom faucet in a couple of days, so I can see how the pressure is there. In the meantime, I ordered a replacement cartridge that I can experiment on with a drill.

 

[Reach4]

Get a GHT pressure gauge too. 0-100 psi or 0-60 psi if you can find one. Avoid 0-200 psi.

Actually GHT pressure gauges are probably carried locally at your hardware store or farm store.

 

[Jadnashua]

Newer shower heads almost certainly have a lower GPM output than older ones. But, people often confuse pressure and volume. ON a showerhead, you want some velocity, otherwise, it's more like a rain shower head. To get velocity through a nozzle, you need a restriction, otherwise, it doesn't speed up. So, it somewhat depends on where any restriction is in the supply. If it's at the valve, then that means the shower head won't be seeing an excess volume, so it won't try to speed up the flow to maintain the same (or as much as it can) volume...you always want more supply than the shower head can pass to maximize the velocity increase. The design of the showerhead can vary the outlet feel of the head quite a bit based on the desires/goals of the designer...they may not match your preferences.

Installing pex with lots of fittings to make changes in direction costs more, and will lower the pressure and volume available at the end point. THe stuff bends, so fittings to change direction often aren't needed.

FWIW, when doing pex, many tend to use way more fittings than needed, and each of them will add friction and (slightly) decrease the volume available. The fittings with crimp rings will affect that more than those that rely on expansion, as the ID is decreased by the crimp ones more than the expansion ones.

 

[JeffeVerde]

The surest test is a pressure gauge, comparing readings at one of the shower heads to a faucet upstream of the in-house plumbing (hose faucet near the main entrance?)

If you noticed the issue immediately after the repipe, it's possible you introduced some crud into the system and have clogged the shower heads, or the flow restrictors, or, depending on the style, even the tub/shower diverters. If you didn't do this after the repipe, remove and examine/clean all the aerators, shower heads, and flow restrictors, and run all the fixtures to flush them. Before tearing into the cartridges and diverters, I'd get a pressure gauge and confirm that the pressure at the main entrance is in fact higher than at the fixtures.

 

[Valveman]

If the bladder in the tank is bad the pressure will be low and you are cycling the pump to death. Replacing the tank with a PK1A kit will not only fix the cycling problem but uses a much smaller and less expensive pressure tank while delivering much stronger constant pressure to the house.

 

[Glenn Stowe]

I had to google that PKIA kit, but that sounds like a fantastic idea. I'll be doing that.

I did get a pressure gauge, weird readings around the house. I have a drain faucet right next to the pressure switch, and screwing the gauge into that one shows 35 lbs. But the gauge on the pressure switch right next to it reads 65 (I have it set high). I'm going to be ripping all that out and replacing the tank and all the fittings anyhow, it's a real mess of partially corroded stuff. Hopefully when I clean it all up this will solve itself. Thanks for the tip on the PKIA kit that sounds like a fantastic idea. I live in constant fear of the jet pump failing in the middle of the winter. It's 100 feet out into the lake under 3 feet of ice.

 

[Reach4]

I did get a pressure gauge, weird readings around the house. I have a drain faucet right next to the pressure switch, and screwing the gauge into that one shows 35 lbs. But the gauge on the pressure switch right next to it reads 65 (I have it set high).

If pressure gauges differ by more than what can be accounted for with altitude, and while there is no flow, probably one of the gauges is bad.

If they differ only when there is flow, then there is probably a blockage, such as a clogged cartridge filter.

 

[Jadnashua]

If the tubing that goes to the pressure switch is partially clogged, it may not be able to sense the pressure properly, and you can get some flakey results.