No water in shower?

[carzt]

I'm renovating an existing house which I don't yet live in. The bathroom was just redone (including new pipes) by a professional plumber. There is quite good water pressure in the sink, light pressure in the rain shower, and just a very slight trickle in the shower and bathtub. The plumber says the pressure is too low, and suggests a water pressure tank. Note this is in the Philippines.

I've included a diagram of the plumbing below.

Is it likely that the lack of water in the shower/tub vs. the sink is just low pressure due to the additional elbows in the pipe going to the shower/tub (8 elbows) vs. to the sink (5 elbows)? How can I estimate the additional pressure required (and thus whether a pressure tank will help and what I should get)?

Thanks for any advice,

Chris

[hj]

With low pressure elbows have negligible effect on the delivered pressure. We would have to know more about your system, such as whether it is a gravity system using a tank on the roof, or where the water comes from. A "pressure tank" does not create pressure, so it will not help unless you have some way to pressurize it, such as a water pump.

[carzt]

The water comes directly from the main water utility pipe. No water tank on the roof.

If we get a pressure tank, it would of course be accompanied by a pump to create the pressure

[jadnashua]

The size of the pipes and the actual pressure you have will determine how much water you can get there. If the pipe diameter is too small, or the pressure is low, you cannot provide enough volume to do what you want. Now, how many heads are you trying to run in the shower at once? That may be an issue with the valve chosen...it might just have too small internal passageways to provide the desired volume at a nice pressure.

I dont know how easy it would be to find, but a pressure gauge is the only way to actually tell what your supply pressure is. In the USA, you can pick up a reasonable one for about $10US. As HJ said, the number of elbows probably isn't an issue, and if it is, its effect is small.

[Terry]

They do make products that increase water pressure, typically and tank and pump combined to boost the pressure.

A few fittings on the way to the valves isn't causing your problem. You may want to try flushing the lines though. Have you put a pressure gauge on the system to find out what your static pressure is?

[bluebinky]

Maybe some kind of obstruction got into the mixer or diverter valves?

[carzt]

Thanks so much for all for the comments! My replies and follow-up questions below.

- I am only trying to run one head at once. There is a tub faucet, a shower head, and a rain shower head. But I'm only turning on one at any given time. Even so, only a few drops come from the tub faucet, a small trickle from the shower, and low flow from the rain shower. (Pressure in the sink seems fine.)
- I bought a pressure gauge. I can try it at the sink to measure the pressure I'm calling "good/normal". I can attach it to the tub outlet, but I know the pressure there is essentially zero. Or should I be measuring pressure before the water line ever gets into the house?
- If the 3 extra bends to the bathtub faucet (vs. the # of bends to the sink) are very unlikely to cause the problem, then it has to be some sort of obstruction (is that right)?
- So I need to try:
- flushing the lines (hopefully the plumber knows how to do this)
- looking for an obstruction in the diverter or mixer. Can I do this without opening up the wall?

- Chris

[Terry]

flushing the lines (hopefully the plumber knows how to do this)
- looking for an obstruction in the diverter or mixer. Can I do this without opening up the wall?

Sometimes.
I would first look at the aerators on the faucets, making sure they are clean.
Open all of the shutoffs, just make sure they are partially open.
If there is junk in the cartridge, that can be serviced without going into the wall.

[carzt]

Terry, hj, jadnashua, and bluebinky:

I met with the plumber on Saturday. He said the problem was low pressure, but he hadn't actually measured the pressure. So we measured it and the pressure is about 48 psi. Shouldn't be a problem, right? So we discussed further and he admitted he isn't very familiar with this sort of imported equipment (mixer/diverter).

Previously we had the hot water off so water was only actually coming in to one side of the mixer. When we turned on the hot water so both input pipes to the mixer had water, then pressure from the rain shower was very good. But when we turned the diverter handle to send water to the bath tub or regular shower instead there was almost nothing.

I had the plumber take everything off (without opening up the wall) and I noticed that when the mixer was still in place but the trim was off the diverter, water was only coming out of one of the diverter holes (see attached picture). I believe this is the problem - there must be something blocking the other two holes or somehow it's installed incorrectly. Is this right? The plumber said he would open it up and check.

Thanks again,

Chris

[jadnashua]

All modern shower valves will (or at least should) not work until you have (nearly equal) supply water pressure on both sides - you must have BOTH the hot AND cold supplies turned on for them to work. This is because of an internal pressure balance valve or check valves (depending on the design) to prevent scalding when say someone flushes a toilet on a system that can't maintain the pressure properly.

[carzt]

Thanks jadnashua. Now that we have both the hot and cold supplies on, there is strong water flow to one of the three input holes in the diverter, but the other two still have no water flow at all. Presumably the plumber can figure out why that is.

[Terry]

48 PSI is plenty
With a balanced valve, if the hot water is shut off, it will match that incoming pressure and force the cold off too.
Some diverters have an incoming port, and then two ports out, which can be shower head, tub spout, or hand held.
What brand of faucet are you installing? I think we are getting close on this.

[carzt]

Terry:

I think the diverter has one incoming port and three ports out. The one incoming port seems to split to 3 separate holes which feed into the diverter "cartridge". Water only comes from one of those three holes right now.

The diverter is: PN-199733B - Pioneer Three Way Diverter Valve
The mixer is: PN-4020B - Pioneer Pressure Balance Valve

- Chris

[hj]

The diverter, if it is NOT part of the faucet will only have water coming out of one opening from the control valve. The other two openings go to the two devices, whatever they are. You have a "confused" plumber is trying to "learn" about the problem while you are paying him. Usually a very expensive way to get something fixed, especially if he is just guessing at what has to be done. WIth 48 psi you do NOT have a problem with "low pressure" and he could have figured that out within 5 minutes after he got to your house.

[carzt]

Thanks all for the help. The issue was just some junk in the pipe which clogged the diverter. Your comments gave me the confidence to tell the plumber that his prescription "the water pressure is too low" was wrong!