No pressure in my shower

[loki993]

I've been fighting with this for over a month now and I'm out of ideas. I figured I would try one last thing before calling in someone that will almost surely result in a hefty bill to fix.

First off when I moved in the house had been gutted and completely remolded so everything in it is new.

Basically over the past few months my shower has gradually lost water pressure. For a while it was annoying but tolerable, then it lost so much that i was actually pretty hard to even take a shower. To now where I have no pressure at all. I get a trickle at the faucet and when trying to turn the shower on I get nothing not even enough pressure to fill the tube and come out the shower head.

The shower is a Delta Monitor 13. First thing I did was change the cartridge. I've checked under the house to see if there are shut off valves, there are none. I can run the water without the cartridge in and it flows and I did that for some time to see if any blockage or gunk would be cleared but I didnt get anything. We also ran the old cartridge without the balancer in it at all and still got no pressure. I would have assumed I would have at least gotten something doing that.

The house uses an on demand water heater, I've ran water out of that and checked that for blockages and I cant find anything. I cant really check after the heater though as it goes right in the wall and to PEX I'm assuming.


Everywhere else in the house seems to be working ok, its just the shower thats had the huge falloff.

I don't think its the valve, the original I pulled out didn't even have much gunk or dirt on it. I ran the shower with no faucet or valve on it for about 10 minutes before installing the new cartridge to make sure anything was cleared out as well.

Also like I said everything in the house is new. The Shower, Faucet, plumbing is brand new PEX throughout, and the water heater.

Im at a total loss here.

Any ideas before I either have to start punching holes in the shower or call someone in?

[jadnashua]

All shower valves are required to have one sort of anti-scald technology in them. The most common one is pressure balance. To work properly, the pressure on both the hot and cold must be within specs and ideally, equal. It is not uncommon for a tankless system to have internal flow restrictions, meaning that the outlet pressure could be lower. This can be enough to cause the spool valve to close, shutting down any flow. Depending on the tankless system, you might notice it getting worse and worse as the inlet water temp decreases as winter approaches - some tankless systems restrict the flow so that they can transfer more heat which maintains the set point on the outlet temperature.

You might find that reducing the set temp on the tankless would mean that it won't need to reduce the flow to produce the desired temp, making it more equal with the cold supply, and thus keeping the spool valve centered and not shutting things down. This can be annoying, depending on what you need for outlet temp (typically, you'd want more for washing dishes, and maybe for the washing machine, if you use hot for it).

Try dropping the thermostat on the tankless to something like 105-110 degrees and see if the problem still exists. that means that you'd be using almost all hot in the shower and you MIGHT need to readjust the max temp setting in the valve to allow it to get hot enough for you, but as a quick test, it would tell you if it is the balance in pressure between the hot and cold.

[loki993]

I do suspect, simply from a process of elimination that it could be the water heter. Ill check it, its factory set at 120 and I have to open it up to lower it, if I even can. I was doing a little reading and it seems they need to be flushed periodically because scale can build up. Its only been probably 6 months but the water here seems to have a lot of calcium in it, plus who knows how long it was sitting before I moved in and what gunk that moved. So I'm wondering if I may have some build up. Maybe its just enough to cause issues with the shower. I need to pick up a submersible pump to do that though.