Poor flow in tub/shower

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Milanomike

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OK, I've got very poor flow in my hall bath, the tub/shower to be precise. Flow (or water pressure) is fine in the 2 bath sinks and everywhere else in the house. I checked pressure and I've got 60 psi in the house, just like my regulator says I should have, great. As I stated pressure is fine in every other faucet, tub or shower in the house.

The tub/shower unit is a single handle American Std from about 12 - 15 years back. I replaced both the cartridge and the anti-scald unit but flow remains poor. Surprisingly neither of the old units seemed too gunked up. I have not measured flow yet, but if I remove shower head, water flow does not even make an arc from the pipe, just drops straight down into the tub, same with tub spout. So, flow is low.

I have not removed the new valve and turned water on as valve is behind tile, so no place for water to go anywhere but down the wall and to my 1st floor ceiling where a potential mess could be made.

I'm thinking I remove the new anti-scald valve and cartridge and run something like 12 gauge wire into pipe near valve body, maybe something is blocking both hot and cold feed lines to the valve body? Daughter comes home from school in a week or so, so complaining will start.....

Any thoughts/suggestions are welcome.

Thanks for any help in advance.

Mike
 
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I have not removed the new valve and turned water on as valve is behind tile, so no place for water to go anywhere but down the wall and to my 1st floor ceiling where a potential mess could be made.
Any thoughts/suggestions are welcome.
Suggestion: Hire a local professional to complete this repair before you create a "potential mess".
 

Milanomike

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Thanks for the tip, but I've done loads of plumbing including re-plumbing this entire bath a dozen or so years back. So, I'm not afraid of this valve and understand plumbing. just looking for any suggestions anyone might have.

I've been searching the sight and am starting to think something must be partially blocking the valve. Will try and figure if it is just the hot or cold or both. Maybe I can rig something that will allow flowing water from valve without cartridge and anti scald unit in there and send the water out into the tub.
 

Smooky

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There may be trash in the Cartridge or pressure balance unit or spool. You could replace them. If you take the old one out you may want to flush out the hot and cold line before installing a new cartridge and pressure balance unit. You, may need something like aluminum foil to create a splash shield to prevent water from getting in the wall cavity. It is best to have a helper when you do that.
 

Reach4

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A suitably sized food can might make a good splash shield.
 

Milanomike

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Reach4, great tip on the using a can, thanks.

I'm into the week or before I can take apart, but will report back, hopefully get home from work early one evening. Should only need an hour if that for this test. Thinking #2 daughter will be enlisted to help......
 

Jadnashua

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IF the rough-in valve has individual shutoffs, make sure that they are fully opened. Some brands include a filter screen on their inlets, and may take some disassembly to find and clean or replace (check the parts breakdown for the valve you have - not all have this). Some valves have two outlets: one for the tub, one for the shower, but the shower one is often smaller since by code, it doesn't need as much flow as you would want when filling the tub. Some, use the same output, and then use the diverter to decide where it goes rather than just closing off the lower path (gravity keeps it from going out the shower head in that case when both ports are open).

If there is any galvanized steel piping to that valve, it could be squeezing off the supply. Pressure (no flow) would be the same, but you'd never get great volume through it. While not all that common, sometimes, something ends up in the supply lines (pieces of a washer, balls of solder, or who knows what), and that could be restricting the flow to the valve. Many manufacturers list the flow volume from their valves, and it shouldn't be too hard to check that. The spec usually is at a certain static pressure, and if yours is higher or lower, the resulting volume would change accordingly.
 

Milanomike

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OK, guys, this has been a while as I've walked the dog on this one, but with holidays coming, time to figure out what issue is.

Anyhow, I killed the afternoon fiddling with this and learned a few things:

I got the screw stops on the hot and cold inlet free by removing complete unit and soaking in vinegar. Great!

So, I put the stops back in, screw 'em down and turn on water. I cut up a milk jug for a shield, works perfectly and learn the cold flows perfectly.

I also learn the hot does not, so is it between the screw stop and body or before the screw stop? Well, with my handy dandy shield I quickly learned that I have low hot water flow before the screw stop. To me that means poor flow to the valve. so valve is not the issue.

Bath has 2 sinks in it and both flow perfect, great pressure. So a clog or blockage of some sort is between the sinks and line to tub or up to tub. I replumbed this whole thing like 15 years back and all was well, but I don't remember how it flows to the tub......

Obvious question, how to figure it out or get it the heck out of there.

Any help appreciated as always.
Mike
 

Cacher_Chick

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There are few options other than to cut the pipe further upstream and recheck the volume there. If you are going to fix it, you are going to have to be prepared to re-pipe problem section or open the system up at each joint, working back in search of the problem. At 60psi and using a standard 2.5 gpm showerhead, there should be little reason for complaints.
 

Milanomike

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Cacher_Chick; Ugh, was afraid of that, but was hoping I could somehow backflush. This will be a mess.

rjbphd: Unfortunately the valve ain't the issue, so Moentrol won't bail me out. Though I did put a Moen faucet in my new vanity/sink in the MBR. This bath will have to do with Am Std.
 

Cacher_Chick

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You first need to seek out the answer as to how both the hot and cold could suddenly experience a blockage, both at once? It might be time for another diagnosis.
 

Milanomike

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Poor flow is only on the hot side. Like I said I redid this bath some years back, but 6 - 12 months back this nonsense started. Thinking my next step is to disassemble again, remove screw stop on hot and flow water for 5 or 10 minutes with my handy dandy shield and see if it clears. I'm at a loss as to how the line could have gotten partially blocked. Next report will be after I let water run thru it for a while, maybe I'll get lucky. Cold blasts how at double or more pressure. Thanks for the help. Mike
 

Cacher_Chick

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I have heard that some valves have inlet screens, but have not ran into that myself. It would be expected to see somwhat lower flow from the hot piping. Did you replace the pressure/balance cartridge and the regular cartridge with O.E. American Standard parts?
 

Milanomike

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yes, replaced pressure balance and cartridge with new parts. And, yes, American Std not aftermarket, been burned too many times .... We'll see what happens this weekend.

I've had the valve apart and can fish a zip tie thru it to the 1st elbow about 3 inches away with no issue, so worse case I could open wall in bedroom and cut out section of pipe from elbow near valve going to the floor.

Might think about back pressure with my air compressor and hope it flows out to the basement
 

Milanomike

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Well, I'm throwing in the towel. I tried letting it run to flush it, gave it ~20 minute, turned off and on to try and bump it out, no go. Then I researched how to back flow. Cleaned out the sink nearest the tub real well, but no go. Finally, tried compressed air thinking I could blow it out the hot feed below one of the sinks, no go. I did move it though as flow on the hot is maybe a bit worse or at least somewhat different.

I'm sure rjbphd will chime in with an I told you so, but I'm gonna call a plumber (as soon as I find one) and see if they can make it better. I have great pressure at both sinks in the bathroom, just not at the tub, something is in there between the sink closest to the tub and the tub. Guessing it is a sediment chunk from the old hot water heater, but that is just a guess.
 

Milanomike

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OK, after calling around and getting guys who say we do this all the time, I had them come over to bail me out and he concluded I have a blockage in the pipe, beautiful!

We concurred that it made the most sense to cut drywall in bedroom behind tub/valve. Me and the pro concurred the blockage was in the hot line between the sink closest to tub and the tub. We figure on cutting pipe near elbow that takes a short piece to the valve, hook up plastic hose with clamp and see if I can flush the offending piece out.

He said my plumbing looked real good though as we were in the bath and basement. Showed him all I had done. Hoping this does it as next step would be opening LR ceiling, definitely undesired. Figuring I got a good shot of dislodging or cutting out at least the vertical run to the valve. Hoping, I can fish with some wire or something if need be.

Starting to think I don't need this tub/shower that much as daughters aren't here much, if I sell, I take $1K off and next guy works it a bit....laughing.
 

Milanomike

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OK, last post and thanks to all for any input, except the go hire a licensed plumber recommendation.

Cut a hole in the bedroom wall to access the hot pipe, cut pipe and found all was clear the shower valve, hooked up hose flushed, lots of sediment came out, but flow was 1/2 everywhere else. Used some 12 ga Romex I stripped out of the 12-2 sheath and used it to fish down as far as I could. I could not get past a ball valve (did not recall installing), but may have put in to test/flush all new bath plumbing 14 years back. Boom, cut it out and found it was 75% clogged, yeah, I got lucky, it was what I'll call hot water heater sediment. Shower flows well now. Did not cut hole to access cold as it ain't broke today. So, fixed it in a few hours, a small piece of drywall and a few hours this weekend should wrap it up. Thanks for thinking of me. Mike
 

Reach4

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I got lucky, it was what I'll call hot water heater sediment. Shower flows well now.
Congratulations! Nice troubleshooting and action. You probably won't like it pointed out that a plumber might have cured this 7 months ago. It was good you had another bathroom. A term you might look for if selecting a ball valve in the future is "full port".

What did the debris look like? Pieces of plastic? That can happen if a WH diptube disintegrates. Check your aerators around your house. Do they have debris? Maybe you want to consider a whole-house filter.


Here is a simple WH flushing procedure while you are thinking about it:
Flushing can be done different ways. The simplest is to
1. Turn off the water, and put the WH in vacation mode, if it has one. Otherwise off.
2. Open a hot water tap to pass air.
3. Drain the WH completely
4. Turn the water supply on fully for a few seconds, and turn off. You are trying to cause turbulence to the bottom of the tank.
5. Do steps 3 and 4 several times. If you have a way to monitor the drained water, you could judge by what you are getting out.
6. Turn the water and WH back on. Close the hot water tap once the air has been expelled and just water is coming out.​
 
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