I've had low flow problems with this unit several times over the past years. Delta has been good about sending me a cartridge when needed, but more often than not, I think the problem has been in the body of the unit. (Well water plus occasional fine sand problems. Back-flushing--with water--seems to help the most.) But others on-line describe similar problems.

1. Are the pipes going to the tub and the shower the same? Or is there a restriction in one and not the other. (I note someone here says they 'drill out' the shower side, or turn the body upside down.) Is this restriction common to other brands/models?

2. I don't entirely understand how the spool valve works but it appears that all the water needs to pass through the two maybe 3/16" diameter SS holes in the valve? If so, won't that seriously impede the amount of water, to either the tub or shower head?

Thanks.

One thing that happens is the when it is installed for a shower only and NOT inverted, the plugged tub port creates a "sump" which can accumulate debris or calcium buildup. When that happens, backflushing may help, but I usually have to remove the cap on the bottom and push a wire up through the valve into the shower riser to clear it out.

It does not impede it to the extent that the shower valve can't produce the 2.5gpm at the shower head.

I still don't understand why you'd want to take water moving through 1/2" pipes and force it through ~3/16" holes, to fill a tub? Seems less than stellar design to my non fluid dynamics mind.

How large do you think the water valve seat openings are in ANY valve. NONE of them have "1/2 inch openings. Most are in the range of 1/4" or so.

I know none are 1/2". Those I've seen--including sinks--SEEM considerably bigger than the holes in the spool valve. My guess--and it's definitely an uneducated guess--is that a standard 2 handle tub/shower valve will be bigger than these. I'd also guess small differences in diameter will dramatically change flow?

I am posting a copy of a post from another persons review of the delta valve. I have used at least 6 of the delta valves and never had a problem. I am posting this to just get some opinions from the great plumbers on this site. Does the delta 134900 valve maybe have a problem?

If your water flow has slowed to a trickle and you are hoping that a new cartridge will fix it, sorry but it probably won't. The problem is a hopelessly flawed design from Delta.Once the water flows through and leaves the cartridge, it goes back into the valve body on its way to the tub spout. Unfortunately in the valve body it has to go through a conical mixer/pressure reducer (not sure what function they were thinking for the internal cone) which ends with a 1/16" clearance to the valve wall. So, unless your shower water is perfectly pure & filtered, any errant pieces of rust, hard water deposits, silt, sand, etc are going to get stuck at this point. They will build up until your water flow trickles to nothing ! The only way I've found to fix it is to get access to the bottom of the valve. Then remove the pipe going to the spout and create a thin sheet metal tool to stick up into the orifice to dislodge the debris. If you have this type of valve, you'll be able to feel the bottom of the cone if you stick your pinky into the bottom about 3/4". I have used this procedure on a valve in one of my rentals twice and both times flow was restored.IMO this is a fundamental design flaw on the part of Delta, rendering these valves totally defective.

I'm no 'great plumber' but I'd readily agree it APPEARS to be a design flaw. If you have nice city water, you're unlikely to have a problem. Any crud in your water--which admittedly shouldn't be there--and you will have this problem. BTDT x 3 now.

Thanks for the reference.



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quote' Unfortunately in the valve body it has to go through a conical mixer/pressure reducer

I do not know where you are buying your valves, but the ones I use, do NOT have any kind of "conical mixer" in the tub spout port. It is just a "hollow area" with a large opening from the valve and a smaller one going up to the shower.

Hmmm...wonder if they might have changed the design, over the years? My unit is 6 years old I think.

To my knowledge, I have never seen what you are describing, at least not the way you describe it.