Poor Pressure From a Delta Single Handle Bathtub Faucet

[Prkno]

I was wondering if I could get some advice on this one. The water pressure coming out of the tub faucet has reduced significantly. The faucet is a 30 year + Delta single lever which to remove would require breaking the front tile and sawing through the surface it is mounted on or going to the next room and breaking through the wall to get at it, neither a very good option. I used an overhaul kit (genuine Delta ball and springs) but it didn't help. Can anyone give a step by step method for diagnosing the problem? The piping is galvanized but the pressure is fine everywhere else in the house including the sink next to the tub. Any info is appreciated. Thanks.

[johnjh2o1]

If the piping is galvanized the lines are starting to close up do to rust. They should be replaced. My guess is that the location were the line is most restricted is were the galvanized is connected to the brass Delta valve body.

John

[hj]

IF both hot and cold have the same flow, AND it does not change when you switch to the middle "warm" selection, the the obstruction is in the valve body itself. Probably at the point where the flow exits the body and goes down to the spout. Applying pressure to the spout connection, with the valve disassembled and the shower arm capped off might clear it out.

[jadnashua]

Is the piping to the tub spout also galvanized? That often lasts a long time, but any galvanized will eventually rust out from the inside...it could have a very small working diameter. Don't confuse pressure with volume...the pressure in a straw would be the same as a fire hose (assuming your supply is adequate of course!), but you'll definately get a LOT more volume from the fire hose! Your piping, being galvanized, make now resemble that soda straw on the inside. Plus, turning the water off then on again will often dislodge some of that rust, and it could be clogging up any inlet filters or even the new cartridge. Brass and copper are much longer lasting and better performing than galvanized - but, they cost more on install (not in the long run), so they get used.

[Prkno]

Yes, it is all galvanized. I was hoping there could be a way to determine for certain if it is the piping or the faucet. To get at the faucet would require a not insignificant tear-out of tile. The volume is fine everywhere else

[hj]

quote; I was hoping there could be a way to determine for certain if it is the piping or the faucet

Did you read my answer which told you HOW to make that determination?

[Prkno]

Sorry about that HJ. Yesterday was an off day. So I read your answer and yes, it is just as you suggested, there is no change in flow regardless of where I turn the knob. I'm not sure what you mean by applying pressure to the spout. Also, when you say the valve body disassembled, do you mean just pulling out the ball and springs and washers? Plumbing is definitely not my forte. Thanks.

[jadnashua]

Try shutting the water off, remove the cartridge, then have someone turn the water back on for a moment- it will go everywhere, but if there's an obstruction in the line, it might clear itself.

If the volume doesn't change when you change the temperature, the obstruction is likely in the path to the spout. When you're mixing both hot and cold, you'll get more volume than you would if it was just using the hot or cold by itself.