As a result of a small leak I had a short run (5-6 feet) of the original galvanized hot water (horizontal) pipe replaced w PEX. This replacement PEX tubing is connected to a foot of copper coming out of my hot water heater, runs horizontal to the "T" connection just prior to the vertical run. There are no bends, it's a straight horizontal run.

Since replaced I have very low pressure in TWO PLACES in the house. An original shower (original house plumbing) and newer house addition ( new vertical plumbing, etc..) Jacuzzi tub. Separate bathrooms but both on the 2nd floor of house. I might add that the "other" hot water pressure in both these bathrooms is normal at the sinks, new construction shower next to Jacuzzi, etc... Also, prior to this PEX installation, the original shower had by a long shot the best pressure of any hot water source in the whole house.

I might add that I have disassembled the (original) shower plumbing down to and replaced the valve, cartridge as I thought something might have been pushed through, stuck in the valve somehow. Not the case. The shower is unusable as the pressure is too low and shuts off. As per the Jacuzzi, I have not messed with it as we use less and still fills although very slow.

Is it possible that PEX has affected pressure in two very distinct locations in the house, but has not affected other sources? Seems way to coincidental, but don't want to have to pay for a copper run if I'm not correct in my assumption.


Your help in greatly appreciated!
Chris

On that piece of old galvanized pipe that they removed, is the inside of it half full of rust or debris and the waterway is much smaller and restricted than it should be? If so, if the pipes going to the shower that has low water flow are also galvanized they may be in similar condition as the old section of removed pipe. Then if the plumbing work that was done dislodged some pieces of debris they could have moved into the shower pipe somewhere and is clogging it.

If the tub spouts and other hot water faucets in the house have strong hot water flow then the 6 ft section of PEX wouldn't seem to be the problem, but getting it installed may have disturbed other things so that explains the timing. If most of your house still has galvanized pipe and it is several years old it can often be like the arteries in a couch potato individual. The inside of those pipes can gradually accumulate rust and buildup, then if you do some plumbing work you risk having chunks of that stuff coming loose and flowing in the pipe to another location.



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Thank you for the post.

I can't speak to what the inside of galvenized looked like, I did not do the work. 1918 house I can only assume was gunned up.

I gather what you're saying is this is likely debri lodged in, near each outflow of hot water and is entirely random? No rhyme, reason why it chose these two unique locations to lodge?

Is their a safe way to flush, clear without creating bigger issue? I do know that the overflow tub in basement was open to make sure water was flushed their first as it was turned back on, gradually rest of house floor by floor.

Well, I've seen the inside of galvanized pipes that had a lot of stuff built up, and they hadn't been in service as long as yours since 1918. But this is just an idea, since the problem began right after the pex line was installed it would seem to be related to the install. I'd think if the pex line itself was the problem you'd see low pressure/low water flow in all hot water locations, and as long as it isn't kinked or collapsed it should be ok. The logical thing to think about is something blocking the pipe(s) to the showers unless there is something you haven't mentioned that would have a bearing on the problem. When being used the showers would have a larger volume flow and for a longer time than the sink faucet, so the first time the showers were used after the pex install that might be where any debris in the line went. Just throwing an idea out there. I don't know of an easy way to flush the hot water line to the shower. You can try taking the shower head off and running the hot water full blast, and any part of the nearby hot water pipe to you can get to you can try rapping the pipe with a screwdriver handle or something. Be aware that this might cause some debris in the pipe to come loose but at this point you may not have much to lose.



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So is there a difference between low pressure & low flow?

People often use the two terms interchangeably because they are related and get the idea across when describing a problem. If you have low pressure you will generally have low flow, with the size pipes we use in homes. But you can have normal or high water pressure and still have low flow due to any number of reasons.

I think of low flow as a smaller volume of moving water, like you will have when a valve is barely turned on, even though the water coming to the valve can be a higher pressure. If your pipe is corroded/partially blocked on the inside and reduced in size for the water passageway then the volume of water that can move thru it per minute is reduced, even if the pressure is still normal. Some people might refer to this as low pressure but really it isn't. The water supply coming to your house has normal pressure and that pressure is felt throughout your house pipes but when you open a valve you can get low flow (low volume) because the water can't move fast enough thru the restricted pipe.

What about getting the plumber that installed the pex to come out, show him how the bathroom shower is not working, get his opinion? He can tell you if the section of old pipe he removed was badly corroded inside or not. Some plumbing problems are fairly easy to figure out over the internet but many problems are best solved by a plumber in person to make an evaluation.



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I can assure you that the pex is not the problem. The rust and debris that was dislodged during the removal of the galvanized pipe is. You have to find out where the debris is trapped, or cut a pipe and backflush the debris out.

All that I've been able to read, find says can be (usually is)very small debi that ends up lodged in or near cartridge vs larger piece obstructing pipe. If there's nothing viseable in the cartridge can I probe the pipe w something to loosen, unplug safely? I guess assuming it's w/in a foot of access point...

If you can get to the open end of the pipe you can run a wire down it and try to dislodge something. The water will be shutoff while doing this so if you do dislodge something it will still sit in the pipe until you turn the water back on and flush it out. A wire coat hanger can be straightened out and used for short distance. Something like 12 or 14 gauge solid strand copper house wiring (one wire, not the 2 or 3 wire still inside the sheath) can be inserted a greater distance. You can probably fashion a hose of the right size to connect to the end of the pipe, maybe use a hose clamp, so when you turn the water back on the water (and hopefully any debris) will run into the tub or a bucket.

If you try something like this take a good look into the pipe, evaluate how much or how little the galvanized pipe is rusted and clogged. Also, did you call the plumber that did the pex replacement and get his opinion on what to do? He's been in your house and seen your piping, he could be invaluable in solving this.

Example of galvanized pipe that's several years old, hopefully your pipes are not this bad:





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sometimes you can turn the water back on with the cartridge removed and the debris will just be forced out.
to answer your question, yeah you can poke a wire into the hot or cold openings to reach into the pipes connected to the valve inlets..