Hot water issue in shower/tub

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Nelsonba

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When I turn the hot water handel in my tub/shower water comes out fast at first for about one second then the water pressure drops substantially. To get the mix comfortable, the cold has to barely be turned on. I've noticed that the water pressure in the sink is lower for the hot than the cold, but it's not as noticable as in the tub/shower. I've included a couple of pictures to show what it looks like. Any idea what's going on? All I want is a comfortable shower in the morning! Thanks
 

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Verdeboy

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As I mentioined in your last post of this same question, you probably have some debris, maybe a little pebble or piece of rubber, that is blocking your hot water flow in the bath. When you release the pressure, by turning off the water, it loosens up this debris, and when you turn the water back on it takes a second to block the flow again.

You'll need to shut off the water to the tub, remove the handle and the stem, and check for debris.
 

Nelsonba

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What tool do I need to get the stem out? I can't get a normal wrench on the nut because it's below the tile threshold. Do they make a socket that allows for the stem to pass through?
 

Verdeboy

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I assume you must have gotten the handle off some way. You need to buy plumber's sockets to remove the stem. Occasionally, you need to chip out some of the tile to make room for the socket.
 

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Nelsonba

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I ended up buying a tool to remove the handle. Worked like a charm. I'll buy the sockets tomorrow and let you know what I find. Thanks!
 

Mikey

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The sockets are also available individually, but you've got to know the exact size -- they go up in 1/32" increments.
 

Nelsonba

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OK. I got the stem out, but I didn't find anything that looked out of the ordinary. The valve seemed to be in good condition. I ran water straight out the pipe with the valve out and the pressure did the same thing. Came out strong for a second or two and then dropped. I did a little more digging around in my basement. It looks like the cold water branches off to the rest of the house right after it comes into the house. Then it runs up into the ceiling (through old pipes), meets up with an outdoor faucet and then eventually runs into the water heater. The hot water pressure throughout the house is lower than the cold, it's just more noticable in the tub for some reason.

Do you think the problem is that it runs through the original piping, which is 75 years old, before reaching the water heater?
 

Jadnashua

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Is the original piping galvanized? If so, and it is 75-years old, it's probably time to replace it. Now, also check to see if you are getting any little white flecks in the hot water. There were a few hot water heaters that had the plastic dip tube (a tube that directs the cold water to the bottom of the WH tank) that tended to disintegrate. Depending on their size, this could be plugging the outlet when it flows. When it stops, it could be falling away from the outlet.
 

Mikey

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You've got a flow restriction somewhere in the path from the supply, through the WH, and through the HW lines to the fixtures. With all fixture valves off, the water can seep through the restriction and equalize pressure throughout the pipes. When you open a faucet, the pressure on the faucet side is initially OK, but quickly drops off.

I would probably try disconnecting the HW pipe at the WH and backflushing the pipe(s) from the fixture end(s), and see what, if anything, flushes out. If you've really got 75-year-old galvanized pipes, it won't be pretty.

Have you drained/flushed the WH recently? It'd be interesting to see what come out of there also.
 

Nelsonba

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Would it make sense to hook up a hose to the water heater and see what kind of pressure I get out of the drain? I would assume that this would let me know if the problem exists before or after the water heater.
 

Jadnashua

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YOu could isolate whether the restriction is on the inlet ot the WH or if it is the outlet. Keep in mind, the drain port on the tank is on the bottom, the house output on th etop, so if there are some floaters that block things, getting good pressure out of the bottom tells you the inlet is not blocked.
 

Mikey

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There's another thread describing a problem similar to yours, to which I earlier replied:

When the failure occurs, you could open the WH drain and see what kind of pressure you've got in the WH. This could rule out any problems with the supply or dip tube. A better method would be to attach one of those cheap hose-bib pressure gauges to the WH drain and just monitor the pressure all the time. If the gauge shows pressure in the tank, but there's no pressure at the fixtures, there's a problem somewhere after the dip tube. Can you post a picture of the HW plumbing from the tank to the point where the HW pipes diverge?

Jim's last post emphasises that this will only isolate the problem to a point beyond the inlet.
 

ss3964spd

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IMO, you want to carefully consider if you really want to open the drain on the WH. Those drain valves are not of the highest quality.

If it's an old unit and the drain valve has not been opened/operated for some time it's quite possible that it may not seal again when you close it resulting in a slow drop - much the same as what happens with fixture stops that haven't been used.

Dan
 

Nelsonba

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So I've been putting this off for a while now because I've been renovating the bathroom. I'd like to take care of it now though. The water pressure problem appears to be much worse in the shower than anywhere else in the house, so I'm not sure that this is a water heater issue.

I have an idea, but I don't know if it's practical. Do faucet stems come with smaller threads? If I replaced the cold water stem with one that opened more slowly, I think I could successfully cheat the problem.
 

Verdeboy

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It might be easier to just heat some water on the stove and fill up a 5 gallon bucket that attaches to your shower head. Sorry, someone just posted that earlier and it stuck in my brain.

If you tighten up the packing nut really tight on the stem you already have, it will make it more difficult to open the valve. Thus, you might achieve the same thing. Of course, this does not address your underlying problem.
 

Bob NH

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You can try the following:

1. Put the shower control back together.
2. Turn off the cold supply to the water heater, but leave the cold and hot supplies on to the shower.
3. Find a large outlet for hot water, such as the laundry sink or washing machine connection, somewhere off the line between the water heater and the shower. Open it all the way. If nothing else is available, use the water heater drain (actually prefereable because you get all of the pipe). If it is a valve, it should be OK.
4. Turn on both the hot and cold water at the shower and try to hold something over the shower outlet to force all of the water from the cold supply back through the hot water pipe, hoping to force whatever junk is in the pipe out the open hot water faucet. If you can't hold it, you can take the shower head off and put a 1/2" threaded pipe cap (PVC will work since it is only cold water.) over the shower pipe.
 

Nelsonba

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Last night I flushed the water heater and then tried to dislodge the blockage by doing what bob suggested.

1) I capped my shower head and turned off the cold supply to the water heater.
2) I left the cold supply to the shower on and turned on both the cold and hot water faucets in the shower, running cold water back through the hot water supply piping to the water heater.
3) I checked the water pressure at the hose I had hooked up to the water heater drain and it was fine.

Neither flushing the water heater or the hot water line did any good. The pressure is still low.

I think this tells me the problem is either with the inlet to the water heater or the stretch of galvanized piping before it.

Would you agree? If so, how do you fix it?

Thanks
 

Nelsonba

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It's Fixed!

I took the stretch of galvanized out of the equation and now my pressure is equal for both hot and cold. Thanks!
 
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