# Low hot water pressure in bath tub



## Alan (Apr 12, 2006)

if you've isolated it from other fixtures in the house, it has to be a clog in the valve somewhere. What kind of valve is it?


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## dirtrider73068 (Feb 24, 2010)

I don't know what kind it is, I know its old, unless you are referring to what is a old style rubber washer kind that presses into a round seat to shut off the water flow.


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## Snav (Aug 20, 2009)

Where are your pipes? In the walls, under the floor in a crawlspace or bacement? In the attic?

If you can see your pipes - are they different than the other pipes in your house?

What I would do to temporarily figure out the problem is to remove the faucet/tub/shower area and attach on a hose bib (like an outside water-hose faucet tap) and see if removing the actual shower-valves affects water flow.

If water flow is good from your temporary hose bib - then it's your tub attachments.
If it's low coming out of your hose bib - then it might be your pipes.

Just tossing out some ideas, here:
If your pipes are copper or galvanized steel then they might have been bent or crushed, hindering flow.
If they are Pvc, cpvc (both are a stiff plastic that doesn't flex well) then they might be undersized or clogged somehow.
If it's PEX (a flexible pipe) then perhaps it has too many hoops and loops - or the wrong size was used *3/8" instead of 1/2" - for example*.

Or- it could be a sign of a leak - my sink water-flow weakened due to a small leak and eventually the pipe burst, ending all water flow and alerting me of the problem.


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## dirtrider73068 (Feb 24, 2010)

I have a crawl space so I can see the pipes and from before I have seen before they look like they are copper pipes. When you say a hose bib how do I hook that up? Do I hook it up where the valve is at?

I talked to a guy at work today that does irrigation and some plumbing and he mention the valve needs to be changed out with a new one, like its not opening fully. But I did a test and took the cold valve out and put it in the hot side and it still flowed out slow, and the cold side from what I can remember flowed that same as with the cold valve in it. So I don't think its the valves.

I thought if I have to replace or clean out the manifold or shower valve mixture assembly how hard is that do and how is it installed in the wall? Did the build the wall then install the assembly in the studs or do the build the studs around the assembly? Do most manifolds screw on to the copper inlet pipes or solder them on?


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## Alan (Apr 12, 2006)

dirtrider73068 said:


> I have a crawl space so I can see the pipes and from before I have seen before they look like they are copper pipes. When you say a hose bib how do I hook that up? Do I hook it up where the valve is at?
> 
> I talked to a guy at work today that does irrigation and some plumbing and he mention the valve needs to be changed out with a new one, like its not opening fully. But I did a test and took the cold valve out and put it in the hot side and it still flowed out slow, and the cold side from what I can remember flowed that same as with the cold valve in it. So I don't think its the valves.
> 
> I thought if I have to replace or clean out the manifold or shower valve mixture assembly how hard is that do and how is it installed in the wall? Did the build the wall then install the assembly in the studs or do the build the studs around the assembly? Do most manifolds screw on to the copper inlet pipes or solder them on?


:whistling2:
Terminoligy is all wrong here. Valve body (brass housing in wall) - cartridges/spindle assemblies (go inside of valve body) - Trim (covers valve body and guts)

If you've swapped the spindle assembly from cold to hot and have the same result, then you've now isolated it to either a clog in the valve body, or a clog in the hot water line going to the valve body. Pull the hot cartridge out and get someone to help you turning the water on and off (hopefully trying not to make a huge mess in the process) to see if you can blow something out of the line. The orifices in the cartridges are kinda small, so you may get it out without the cartridge in there.

In order to replace or remove the valve you need access through the wall behind it, OR you have to demolish your shower or tub/shower whatever you've got. We try to work on them from inside the tub or shower. If it isn't leaking then there isn't any sense in replacing it. You have something blocking that line and you need to try and flush it out.


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## plumberinlaw (Feb 22, 2010)

take the diverter apart and rebuild it

OOPS sorry I read it wrong , thought it was a three valve diverter


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## holman23 (Feb 25, 2010)

ithey do make a remodelers kit if a person wants to take out a 2-handle t/s faucet. it is an oversize chrome cover plate also calles trim plate which allows you to take out old faucet without demolishing the wall. it is tight area to work in but you said you had copper lines hopefully 1/2" feeding old fixture. you might be able to use sharkbites to re hook up new valve


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## plummen (Jan 10, 2010)

plumberinlaw said:


> take the diverter apart and rebuild it


 what does the diverter have to do with hot water pressure when the cold is fine? :whistling2:


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## dirtrider73068 (Feb 24, 2010)

*In order to replace or remove the valve you need access through the wall behind it, OR you have to demolish your shower or tub/shower whatever you've got. We try to work on them from inside the tub or shower. If it isn't leaking then there isn't any sense in replacing it. You have something blocking that line and you need to try and flush it out.
*
Ok now when you say access through the wall behind it, I can do that from my kitchen cabinets, since my bathroom wall is at my kitchen wall. But my If i need to take it out, does the feed lines screw onto the valve body/manifold, or do they solder them in?


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## arcticbouncer (Jan 24, 2010)

Sell the house move somewhee with sun and sand, That is the only logical solution I can think of!


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## Alan (Apr 12, 2006)

dirtrider73068 said:


> *In order to replace or remove the valve you need access through the wall behind it, OR you have to demolish your shower or tub/shower whatever you've got. We try to work on them from inside the tub or shower. If it isn't leaking then there isn't any sense in replacing it. You have something blocking that line and you need to try and flush it out.
> *
> Ok now when you say access through the wall behind it, I can do that from my kitchen cabinets, since my bathroom wall is at my kitchen wall. But my If i need to take it out, does the feed lines screw onto the valve body/manifold, or do they solder them in?


It depends on the valve. You can get them in a lot of different varieties of connections. :thumbup:


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## dirtrider73068 (Feb 24, 2010)

Awesome, it would be my luck it would have to be soldered on. Well here is another question, when its installed, do they notch the studs for the vavle body to fit in, or do they build the studs around the valve body? If its the latter I can cut a access panel in my kitchen cabinet to access it and maybe by hopes I can unscrew it and see if it has alot of build up. From what I have tried and what I can see I think it has some build up in the hot water line either right at the valve body or inside the valve body. If there is something I can pour down the shower head line to get into the valve body to maybe dissolve the build up I would sure rather try that then having to cut into the cabinets and walls.


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## Alan (Apr 12, 2006)

Sometimes the water lines have to travel through the studs to get to the valve, but as a general rule, there's no valve directly behind the valve. It's too hard to get it in there that way.


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## dirtrider73068 (Feb 24, 2010)

Ok well here is something else I just remembered, The last couple times I have turned on the hot water to shower, there comes some thumps and bumps like there is air pockets in the lines? Doesn't make sense cause there shouldn't be a leak and never had a leak and this has been a ongoing problem since i had bought the house. 

Also my hot water never had a pop off valve on it, doesn't need something that lets air in the hot water tank to keep from having a vacuum, or does it use the line coming in to pressure the tank?


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## Alan (Apr 12, 2006)

dirtrider73068 said:


> Ok well here is something else I just remembered, The last couple times I have turned on the hot water to shower, there comes some thumps and bumps like there is air pockets in the lines? Doesn't make sense cause there shouldn't be a leak and never had a leak and this has been a ongoing problem since i had bought the house.
> 
> Also my hot water never had a pop off valve on it, doesn't need something that lets air in the hot water tank to keep from having a vacuum, or does it use the line coming in to pressure the tank?


Incoming cold pressurizes the hot line.

You do need that 'pop off' valve. Temperature and pressure relief. 

It keeps your water heater from exploding and going 300 ft in the air through your roof.


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## dirtrider73068 (Feb 24, 2010)

I tried fiddling with it some more tonight and this is what I found out. I took both hot and cold valves out, turned on meter, and the cold side shot to the back of the tub, hot side came out about 6-8 inches and that was it, hardly any pressure. The valve seat was clean, I tried removeing the seat but it wouldn't budge so I left it alone trying to see if I could find any build up behind the valve seat. I did discover that the valve/manifold body is screwed onto the inlet pipes feeding it, so when I can figure out a good way of getting to it and takeing it off to check the pipes I can.

I read that vinegar will soften and dissolve calcium build up, but could take several hours. So I have a idea I wonder if it will help, since my crawl space is a freaking mud pit, is to turn off water, remove shower head, open hot side, using my air compressor set on low pressure back blow to empty some of the line and then pour a bunch of vinegar in and let it set over night and see if it helps.

I also let some of my water drain out the tank into a pan and it had some sand in it and looked pretty dirty, so at least for starters this weekend, I am looking at draining the water tank and see what that does. I think that sand had been in there a long time.


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## Klawman (Nov 10, 2009)

Alan said:


> Incoming cold pressurizes the hot line.
> 
> You do need that 'pop off' valve. Temperature and pressure relief.
> 
> It keeps your water heater from exploding and going 300 ft in the air through your roof.



That is flat wrong. That tank that reached 300' didn't have to go though a roof, since it was part of a test conducted in an open field. I don't know of any tanks flying over 150' through roofs.


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## plumberinlaw (Feb 22, 2010)

You stated the pressure at the sink was good, here is an Idea. shut off hot at the tank, remove aireator at bathroom sink, backflush with either air or water from hot in tub to lav. sink If using compressed air I would start low and work up. You may end up replacing that line anyway, Why is your crawl so muddy? you may have another problem

to access the valve body there should be a panel on the wall behind it or you will need to make one. you don't want to remove any tile unless there is no other option


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## Alan (Apr 12, 2006)

Klawman said:


> That is flat wrong. That tank that reached 300' didn't have to go though a roof, since it was part of a test conducted in an open field. I don't know of any tanks flying over 150' through roofs.


It was an obvious exaggeration. :whistling2:


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## dirtrider73068 (Feb 24, 2010)

plumberinlaw said:


> You stated the pressure at the sink was good, here is an Idea. shut off hot at the tank, remove aireator at bathroom sink, backflush with either air or water from hot in tub to lav. sink If using compressed air I would start low and work up. You may end up replacing that line anyway, Why is your crawl so muddy? you may have another problem
> 
> to access the valve body there should be a panel on the wall behind it or you will need to make one. you don't want to remove any tile unless there is no other option


Well any time it rains real good or wet for a long period of time it will get muddy, I don't know why but it sucks. I don't have any tile just a vinyl tub surround, but its glued onto the sheetrocked wall. But I can come in behind from my kitchen cabinets, but there are problems with undoing some of the lines would need to be accessed from the tub. I hope I don't have to replace that line I am dearly hopeing back flushing it and letting the vinegar soak on it will help it, and buy me some time.


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## Klawman (Nov 10, 2009)

Alan said:


> It was an obvious exaggeration. :whistling2:


Mine was an example of what passes for my wit or lack of any. Did I tell you about the still Grandpa made from an old water heater?


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## Mike Swearingen (Mar 15, 2005)

dirtrider,
Before you tear into anything from behind, you need to know that there are new large estucheon plates for covering the larger hole from cutting in to get to a tub wall valve from the tub/shower side to replace them. Can be found at most professional plumbing supply houses. (Going in from behind isn't always an option or the best option, and that's why they sell those.)
Now, before you demolish anything, your problem could well just be debris from the water heater itself in the hot side line that floats up and partially blocks that side of the valve when the hot water is turned on. It is probably just a bit too big to blow out past teh seat and the opened valve stem.
Turn the water off, and take the hot water valve completely out. Also unscrew (counter-clockwise) the valve stem seat in the valve body with a seat wrench or large Allen wrench that will fit it to open the water opening to the max (if you have that kind).
Now have someone turn the water on and off to blow it out into the tub/shower. (Hold a towel over the faucet if you think that it's going to blow out into the bathroom.) If you can still see debris blocking the opening, you probably can break it up with a phillips-head screwdriver (that's what I have used in a similar situation).
Good Luck!
Mike


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## dirtrider73068 (Feb 24, 2010)

Mike Swearingen said:


> dirtrider,
> Before you tear into anything from behind, you need to know that there are new large estucheon plates for covering the larger hole from cutting in to get to a tub wall valve from the tub/shower side to replace them. Can be found at most professional plumbing supply houses. (Going in from behind isn't always an option or the best option, and that's why they sell those.)
> Now, before you demolish anything, your problem could well just be debris from the water heater itself in the hot side line that floats up and partially blocks that side of the valve when the hot water is turned on. It is probably just a bit too big to blow out past teh seat and the opened valve stem.
> Turn the water off, and take the hot water valve completely out. Also unscrew (counter-clockwise) the valve stem seat in the valve body with a seat wrench or large Allen wrench that will fit it to open the water opening to the max (if you have that kind).
> ...


Now that sounds better, that way useing that plate, I will check in to that. I tried to take out the valve seat last night have the right tool for it, but it was tight and didn't want to mess it up, but I may turn on the hot side let it heat it up, take it apart and then try again. Still going to back flush and try the vinegar trick to see if it will help.


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## dirtrider73068 (Feb 24, 2010)

Another update, I had to crawl under my muddy house to check another issue have floor in bedroom sagging like its giveing way, well while I was muddy from being under there I checked my water lines, they are all copper, and are 1/2" lines since the elbows and T's say 1/2" in them. Everything looked good no sign of leaks. 

I wish I could draw up something to show how its routed to see if maybe that has something to do with it, but will try to explain it. Water comes in the house from main T's at front outdoor spigot, continues to back part of house, T's into HW tank, then cold goes on to bath and kitchen all being close. Coming out of HW tank it goes bath sink first, T's for kitchen and bathtub. Since its only the bath tub hot side thats being the issue, if the line has to be replaced, I can come back about just guessing 6 ft to the T running to the kitchen sink and do replacement. The fun part is going to be getting all the right connections, especially for the valve body. Now if I have to do that I may as well use that plate thing and cut out my tub wall and replace/update my valve body, valves and make that part current. 

Now runs a new question, if I replace that line back to that T for the kitchen and find there is no clog or blockage, what is the next step? Or can the copper lines be remove heated desoldered and looked into to see if the lines are blocked, if clear resoldered back together and reinstalled? Just trying to save money or do it very cheaply, I do have some other line to use for replacement, have a hot/cold lines going to the garage for when a washer machine was used, but I don't want to do that cause I eventually want a wash sink in in the garage.


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## dirtrider73068 (Feb 24, 2010)

Update again, I got to messing with it again trying to get vinegar into the line. I discovered something behind the valve seat, after really haveing to put force on removeing the valve seat, I found it was a part of a old valve where the rubber washer goes, how it got behind the valve seat is beyond me. I also tried to put a wire hanger down the line to see if maybe I could break up any calcium build up but could get the wire to go anywhere unless I was catching on something, cold side the wire goes right in. I wonder if there is a screen on the hot side where the line screws into the valve body? Though I do have some better pressure and flow on the hot side but would like it to match the cold side.


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## wrangler (Oct 9, 2008)

I know that you wrote that under the house the lines are copper, but are they copper ALL the way to the valve? I've seen many houses where they had the galvanized pipe replaced except for the last two feet from the floor to the valve. The hot had so much build up in the remaining galv pipe that almost no water was coming through. 
I do agree that you best bet is to upgrade your valve to a single handle/cartridge and the Remodelers escutcheon.


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## dirtrider73068 (Feb 24, 2010)

I am pretty sure its copper all the way up to the valve body from what I see inside the wall, but really don't know untill I cut it out and look at. I would think it wasn't copper it would be more built up and blocked than what it is. I also forgot to mention I drained or flushed some of the hot water tank, and it wasn't that bad, I left the water on, and opened the valve and put the end of the hose in a pot to catch what ever came out and let it run about 10 min, a very little sand and small particles of calcium came out.


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