Little or no hot water in one bathroom

[cresttd]

I am new to both this site and to plumbing so please be gentel with me.

The problem is in the master bath, The rest of the house is fine. It takes a very long time for hot water to reach the bathroom, (located about 60' from hot water tank) and when it gets there it is not very hot. I do not think it is on a seperate run as there is another bathroom between this one and the water heater and there only seems to be one line out of the tank. Any suggestions? This is my fiancee's house and she says it has been like this since she moved in three years ago. She had a plumber out to check it but apparently he said there was nothing wrong. I am a novice when it comes to plumbing, but there is clearly someting wrong...I just have not clue what it might be.

 

[Jadnashua]

Does the water line run through a concrete slab? Through a basement? Can you see it anywhere other than at the water heater?

My first thought is that it was probably run without any insulation, and it is just cooling off on its way from the heater to the last bathroom. My guess is that if you let the water run, check the temp along the way, you'll find the ultimate water temp falling as you get further from the water heater.

You can set the hot water heater thermostat higher, so it is still hot when it gets to that bathroom, but keep in mind that it will be much hotter closer to the hot water heater and that can constitute a safety hazard, and will cost you more in energy.

If the line runs through a basement, get some insulation and cover all of the pipe. If it runs through a slab, think about adding a second water heater near that bathroom.

Or, run a new line (very messy) and insulate it well...consider a hot water recirculation system if you use that bathroom often and want hot water there without having to wait a minute or two. My unprofessional opinion.

 

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[cresttd]

Thanks for replying. The lines run through a concrete slab. The house is in a cookie cutter type community so I am attempting to get a plumbing riser from the builder, at least then I could be sure where the lines run. I ahve talked to other people in the community and nobody else has this problem. Not many options for adding an additional hot water tank, would tankless or on demand work?

 

[Jadnashua]

I'd raise the water temp on the heater to just below the max you are comfortable with in stages to see if you can reach a setting you can live with. If you have no room for another hwh (tank-type), then you might consider a tankless. I'm not a particular fan of them, and it might be cheaper to tear things up and just run a new water line that can be insulated. It would work, but you may have the same problems - you'd have to run either a new gas line or significant electrical service for a tankless system to work. You may not have a big enough electrical service, so consider that in the cost mix, too. If you ran a new pipe through the attic closer to the ceiling in the insulation, you might be able to do this without tearing up the walls. You could use PEX, which would allow you to run one continuous line without joints except at the ends and get it through the joists.

Last thing I can think of...is the water temp different at the shower vs the vanity? If so, then there may be a high temperature limit adjustment that needs to be tweaked on the valve. It could be limiting the max temp available.

As I noted, I'm not a pro...maybe one of them will have some other suggestions.

 

[cresttd]

Never thought of running the pipe through the attic. I will also check for an adjustment on the valve at the shower, though I am pretty sure the problem exists at the vanity as well. Thanks for your help, now I have a place to begin.

 

[Master Plumber Mark]

check the pressure balanced valve first

try takeing a shower and when it starts to get
pretty cold , get out and check the Lavatory sink...


if it is still pretty hot, then its going to be a problem with
the pressure balanced valve

 

[marksman]

I used to be a 'maintenance technician' for an assisted living facility with 56 apartments, and state regs required constant water temp testing throughout the facility.

It was quite common to get a 20 degree spread in readings around the facility, with all water coming from the same boiler.

The variance is eplained by distance from the tank, ambient temperature along the run and other variables.

If your hot water pipe runs thru concrete for part of the run, the concrete will approximate ground temperatre at around 55 degrees, which will have a cooling effect on the hot water. If you let it run long enough to warm up the concrete around the pipe, the end temp will eventually rise.

A better solution would be to put an on demand tank near the shower getting the cool hot water.

 

[mcameron68]

Same Issue

Hello everybody, thanks for all the great help Ive been reading.

So, I have a very similiar situation except my plumbing goes through the attic.
I havent had a chance to see if it was insulated or not, but its only 20ft or so from another bathrom that gets plenty hot water.
The master does have 2 vanity's and they also experience the same issues.
Heres the wierd thing (or maybe not, im not a plumber), when im taking a shower I will run the faucet until it gets hot, then switch to the shower head and the water temp will slowly decrease, then if I switch back to the faucet it will go back up. Obviously this burns through the hot water pretty quick, so my wife gets quite unhappy when I do that. My water heater IS 15 years old, and I recently called my home "warranty" service regarding the issue. The plumber came out and replaced my anode rod which had withered down to about 12" and absolutely no plastic tubing.
This is the first winter that I have lived in this house, and its not like im in a super cold climate (N. CA.) But still, luke warm showers are no fun.
Thanks for any help you can provide.

Edit: Actually now im not sure that my plumbing is run through the attic, I guess I was thinking of my last house. I dont see any water pipes in the attic, so im guessing it must be run through the concrete. Is that right? Could it be buried beneath the insulation? I can see the framework, I imagine it would still rest on those if it were in the attic.
Thanks

 

[Mike Swearingen]

If plumbing is run through the attic, it should be beneath the insulation. You'll just have to pull it up to see.
It's more likely that it runs up through the walls to the fixtures, unless you're on a slab and the plumbing has been replaced at some point.
Mike