Thread: Plumbing problem.

Originally Posted by Disco-tastic

I am currently renovating our main bathroom and we have an unusual problem...

When i run the bath in the second bathroom the water is only lukewarm, instead of its normal warm temperature. The weird thing is, when i run the basin hot tap, the water from the basin hot tap is cold, and the water in the bath becomes hot! Huh!? Both taps are on a hot water line with a tempering valve, installed straight after the hot water system.

The hot tap to the laundry is hot so its not the hot water system. The pipe after the tempering valve is hot so i dont think its the valve. My guess is its caused by an airlock in the system upstream but i am stumped as to how one hot tap can be cold and the other hot, when they run off the same single line.

At this stage all of the pipes in the bathroom have been capped, and the air in the pipes has not been purged. When we had the second bathroom installed we had the tempering valve installed on the lines that feed the shower, bath and basins. All other hot taps are connected directly to the hot water system. None of the taps on the tempering valve line are mixers, so there cannot be cross flow from a faulty mixer.

Due to the caps i have i cannot purge the lines without them leaking,and I am still a couple of weeks away from finishing the bathroom,so if i can address the problem now it will be great!

Any ideas?

Cheers

Dan

Is the bath tap a mixer or individual taps? If its a mixer the valve inside could be screwed. Just having a guess

Hi,
Does any water flow to any hot taps if you turn off the cold water supply line to the hws, (or an outlet from the hws).
I'm thinking along the lines of an accidental joining of two pipes or a backflow through a tap with out a jumper valve, turned on but blocked from flowing somehow.
No, I'm not a plumber.
Cheers

Originally Posted by austastar

Hi,
Does any water flow to any hot taps if you turn off the cold water supply line to the hws, (or an outlet from the hws).
I'm thinking along the lines of an accidental joining of two pipes or a backflow through a tap with out a jumper valve, turned on but blocked from flowing somehow.
No, I'm not a plumber.
Cheers

You missed your calling in life Danny Boy!

DL

Originally Posted by 350RRC

You missed your calling in life Danny Boy!

DL

Oh Danny boy, the pipes, the pipes are calling,
From tank to tap, and to the bathroom sink,
The heat has gone, and all the water's lukewarm,
It's you, it's you, must solve it for your wife.

My guess is the tempering valve needs adjusting he tempering valve should be adjustable to to adjust the temp of the hot water by mixing cold & hot water to desired temp. The one on our hot water system has a removable orange plastic removable cap , once removed there is a tringular spindle that adjusts the mix , we were supplied with a small spanner with a triangular hole to adjust the spindle. I use it to adjust the temp for summer & winter. You may have to lok up the brand you have to se how to adjust it.

Originally Posted by LRJim

Is the bath tap a mixer or individual taps? If its a mixer the valve inside could be screwed. Just having a guess

There's no mixers on that whole line

Originally Posted by austastar

Hi,
Does any water flow to any hot taps if you turn off the cold water supply line to the hws, (or an outlet from the hws).
I'm thinking along the lines of an accidental joining of two pipes or a backflow through a tap with out a jumper valve, turned on but blocked from flowing somehow.
No, I'm not a plumber.
Cheers

I havent tried that but due to the tempering valve cold water would still flow out.

Originally Posted by 1950landy

My guess is the tempering valve needs adjusting he tempering valve should be adjustable to to adjust the temp of the hot water by mixing cold & hot water to desired temp. The one on our hot water system has a removable orange plastic removable cap , once removed there is a tringular spindle that adjusts the mix , we were supplied with a small spanner with a triangular hole to adjust the spindle. I use it to adjust the temp for summer & winter. You may have to lok up the brand you have to se how to adjust it.

I have adjusted it and it didnt make any difference. The temp of the outlet pipe of the valve is hot, like it should be.

I should have added that all the plumbing was working great until I turned off the water to have some pipe replaced (the previous owner installed flexible braided pipe within the wall, which i wanted replaced with copper). Since then it hasnt worked properly.

The thing i cant figure out is how one tap can be cold and one hot, when they are both on the same line...

What style tempering valve?

Some require the same pressure on all 3 sides of the valve to function correctly

the HOT inlet side of the valve is the valve that is regulated. if the cold side has a higher pressure than the hot side then the cold water pressure will keep the hot side closed until the flow through the valve is causing the pressure to drop sufficiently for it to function again.

theres a 3 port and 4 port valve, Assuming you have a 4 port (because I cant think of how this would work on a 3 port unless you have a bridge between hot and cold with the plumbing sequence going regulator bath-Sink with the bridge exsitsing between the bath and sink

assuming its not a hot-cold link and its a 4 port regulator theres 4 ports

1. Cold water in
2. Hot water in
3. Regulated hot out
4. unregulated hot out
   

without knowing exactly how the plumbing is done assuming you aimed to have the sink on one port (hot unregulated) and the bath on the other (hot regulated)

If you have this valve plumbed up incorrectly its possible (and this is only theoretical you can do it deliberately but why would you?) That if you have the vavle plumbed in 180 out (inlets to outlets) and you're running the bath off of what should be the regulated hot and the tap off of the unregulated hot side the balancing is working backwards dumping cold water out the sink while trying to blend to the bath.

I dont think the newer 4 port valves should let this happen as the outlet sides should have one way valves in them.

I should have added that all the plumbing was working great until I turned off the water to have some pipe replaced (the previous owner installed flexible braided pipe within the wall, which i wanted replaced with copper). Since then it hasnt worked properly.

This is the area that I would first be looking at for the problem, As you say everything worked perfectly BEFORE the braided lines were replaced.