It's a mystery...! All aspects of plumbing questions and answers, help, tips and information

[163013]

Hello all. Exactly a year ago I installed a bathroom suite for a friend. Having re-plumbed so the bath went to the other side of the room,I used end feed soldered joints. So the cold feed goes like this-from the mains,using 15mm copper,a tee for the wash basin,then running under the bath and into the studded wall to go up for the mixer shower. The cold for the bath is tee'd from this,and up into the tap. (pause for breath...). The problem is,the (second hand) cold bath tap gradually stiffens up,and no cold will flow through it. Then there is no cold for the shower. :( I have already had the tap off,and opened up the gate valve before the bath tee,and water flows no probs. Then gradually the problem re-occurs. I am thinking the tap spindle needs copper greasing? But why is the shower affected? Bearing in mind there is no leaks,( the floorboards were up for a good few weeks while I did the tiling,and kept checking the joints,)and the sink cold works fine-is it an air-lock? And if it is what do I do? :? :?
Thanks in advance guys......

[plumbbob]

So the cold feed goes like this-from the mains,using 15mm copper,a tee for the wash basin,then running under the bath and into the studded wall to go up for the mixer shower. The cold for the bath is tee'd from this,and up into the tap. (pause for breath...).

I'm just a little confused by all this. Is the cold feed to bath and shower mains or low pressure? Is the hot fed from a combi boiler or DHW cylinder?

[Barry Bunsen]

Hi
When you say the gate valve is before the bath tee do you mean inbetween the bath tee and the bath tap? Does cold water get to the mixer shower when the gate valve is closed?

[163013]

Thanks guys for showing an interest....
Anyway-it's a combi boiler,and pressure is good(as I said the basin works fine.) The gate valve is before the tee for the bath. i have since been back to dismantle the tap body,replaced the washer,and copper-greased the spindle. So then the tap worked fine,and cold got to the mixer shower.
Problem is if they ring me in a couple of months and say it's happened again,I will be stumped. :? By the way,the shower is also second hand , so could it be scaling up?
Thanks again.

[plumbbob]

Having a combi reduces the possible causes considerably. The trouble is, what it does leave is not much.

The problem is,the (second hand) cold bath tap gradually stiffens up,and no cold will flow through it. Then there is no cold for the shower. :(

I can't see how any fault with the tap can effect the shower. If it were me, I would strip the gate valve to check its operation. Gate valves ought not to be used in high pressure system anyway.

You say,

I have already had the tap off,and opened up the gate valve before the bath tee,and water flows no probs. Then gradually the problem re-occurs.

which appears to indicate the valve is functioning correctly -maybe.

I wouldn't assume the shower is scaling up either as that fault wouldn't be intermittent. Let's hope you don't get the phone call!!

[163013]

Cheers plumbbob.....
Like the subject says-it's a mystery.
Could've put a few expletives in there but hey. :?
Just one thing...howcome gate valves ought not to be used? Was advised to use them over iso valves as the flathead slots can wear down and render them difficult to use(?)..and I took a new lever valve with me to replace the gate valve because I assumed there must have been debris in it,but as said when tested there was no need.
But you can't teach experience so any advice is welcome... :)
Fingers crossed eh!

[plumbbob]

Just one thing...howcome gate valves ought not to be used?

Gate valves cannot guarantee a watertight seal when under pressure.

Was advised to use them over iso valves as the flathead slots can wear down and render them difficult to use(?)..and I took a new lever valve with me to replace the gate valve because

I wouldn't say slot damage is an issue if the right sized screwdriver is used, it isn't as if they are used regularly.

The main problem with gate valves is they corrode quickly and henceforth can be unreliable and unpredictable.