Hot water sink tap problem

[Rollerball]

Some months ago the hot water sink tap in my bathroom developed a
problem where the water flowed a lot slower out of the tap as it got
hotter (water flow was initially fine when cold). This increased in
severity over a few weeks until it would come out at no more than a
dribble when the water was hot or cold.

The plumber replaced the brass cartridge assembly inside the tap (the
tap must be about 20 years old at a guess) and all was well. This was
about two months ago

However, over the past two weeks the problem has started to return.
Cold water flow isn't bad, but once it gets hot it comes out at a
dribble. Surely the new cartridge can't already be developing a
problem?

The water flow was fine for a good two months after the plumber (a
good, reputable guy) replaced the cartridge.

Could another part of the tap also be faulty? Or might the replacement
cartridge be at fault?

Just to give you an idea, this is the general type of cartridge in use
(but not the exact same model):

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=110499284236

Thanks

 

[dextrous]

Could well be the new valve has developed a fault. Quite a lot of these are now cheap imports. First thing I'd check would be the rubber washers within.

 

[Rollerball]

Thanks, if I could find the type to get I'd just buy another now that I know what to replace.

So it's definitely not possible that something else in the tap has a problem?

 

[dextrous]

The cartridge controls the flow, so I cannot imagine anything relating to the tap body that is causing a problem.

 

[picasso]

have a look here

http://www.lunns.net/tapspares/

 

[Rollerball]

Thanks for that - probably the closest there is the:

Armitage Millenia 1/2" Mk4 Washer Valve aka Kingston 20 Spline Washer Valve

although that's not exactly the same (there is less smooth metal on mine below the lower thread, plus on mine there is a noticeable gap between the smooth area and the lowermost metal area that has a washer at the very bottom).

 

[dextrous]

Can you isolate the supply to the tap while you take out the cartridge and go to a plumber's merchants? Have you actually tried just replacing the washers, by the way?

 

[Rollerball]

Can you isolate the supply to the tap while you take out the cartridge and go to a plumber's merchants? Have you actually tried just replacing the washers, by the way?

Yes, I can isolate the supply to just that tap.

Haven't taken the unit apart yet, but will do so in the next few days.

 

[dextrous]

Here's hoping it's a 20p fix

 

[Rollerball]

I can but hope.

 

[Rollerball]

Finally got around to dismantling the tap and have now 'fixed' this - I say 'fixed' as the problem seems to be with the design of the cartridge!

Inside it there is the main brass and washer component which moves up and down as the tap is turned on or off - the top end of this is hexagonal which in turn fits into a hexagonal opening inside the cartridge at the top end of the cartridge.

The problem occurs if the tap is turned off too hard - the top end hexagon (which moves up and down) slips out of the hexagonal opening and then doesn't line up to fit back in properly, so preventing the tap from turning on fully!

Hope I explained that okay as I don't know the correct names for the cartridge parts.

So my best bet now seems to get a better quality cartridge ........ or be very careful not to turn the tap off too hard.

Thanks again for everyone's pointers on this.