Ongoing issues with hot water sink tap

[jamma-plusser]

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):

[John]

Do you tend to be heavy handed at turning the tap off? If so I believe the washer can compress and the inner (moving) part of the cartridge can be forced out of its hexagonal body and jam. this causes it to not open fully.

Remove cartridge and inspect.

[jamma-plusser]

No, I don't think I'm heavy-handed with it. It does though seem to 'jam' when fully open or fully closed.

Note: When the water is running hot it simply won't unscrew that far, but when cold it will. Presumably something is expanding with the heat and causing the problem?

Will do when I can.

Ta.

[dennis]

Been there, fitted new washer, problem fixed. It was quite common with delta flow taps IME.

[jamma-plusser]

Surely though this shouldn't happen on a cartridge that's only been in occasional use for 2 months?

[The Medway Handyman]

Wouldn't have though so, its never happened to me - but it could be.

There isn't really another part of the tap that has moving parts.

cheap enough to do.

[spamlet]

Hi Jamma,

If you haven't sussed this yet: looking at your picture, I would say there is a chance that what is happening is that the nut that holds the washer down has come undone so that when you 'open' the tap, the washer does not lift with it. Then when the water warms up the washer expands and blocks the outflow. Probably the original valve had a rusted washer holding screw (very common) and the replacement just wasn't on tight. (I've found this problem a number of times in central heating drain valves, though in that case the water drains out but you only find the washer has come adrift when you try to turn it off again and it won't stop dripping.)

S