Weird long term issue with the Hot Water Tap in the Bathroom

jasonb

Hi there,

I've had this issue for years, and have never got to the bottom of it.

I live in a bungalow, and my bathroom sink has a monobloc tap. For years the hot water tap has been dodgy. Sometimes it works perfectly. Sometimes it starts ok, but quickly the pressure dies down to a dribble. And sometimes nothing comes out at all. I've never been able to figure out a pattern, it just seems random. The cold water tap is always fine, and the hot water tap in the kitchen is fine too.

A while ago I got some work done by a plumber and just before he left he had a quick look at it and couldn't see any obvious issue with the tap itself. He suggested disconnecting the "flexible hot water hose" (what I'm calling it - I'm not a plumber) from the hot water supply pipe in the bathroom and then see how the hot water flows out of that hot water supply pipe coming from the ground. I had to leave, so I told him I'd try it myself.

I tried it the next day, turning off the hot water supply in the hot press, disconnecting the flexible hose, and then turning it back on again with the hot water pipe curved into a basin. It coughed and spluttered a bit and then hot water flew out with great, constant pressure. I turned off the hot water, reconnected the flexible hose, and it was back to working intermittently.

This, to my layman's thinking, suggested an issue with the tap itself or the flexible hose. I was planning to replace the bathroom sink tap anyhow, so decided to give that a go.

I did that today, and the issue is still the same (at the moment there's no hot water at all coming out). Once again, to test, I turned off the hot water, disconnected the new flexible hose from the hot water pipe, and turned the hot water back on again, and after some spluttering it once again came out great from the hot water pipe. Once I reconnected, nothing again (though it might easily work tomorrow if it feels like it).

So, I'm at a loss. The tap and flexible hose have been replaced, so it can't be them I assume? The only things I can think off is that the top of the hot water supply hose is only 1.5 feet off the ground, and the tap is 3 feet off the ground, so could that be an issue? Or also when the water flows fine it's just an open hose, but when it's not working it's connected to a monobloc tap that also gives access to the cold water so it's all connected (for example, if I turn on the cold water and let it flow, and then turn on the hot tap - when it's not working - the cold water pressure drop a little). Could that connect be causing an issue? When it flows out of the pipe it feels like a pretty decent pressure, could there be too much pressure for the hot water tap in the monobloc to handle? That seems weird to me though?

Any ideas at all out there, I don't know what it could be? Especially as sometimes it works perfectly for days, I would have thought either it works or it doesn't?

Thanks...

10-10-20

Is the brided hose kinked? If it's kinked or twisted then perhaps the heat from the water is softening the internal rubber pipe and allowing it to block the flow, only restoring it when the temperature reduces back down again.

Also is there an isolating valve on the pipe water at the joint with the braided hose? Is there any chance that either it's blocked or some rubble or masic is flowing within the pipe and getting trapped at the valve?

jasonb

Thanks for your reply. Pretty certain there's no kink, none I can see anyhow, and with the braid design it should be fairly obvious. This is a new braided pipe that came with the new monobloc tap, I didn't notice a kink in the old braided pipe either.

There's no valve between the hot water pipe and the braided pipe, presuming by valve you mean something I can open and close? There is a brass "join" that is attached to the hot water piper and the braided pipe screws on to it. It's also new, I replaced it when replacing the old tap, and I couldn't see any blockages.