tepid water upstairs after being hot for 30 secs. ok downst

[brich]

Hi there, I'm new to this forum, and chances are I've caused this issue as I tend to have a go myself rather than get in an expert from the start.

I have a house that I let out. About a month ago I changed the kitchen tap as the old mixer was broken. On completion, the tap was working fine, but there were no tenants in the house to say whether anything had changed afterwards.

New tenants moved in last week and they contacted me to say that when they try to run a bath, the hot water is hot for around 30 seconds then it goes tepid. It stays hot downstairs when they run it. As far as I am aware this wasn't an issue before I changed the tap.

From recollection the tap pressure dowstairs used to be a bit extreme, so I may not have turned the cold water feed back as high as it was previously.

Is increasing or decreasing the mains cold water feed likely to affect the hot water feed upstairs, or is it more likely to be a problem with the combi boiler ?

The boiler is an Ariston 23 microgenus mffi. Not exactly state of the art, but it has done a reasonable job for the last few years and was serviced about 4 months ago.

Any replies would be very much appreciated.

Billy.

 

[picasso]

your new mixer taps are likely to be the problem, fit a check valve on the hot supply to the tap and it should solve it.

 

[brich]

Picasso,
thanks for your reply. It's the hot water tap in the bath upstairs that is running tepid. Would adding a check valve to the kitchen mixer affect the bath water upstairs.

Apologies for my ignorance.

 

[JohnD]

most likely you have got mains-pressure cold and tank-fed hot. In a mixer the cold overwhelms the hot. Sometimes it even pushes up thr hot pipes into the hot cylinder (which also causes overflows)

If you put your hand on a "hot" pipe under a hot tap, and discover it is very cold, even when you have recently run hot water, that will be the culprit tap, and you can put a non-return valve on the hot pipe.

Failing all else, you could fit separate pillar taps instead of mixers.

If it is happening at a bathroom mixer, another cure is to run the pipe to the cold tap from the loft tank, then it will be at the same pressure as the hot.

Shower mixers, and those ceramic mixers with a joystick, are especially bad for this.