Hot water from combi now only warm

[mayfel]

Hi all!

Right, about a year ago I had to replace the diaphragm on my boiler (Ravenheat CSI/HE) because the water was running hot then cold (and eventually just cold). It worked and I've had hot water to this day!

However, just recently the water has been only warm - warm enough for a bath but not as warm as I'd like it. Baths used to be really hot before and I had to add cold to get it right. I've now upped the boiler temperature but it hasn't made much difference.

I've checked the diverter valve shaft and microswitch and they're fully extended. The water is perfectly consistently warm - no fluctuation in temperature.

I also tried the old: leave the heating off, run hot water for ages and then felt to see if the central heating pipes have warmed up to see if hot water is leaking into there but it isn't.

Any ideas what this could be? Cheers people!

 

[muggles]

When was it last serviced? Could be a problem with the heat exchanger scaling up, could also possibly be a gas valve issue

 

[booty40uk]

Does reducing the flow at the tap make any difference?

 

[mayfel]

Admittedly it hasn't been serviced for 3 years.

On the running slow front I'd previously read that but hadn't bothered trying because I knew it normally comes hot even with the bath tap on full (the bath tap is actually a sink tap). I just ran the water for the washing up though and I'd left it running slowly without thinking about it and when I came back it was really hot. What would cause the boiler to not be able to deliver the normal level of hot water at the normal rate? The heating is fine and as hot as ever.

Cheers!

 

[dcawkwell]

Sounds like the gas valve isn't giving full power.
It could be simply the hot water sensor isn't working properly
and the boiler thinks it's hotter than it is.