Just recently my boiler has started to exhibit a problem whereby the DHW
takes longer than usual to reach full heat, and the full heat isn't really
that hot (49-50 C). When the tap is turned off the temperature reading on
the boiler jumps up a bit, maybe by 10 C or more.

The problem only seems evident when the CH is not running. It also seems to
vary slightly, in that the temperature seems to fluctuate slightly during a
shower.

The DHW temperature control on the boiler seems to have no effect - and
never has done even from new. Resetting the boiler has no effect. There
are no error codes etc. The only other problem I have with the boiler is
that occasionally in the winter (maybe 3-4 times per year), and strangely
generally around late afternoon/early evening the boiler fails to ignite - I
kind of put this down rightly or wrongly to gas pressure issues.

From a previous post there was mention of the diverter valve being a
possible cause, but the CH flow pipe doesn't seem to get particularly hot
unless the water is running for a while (e.g. a for a shower).

Thanks in advance
Brett

On Sun, 25 Feb 2007 12:23:53 +0000, Brett Jackson wrote:

Just recently my boiler has started to exhibit a problem whereby the DHW
takes longer than usual to reach full heat, and the full heat isn't really
that hot (49-50 C). When the tap is turned off the temperature reading on
the boiler jumps up a bit, maybe by 10 C or more.

The problem only seems evident when the CH is not running. It also seems to
vary slightly, in that the temperature seems to fluctuate slightly during a
shower.

The DHW temperature control on the boiler seems to have no effect - and
never has done even from new. Resetting the boiler has no effect. There
are no error codes etc. The only other problem I have with the boiler is
that occasionally in the winter (maybe 3-4 times per year), and strangely
generally around late afternoon/early evening the boiler fails to ignite - I
kind of put this down rightly or wrongly to gas pressure issues.

From a previous post there was mention of the diverter valve being a
possible cause, but the CH flow pipe doesn't seem to get particularly hot
unless the water is running for a while (e.g. a for a shower).

What flow rate are you getting in litre/min from the hot tap?
At this time of year the boiler needs to heat the water by 45C

So the 8-9 litres/min should be the max you should get.
If it's somewhat less then there may be a fault in the modulator.
If it's about 8-9 litres/min then you will need to draw water a little
less quickly to get it hotter.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards

"Ed Sirett" wrote in message
...
On Sun, 25 Feb 2007 12:23:53 +0000, Brett Jackson wrote:

Just recently my boiler has started to exhibit a problem whereby the DHW
takes longer than usual to reach full heat, and the full heat isn't
really
that hot (49-50 C). When the tap is turned off the temperature reading
on
the boiler jumps up a bit, maybe by 10 C or more.

The problem only seems evident when the CH is not running. It also seems
to
vary slightly, in that the temperature seems to fluctuate slightly during
a
shower.

The DHW temperature control on the boiler seems to have no effect - and
never has done even from new. Resetting the boiler has no effect. There
are no error codes etc. The only other problem I have with the boiler is
that occasionally in the winter (maybe 3-4 times per year), and strangely
generally around late afternoon/early evening the boiler fails to
ignite - I
kind of put this down rightly or wrongly to gas pressure issues.

From a previous post there was mention of the diverter valve being a
possible cause, but the CH flow pipe doesn't seem to get particularly hot
unless the water is running for a while (e.g. a for a shower).

What flow rate are you getting in litre/min from the hot tap?
At this time of year the boiler needs to heat the water by 45C

So the 8-9 litres/min should be the max you should get.
If it's somewhat less then there may be a fault in the modulator.
If it's about 8-9 litres/min then you will need to draw water a little
less quickly to get it hotter.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he
http://www.makewrite.demon.co.uk/GasFittingStandards

Thanks for your response Ed.

Since posting I've done a little more investigation...

I removed the head from the diverter valve and pushed the valve in manually.
The water seemed to reach full temperature as expected. I also checked the
voltages in to the diverter head and although I've no knowledge of the exact
signals required, there was definate switching of 240 volts when switching
between CH and DHW. The only thing that concerned me was that there was a
fair bit of force req'd to manually operate the valve. Not sure if this is
normal or not?

The flow rate hasn't changed from when the boiler was working normally, and
when I say 49-50 C that's just the readout on the boiler - the temperature
from the tap is maybe only 40C or so.

I'm thinking that this is now either a fault with the diverter head, or with
the mechanical valve itself being too stiff.


Thanks
Brett

On Sun, 25 Feb 2007 19:53:52 +0000, Brett Jackson wrote:

"Ed Sirett" wrote in message
...
On Sun, 25 Feb 2007 12:23:53 +0000, Brett Jackson wrote:

Just recently my boiler has started to exhibit a problem whereby the DHW
takes longer than usual to reach full heat, and the full heat isn't
really
that hot (49-50 C). When the tap is turned off the temperature reading
on
the boiler jumps up a bit, maybe by 10 C or more.

The problem only seems evident when the CH is not running. It also seems
to
vary slightly, in that the temperature seems to fluctuate slightly during
a
shower.

The DHW temperature control on the boiler seems to have no effect - and
never has done even from new. Resetting the boiler has no effect. There
are no error codes etc. The only other problem I have with the boiler is
that occasionally in the winter (maybe 3-4 times per year), and strangely
generally around late afternoon/early evening the boiler fails to
ignite - I
kind of put this down rightly or wrongly to gas pressure issues.

From a previous post there was mention of the diverter valve being a
possible cause, but the CH flow pipe doesn't seem to get particularly hot
unless the water is running for a while (e.g. a for a shower).

What flow rate are you getting in litre/min from the hot tap?
At this time of year the boiler needs to heat the water by 45C

So the 8-9 litres/min should be the max you should get.
If it's somewhat less then there may be a fault in the modulator.
If it's about 8-9 litres/min then you will need to draw water a little
less quickly to get it hotter.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he
http://www.makewrite.demon.co.uk/GasFittingStandards

Thanks for your response Ed.

Since posting I've done a little more investigation...

I removed the head from the diverter valve and pushed the valve in manually.
The water seemed to reach full temperature as expected. I also checked the
voltages in to the diverter head and although I've no knowledge of the exact
signals required, there was definate switching of 240 volts when switching
between CH and DHW. The only thing that concerned me was that there was a
fair bit of force req'd to manually operate the valve. Not sure if this is
normal or not?

The flow rate hasn't changed from when the boiler was working normally, and
when I say 49-50 C that's just the readout on the boiler - the temperature
from the tap is maybe only 40C or so.

I'm thinking that this is now either a fault with the diverter head, or with
the mechanical valve itself being too stiff.

But that part of the story doesn't entirely sit with the CH pipes not
getting hot when running the HW.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards