my Ravenheat Combi boiler had a problem recently where it was on zero
pressure, so I turned a plastic tap underneath which was connected to
a felxible pipe, which seemed to let more water into the boiler.

The radiators now all work full heat, but the hot water isn't very
hot, and the hot water isn't hot at all when the switch is switched
from central heating and hot water to just hot water. I've tried
varying settings on both thermostats.

It seems like something's wrong as the boiler used to be fine to pump
out hot water when the switch is just set to hot water.

Pressure is about 0.8 bar cold and i'm not sure what it is when hot
but its over 1 bar.

Has anyone got any ideas please before I call out a plumber?

Many thanks.

On Wed, 04 Apr 2007 01:19:10 -0700, iceland_potter wrote:

my Ravenheat Combi boiler had a problem recently where it was on zero
pressure, so I turned a plastic tap underneath which was connected to
a felxible pipe, which seemed to let more water into the boiler.

The radiators now all work full heat, but the hot water isn't very
hot, and the hot water isn't hot at all when the switch is switched
from central heating and hot water to just hot water. I've tried
varying settings on both thermostats.

It seems like something's wrong as the boiler used to be fine to pump
out hot water when the switch is just set to hot water.

Pressure is about 0.8 bar cold and i'm not sure what it is when hot
but its over 1 bar.

Has anyone got any ideas please before I call out a plumber?

Many thanks.

It's very likely the diverter valve. Switch the CH off, run a hW tap,
if the boiler fires and the CH flow pipe gets hot the that's really all
the proof you need.


--
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

On 4 Apr 2007 01:19:10 -0700, "iceland_potter"
wrote:

my Ravenheat Combi boiler had a problem recently where it was on zero
pressure, so I turned a plastic tap underneath which was connected to
a felxible pipe, which seemed to let more water into the boiler.

The radiators now all work full heat, but the hot water isn't very
hot, and the hot water isn't hot at all when the switch is switched
from central heating and hot water to just hot water. I've tried
varying settings on both thermostats.

It seems like something's wrong as the boiler used to be fine to pump
out hot water when the switch is just set to hot water.

Pressure is about 0.8 bar cold and i'm not sure what it is when hot
but its over 1 bar.

Has anyone got any ideas please before I call out a plumber?

Many thanks.


On the assumption that this is not a troll.....The plastic tap you
refer to is the control for the Filling Loop to increase the pressure
in the boiler .The instructions that were left by the installer ( They
were weren't they?) will explain all ( You have read them haven't you
??) .

AIUI the pressure should be read when cold and not hot so it might be
that you need to put more water in when it's cold .

Is there not a temp control for the HW so you can increase it to a
temp that suits you ?

Thanks Ed and Stuart,

Ed - sounds like it could be that, although when I turn the hot tap
on, there is immediately a burst of hot water, then it goes lukewarm
at best for sustained periods of time.

Stuart - Why would I be a troll? I have a problem with my boiler, so
I posted to a diy usenet group, please explain why you think I may
have been a troll?

I have put more water in the boiler from cold though to raise the
pressure to 1.2 bar, this seemed to work for a bit then after a day or
so I'm left with the lukewarm-at-best problem as described.

On Tue, 10 Apr 2007 01:35:16 -0700, iceland_potter wrote:

Thanks Ed and Stuart,

Ed - sounds like it could be that, although when I turn the hot tap
on, there is immediately a burst of hot water, then it goes lukewarm
at best for sustained periods of time.

Stuart - Why would I be a troll? I have a problem with my boiler, so
I posted to a diy usenet group, please explain why you think I may
have been a troll?

I have put more water in the boiler from cold though to raise the
pressure to 1.2 bar, this seemed to work for a bit then after a day or
so I'm left with the lukewarm-at-best problem as described.

The most likely failure modes a

1) The water flow diaphragm has partly split is becoming less sensistive
and effective, whilst it still switches the boiler on it is not strong
enough to move the valve fully to the DHW position.

2) Due to anyone of a number of problems the diverter valve is too stiff
to shift to the DHW position.

HTH

--
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 Ed,

I ended up getting a gas boiler firm out under a caveat of my home
insurance who took a look. After much tutting he decided a whole
diverter valve replacement was required. He's due to come tomorrow,
lets hope this sorts out my boiler.

Just for completeness, thought i'd post. The diverter valve was
replaced and boiler sorted.