worcester 35cdi hot water problem

[hunter123]

hi guys

my boiler works fine with central heating, and hot water works fine once the heating is on, but as soon as the heating is turned off and i open the tap/shower at high pressure the water is not hot but just little warmer than cold.
i've tried a few things like turning the hot water temp gauge knob to maximum and other things but its the same story.

i have also just tried to open the tap or the shower not at full pressure, that seems to do the trick. but i am having to wash up in small amount of water coming out of the taps.

could it be hot water pump?

plz help me out guys.

 

[cjb1971]

does the boiler fire up when you turn the water on only at high pressure?

 

[ChrisR]

Is yours the earlier 35cdi, with 2 pumps?

 

[WDIK]

got a smaller version, 30cdi and it did the same.
water too hot then going cold. then stopping on high limit.
apparently worcester know this and later models had a buffer vessel.
firstly dont turn the temp up, that what causes the problem it causes the burner to modulate too quick, ive got mine around 45-42c.
secondly theres a setting in the controler, to give i think its instant hot water, that cured it for me and its fine.
ps this boiler has been discontinued.

http://www.worcester-bosch.co.uk/index.php?fuseaction=literature.detail&con_id=127779

 

[ChrisR]

wdik - the 30 cdi is not a "smaller version" of the questioner's boiler. It's nothing like it. And it probably is NOT the one you've given a link for.

 

[hunter123]

yes the boiler is the one with two pumps

and the boiler demand and flame comes on even if i open the tap half or full. but at full the water is just warm no way at the temperature it should be.

 

[hunter123]

and whatdo iknow you never explained how you cured it?


wheres the controller and what?

 

[WDIK]

firstly dont turn the temp up, that what causes the problem it causes the burner to modulate too quick, ive got mine around 45-42c.
secondly theres a setting in the controler, to give i think its instant hot water, that cured it for me and its fine.
ps this boiler has been discontinued.

http://www.worcester-bosch.co.uk/index.php?fuseaction=literature.detail&con_id=127779[/QUOTE]

 

[gas4you]

Don't know this boiler, but I would suspect the dhw pump.

 

[WDIK]

i dont know the older version either

 

[NickofBristol]

Hi there

Have got exactly the same problem. Have had various plumbers in who have not been able to fix so need help!!

Please can "whatdo i know" explain what the setting in the controller was that could be changed (to give instant hot water) which fixed the problem.

Thanks