Bosch Worcester 230 water running cold

[robriley]

Hi,

I have a Bosch Worsester 230 combi boiler (gas), i reckon its about 8 years old. Over the last 4 weeks we have been experiencing the hot water from all taps in the house running cold after 20 secs, particularly annoying when in the shower.
This only happens when the CH is off, if the CH is on we get constant hot water no problem.
The boiler comes on ok when the hot tap is turned on, after about 20-30 secs all the flames just go out, if the hot tap is then turned off then on again the flames do not re-ignite. If left for 30 secs or so then the hot tap is turned on the boiler ignites ok.

No work has been carried out on the boiler recently which may of triggered the issue.

Is there anything i can try before calling out a plumber?

Hope you can help

Rob

 

[gas4you]

I would say the water to water HE is blocked or scaled up, causing the boiler to go to overheat, shut down, cool down, then allow itself to fire up again.

 

[Corgigrouch]

I'd be inclined to have a look at the diverter valve

 

[robriley]

Hi, the boiler now does not ignite when any of the hot water taps are turned on. The heating works fine, and i can get hot water when the heating is on. Any further adeas?

 

[Gasguru]

When a tap is opened check the pin operates the microswitch assembly on the end of the diverter valve...lower LHS.

If not, probably just needs a new diaphragm....genuine Giannoni kits around a tenner....you will also need to replace the O ring on the slip coupling to the heat exchanger.

Boiler is more like 12-15 years old.

 

[diyhandyman]

seems odd, a combi doesn't provide both HW and HTG together, it is HW priority!!

 

[Rob]

Read again handyman. Problem is no HW when HTG is off.

Diaphragm is failing and not lifting enough to operate microswitches but it is enough to allow some power to the calorifier.

 

[diyhandyman]

sorry yes of course.

some diverter valves use the venturi type diverter valve and some a wax capsule, but i believe the diaphragm type is the most popular.