Have 4 year old Worcester-Bosch 29kW Condensing boiler heating house
and megaflow tank.

The heating/hot water wasn't getting hot - pump appeared to have
jammed and was replaced last week, howver problem continues.

In both CH and HW mode, burners kick in, reported temp climbs to 75C,
then burner cuts out, temp drops to about 45C before cutting back in
again.

Flow-out pipe from boiler can be held in hand, so never gets to 75C.

Pump appears to be running and 3-way valves appear to be working OK.

Any thoughts? Heat exchanger ?

thanks
Charlie

"charlieB" wrote in message
Have 4 year old Worcester-Bosch 29kW Condensing boiler heating house
and megaflow tank.

The heating/hot water wasn't getting hot - pump appeared to have
jammed and was replaced last week, howver problem continues.

In both CH and HW mode, burners kick in, reported temp climbs to 75C,
then burner cuts out, temp drops to about 45C before cutting back in
again.

Flow-out pipe from boiler can be held in hand, so never gets to 75C.

Pump appears to be running and 3-way valves appear to be working OK.

Any thoughts? Heat exchanger ?

thanks
Charlie

Sounds like the 'over-heat' sensor is kicking in. There could be some debris
in the bottom of the boiler, that is restricting water flow. 4 years old?
best bet maybe to get it serviced, before the really cold weather arrives.

Bertie