raven heat losing pressure hot water hot and cold

[lordyjordy111]

Hi people

I'm a trainee heating engineer and have posted on here quite a few times now

my sisters boiler is a raven heat and when she turns on the hot tap in the bath it is running fairly hot then cold.
also at the same time the room stat is turned off but the flow pipe is getting hot on the rad when I turn the bath (hot) tap on

I believe this is the divertor valve inside the boiler????

another problem is the she keeps topping the pressure up but there is no leaks on the system.

it loses pressure instantly (without heating up and out prv beacause expansion vessel)

any thoughts? i think new boiler

 

[Mbear]

What's wrong with replacing the Dv and pumping up vessel. It's your sister for god sake, try save her some money lol

 

[Billy Bob Bob]

DV OR PLATE HEAT EXCHANGER,or both are the hot water problems,as mbear said you could just need to re pressurize the EV that would help the pressure issues,if that fails then either replace the OE part or fit a external EV

 

[lordyjordy111]

that's my point.... it can't be expansion vessel as its losing pressure without heating up so as gas man said i'm thinking heat plate heat exchanger.

if plate h/e would that be why hot water tepid then cold

and yes its my sister that means ill be changing the boiler for zip.... well almost:smiley2:

 

[Billy Bob Bob]

plate heat blocked would cause the primary ntc to shut it down,but sometimes it takes out diverter safety spring as well,losing pressure is a different fault and unrelated,you need a few years of repairing boilers to understand the workings and failings of a combi,your sisters boiler has 2 faults but as mbear pointed out they can be fixed for half the price of a new boiler,welcome to the world of old, knackered boilers,replacing the boilers the easy option ,fixing it takes more than you know at this moment in your training

 

[Mbear]

Just remember if the boiler itself ain't losing pressure then even fitting a new chb won't solve the pressure issue. Hw wise it could be either or plate/dv. Hard to diagnose without being there

 

[lordyjordy111]

I know I'm showing my inexperience but whats an ntc?

anyway cheers for the advice gas man you are a legend

 

[Billy Bob Bob]

I know I'm showing my inexperience but whats an ntc?

anyway cheers for the advice gas man you are a legend

nominal temperature coefficient NTC or easier to call it a thermister

 

[Mbear]

Negative tempreture co-efficient

Sensor basically, and yes that does show inexperience lol. On older boilers they used ptc's