BG(worcester) 537/i combi temp display question

Quick question for anyone in the know about the aforementioned boiler.

Does the digital temperature display on the boiler when drawing hot water base its reading from the DHW sensor, or is it the primary circuit temperature sensor?

Background reason for asking: My pensioner parents combi has starting cutting out when using the shower from what seems to be over temperature from looking at the boiler display (goes over 90 degrees then shuts off burner).

Shower filters are clean, new mixer cartridge installed and same problem - so not shower issue.

Very soft water area so no limescale problems.

I noticed today whilst there that the actual water temperature leaving boiler was cooler than displayed, so used a thermometer and found out it was 25 degrees out.

They have already have a BG fixed price repair booked for tomorrow, but having noticed this issue I wondered if it was worth getting a DHW sensor on standby incase this is the fault and the engineer doesnt have the part on his van.

Its very close to christmas so could be difficult getting parts, and my mums just had major heart surgery and will be released from hospital in the next few days so I want to know the shower will work for her. A nearby merchant has one DHW sensor in stock and thought it might be worth popping in first thing tomorrow and splashing £10 just in case.

Any help would be greatfully recieved.

Thanks.

It's displays the primary temperature. It'll be the Plate heat exchanger, it will be blocked.

martyndc88 said:

It's displays the primary temperature. It'll be the Plate heat exchanger, it will be blocked.

Click to expand...

Thanks for clarifying that, thought it seemed to be the other possibility.

I'll leave it up to the engineer to sort it.

BG engineer looked at it this morning and concluded it was plate heat exchanger as suggested.

They are sending out another engineer who has ultrasonic bath to clean it out.

Thanks for the input.