Franke Omni QHT-1 Boiler not hitting 100C

[Gurj]

Hi guys. I got hold of a 2nd hand Franke Omni 4 in 1 with QHT-1 boiler. Had some leaks here and there, but sorted that out. Flushed system with Kilrock Descaler, all good. Everything works.
Got new Franke 08 filter.
I get hot water from the tank but it doesn't seem like it's 100C. I've changed both Thermostats with new 100C ones. But it still feels like it's not as hot as 100C.

Any ideas what else I can do ?
Shall I change thermostats for higher temperature ones ? I know that's not a good idea because it may damage the heating element.

 

[Harry Bloomfield]

I get hot water from the tank but it doesn't seem like it's 100C. I've changed both Thermostats with new 100C ones. But it still feels like it's not as hot as 100C.

Have you tried measuring the actual temperature, guessing is simply not enough.

 

[Gurj]

Have you tried measuring the actual temperature, guessing is simply not enough.

I'll get my meter from my other house on Monday and get actual readings.
But in the meantime any other suggestions would help.