Heatline Capriz 28a - DHW cut off after 30 seconds

[bassmonster]

OMG, what a nightmare of a job.

The boiler DHW would cut off after about 30 seconds. Central heating was OK. The fault code was F20 and having a look at the manual, it was stating to be an overheating problem. Code F24 was also showing which was pointing to water circulation problem.
I isolated the power, flow, return and cold inlet. My first thought was that it was a blocked plate heat exchanger so I went straight to the cap and…….PSSSSHHHHHHHHHHHHSSHHHHHHH……..water gushing out like there was no tomorrow…no matter what I did, I just couldn’t push the cap back to lock into place…..as you can imagine, I was feeling a grade A prize prat…..the water then finally stopped…
There was now water everywhere you can imagine inside the boiler…I spent the next hour or so drying everything…the filter was indeed completely blocked with what looked like black coal which I cleared…

Thankfully, no water got onto the PCB but the display panel board was wet which I dried with a hair dryer with the cool setting.
After ensuring that everything was dry, I switched on boiler and BANG….only kidding, miraculously, the boiler fired up..heating and DHW working just fine…checked gases with my FGA….all OK….

Needless to say, it was a freebie…..
Anyway, question I’m asking, after isolating flow, return and cold inlnet, should I have have opened DHW tap to empty the boiler?
Anyone else have had Prize prat moments on a job?

 

[Aquazone]

If you only isolate the cold inlet, all the mains throughout the boiler is still pressurised. I normally isolate, open nearest hot tap to just release pressure, then open upstairs hot to drain. If you don't open taps above boiler you can bet the customer will when you have plate out and send water everywhere!!!

 

[Leo21]

Why free? You fixed it, and the water dried out I'm betting.

 

[bassmonster]

After feeling like a right knob and wetting the floor and their bed, I've put this one down to a learning experience.