Vailant Aquaplus, overheating when running hot water.

[nicho]

Hi all, my mate has a vailant aquaplus combi & it is cutting out when he runs the hot tap (the temperature rises rapidly, then it cuts out). It shows a fault code 24, which i am led to believe is due to poor circulation. he said it makes alot of noise when running, consistent with possible circulation problems. As the hot water heat exchanger is so small, could it be "furred up"? We live in hartlepool which is a notorious hard water area. Forgive the lack of knowledge (we are both sparks), but are not totally useless, so i would like to know if we could descale the heat exchanger to solve the problem? Also would love any further help if we are barking up the wrong tree. I know you can get additives to clean the system that you add, but don't need to drain off after use, but do these just clear sludge or can you get a descaler that does the same job? Failing that, the heat exchanger doesn't look to difficult to remove, so could we take it out & descale it with kettle descaler, without damaging it? Hope you guys can help, cheers,Andy

 

[gas4you]

Does one assume it works ok for heating?

If not check the pump first.

If it does then cleaning out the plate HE is a good first step.

I use Fernox DS40 or DS3 depending on what you find in it after removal.

Many on here recommend 'Spirit of Salts' which is HCl.

I have never used this as yet so cannot comment.

 

[nicho]

Thanks for the reply, my mate had already took out the heat exchanger & descaled it & it seems to have done the trick, but i thought i would thank you for your advice anyway. To answer you 1st question, it worked ok on heating, cos the first thing i thought was it could have been the pump. cheers, Andy.