Auto Sleeper Broadway 2017 Model.

I am currently in Austria and sensors are working fine. I bought two packs of Aldi's citric acid but cannot be sure whether I used one pack or both. I would need to check whether i still have a pack left. The packs had two or three sachets and I dissolved each sachet in a bucket of water and then used the whale filler pump to pump that into the tank. As I have said earlier in this thread or maybe in another I used warm water at first but the pump did not seem to like that. As far as I remember I pumped in around 6 buckets of solution or water iaround 50 litres. I left that for about 3 or 4 hours and then topped up the tank and left it overnight. That was all at the beginning of the season so the hot tank of the boiler was empty. I then opened the hot tap to get water into the pipes and fill the hot tank. I left that for about 3 hours more before draining down completely ( as for winter layup), refill and drain twice more to remove lemon taste.
My reasoning for all that was that warmish solution would work best and the lowest sensors would be worst furred. A longer period at a greater dilution would be ok for the higher sensors. Also I did NOT want to have the solution in the hot water tank for longer than absolutely necessary - obviously a few hours was a guess on what was needed.
It seems to have worked.
Amazon sell 1kg citric acid cheaper than Aldi.
Hope that helps.

Thank you . I will order some when I get back to the UK in November.

Inspirrdron, thanks for this, doing ours soon. One question please, did you use the water heater to heat the water you put into the hot water tank? I have read others did that, but am worried it might cause a problem. 

Thanks.

A DEFINITE NO! If you want to see what would happen put a spoonful of citric acid in your furred home kettle and watch, with the lid off, when you switch it on. The amount of CO2 given off is quite alarming.
I only used warm water in the bucket to help the citric acid crystals to dissolve. Also, as I implied, you don't want too much effect in the boiler for fear of causing leaks in the seams of the tank. Truma boilers are fussy about what cleaners you use. You also have to be careful not to get chlorine based cleaners into the hot tank.

Thanks for that, my inclination too. I tried it out on my furry kettle and the speed it removed the lime scale was incredible. 

H