De-scaling the water heater

We have a Bosch Filtrino water heater for heating water for tea & coffee, as it heats 250ml of water at a time, by induction, saving energy compared with a kettle's power requirements.
http://www.bosch-home.co.uk/products/kettles-toasters/hot-water-dispensers/THD2063GB.html

There are two indicators to the bottom-left of the device. The upper indicator lights wen a certain number of measures have been dispensed, indicating that the filter probably needs changing. This light has been lit for a few months, as we promptly lost the manual and don't know the process for extinguishing the light. The lower indicator is the relevant one here, though.

It lit a few weeks ago. Looking online, I see that it means that the device needs to be de-scaled. We live in a very hard water area, so it's no surprise that de-scaling is needed, and our previous water heater had to be thrown away after lexcessive limescale build-up clogged all the internals and the motor burned out.

So, we're aware that we need to perform regular maintenance. As I mentioned, we lost the manual. So, we didn't bother doing it.

Anyway, it stopped working last week. I decided to bite the bullet and find a manual online that would tell me how to de-scale the device.

After perhaps 30 minutes searching, I finally found the manual. It wasn't easy to find. The manual had a whole section on how to de-scale the device.

I read the instructions ... turn the device off, empty the water chamber, refill it to a "de-scaling mark" with limescale-removing solution, turn the device on while holding the "power" button down, and wait 10 seconds, until the solution is passed through the device. When completed, run 3 tanks of water through the device to make sure all the de-scaler is removed.

Ok, all sounds straightforward.

Until I reach the "limescale-removing solution". I double- and triple-check the instructions, and they read "use the instructions for your limescale remover to produce the correct strength of de-scaling solution". I read the instructions on the bottle of "Limelight" that I have. It just says "Safe for use throughout the bathroom and the kitchen. Can be used neat or diluted". this presents me with a dilemma. Should I use it neat, pouring the whole 500ml bottle of limescale remover into the water heater, or should I dilute it?

I decide that I should dilute it, because I can always retry the process if it doesn't work very well, adding more limescale remover until it works properly. So I add a couple of long squirts of the limescale remover to 500ml of water, and begin the process.

The water doesn't flow very fast, but it DOES flow. After it's finished, I can see some flakes of limescale in the jug, but the "please de-scale me" light is still lit, so I pour the waste water back into the chamber and try again.

The water flows a little faster this time, with more flakes, but the light is still lit. I try again.

The water flows faster still, with a cloud of limescale in the waste, but the light is still lit. I wait for it to settle in the jug before decanting into the chamber and trying again.

The water is almost back to its original flow-rate, with more cloudy waste water. Eventually, after perhaps 10 of these run-throughs, the "please de-scale me" light is extinguished.

Folling instructions, I run 3 tanks of water through the device. I run another three tanks, just in case.

I heat water for a coffee. It tastes of de-scaler. I pour the coffee away.

I run another three tanks of water through the device. No change - still tastes like de-scaler.

I run tanks of water through the device for hours. When I'm finally fed up with this, I make coffee for Doris and myself. Doris complains that it tastes of de-scaler, but dammit - I'm going to drink it anyway.

For the next week, I have instant coffee and I have to brew filter coffee for Doris. She eventually relents, saying that the taste is almost gone. This leaves me with one question: if limescale remover is safe to use throughout the bathroom and kitchen, how toxic is it going to be if drunk?

Check the oven

Doris told me that she was baking bread. When I went to make coffee later, I noticed that the breadmaker wasn't switched on, so I pressed the "go" button, and it started counting down 5 hours. When I told her of it, she summised that she had pressed the button to lengthen the baking time to 5 hours instead of pressing the button to bake.

When it was done, Doris removed the bread and left it to cool. After a while, I cut some slices, so we could have warm buttered bread for our tea.

I slathered Doris's slices with butter, but used the last of the tub on those. I looked for another tub of spreadable butter in the fridge. Nothing. I shouted to Doris in case I was man-searching, but she confirmed that we were out of spreadable butter. Ok, we have non-spreadable butter.
I couldn't find any non-spreadable salted butter, so I called again, and she confirmed that we didn't have any salted butter either. Ok, I thought, I can't have buttered bread - I'll toast mine and put cheese on it.

So, I switched the grill on (toaster oven?), and put the slices of bread into the toaster. I then cut slices of cheddar to lay on the toast for grilling.

When the toaster popped, I lay the cheese on the toast, and opened the grill door to pop the toast in, whereupon I discovered two thick steaks, vacuum packaged in plastic, being baked!

When I brought her buttered bread to Doris, I told her this story.
Me: " ... so I turned on the oven to preheat and -"
Doris: "THE STEAKS!"
Me: "Yes, the steaks. I found them hot, and I've taken them out of the oven"
Doris: "Is the plastic packaging all melted on them?"
Me: "I don't think so - it looks ok; only partially melted"

We ate the steaks in sandwiches for lunch today. They were delicious, and I didn't notice any taste of plastic at all!