If your cylinder is a white one, it will probably supply two of you with water all day if you run the boiler HW cycle for half an hour or so, morning and evening. Each cycle will probably be enough for one bath and one modest shower. If you can time it to be still running while the bath is run, it will reheat itself while you're splashing about. There is very little to be saved by restricting the timings, but avoid letting it be on all day, as the boiler will tend to run for a few minutes every time you use a sinkful of hot water, which is uneconomical for the boiler. If you find half an hour twice a day is not enough, try an hour, especially if you can overlap onto the main usage times.
This depends on it being 200 litres or so, which they usually are. The capacity may well be printed on the side or on a maker's plate. If not, how tall and how fat is it?
An ordinary copper cylinder, insulated in yellow, green or blue, is typically only about 120 litres, which is about enough for one bath, but if the boiler is on a HW cycle while you run the bath, it will be hot again in about 20 minutes, if the boiler and cylinder are both quite modern.
I posted previously about the heating in my new house and have got the hang of that now.
So I need some help with the hot water now. My previous house had a condenser boiler in the kitchen - no large tank - so it was hot water on demand. My new house is a new build and has a boiler in the kitchen and a large tank upstairs. I believe, from replies to my last post, that it is a modern, high-spec pressurised system. The hot water can be programmed to be on always, off always or to come on and off once, twice or three times a day. It also has a boost function.
So please help. I'm clueless. How many times a day should I set it to go on/off in a day, and for how long? We are a couple, no children. We only use hot water for showers, baths and hand washing etc. We have cold feed dishwasher and washing machine. We usually have either 1 bath and 1 shower or 2 showers in the each evening and sometimes daytime showers.