New system boiler and cylinder in kitchen

[positivity123]

We are reconfiguring our downstairs and have decided to get a system boiler and cylinder to replace the combi boiler which is currently under the stairs as it will struggle.
The under the stairs cupboard is going to become a downstream toilet so we will need the new boiler and cylinder in the kitchen.
Does anyone know what space I will need. The space between windows and doors is about 700x1300. Does this sound enough?
Do you think it will be noisy? Anything else I should think about?

Depends how big a hot water cylinder you choose. Our hot water cylinder is in a cupboard and is quite large. I wouldn't want it in sight in the kitchen. Would you be boxing it in?

You looking at something along the lines of a megaflo? pressurised systems also require an expansion vessel so a bit more space there. Ours in a 270l cylinder with vessel above and will fit in a cupboard 700 wide but floor to ceiling and you need to account for pipes too. Boiler is located in the loft for us which seems to be working just fine but frankly I'm more used to it being simpler to access!

A system boiler is generally quieter than a combi because it does not fire up at full power every time you turn the tap on.

When you use the timer/programmer, they usually start half an hour before you get up in the morning, or home in the evening, and will be ticking over at low power the rest of the time.

Modern boilers modulate down the flame size according to demand and (apart from combis) seldom need to run flat out.

The boiler is likely to be small enough to fit in a kitchen wall cabinet (there must be access for servicing) and the cylinder will be tall rather than fat, but can go at the end of a run of cabinets. Again, it must be fully accessible for servicing. The cabinet will be modestly warm so often used as an airing or coat cupboard (modern insulation means there will not be as much waste heat as from an old-fashioned cylinder). The cylinder can be anywhere in the house, but is very heavy (preferably not in a loft)

This is all really helpful, thank you.
Our architect has drawn up a picture so I think it looks ok but it's great to understand how it will work. Can you helpful bunch take a look and see if it looks in the right place or any other ideas you may have?

I think he's drawn the boiler room so you can't stand in front of it and pull the casing off towards you for maintenance. The casing is the same size as the boiler.

The cylinder will have pipes coming out of the front and sides so needs more clearance

Presumably he intends the boiler room to be built round the equipment after it is installed, and demolished when it needs to be replaced. Like a submarine engine.

I'd have a pair of rebated fire doors on the boiler room to muffle noise, as it's in a living room.

Is there an extractor fan in the WC?

There is a small window in the WC.
The cupboard for the boiler would be 700mm deep and 1200 long. The doors would open out where the sofa is. I'd pictued using full length kitchen cupboards and moving the sofa when we need to get to the boiler.
Do you not think there is enough space? Definitely not going for the submarine option!!

in the drawing, the boiler casing can't be pulled off in either direction.

it would have the best chance if it was facing the sofa and spaced off the end wall by more than the thickness of the frame.