Question 2 of 4
What energy source are you going to use?
Electricity
An electric boiler doesn't produce any gases you can thus place it anywhere.
It makes it a nice choice if the placement is restricted by space or pipings.
Furthermore, you'll have hot water arriving really fast if you place it close enough to your shower or bath.
They take a little while to heat up, but multiple people can use hot water at the same time while still enjoying good temperature and pressure.
Renewable
A boiler powered by renewable energy is both great for the planet and for your finances.
This type of boiler uses the heat present in the air to heat up water, which leads to impressive energy savings.
It still works great in cold weathers, even though the energy savings are slightly reduced.
Most models have an additionnal standard electric heating system in case it struggles to keep up with water consumption.
Gas
If you do have gas pipings in your house, an instantenous gas boiler might be a good solution for you.
This kind of boiler heats up the water right as you use it, which means you will never run out of hot water while using it.
The drawback is that the hot water flow is limited, so if multiple people use hot water at the same time, it will not be able to get as hot.