The boilers I fit predominantly are Viessmann.  These are broken down into 4 types:

• Heat only: as the name says only makes heat, no pump or controls.  Requires hot water tank if hot water required.
• System boiler: This boiler also contains the system pump, diverter valve and controls package.  Requires a hot water tank if hot water is required.
• Combination boiler: Makes hot water on demand and heating.  No hot water tank required.
• Storage combination boiler: Allows much higher flow rates for the hot water out of just one box. Floor mounted.  No hot water tank required.

Wet solar systems (solar heated hot water) I believe are highly underrated. They work very well even in Britain!

I am a approved installer for Mitsibishi for their Ecodan range of air source heat pumps. In my opinion, they are very good in buildings with low heat loss.

While I install conventional hot water cylinders and unvented hot water cylinders; for many applications, I am a strong believer in a thermal store.

Pumps are installed to boost the hot/cold or both water services to a building. This can be because of low incoming water pressure from the mains...