A boiler and a hot water tank ... what is this configuration? (UK)

Question

I'm a west-coast American living in London. I've mostly known homes with electric baseboard and central forced air heating, and a single hot water tank for showers and taps. In the UK hot water fed radiators seem the most common home heating solution, and I'm really not too familiar with how these systems are configured.

I was looking at a small row house recently that had a boiler in the kitchen and a water tank in a separate room (next to a bathroom). The boiler was gas powered, while the water tank was electric. I was offered a brief explanation of how the two systems inter-opted, but it didn't really make sense to me. There definitely was some kind of communication/connection between the two - they weren't two completely independent systems.

My question is, is this a common set up, even for a smaller (relative to US standards) place? And what would be the advantage to doing this over using just one system over the other?

Answer 1

Yes this is common in the UK.

The boiler will feed hot water into the heating coils in the tank as well as providing the hot water for the radiators.

The electric (or immersion) heater will be there either as back up (in case the boiler fails) or to heat the water on cheaper electricity (Economy 7) overnight.

There'll be a thermostat on the tank which feeds back to the boiler to turn off the heating when the water is hot enough, but other than that there's no direct communication between the immersion heater and the boiler. There might be communication via the timer used to control when each is turned on, but that's not usual.