Multi-point tankless water heaters

[Invader75]

Hi folks,

 

I have a garden annexe that is open plan with a wet room. Currently we have two small water heaters heating the water for the kitchen sink (underneath) and the small wet room sink (underneath).

 

I'd like to have a more efficient tankless water heater that will proved hot water for two sinks so we can eliminate the need for two. 

Does anyone have experience of these and could advise on any issues to watch out for or brands to look into. 

Many thanks

[JohnMo]

Basically as they are direct electric the efficiency will be exactly the same heating water. Storage losses may be smaller with a single bigger cylinder if the surface area in the combined cylinder is smaller. But if you already have 2 the cost pay back from improving efficiency, to pay for a 3rd bigger unit, would several life times.