Do you mean, what we might call in the UK a "multipoint"? It can do one or both jobs. Heat hot water by gas only when the tap is turned on or centrally heat a house and provide hot water at the turn of a tap. We don't have central heating and have a multipoint for hot water only. It works fine, gives plenty of HOT water, can be mixed for a shower and fills a bath with no problem. Yes I would say it's well worth it as you only pay for what you consume and don't waste heat back into the environment.You do need to check that it can run a shower as there are underpowered ones available that will give hot water and fill baths, but do not have sufficient ability to mix with a shower under pressure.

Cheers.

Eric