Are combination boiler/DHW units a good idea?

[mcbane]

I have a detached garage that includes a bathroom with shower. I was looking at the Laars Mascot boilers, and wondering how well the “combo-heat” versions work. In theory saves me the trouble of a separate water heater.

Anyone have experience with the combination units? Is there a downside?

 

[billconner]

Lots of variables but 25 year old house we bought a few years ago has an oil boiler for hot water heat and a hot water tank as another zone. Works fine and in theory is efficient or for the era it was. The previous owners used the basement a lot - semi finished - but the boiler running all summer just foe domestic hot water added a lot of heat (they said and I suspect true) so the added an electric hot water heater. Switch a few breakers, flip a few ball valves, and summer dhw us electric.

YMMV, but possibly a consideration.

 

[Jackfre]

Any time you talk combo units you begin with the dhw load. How much hot water do you need? What is the heat load? Do you have radiant or hot water baseboard or hydro air? To your primary question, most gas boiler manuf have combi boilers and it is the fastest growing segment of residential boilers, so yes they work, again, depending upon loads. The trick for you is finding the right contractor to install and back up your choice. I will pm you a recommendation.