combi boiler and unvented cylinder in one system

[sasik]

My customer got a new combi boiler and they would like to add a new unvented hot water cylinder to the system. Is this possible? Can they run the combi boiler as a system boiler? And if so how do I plumb the cylinder into the system? The only way I could think of is if I cup-off the hot water out let from the boiler and tee off the primaries to the cylinder coil with a motorised valve + programmer. What do you think?

 

[Cds]

I had a combi and cylinder at my last house. The DHW from the combi supplied the kitchen sink and cloaks wash basin the cylinder supplied the bathroom. This way you get instant water for the sink but plenty of stored water for the bath and shower.

 

[WHPES]

Why do they want an unvented cylinder? Is the combi too small to provide sufficient hot water for their needs or did they select the wrong type of boiler? The whole point of a combi is to remove the need for a cylinder.

I guess you could include one on a branch from the primaries but you will have to be careful to get the controls right. I think you still need some basins connected to the hot water side of it.