Baxi Combi with DH Tank and 2 CH Zones

[howbut82]

Hi All
I am planning for a house extension at the moment and would like to implement the attached scheme in the Central Heating work.
The house will have 1 bath + 2 showers when completed, for 3/4 people. The existing combi is a Baxi 30kW, 2 years old, from the previous owner. Since it would be a shame to dump and to replace this relative new boiler, also to achieve electric hot water back-up (just in case), I am planning to introduce a DH cylinder connected to the CH circuit.
The existing DHW outlet (from combi) will be used for the kitchen sink only, to keep water flow within the boiler. I will manually set the CH setpoint temperature at 60C on the boiler.
I think it should work but would love to hear other's opinion.

I am planning to buy an indirect cylinder (@£500) + other accessories. Very likely I will explore different wiring to link with Hive or Wiser smart control.

 

[oldbutnotdead]

Check the heating output rating on the Baxi (the 30kw headline number is usually for DHW), long as your total heatloss plus 5kw for the cylinder is inside that rating then yes, no reason why not. You've got other options (you could run 1 shower on the combi, for instance so you don't need a massive cylinder).

 

[ianmcd]

Yes very common to do this, you will be better with an unvented cylinder in you have adequate flow rates, other wise you will need to fit a tank in the loft