Large Extension - Oil Boiler Advice + UFH

[George T]

we are planing a large 11m x 11m 1.5 storey extension on the side of our house. We have no access to mains gas.

Our current setup is as follows: (installed in a new build 5 years ago)
4 Beds 3 Baths
worcester bosch combi boiler (located in car port/shed detached from house)
UFH downstairs - 5 zones
Rad’s upstairs - 8 in total

Extension:
2 beds 2 baths
110M2 of UFH (will require a new separate manifold from existing setup)
Wood burning stove

3-5 showers in use each morning during an hour slot.

Currently the combi boiler is inadequate for our needs. From the initial reading I’ve done people seem to be suggesting a system or regular boiler paired with a large unvented cylinder. (With possible solar panel paired to it).

I would welcome advice/suggestions on the above on what route is best to take.

 

[SimonG]

The combi will be woeful.

What size is it. Could run the cylinder off of the combi.

Needs to be sized correctly, but may save needing a new boiler.

 

[George T]

Indeed. From the day we moved in the combi boiler can’t handle the morning shower usage.

It’s a greenstar heatslave ext 18/25.

 

[MikeJhn]

Sounds like a candidate for a professionally designed thermal store, consider UFH for the extension, easy to incorporate whilst it's being built.