Extension - seconded zoned gas boiler

[ianmcd]

Thank you all for your advice; it’s been very helpful.
I’ve had an attempt at estimating the spare capacity of 60E at 17.58kw.

• 1x Double 60h x 16w / no fins 1,750 Watts
• 1x Double 60h x 95w / no fins 1,050 Watts
• 1x Single 60h x 175w / no fins 1,470 Watts
• 1x Single 60h x 80w / no fins 735 Watts
• 1x Single 60h x 110w / no fins 980 Watts
• 1x Double 70h x 60w / double fins 1,340 Watts
• 1x Double 30h x 145w / double fins 1,900 Watts
• 2x Double 30h x 145w / double fins 3,800 Watts
• Water Cylinder 3,000 Watts
• Total 16,025 Watts

If I’ve estimated correctly, I’ve got maybe 1,500 Watts of unused capacity.
For a 7m x 7m and vaulted ceiling, I was thinking I’d need nearer to 10kw.
Would this take me beyond marginal ?

best D

And do you really need all these rads on at the same time ? I have 14 rads and a towel rail, lucky if I have 4 on at the same time , no point in heating spaces that are not being used