What size boiler?

Jojag5280

 Long story but we’ve had a our very old  30kw boiler replaced for a heat only 18kw boiler and I’m not sure it’s big enough. We’re in a 5 bed semi over 3 floors, 10 rads, 2 baths, high ceilings and no cavity insulation. Online calculators are all saying should be a 24kw. Anyone have any ideas?

Farway

Who decided 18Kw was enough?

Did you do your online sums prior to replacement?

Who paid the piper to play the tune?

RelievedSheff

If it is a condensing boiler it may well be fine.

Ours is woefully over sized for the house (30kw for a modest 3 bed detached) and we have to run it with all TRV's fully open to get it to drop into condensing mode and run at it's most efficient. 

daveyjp

First job of a boiler install is a calculation of which size is required.
We have a huge boiler for the number of radiators, but as its a combi it is sized perfectly for the mains water flow rate.

clive0510

1st thing I did here before  we had combi boiler installed was to get the guy round here and have a ,look. had to have the old solid fuel boiler and tank removed. new boiler, new pipework, rads etc. so basically get the man there so he can tell you whats needed.

thorganby

RelievedSheff said:

If it is a condensing boiler it may well be fine.

Ours is woefully over sized for the house (30kw for a modest 3 bed detached) and we have to run it with all TRV's fully open to get it to drop into condensing mode and run at it's most efficient. 

It is not woefully over sized, the Ideal Logic 35 automatically modulates the central heating output between 7.1 and 24.2 kW max

Your boiler only has a maximum output of 35 kW for hot water, not heating.

You are suffering from the all too common obsessive condensing disorder if you believe that is the correct way to run your central heating system.

Seek help now!

tacpot12

Whether or not running the boiler in condensing move is correct for your heating system is debatable, that running in condensing mode is more efficient is not.