Condensing Boiler

[Hedley]

Currently investigating the options for changing to a Condensing Boiler. SEDBUK gives me boiler size of 13KW as suitable, installer suggests 24KW based on 4 beds, 1 bath. Any thoughts would be welcomed.

 

[heytesto]

Are you talking about a combi?

 

[Hedley]

Sorry, should have indicated it's a conventional, i.e. non combi.

 

[JohnD]

Do they still make a 13kW boiler?

I used to have a 15kW, whicj was adequate (once I had cavity wall insulation and topped up the loft) but would run continuously in very cold weather. Be aware that with such a small boiler, the rads will cool down when you run a bath in winter and the cylinder load goes on.

My new one is 24kW but modulates and rarely runs flat out - it will do when warming the house from cold for half an hour to an hour.

You need as lot more power to heat up cold rads and a cold house quickly, than to keep it ticking over.

I am a householder not a pro.

 

[D_Hailsham]

Sorry, should have indicated it's a conventional, i.e. non combi.

The Sedbuk calculator is reliable, I have compared it with several room by room calculators and it is always very close. So much depends on the U values, window areas etc.

My fully insulated 4 bed, 1 bath, 1 ensuite shower, house has a conventional boiler with a 14kw boiler and it keeps everyone warm (21C) all year round.

I would go for a slightly larger boiler than Sedbuk say, e.g 15kW so you have something in hand.

It might be worth finding out what the total output is from your radiators. The Stelrad Elite Catalogue will help. But don't forget that the rads may have been installed when the house was built, before any insulation, double glazing was done, so they may now be oversized - which is a good thing for a condensing boiler.