How do i know what kilowatt gas combi boiler i need to buy?

Question

we want to change our gas boiler to a new combi how do i know what kilowatt i need and whats the average price to have one fitted

Answer 1

What you really need to know is the BTU of the system you are trying to replace.Boilers are rated by BTU's wich is the amount of energy they consume.Be aware of combi units,especially on demand style heat units I don't particularily reccomend them technology has not completly caught up to them yet and we see alot of maint. issues with them.I reccomend a high efficiency boiler with a side arm indirect water heater look at Triangle Tube Prestige Boilers at 96% efficient most relliable

Answer 2

if you take the cover off of your old boiler you should find a metal data badge looking back at you, (before you remove the cover make sure that the electic supply to the boiler is isolated for safety reasons)

on this will be the rated output (probably in btu's) if so you need to convert the btu into a kilowatt rating (3412 BTU's in 1 kW, therefore divide your number of BTU's by 3412. The resulting answer is the same value but in kW.)

Provided that your old boiler was heating your house ok, then the same rated combi would be ok.

If your house is a standard 2 or 3 bedrooms then 24kw should be ample.

4 or 5 beds then you would need to consider a 30kw.

anything over that then check with boiler manufacturers because you will be entering into the realms of getting a small commercial boiler.

As you will have to get a corgi installer to fit it for you, why not ask him to size it for you.?

Just so you know, it is against the law for anyone who is not qualified & corgi registered to install any gas appliance as this would be putting your safety and that of others at risk, also any manufacturers warranty would be in valid.

hope that helps

Answer 3

It's impossible to give an accurate price without surveying the job first. Get several quotes and the companies giving you these quotes will tell you what size boiler you need. It's usually better to get a combi with a slightly higher output than necessary as then you'll have more than enough hot water.

Answer 4

Combi boilers can vary in size from 24-36kw for domestic use,a 24kw will heat a 4 bed house no problem,but the hot water performance on this size of boiler is poor.A 36kw boiler will heat 20 radiators of average size and will give you a better flow of hot water,roughly 14-15 litres a minute.Some manufacturers have combi's with heat stores on them that will improve the flow rate,but they are normally more expensive appliances.

If you live in a house with lots of hot water outlets and say a power shower,a system boiler might be more suited to your needs.These boilers work on the same principal as your current one and would be cheaper to install.

The price for installation will vary depending on the installer,boiler make,and the amount of controls req'd to bring the heating system up to current standard.

Shop around and stay away from British gas.

Answer 5

Go to the manufacturers website - Just google gas boilers! They will have a list of available boilers - plus and minus and a form of questionaire so you can work out what type and size is needed. Not advertising here but try Worcester Bosch site - as an example. Hope this helps

Answer 6

find a decent plumber preferably one that has been recommended. He will advise you. you will need one anyway, corgi registered too

Answer 7

There are calculators on the net. Also Wickes have a calculator. In any event aim high if you can afford to as you will get better hot water flow, with no space heating penalties as combis 'modulate' their output to the radiators as required.