We'd like to remind Forumites to please avoid political debate on the Forum... Read More »
📨 Have you signed up to the Forum's new Email Digest yet? Get a selection of trending threads sent straight to your inbox daily, weekly or monthly!
Combi bolier power output questions?
Options

covbaldy
Posts: 124 Forumite
How can I work out which combi bolier I will need for the house I'm about to purchase?
Its a 3 bed semi house - with double glazing. Rooms are quite large in size (its an old 1940's semi). Theres one bathroom. Normal kitchen appliances.
My dad thinks I'll need a 24 Kw unit - I would suspect more power is needed?
Can anyone help me out?
Thanks
Alan
Its a 3 bed semi house - with double glazing. Rooms are quite large in size (its an old 1940's semi). Theres one bathroom. Normal kitchen appliances.
My dad thinks I'll need a 24 Kw unit - I would suspect more power is needed?
Can anyone help me out?
Thanks
Alan
0
Comments
-
covbaldy wrote:How can I work out which combi bolier I will need for the house I'm about to purchase?
Its a 3 bed semi house - with double glazing. Rooms are quite large in size (its an old 1940's semi). Theres one bathroom. Normal kitchen appliances.
My dad thinks I'll need a 24 Kw unit - I would suspect more power is needed?
Can anyone help me out?
Thanks
Alan
Ours was a 24KW combi in our old place which was a 3/4 bed terraced. Only just about good enough in my opinion a bigger one would have been better.
Incidentally Combi's are usually rated higher than standard boilers due to the need to heat a volume of water rather rapidly.0 -
Hi,
What you ought to be considering is the combi's ability to heat water first rather than its central heating ability, having a boiler that can only produce a piddling little stream of hot water is sheer misery so go for the highest hot water flow you can find. As far as house heating goes the boiler size is nowadays largely irrelevant as they are what is known as "modulating" this means that they turn their own gas up and down so as to maintain the return water temp at the correct temperature for condensing to take place. Houses take surprisingly little to keep warm in the long term, imagine having 24 1Kw heaters going all the time. Go for a big one - I like Vaillant.The quicker you fall behind, the longer you have to catch up...0 -
So can anyone recommend a bolier? I have been recommended a Alpha or a valliant.
Has anyone purchased one recently?
Thanks0 -
Good question. I too am looking for a new boiler. Our current combi is older than me!
We have a similar size house; three beds, largish rooms, eight radiators. No bath to worry about so the flow/stream of hot water would only have to cope with a hot tap on the sink.
I have no idea where to even start, what with the btus and the kws and what not, I havent got a clue.:A:A:A:A:A:A0 -
Any combi with a flow rate higher than about 12/13 litres a minute tend to operate on a heat store/preheat principle, which will cost more to run and many only supply a limited amount at that rate before exhausting the supply and reverting to normal combi flow rates until the store is replenished. These will cost more to run, which is why several introduced 'intelligent' pre-heats that record times of biggest use and then preheat accordingly.
If you have no real need for major flow rates, I would stick with a normal condensing combi, such as an Alpha CD32C or a Vaillant Ecotec Plus 831.0 -
covbaldy wrote:So can anyone recommend a bolier? I have been recommended a Alpha or a valliant.
Has anyone purchased one recently?
Thanks
Some pointers:
The worceter bosch site will allow you to type in the property details and tell you what boiler you need.
Boilers recommended from past users are not neccessarily good ones now they changed to condenser type.
Many boilers have same hot water and heating performance. To get the hot water they are over specified for heating. In recognition of this the CDi range have 30Kw heating for the 30, 35, and 40CDi even though the water is 30, 35, and 40Kw with the 40Kw giving around 16l/min.
The sedbuk rating is misleading. It is all about heating efficiency and not hot water supply. Infact many boilers use condensing on heating only and they are 10% less efficient on hot water. The CDi range condenses on both heating and hot water. If it were me i'd go for the biggest CDi i could afford but what do i know, i'm not a heating engineer!
It costs nothing say thankyou!Cash ISA rate 6.5% fixed for 2 years. Mortgage rate 0.75% = 5.75% profit on £75K = £4500 per year:j
Mortgages make money. Definitely don't wanabee mortgage free!0
This discussion has been closed.
Confirm your email address to Create Threads and Reply

Categories
- All Categories
- 351K Banking & Borrowing
- 253.1K Reduce Debt & Boost Income
- 453.6K Spending & Discounts
- 244.1K Work, Benefits & Business
- 599K Mortgages, Homes & Bills
- 177K Life & Family
- 257.4K Travel & Transport
- 1.5M Hobbies & Leisure
- 16.1K Discuss & Feedback
- 37.6K Read-Only Boards