which boiler suits my situation better?

[Neddy1984]

I want to have a heat only boiler installed but first need some basic info. Its between a vaillant 428 and vaillant 438.
I know the 428 has 28kw output and the 438 has 38kw output, but what is the significance of this??
Does it mean the 438 will heat my house/cylinder quicker, or does it mean the 438 can heat a greater amount of water whereas the 428 would struggle to heat large amounts of water??
Please help!
I dont want to have to spend more on the 438 if it will do exactly the same job as the 428. By the way, there are 12 rads in the house, most of them the single rad type, and I have a 120 litre H/w cylinder.

All positive comments will be greatly appreciated

 

[Burner 1]

Hi there,

measure the length x width x height of each room in feet, then times that by 5 and add 20%, this will give you your BTUs if you divide that by 3412 then it will give you your required KW, allow an extra 3kw for your hot water cylinder, you will find that the 428 will proberly be big enough.

cheers.

 

[diamondgas]

I want to have a heat only boiler installed but first need some basic info. Its between a vaillant 428 and vaillant 438.
I know the 428 has 28kw output and the 438 has 38kw output, but what is the significance of this??
Does it mean the 438 will heat my house/cylinder quicker, or does it mean the 438 can heat a greater amount of water whereas the 428 would struggle to heat large amounts of water??
Please help!
I dont want to have to spend more on the 438 if it will do exactly the same job as the 428. By the way, there are 12 rads in the house, most of them the single rad type, and I have a 120 litre H/w cylinder.

All positive comments will be greatly appreciated

28kW is probably overkill Neddy 1984 .... IMO

Ask your plumber what they think would best suite your needs. Do you have a boiler in at the moment and if so what size is that one?

 

[jtsplumbing]

If you are just replaceing your old boiler what size is this ? just as a guide line, does it run everthing and get it to required temp ?

 

[Nostrum]

Get a proper heat loss calculation done!

None of this height x length of your arm / by your boot lace diameter +15% business.

These calculations are way out of date, and your old boiler was probably oversized as well, plus you've possibly had double glazing and insulation etc upgraded since it was fitted.

The smaller the boiler you can get the better, as it will have a lower minimum output so you'll be able to tick over for longer and save fuel as the demand drops, plus it'll be cheaper in the long run. A heat only boiler of 28kw, let alone 38kw could heat a castle! ( not quite)

 

[jtsplumbing]

Probley to small for your castle sambotc. would it do the east wing ??

 

[Nostrum]

East wing! let me think.... thats my kitchen... and dining room... and probably half my living room aswell!

 

[desrob]

Hi there,

measure the length x width x height of each room in feet, then times that by 5 and add 20%, this will give you your BTUs if you divide that by 3412 then it will give you your required KW, allow an extra 3kw for your hot water cylinder, you will find that the 428 will proberly be big enough.

cheers.

wow, i'd prefer a proper calculation done whats the floor made of, any double glazing etc etc,and as diamond say a bit on the large side,

 

[diamondgas]

wow, i'd prefer a proper calculation done whats the floor made of, any double glazing etc etc,and as diamond say a bit on the large side,

I agree a calculation is the way forward

 

[Burner 1]

In this castle of yours, would it heat your stables were you keep your high horse, its just a rough guide, the property may have been extended or have plans to. be honest you lot who has the time to spend hours doing heat loss calcs, if its double glazed etc leave the 20% off. simples.

 

[Nostrum]

I prefer a low horse, no need to get the step ladder out to saddle up.

I don't know why you took it personally burner1 it's just a bit of an old fashioned way of calculating heat loss. These days the attention is on saving money and it's not outside the scope of a heating engineer to do a room by room calculation which take about 2 minutes a room.

12 Rads mostly singles and a 120 litre cylinder, I reckon you'd be looking at more like a 15-18kw boiler unless they are 3 metres long or massively undersized, so it pays to do the maths in the long run.