Allowances for Rad Sizing for a Room With ..

[bengasman]

Sorry to interupt your argument.

Not at all, always helpful when things get confirmed by a third party. If memory serves, the horse power was mainly ditched as a unit for 2 reasons:
1. It is not compatible with other SI units.
2. The variety of horsepowers e.g. bhp, SAE hp, DIN hp.

Does that sound familiar?

 

[ray99]

Sorry to interupt your argument.

Not at all, always helpful when things get confirmed by a third party. If memory serves, the horse power was mainly ditched as a unit for 2 reasons:
1. It is not compatible with other SI units.
2. The variety of horsepowers e.g. bhp, SAE hp, DIN hp.

Does that sound familiar?

Yes that is right.
As with many things there are different ways of measuring. Contrast ratios on televisions for example can be static or dynamic (possibly other ways too) and give vastly different figures so I believe all you get now is low, medium or high.

 

[DIYWell]

I'm still going to just pick any old online calculater, bugger the undocumented assumptions, and multiple what ever number it comes up with by 2.

Much like selling a secondhand car really.

 

[Foobix]

It would appear you missed the word output
As with cars, the performance is defined by how many kW comes out of the engine, not how much fuel you burn. As such, I only use the output in my calculations, not the input.

I'm still not with you here Ben.
A gas rate test measures the amount of gas being burned by the appliance.The test uses a measurement of time to burn a volume of gas to work out the heat input.
Now,a boiler with a 20kw output and only 40% efficient will have a much larger heat input(roughly 50kw?) to achieve the same output as the band A appliance.
If one boiler needs to burn 50kw/hr to match another only burning only 21kw/hr then how will they heat identical systems at the same time?
Next you will be telling me the old relic has a gas rate of 5M3/hr,10 mm injectors and a heat exchanger the size of a small wheelie bin.

 

[bengasman]

Like I stated before, the only thing of interest in terms of heating capacity, is the output; the input is totally irrelevant for this aspect.

 

[RichieHoneybucket]

Like I stated before, the only thing of interest in terms of heating capacity, is the output; the input is totally irrelevant for this asspect.

Another pearl of wisdom from the oily rag car grease monkey.

Engineers LMFAO!!!

 

[RichieHoneybucket]

When we British talk about cars we say HP. Same as boilers are BTUs.

 

[electronicsuk]

I bow to your superior knowledge oh master.
Please,just one thing,enlighten me.
I do not understand how a boiler with an efficiency of only 40% can match a similarly rated appliance with an efficiency of 90%?
If 60% of the heat is lost on this band 'K'(it must be 'K' mustn't it?)appliance,whilst only 10% is lost on the band 'A' rated appliance.
50% more heat being delivered in heat transfer to the radiators yet you state the systems will reach a set temperature at roughly the same time.

I'm not a plumber or gas engineer but rather an electrical engineer, so should probably stay well out of this. However, surely any heating appliance, be it a gas boiler or electric immersion, will deliver its rated output power into the load regardless of efficiency. On that basis, a boiler of 24kW output and 60% efficiency will provide, say, 10kWh of heat energy in near enough the same time as an identical output boiler of 90% efficiency. The latter will use less gas in doing so, but the energy transferred into the load in a given period of time (in this case the water in the HX) will be the same.

Unless, of course, manufacturers have suddenly started providing output ratings before taking efficiency into account, such that if you are sold a 20kW 90% efficient boiler, its output power will actually be 18kW.

 

[RichieHoneybucket]

They hide the figures with churning out boilers with huge range rating capacity. I mean one salesman tried to sell us a boiler that was 120% eff.
Did he think the customer could get a rebate from BG???....All smoke & mirrors mate, smoke n mirrors.

 

[Foobix]

Swallow your pride occasionally, it's non-fattening!