Why is it important I get the right BTU calculation for my room?
27 February 2023
To ensure you are getting the best value for money, you need to know the BTU requirements of the room you want to heat. However, understanding the space and how you use it will help you design a more flexible and cost efficient heating solution.
Understanding the thermal challenges of a centrally heated room
To heat any space you need to calculate the BTU’s required (or British Thermal Units - the industry standard unit of heat for central heating). This is because all radiators come with a BTU rating, which tells you the maximum heat output the radiator is capable of.
So in theory, it should be simple – calculate the space and BTU’s required by measuring the area of the room (width, length, ceiling height) and using an online BTU Calculator – then choose a radiator with sufficient BTU output to heat the space. However, you also need to consider rooms have different uses and heat demands. Some are square, have small windows and only one door - whilst others come with large windows, multiple doors and can be irregular shapes. So even though two rooms could be exactly the same area and be used in the same way – their heating requirements will be very different.
What about the heat that escapes?
BTU calculations account for the heat required for a room to achieve an appropriate temperature – but your calculations also need to incorporate and estimate for the amount of heat that can escape. This is so your heating solution is able to maintain the desired temperature, i.e. accounting for the estimated heat required, plus the heat loss to maintain the desired temperature. Better insulation, less drafts, fewer windows equals less BTUs required, while the same is true for the opposite. So although BTU’s is purported to be an exact science, there’s a lot more to getting it right than some would have you believe. Doors and windows represent the thermal weak-points of any room, so you’ll need to estimate the additional heating required. You’ll notice our online BTU calculator has three options for insulation quality, better than average, average and worse than average – consider the factors above when making your selection.
3 questions you need to consider when specifying the BTU to heat and maintain room temperature:
1) Is there a secondary heating source impacting on the room?
Living rooms may have a fire, kitchens have ovens and hobs, the central heating boiler may be located close by. Are the windows south facing and the room heats naturally or does it have north facing patio doors which keep the room cold?
2) How is the room to be used?
This may seem obvious, but is it an occasional use like a spare bedroom, or a room where you spend lots of time? It’s much more efficient to manage the heating and isolate unused rooms with thermostatic radiator valves – using a trace heat to keep the room aired but with the flexibility of quickly increasing the heat when in use.
3) Is the radiator in the best position?
If you want to provide a comfortable level of background heat, where should you place the radiator is a key question. In most circumstances, unless you’re having a significant makeover, moving radiator is an expensive option. However, spreading the heat requirements over several radiators may be a more efficient, flexible and cost efficient solution. You may want to consider electric or infrared supplementary radiators – more about this later.
It’s all about the BTU’s needed to get the job done in the most energy efficient way
When specifying the BTU calculation for a room or space in your home, it’s about the generating the appropriate heat output in the most efficient way. Each room, or space within your home, will have different needs. For example, an entrance hall is unlikely to be a place where you spend a sustained amount of time, so typically needs a lower temperature than a lounge area, where you may spend time sitting, relaxing, watching TV or reading for long periods.
One high BTU radiator or several radiators sharing the BTU load?
There are several theories about how this should be achieved. For example, old fashioned central heating systems my have a single high BTU radiator to heat the entire space. This most likely results in cold spots in the areas furthest away, which in turn creates a thermal flow resulting in drafts. Which means the room takes a long time to reach a comfortable temperature.
Adding supplementary radiators for a more efficient, flexible and cost effective solution
To get more even heat disbursement, you may find adding a supplementary radiator, and splitting the BTU load strategically across the room is a better solution. This is where an electric panel radiator or infrared radiator provides the most cost effective options to supplement the wet central heating system - because electric radiators are much easier and cheaper to fit. They can also be used in isolation, providing quick local heat when it’s not quite cool enough to have the central heating system on – but a little too cold to sit comfortably in the room. The only thing you’ll need to consider is electric radiator heat output is calculated in watts. 1 watt of energy is equivalent to 3.41 BTU’s – but our online BTU calculator can calculate the watts required for a room too.
Remember BTU calculations are always an estimate
The dynamics of your house aspect, for example is it south facing or in a shady spot? It’s construction, insulation qualities and glazing, plus the room aesthetics – ceramic floors or deep pile carpet will all influence the BTU’s required. Any BTU calculator can only process the most common factors that affect heat loss and cannot take into account all factors relating to your particular requirements. So when in doubt, over calculate – as thermostatic radiator valves can be used to ensure your central heating wet radiator only consumes the heat energy required to heat the room.
With so many brands, styles, sizes and colours to choose from, without a bit of expert help, it can be difficult to know where to start. If you would like to know more information about our radiator and valve ranges within our portfolio, then call us on 01530 564122 or get in touch via the contact form on our website.
