BTU calc help

[Pipedreamer]

Worked it out approximately 2 outside walls etc

Sorry I’ve mis typed something there it’s four external walls with three as I stated and the other is one single skin stone wall (don’t ask me why!)

 

[ShaunCorbs]

7.4kw

 

[SJB060685]

Its quite a time consuming and complicated task really and you need to know some data first if you're going to do by hand, although there are websites/software out there that do it for you but they also require the same data, however I would prefer to do by hand. There's two ways a room/building loses heat. 1. Ventilation heat loss and 2. Fabric heat loss. When calculating the ventilation heat loss you need to the total volume of the room, the air changes per hour for that type of room, the design outside temperature and room target temperature. Example.
3m x 4m x 2.4m = 28.8m3, now x that by air change rate, then x that by the design temperature difference and then x that by 0.33 to get your total ventilation heat loss in watts.
Fabric heat loss is a bit more complicated.
The calculation is. Surface area x temperature difference x U value = rate of heat loss in watts.
You would need to know the U value for all materials in the walls and that of windows doors etc.

 

[Pipedreamer]

7.4kw

Any workings?, pretty please

 

[Pipedreamer]

Its quite a time consuming and complicated task really and you need to know some data first if you're going to do by hand, although there are websites/software out there that do it for you but they also require the same data, however I would prefer to do by hand. There's two ways a room/building loses heat. 1. Ventilation heat loss and 2. Fabric heat loss. When calculating the ventilation heat loss you need to the total volume of the room, the air changes per hour for that type of room, the design outside temperature and room target temperature. Example.
3m x 4m x 2.4m = 28.8m3, now x that by air change rate, then x that by the design temperature difference and then x that by 0.33 to get your total ventilation heat loss in watts.
Fabric heat loss is a bit more complicated.
The calculation is. Surface area x temperature difference x U value = rate of heat loss in watts.
You would need to know the U value for all materials in the walls and that of windows doors etc.

Thank you.

 

[ShaunCorbs]

Any workings?, pretty please

don’t work it out long hand I use a program

 

[SJB060685]

don’t work it out long hand I use a program

Admittedly if the program has all the data needed it's quicker but it's more satisfying to do long hand, well for me it is. A room such as that in question would only take 10-15 minutes to calculate and the more you do these things the more it sinks in lol. I am surprised your program has arrived at a figure of over 7kw but then I haven't run the maths.

 

[Pipedreamer]

don’t work it out long hand I use a program

Which one?

 

[ShaunCorbs]

Heat Engineer

www.heat-engineer.com

 

[SJB060685]

So you do use it Shaun. Haven't got round to trying it myself yet.