Radiator Size Calculator

[stevebamford]

Hi Guys

Edit - just updated link

I've been playing around with an online calculator to work out radiator sizes.

http://www.radiatorsizingcalculator.co.uk/

I know there are a zillion ways to do the calcs but I was wondering if anyone had any pointers about the calculations ? I was thinking of having 3 levels of complexity ?

1) Simple
2) More Complex
3) All singing and dancing

I've had a go a at the simple one - for the more complex one I was thinking of adding a few more options ...?

Is this the sort of thing people would be interested in using or are there so many online already that its a waste of time ? I can change it so its in the most useful format for you guys ? Any another features you might find useful (e.g. email the figures etc...?)

Cheers

Steve

 

[D_Hailsham]

I've been playing around with an online calculator to work out radiator sizes.

I know there are a zillion ways to do the calcs

No there is only one way - the correct way.

I was thinking of having 3 levels of complexity ?

1) Simple

Had a quick look. It makes too many undocumented assumptions to be of any use.

Why, in any case, do you want to reinvent the wheel? The simplest calculator available on-line is the Sedbuk Recommended Boiler Size Calculator, which may not give rad sizes directly, but can be used as a starting point. You could divide the boiler output between the various room according to their volume to give a fairly accurate estimate of the size rad needed in that room.

There are also other on-line calculators - some better than others - as well as those you can download.

 

[JohnD]

I thought you just estimated radiator size by eye

 

[gigz]

No, us professionals measure the window

 

[gremlin16]

No, us professionals measure the window

Is that just incase the rads dont fit through the doors

 

[gigz]

 

[stevebamford]

Thanks DH - sorry for the delay replying.

I'm self-employed and am trying to add a few useful tools to my web site - mainly to show the kind of thing I can do as an example for potential clients.

The radiator calc I'm doing in between other client jobs (so it may take a while to do) but would like to get something useable online (the other online ones I've looked at are pretty basic/clunky or both)

Hopefully it will end up as something that can be used by the professionals ?

No there is only one way - the correct way.

Yeah i know there is the 'proper' way to calculate heat loss (but even then I'd think that some of the parameters are up for discussion) but from posts on this site I'm thinking that its pretty common to use a rule of thumb to work it out

Had a quick look. It makes too many undocumented assumptions to be of any use.

Its very much work in progress!

I'm trying to come up with a couple of 'rule of thumb' approaches (one simple, one more advanced) and then possibly a 'complete calculation' - if I get time to do it.

I was really after some of the rules I could use. e.g.

1) North Facing external wall +10%
2) Window size is +50 BTU /m2 for single glazed
3) French doors are + 10%

etc .. and yeah I made those up by the way

Any pointers would be gratefully received

Cheers

Steve

 

[muggles]

Get yourself a decent plumbers' book containing all the longhand calculations required. You need to build all of these into your calculator. Professionals will only be interested in an all-singing all-dancing version that calculates everything and gives a sensible figure at the end. Such things as wall construction, window size and glazing, and the number of doors into a room need to be considered.

 

[D_Hailsham]

The radiator calc I'm doing in between other client jobs (so it may take a while to do) but would like to get something useable online (the other online ones I've looked at are pretty basic/clunky or both)

I agree about the online ones being basic and clunky. If you want to provide something better you have to avoid both these faults; which will not be easy - particularly the "basic" fault.

There are two downloadable ones on the net:

Kermi Design for Living and Barlo Heatloss Program

It might be worth having a look at these to see how a "complicated" calculator works.

]Yeah I know there is the 'proper' way to calculate heat loss (but even then I'd think that some of the parameters are up for discussion)

Which parameters?

the number of doors into a room need to be considered

And if you want to be really pedantic, you have to take into consideration whether the doors are open or closed!

 

[stevebamford]

Thanks for the tips guys.

I've had a go at the simple and the not so simple 'rule of thumb' methods. Any comments gratefully received but it sounds as if you probably wouldn't use these two anyway.

http://www.radiatorsizingcalculator.co.uk/

I'm planning to add an option to allow a download to a spreadsheet - and maybe so you could get the list emailed to you ?

Now to tackle the full calcs (which I am thinking are going to take a while !) - Time for a trip to the library!

The parameters up for discussion: dunno really just a gut feeling but maybe different proper calcs use slightly different values for say 9" solid walls? Or maybe heat loss through a loft ? Or are there industry standards for these things ? As I said I've not looked into it yet (I sense a headache looming!)

 

[D_Hailsham]

are there industry standards for these things ?

Everything really depends on calculating the U values. A good starting point is Conventions for U Value Calculations.

You also need to know the U values of specific materials, which can vary according to the manufacturer. For example there are several types of breeze block such as thermalite etc.

 

[stevebamford]

A good starting point is Conventions for U Value Calculations.

Oh lordy! Now I do have a headache