Heat loss calculators

Was looking around for heatloss calculator for radiator sizing.

10+ years ago, there were several, typically one from each radiator manufacturer, and I used the Myson Java one (in beta at the time), and it did a very good job.

Just went searching again, and they no longer seem to exist. Has anyone seen a recent one.

I could try firing up the old Windows 95 laptop and see if I can lift the Myson one off it.

Reply to
Andrew Gabriel
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They are still out there or at least they were last year when I was checking the architects rad sizing. B-) Not as comprehensive and as configurable as the old Myson one though, most just have fixed drop down boxes for wall and window types, rather than free form U values. They more or less do the business within an acceptable tolerance, heatloss is not exact anyway.

Reply to
Dave Liquorice

I think they are mainly web based these days. I've seen a few where you enter the room's dimensions and it then gives you the required BTU but not anything which goes into detail of room contruction.

Reply to
David WE Roberts

I recently downloaded and used the Barlo heat loss calculator. It's pretty old, but it worked fairly well for me - the laws of physics don't change after all.

The main issue I had was that it's a 16-bit app, so it wouldn't run on my Windows 7 64-bit OS. So I ran it in an XP virtual machine instead.

A google for "barlo heat loss calculator" should locate it.

Reply to
Caecilius

Years (and years) ago I wrote a calculator for domestic c.heating system. Ran ok under NT4 :-) (Maybe even w2k, not sure now). Was going to re-visit it and put it out as freeware - unfortunately it blows up nicley under xp and I never got around to finding out why. Those where the days etc dah de dah. This doesn't really help you though. sorry.

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Reply to
dave

In article , dave writes

I ended up doing mine manually in an A4 notebook, didn't take that long and I knew it was right, but I do only have one house.

Reply to
fred

How do you do heat loss calcs for floors?

The rest is fairly easy as it is nothing more than the thermal version of Ohms law and making some reasonable assumptions about outside temperatures and U-values of various elements.

Ignoring air changes of course 'cos that's a whole other level.

And you could factor in in solar gain if you wanted to get fancier...

Reply to
Tim Watts

I can let you have an original download. I have it as HeatlossManager98r105.exe downloaded Nov 2002.

Last time I did a heatloss analysis it was for a 4 storey office building and the myson couldn't cope so I did it from scratch on excel. You're welcome to a copy of that, its pretty comprehensive and reasonably self documenting using meaningful names in most of the formulae. It allows input of individual values for rooom temperatures, wall u-values, window u-values, dimensions of floors, walls, windows, room heights, and ventilation rates.

Phil

Reply to
Phil Addison

Notebook currently elusive but my guess would be that I treated it as a horizontal wall and included it in the calculation with U-value and temp diff. I have suspended wood floors so I could have estimated air temps, guessing again that despite ventilation I would have treated that as a sheltered location and calculated with say a min of -1degC underfloor whilst using -3degC for external walls. I have insulated the floors with fibreglass underneath.

ISTR that you have solid floors but again I think there are figures available that estimate U-values for uninsulated floors on earth as well as insulated.

Again not that hard as it's well known how much energy it takes to heat a given mass of air from one temp (outside) to another and you can stab at air changes per hour.

That's easy, no solar up here ;-). Actually, you need to calculate for worst case so solar must be excluded as you have to design to maintain for an overcast winter day at -3degC outside (obviously not as cold as it can go but what design calcs are based on). If you get solar gain then it is an energy saving bonus.

Reply to
fred

Spose it would not be too difficult to do a javascipt implementation of what we have on the wiki page:

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(I have the spreadsheet if you want it)

Reply to
John Rumm

In days of yore, the assumption was that the water would leave the boiler at 180 degF/room tempersture 72degF and radiators were rated accordingly. This is no longer the case, many temperatures are commonly used, so the tables are more complex.

Reply to
harry

So, I lifted the java one off my old WindowsME laptop (using Java 1.3.1). Initially, it wouldn't work properly on XP using Java 6 (1.6). So I installed Java 1.3.1_20, and now it seems to be working OK.

It calls itself: Myson Heatloss manager 2002, Version 1.1B

Reply to
Andrew Gabriel

The 2002 one allows you to specify this, and compensate accordingly. Even before condensing boilers, there were buildings (schools, old peoples' homes) which used reduced flow temperature to prevent burns on radiators and pipework.

I didn't actually use that part of the Myson calculator. I just used it to work out the power input needed for each room. Then I worked out the numbers/style/sizing of the radiators by hand, as I wasn't using only Myson radiators (specifically, I wanted some triple panel radiators which Myson didn't do, at least not back then).

Reply to
Andrew Gabriel

That's arse about face. You calculate the heat loss from U values and use the table to find out what size radiator you need.

Reply to
harry

Amazingly, it even works on Solaris (my normal working environment), providing you install java 1.3 and run it out of a filesystem which is mounted with filename case sensitivity disabled (as is normal for dos/windows), because it tries opening it's own files using different case from the actual filenames it creates.

I know java is always supposed to be portable, but it often isn't in practice.

Reply to
Andrew Gabriel

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