Consistent BTU calculations

[disconotdisco]

Hi,

I am looking to get my radiators swapped out for modern designer radiators so am researching BTU values I'd need to achieve for each of the rooms. I live in a small ex council 2 bed, 2 floored maisonette on the top 2 floors of a 4 floored, mostly brick built block.

I'm struggling to get consistent calculations from different BTU calculators so I'm worried about getting the wrong type. Some ask details about what is underneath or above the room (eg another heated room), some dont. Where they do, theres no options to describe the floor type in the room I need to sort out. (The rooms I'm looking for have a concrete floor but underneath there is another heated flat).

I'm concerned that I'll end up getting unsuitable radiators.

Can anyone recommend the ultimate BTU calculator to use (maybe that takes different room types into consideration) that those of you in the trade would use?

Thanks,

B

 

[Best]

Mears calculator.
Experience helps also.
It should be straightforward to keep the rooms comparable - not have one room greatly over heated compared to another, in a 2 bed flat.
TRV rad valves help keep rads heat under control and you need a room stat at a room or hall with no TRV.
A heating installer will do it all for you

 

[oz-plumber]

I would do the calculations without any consideration to what is below you.
You don't want to rely on their heating to maintain a comfortable temperature in your place.

 

[heatservice]

If your existing rads meet your needs then replace them with modern ones that have similar btu/Kw outputs, you might need to look at a few different makes to get an idea of what the output of your existing ones are, once you know that look for ones listed by the manufacturers of your prefered style. Remember for the same size a modern single panel convector rad ha much the same output as the older double panel rad with no convection fins.

 

[doitmyself]

I would do the calculations without any consideration to what is below you.
You don't want to rely on their heating to maintain a comfortable temperature in your place.

That is good advice.

The Myson Heatloss Calculator is very comprehensive. Check the Tutorial before using.

You don't say which boiler you have; but if it's a modern condensing boiler you should use a Mean Water Temperature of 60C so the boiler condenses more often.

 

[heatservice]

Oversize your rads if you run the boiler at 60 C as radiator outputs are based on water temp of above 80 C.

 

[doitmyself]

Oversize your rads if you run the boiler at 60 C as radiator outputs are based on water temp of above 80 C.

1. The Myson calculator automatically takes mean temperature into account. The same applies to Stelrad Stars.
2. Rad output has not been based on a water temperature of 80C for over 20 years. The current standard (BS EN 442) specifies: flow 75C, return 65C; i.e a mean of 70C.

 

[townfanjon]

1. The Myson calculator automatically takes mean temperature into account. The same applies to Stelrad Stars.
2. Rad output has not been based on a water temperature of 80C for over 20 years. The current standard (BS EN 442) specifies: flow 75C, return 65C; i.e a mean of 70C.

Never tried the Myson one , couldn’t get used to “stars” , is it ok ?

 

[heatservice]

1. The Myson calculator automatically takes mean temperature into account. The same applies to Stelrad Stars.
2. Rad output has not been based on a water temperature of 80C for over 20 years. The current standard (BS EN 442) specifies: flow 75C, return 65C; i.e a mean of 70C.

Sorry about that, Im a bit out of touch with new standards, 25 years ago was around the mid way point of my time in the business.

 

[doitmyself]

Never tried the Myson one , couldn’t get used to “stars” , is it ok ?

It's OK; but not as comprehensive as Stars.

I have found one flaw: if you say there is no window in the roof the program throws a wobbly and shows the heat loss from that room as "NaN". The way round is to say there is a window (any type) but with zero area.

If you change the mean water temperature, the effect is not immediately obvious. The heat loss does not change as internal and external temperatures are the same. But when you go to select the products you will get completely different options to choose from.

 

[AWheating]

City plumbing heat loss calculator works well enough for most jobs. On very cold rooms add 20%

Still don't understand why any manufacturers use btu's anymore. Went out 20 years ago. Stick to watts.

 

[heatservice]

Perhaps we can start using BTU's again when were out of the EU lol talk to many older customers about Kw's and they think your an electrican.

 

[AWheating]

Maybe, but I'd prefere the British thermal watt and keep it metric.