Radiator sizing requirement advice

[feisar32]

Hi all

Please forgive the no doubt easy query, I'm a little confused ...

We're hoping to move into a bungalow in the next few months with an extremely antiquated central heating system. It's going to need a new boiler and rads

I'm trying to work out radiator size requirements but have so far received wildly different answers from five different online calculators for one room. I've looked at PlumbNation, Radcalc, Best Heating, The Radiator Company, and Home Supply. Results vary from 1857 BTU to 3695 BTU

Is there a particular calculator that any of you know from experience to be more reliable than most, or can anyone point me in the direction of some documentation that will describe how to do the calculations manually?

Any advice gratefully received ...

EDIT: okay, my apologies, I've seen some other postings now, and the calculator mentioned in [post=199900]this[/post] post looks good so am about to try that. However, in that calculator, one of the values is "Infil." ... can anyone please explain what this value refers to?

I've also seen "Number of air changes" referred to in the Quinn heat loss calculator for iOS, but not quite sure how to answer that ... ?

 

[AWheating]

infil may be in reference to what insualtion is used inside the cavity wall or in the loft?

air changes can differ dependant on the build of the property and the room. Its how many times per hour the air in a certain room has changed. Mechanical extraction will increase the air change rate ie bathrooms and kitchens. bathroom,WC and kitchens are around 2.5-3 min. changes per hour. Living spaces are normally lower especially in newer build propertys. Open flues can also increase the air change rate.

do a search on google and you should find some good examples.

 

[feisar32]

Thanks AWHeating ... I'm starting to think, after some further Googling and looking at the values available in the Infil. column that Infil. stands for Infiltration, and is the same as the number of air changes.

Hope I'm not breaking any rules by asking another question in the same thread, my apologies if so ...

I think I've got some reasonably accurate figures now thanks to the calculator mentioned in that post. However, I'm not sure how to build in some allowance for some upstairs rooms

The property is a 1950's / 1960's bungalow with a small storage room in the roof space. At some point in the future I hope to convert that and the unused space around it into two bedrooms. As the walls will only be about 1.2m timber frame though, I'm not sure the calculators will work out the requirements correctly ...

Is there any reliable formula or tip for working out rad requirements for rooms like this, please?

 

[AWheating]

the calulations will be the same really, they are based on the room volumes, the structure u values and heat losses, design temps and air changes etc..... so alsong as you have the correct measurements/figures then it should be correct.

obviously if you convert the loft into heated room the rooms below will need less heat due to less heat loss throught the ceiling.

why not get your installer to design the rad sizes and then if they are wrong its not your fault

 

[Simon F]

another couple of possible sites you might find useful or possibly will only add to the confusion.

Stars App | Heat loss calculator for any room

City Plumbing Supplies - Find your nearest CPS branches