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Radiator Delta Ratings Explained

You're probably not an engineer. Understanding the various language and information given, and what it means for you can be confusing at the best of times. This article will look at the Radiator Delta Ratings and how arming yourself with the relevant knowledge can be invaluable.

We aim to keep you safe from radiator rogues and 25% higher heating bills, here's radiator delta ratings explained.

In the UK especially, we're not the greatest at adapting and tend to enjoy doing things "the British way". There's many instances where generally universally accepted standards are shrugged off for the traditional way. Just one example being driving on the left hand side of the road. The reason for this reaching back hundreds of years where having your sword close at hand was the priority. Thankfully not necessary today.

Such reluctance to adapt can be seen in radiator delta ratings as well. With much of Europe using Delta T50 as standard for some time, the UK had to be different of course. Though, you'll be glad to hear that the UK has also now switched from Delta T60, joining the rest of Europe. However, as you can imagine there has been an inevitable transition period.

This has led to some experiencing scams. As a result, not getting the performance expected and around 25% higher bills aswell. In some cases companies might not even know that they're scamming you. Some simply not keeping up with the latest law changes.

With that in mind, we've created this article so that you can understand exactly what Delta ratings means and how they'll affect your decision.

How to Safely Skip this Entire Article

By buying a radiator from us you're shopping with a business who want to ensure that you know exactly what you're paying for - and that what you pay for is what you receive. We intend to stay in business for a long time and tricking people gets you nowhere fast. Hence our entire Knowledge Base of helpful articles which is dedicated to arming you with knowledge. So, if you want to avoid reading this article and avoid any trouble, then buy your radiator or heated towel rail from us. 

  • uses the correct delta ratings as specified in the 2013 EN-442 EEC legislation.
  • We only use updated BTU ratings on all of our products to accurately reflect the REAL BTU of the radiator you're buying.
  • In short, what you see is exactly what you get when you shop with us.


Radiator Delta Ratings Explained, in Plain English

In order to quickly judge one radiator from another, you need to have a way to accurately compare them. BTU rating is how we, and you, compare a radiator's heat outputs. But the problem is that the way you calculate the BTU rating of a radiator matters because the temperature of the boiler supplying it affects the final BTU result. This means that manufacturers and shops (like us) all have to use the same assumed boiler temperature when calculating the output of a radiator so that it has real meaning.

It would just be SILLY if there were multiple points of reference for boiler temperatures, right? Well, the problem is that there are 2 different assumed temperatures used: Delta 50 and Delta 60.

Delta T rating is calculated using the flow temperature of a boiler into a radiator plus the flow out temperature. So, if you have an input of 80 degrees and an output of 60 degrees, then this means that the average radiator temperature would be 70 degrees.

'Room Temperature' is an average accepted to be 20 degrees. So, you take that away and you're left with 50 degrees, or Delta T50.

Delta T50 vs Delta T60 vs Delta T70

  • Delta T50 is what Europe has been using for a while, except in the UK, where we used Delta T60 until 2013. But now we use T50 too.
  • Delta T50 is based on a much lower expected boiler temperature. Which is more in-line with modern insulation and a fear of global-warming-induced-apocalypse.
  • Delta T50 has been officially in use for some time now. T60 is still lingering around because this is an industry where change is relatively slow.
  • Delta T70 is seen a lot less often and is generally only used by certain suppliers. If you're given a BTU at Delta T70, it's usually best to convert this into T50 or T60 to make comparing heat outputs much simpler.

Converting Between Delta T50, T60, & T70

The conversion are as follows:

If a radiator has a heat output of 5000 BTU at ΔT=60, to find the heat output at ΔT=50, you simply multiply the BTU by 0.789.

So your equation would look like this:

BTU (ΔT=50) = BTU (ΔT=60) * 0.789 = 3945 BTU

If you have a radiators with a heat output of 5000 BTU at ΔT=60, to find the heat output at ΔT=70, you multiply the BTU by 1.223.

So your equation is:

BTU (ΔT=70) = BTU (ΔT=60) * 1.223 = 6115 BTU

If you have a radiator with a heat output of 4200 BTU at ΔT=50, to find the heat output at ΔT=60, you need to multiply the BTU by 1.264.

So your equation this time is:

BTU (ΔT=60) =  BTU (ΔT=50) * 1.264 = 5309 BTU


Why Delta Rating is Important to You

Buying a radiator? Then you'll be spending a lot of time looking at BTU ratings. Hopefully, you'll use a BTU calculator to calculate what you need, but no matter if you need 500 BTU or 5000 BTU you need to know that the displayed rating is accurate. Yes, a 1000 BTU radiator might put out 999 BTU. Or, it might put out 1001 BTU with a small margin of error either side, but imagine if the radiator you bought was actually 25% colder than advertised.

(A note on BTU: Remember to always buy a radiator that has a higher BTU than the minimum BTU needed by the room. This gives you a bit more power to keep you out of trouble, and you can simply just turn it down)

That can happen if, say, one store is displaying BTU ratings based on T60, and another one is using the proper T50 ratings. The first store's radiators will appear to be more powerful and better value for money.

By concealing the fact that those figures are based on T60, rather than T50, or just relying on a lack of understanding about this sort of thing, a store can sell low-quality radiators disguised as higher-quality radiators. It also means they could charge more for their high-quality radiators because they've inflated the expected BTU of them.

Of course, this can happen completely by accident by those who haven't moved away from delta 60. But whether purposefully or accidentally, it still leaves you out of pocket if you fall prey to it.

All You Need to Know is...

We use Delta T50 when calculating our BTU figures. Now you know why we're so eager to make sure that our customers understand what that really means.

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