Modern Radiators - Size compared to old?

pmartin86

Evening all

I've recently (2 weeks ago) moved house and need some new radatiors in a few rooms (old, battered, rusted etc)  -I've started looking for the 3 bedrooms that matter and im amazing by the "suggested" sizes - Im used to an old house with a single panel rad with fins, in a 4m x3m room you'd be talking maybe 600x1800 size.

I've just used this:
https://www.diy.com/ideas-advice/calculators/btu-radiator-calculator

For a room thats 3.7m x 3.4 x 2.4m high - Insulated, double glazed windows - and it comes to 3261 BTU

According to Screwfix - a 600x600 Type 22 rad would output 3600+BTU
Kudox Premium Type 22 Double-Panel Double Convector Radiator 600 x 600mm White 3604BTU | Double Panel | Screwfix.com

This seems "tiny" to me - Am I just not in touch with anything modern? Would such a "small" rad heat the room?

Thanks in advance
Paul

Doozergirl

It's a type 2 2, so yes it will
be smaller.  It will be deeper than what you have though.   If you buy a 2 1 then it will be bigger, but still perhaps not as big as you have depending on what it is. 

I use the BTU calculator at Best Heating because it asks more questions, trying to get it right.   

pmartin86

Thanks - My limited research suggests that Type22 are "more efficient" - Is this the case? I'd love to get a plumber on board but regrettably I'm drawing a blank on getting any who are able to come anytime soon - One was booked until April!, so i suspect DIY is the answer, for now at least. My main concern is 2 of the rooms are for young children - 2 and 4, and I really want to make sure their comfortable and safe while the rest of the house is ripped apart.

The Best Heating calculator you mentioned comes in at 1926 BTU - (2 of the rooms are identical except for about 40mm!)

theoretica

Is there any prospect of an Air Source Heat pump or other similar in the house's future?  They work best at a lower water temperature and larger radiators so might be a reason for upsizing.

I am in a room at the moment about 5 x 5m heated comfortably with a 30 x 240 double panel radiator = 60 x 120 in a room about twice the area of yours - don't forget the difference between single and double panel.

pmartin86

We have actually looked at an air source heat pump as part of the purchasing process - I'm very keen to be as "green" as possible as this is our "forever home" - or at least "until the kids have moved out and we can retire somewhere quite - home"

Unfortunately the cost, at the moment at least, is prohibitive - We had 2 estimates, both were just north of 18k - Defiantly something ill be looking to revisit every few years though.

Do you have a rough calculation for how much "extra" capacity would be needed?

Doozergirl

I think it's double the size.  They run at much lower temperatures.  

pmartin86

Thank you - That still only takes it to a 600x1000 - Still much smaller than I'm used to! - Much to consider - thank you both.

FreeBear

As Doozergirl hinted at, a type 22 radiator sicks out from the wall a long way - Something in the order of 130mm if I remember correctly. A type 21 will stick out by about 100mm.

Made the mistake of buying a type 22, but as soon as I offered it up to the wall, I realised just how much it stuck out (like a sore thumb). Swapped for a type 21, and it is much more discrete. Sticks out from the wall about the same as a type 10 or type 11, yet kicks out a bit more heat for the same size.

Depending on how old your radiators are, they may be an imperial size with corresponding imperial fittings - You might need to adapt the pipework, and using new fittings is always a good idea.

ComicGeek

Doozergirl said:

I think it's double the size.  They run at much lower temperatures.  

We work on 2.5 times the output for a radiator used for ASHPs, and even that's at a flow temperature slightly higher than we would want with current efficiencies, say 50/40 degrees (flow and return).

That's also comparing against a modern typical 75/65 degrees heating system, whereas older systems may have been designed even higher at 82/71 - on that basis it would be 2.8 times the output!

ComicGeek

FreeBear said:

Depending on how old your radiators are, they may be an imperial size with corresponding imperial fittings - You might need to adapt the pipework, and using new fittings is always a good idea.

Myson still sell new radiators in imperial size under their Premier HE range, can be really useful for keeping radiator replacements simple.

We have a major housing developer who still insists on using these. Myson undertake the heating designs, and specify these rads to lock in future orders when the house owners come to replace them!

NSG666

Better too big than too small - the TRV will stop the room getting too hot if used correctly.

The number / length of outside walls and the size of windows and what's below and above can account for differences in calculations for near identical sized rooms.

As well as taking measurements for the calculations, where possible I also used to measure the existing rads and try and calculate their output and use the higher of the two figures. The calculators set bedroom temperatures at 18 degrees but I always used to use 21 degrees as nowadays (I believe as never had kids) bedrooms are used as living rooms more than they used to be.

Once you've worked out what heat output you need then refer to radiator output charts as you will probably find a 11 a 21 and a 22 that will produce the output and you can decide which suits the room best.

And I prefer kW for no other reason than it's sometimes a bit easier to put kW into context - 1 or 2kW is generally what one of those free-standing electric heaters produces on low high settings.