Rad Replacement Advice is BTU or Type King!

[djpwsm]

Hi Guys

So purchased my 1950ish ex RAF house in 2014 and it has a mix of single or double panel, no convector horrid looking Rads. They also perform crap. Sure they get nice and hot, almost scolding in some cases as I've wound the TRVs wide open as they simply don't heat the whole room very evenly. Being that central heating was only installed in 2000 when they were privatised, god knows where the Rads come from and why they are so awful. Oh and they decided not to chase any pipes!!!

About this time last year as I needed to ensure the baby's room was nice and warm (before really knowing anything about BTU calculations), I went down to Screwfix (don't shoot me just yet) and brought the biggest Rad that would fit in under my daughters window. Ended up with a 1200x600 Type 22 (or K2 I thinks some people refer to them as (double panel, double convector)) Kudox item (again don't shoot me, I've seen these Rads receive a ribbing on here!). At the same time, I fitted a Drayton Wiser with the room stat controlling downstairs and a rad stat in each of the slept in bedrooms.

The results of this, while our bedroom and the downstairs still has the uneven heating due to the crap rads, at least its more controllable, however when we go to wake the daughter up in the morning, as soon as you open the door, you walk into a lovely eventually heated room, it's not hot, it's just nice and even throughout.

So now I'm looking to fit new rads to the rest of the upstairs. Leaving downstairs for the moment as having an extension next year which will involve taking out some existing walls and moving things around so may as well spec the required Rads then. So my calculations are as followed:

Box Room 14.5m3 and requires 2000BTU as has 2 external walls
Master Bedroom 35m3 requires 4800BTU
Landing 12m3 (doesn't have a Rad atm but can piggyback off of bathroom) 2000BTU again (not 100% as doesn't have a window but calculator insisted on inputting something, however, we do have positive input ventilation so could do with extra).

Therefore was going to just go and get 3 x type 22 double, double Rads in the sizes I wanted that fit below the window or the wall space available best, as they easily meet or exceed the BTU required for each room and I can just control the required temperature via my Drayton Wiser with the addition of 2 new Smart TRVs. Simples, Right?!

Then it dawned on my that the type 22 in the daughter's room does hang off the wall quite far, 135mm to be precise. Not an issue in her room due to the layout but when looking at the other rooms, it is. On the landing, it will just look a bit clunky I think as it's small but in the master bedroom it eats into the walking space at the side of the bed and in the box room could get in the way or could just look weird. I'm not really sure yet as it's empty awaiting total rip out and redo.

Therefore do I simply just find slimmer rads like a type 21 for the master and maybe a single panel single convertor for the landing and box room, that meet the BTU requirements of the room and I will still get that nice even heat that is in my daughter's room or is it the double, double combo that's really pushing that heat all over the room? It kinda stands to reason that it is, otherwise, what would be the point of em?!

Oh ps based on comments on here in another thread, I'll probably look to get some Myson or Stelrad this time assuming they are not massively more expensive. However, if they are, it will be Kudox as it is by far the best Rad I have in my house at the moment and haven't had any issues with it. It fills the room with nice even heat. What else does one want?!

 

[SimonG]

Nothing wrong with the rads from screwfix. I use a lot of the kudox rads.

 

[djpwsm]

Nothing wrong with the rads from screwfix. I use a lot of the kudox rads.

Any thoughts or experience with the Type of Rad @SimonG

I assume the Type 22 (k2) double panel double convector are generally for larger rooms, however, the single panel single convector is the 14 cubic metre box room does little to heat it.

Then I read statements on the internet (usually on retailers websites) such as radiator technology has improved vastly in the last 20 years and they are now much more efficient but they still look like the same old lumps of metal that have hot water flowing through em to me!

 

[Unique]

Hi,
Balanced and clever heating system keeps home warm for long.
First off all i would pay attention to the insulation in the each room. Like around windows doors and ect, hollow spaces between ceiling and floor doesnt help eithe, if there's wind blowing from any corner, none of radiators above will help you in the long term, heat simply escapes.
Second, having different type of radiators (material they're made from) its not energy efficient. Kudox central heating rads BTU are good, just they are made from soft steel, which gets hot very fast but at the same time, when stat is off the cool down fast too, with designer column rads - cast iron, stainless steel and ect, are very durable and offer excellent heat output.
In conclusion i would say, if you can minimise draft coming from all around and controlling all house rads with clever room stat, try to balance it aferwards and youll make it more efficent aplus have your property warmer for longer.
All the best

 

[djpwsm]

Hi Unique

Thanks for the reply.

This house has no drafts lol. It's a brick external and block internal build, with solid internal walls. The cavity was filled with bead insulation, there's about 300mm in the loft and double glazing with no weep vents. Infact, it's so draftless, I had to have positive input ventilation installed as in winter when drying clothes inside and generally not having the windows open, humidity was going through the roof.

Therefore the only draft (although purposely there is on the landing, where the machine vents fresh air into the house. It does have a heating element on it, but its' extensive to run so hence wanted to add a rad to the landing as gas is a far cheaper heating source than leccy.

I'm trying to get some plumbers out here to quote for the replacement of 2 rads, the addition of a landing rad, boiler service and balance the system but it's proving hard to tie you guys down lol!

I guess we're quite lucky that the house is generally quite warm as only really feel the cold first thing in the morning. To give some context, I've uploaded a pic of the current crap rads in the house!

Thanks
Dan

 

[Ric2013]

Then I read statements on the internet (usually on retailers websites) such as radiator technology has improved vastly in the last 20 years and they are now much more efficient but they still look like the same old lumps of metal that have hot water flowing through em to me!

Yes, I've read those too! I saw a detailed explanation from QRL (Quinn Radiators) that defined the "efficiency" in terms of heat output per kg of steel used in the manufacture of the radiator. Which is not what we normally mean by the term.

Your existing radiator (could be a 1970s Myson?) reminds me of the one I fitted in the bathroom of my old old house (long before I trained as a plumber, but I would do the same again in the circumstances) to replace a single panel radiator that was too small. In my case, the radiator worked extremely well as I had calculated the heat output and found that radiator was spot on for my bathroom, as well as free.

Basically, all radiators take in hot water and return cooler water, releasing the heat energy into the air. They are, if you like, a water to air heat exchanger. The more heat they can output, the more hot water they need. So old-fashioned types such as yours give out less heat but also require less heat from the boiler. They are not inherently less efficient.

To answer the question, different types of radiator may give out the heat in different proportions of conduction and convection, but there isn't really very much in it. If you want to go into the minutiae, it has been argued that low water content per kW output radiators will save energy by not overshooting the set temperature when your heating switches off on the thermostat. It has also been argued that high water content radiators will remain hot for a long time after the heating switches off and save energy by avoiding boiler cycling. Bla bla bla.

The only theory I really agree with is that it is better to have 'oversized' radiators running with the boiler temperature reduced to force the boiler into condensing mode, than have to run the boiler at 80°C to get enough heat output from low-output radiators. Although this is only really relevant if your boiler is, indeed, a condensing boiler.

 

[Ric2013]

different types of radiator may give out the heat in different proportions of conduction and convection

EDIT: should have put "radiation and convection".