Annker

Will do and thanks again for all your input. Received great advice from yourself and other here, and confident I have a good understanding of the principles at work.

Thought I'd do a photo dump of some the onsite installation of the details discussed and generously advised on by some of the member here. Just some notes of interest if you are doing a similar job: Lime parge coat. Absolutely brilliant base before doing anything. Fast to apply, inexpensive and It has sealed up the walls greatly. What I have also noticed is the complete lack of any insects, mold or any living organism on the walls, I'm assumed this is due to the dryness and alkaline nature of lime. Pro clima Tescon tape. Not convinced how well this tape will stay adhere to masonry over decades, stick better to timber and best to membranes so assemble it around joist ends accordingly. And get the primer as it greatly increases the bond. Airtightness of studded walls units: I build the wall studs in situ, and before I installed the individual studs I ensured that the floor/ceiling to sole/head plate junctions were airtight. I used a combo of Illbruck FM330 and tapes. I think having a compartilization model in mind is useful so if there are any individual air leaks into the build-up they wont aggregated from wall to wall, cellar to 1st floor, etc. Insulation will be Rockwool as recommended by @Iceverge I also considered using a glass mineral wool, probably also suitable and less expensive but I have better confidence that RW will sag less in the fullness of time

Yes, typically they all quote D50 and some then quote a few other common DT's. But regardless I compared all against D50

Thanks John, that makes sense.

Hi Gus, To my mind this is not the issue, as I am comparing one cast iron radiator section against another. I called CIRC and as expected they can't give a specific reason why their section is upwards of 25% more efficient than all others, but they can say that no customer has raised this issue before. Is it just my experience or do the majority of building product suppliers in the UK seem clueless about their products. Anyway, as you also suggest I think if I use CIRC it is wise to oversize. My AI assistant summarises as such: Bottom line: With an ASHP, the risk profile is asymmetric. Undersized radiators force higher flow temperatures and reduce efficiency. Oversized radiators allow lower flow temperatures and improve efficiency. If you must err, err on the side of larger. Sizing to Paladin/Carron figures while buying from CIRC is a sensible, low-risk strategy. Worst case: you've got slightly more efficient heating and spent a bit more on radiators. Best case: you've sized correctly.

I've also noticed that CIRC state that a 4 column 760x1310 has an output of 2400W; where as their 3 column 745x1310 has an output of 2403W. A smaller section with one less column having a greater(albeit slightly) output surely cannot be correct or am I missing something?

Adds a bit more context that the Cast iron radiator centre are claiming that their 745mm high 3 column section has greater output than the Stelrad 760mm high 4 column section. It just doesn't seem likely to me. The thing is that CIRC seem to be a lot less expensive than all other suppliers, even if in reality you need to size up from their performance tables. I just want to make sure I get genuine performance figures from them.

Well that's what I'm assuming also; that is given that the designs, or material used are not significantly different, the outputs should be more or less the same. So the question is whether 4/5 brands are understating the performance of their product or one brand is overstating their performance. The latter seems more likely. AI suggested that I request their BS EN 442 test documentation to verify the claim output. I will do that tomorrow and imagine more than likely be met with silence.

I'm looking to buy cast iron radiators to install downstairs in a victorian renovation. Cast iron radiator centre are a supplier that seem to be competitively priced, if not one of the cheapest suppliers on the market. A potential catch which I am trying to resolve is the accuracy of their claimed performance (watts). I asked AI to compile a table and it illustrates as I thought, that CIRC claim their sections put out ~25% to 30% more heat than most other brands. As these sections are pretty much the same design, and I imagine are produced from same material, across all brands it seem like a claim worth verifying. Has anyone ever had the similar query? The heating system will be ASHP so I'm keen to match the respective heat loss figures for each room accurately and Obviously I don't want to end up with undersized rads. . 3-Column Cast Iron Radiator Output Comparison (~745-750mm Height) Per-Section Output @ ΔT50 Manufacturer Model Height Watts/Section Cast Iron Radiator Centre (CIRC) Traditional Victorian 3-Col 745mm 115W Shelbourne (CI Radiators 4u) 3-Column 745mm 86W Paladin Victoriana 3-Col 745mm 86W Arroll Neo-Classic 750 745mm 92W Carron Victorian 3-Col 745mm 80W

Interesting, I wasn't aware such slim lights were available. I should have clearer that I have a somewhat specific light design intent, wrt downlighters I want trimless, small diameter and in some instances directional. For what I have seen ticking them boxes means a fitting with a min depth of ~90mm As aside on a previous project I worked with John Cullen Lighting, they were client appointed and initially I thought Lighting design was a makey uppy discipline to extract money out of wealthy home builders but I learnt a lot from them and a good lighting design certainly elevates a project to the high end.

Its a retro fit/renovation. I think it would be near impossible to seal the perimeter of the VCL if it was fitted above the joists, and also more difficulty to fit the insulation to be laid between the joists. Photo below for reference, as you can see its very easy for me to fit the vcl from below. I have a thread going on IWI, my design was largely gathered from very useful info received on the forum and I will updated it once that phase of works is complete