TogCheck
Combined TOG result

Cormar Fairisle and Cloud 9 Radiance: combined TOG for underfloor heating

The combined TOG for Cormar Fairisle over Cloud 9 Radiance, worked against the UHMA underfloor heating rule.

1.52.5
1.8TOG in situ
Marginal · limit 2.5
Published TOG stack (carpet + underlay)
carpet 1.5
underlay 1.3
limit

Combined against the UHMA 2.5 TOG underfloor-heating limit. Under 1.5 also suits a low-temperature heat pump.

Carpet TOGUnderlay TOGPassMarginalFail
Combined in-situ TOG is 1.8, under the 2.5 TOG limit, so Cormar Fairisle with Cloud 9 Radiance is suitable for a standard underfloor heating system. It is above 1.5 TOG, so on a low-temperature heat pump run choose a thinner underlay.
The combined-TOG calculation
CarpetCormar Fairisle (1.5 TOG)
UnderlayCloud 9 Radiance (1.3 TOG)
Published sum2.8 TOG
UHMA in-situ correctionminus 1 TOG
Combined in-situ TOG1.8 TOG
Standard UFH limit2.5 TOG
Heat pump targetunder 1.5 TOG

Cormar Fairisle is rated 1.5 TOG and Cloud 9 Radiance is rated 1.3 TOG. Laid together the combination is what the underfloor heating has to warm through.

The published TOG figures add to 2.8. The UHMA rule subtracts 1 TOG because tests showed real in-situ resistance runs about a TOG below the paper sum, giving 1.8 TOG. On a heat pump running low flow temperatures the floor has less heat to push, so aim under 1.5 TOG and prefer the thinnest underlay in this range.

Related checks
Cormar Fairisle TOG value1.5 TOGCloud 9 Radiance TOG rating1.3 TOGCormar Pimlico with Cloud 9 Radiance1.3 TOG, passCormar Primo Textures Ribbed with Cloud 9 Radiance1.3 TOG, passCormar Primo Textures Weave with Cloud 9 Radiance1.2 TOG, passCormar Apollo Plus with Cloud 9 Radiance1.4 TOG, pass

Sources: UHMA guidance on underfloor heating with carpet and underlay (combined-TOG rule) · How to calculate a combined TOG (UHMA formula, worked) · Cormar Carpets published carpet TOG values · Ball & Young Cloud 9 Radiance underlay specification (6 mm, 1.3 TOG, underfloor-heating rated)