TogCheck
Combined TOG result

Cormar Zenith and Tredaire Colours Red: combined TOG for underfloor heating

The combined TOG for Cormar Zenith over Tredaire Colours Red, worked against the UHMA underfloor heating rule.

1.52.5
2.15TOG in situ
Marginal · limit 2.5
Published TOG stack (carpet + underlay)
carpet 1.5
underlay 1.65
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 2.15, under the 2.5 TOG limit, so Cormar Zenith with Tredaire Colours Red 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 Zenith (1.5 TOG)
UnderlayTredaire Colours Red (1.65 TOG)
Published sum3.15 TOG
UHMA in-situ correctionminus 1 TOG
Combined in-situ TOG2.15 TOG
Standard UFH limit2.5 TOG
Heat pump targetunder 1.5 TOG

Cormar Zenith is rated 1.5 TOG and Tredaire Colours Red is rated 1.65 TOG. Laid together the combination is what the underfloor heating has to warm through.

The published TOG figures add to 3.15. The UHMA rule subtracts 1 TOG because tests showed real in-situ resistance runs about a TOG below the paper sum, giving 2.15 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 Zenith TOG value1.5 TOGTredaire Colours Red TOG rating1.65 TOGCormar Pimlico with Tredaire Colours Red1.65 TOG, passCormar Primo Textures Ribbed with Tredaire Colours Red1.65 TOG, passCormar Primo Textures Weave with Tredaire Colours Red1.55 TOG, passCormar Apollo Plus with Tredaire Colours Red1.75 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 · Interfloor / Tredaire Colours Red sponge-rubber underlay specification