TogCheck
Combined TOG result

Cormar Primo Grande and Duralay System Ten: combined TOG for underfloor heating

The combined TOG for Cormar Primo Grande over Duralay System Ten, worked against the UHMA underfloor heating rule.

1.52.5
1.95TOG in situ
Marginal · limit 2.5
Published TOG stack (carpet + underlay)
carpet 1.4
underlay 1.55
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 1.95, under the 2.5 TOG limit, so Cormar Primo Grande with Duralay System Ten 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 Primo Grande (1.4 TOG)
UnderlayDuralay System Ten (1.55 TOG)
Published sum2.95 TOG
UHMA in-situ correctionminus 1 TOG
Combined in-situ TOG1.95 TOG
Standard UFH limit2.5 TOG
Heat pump targetunder 1.5 TOG

Cormar Primo Grande is rated 1.4 TOG and Duralay System Ten is rated 1.55 TOG. Laid together the combination is what the underfloor heating has to warm through.

The published TOG figures add to 2.95. The UHMA rule subtracts 1 TOG because tests showed real in-situ resistance runs about a TOG below the paper sum, giving 1.95 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 Primo Grande TOG value1.4 TOGDuralay System Ten TOG rating1.55 TOGCormar Pimlico with Duralay System Ten1.55 TOG, passCormar Primo Textures Ribbed with Duralay System Ten1.55 TOG, passCormar Primo Textures Weave with Duralay System Ten1.45 TOG, passCormar Apollo Plus with Duralay System Ten1.65 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 / Duralay System Ten underlay datasheet