Cormar Primo Plus and Tredaire Colours Red: combined TOG for underfloor heating
The combined TOG for Cormar Primo Plus over Tredaire Colours Red, worked against the UHMA underfloor heating rule.
Combined against the UHMA 2.5 TOG underfloor-heating limit. Under 1.5 also suits a low-temperature heat pump.
| Carpet | Cormar Primo Plus (1.1 TOG) |
|---|---|
| Underlay | Tredaire Colours Red (1.65 TOG) |
| Published sum | 2.75 TOG |
| UHMA in-situ correction | minus 1 TOG |
| Combined in-situ TOG | 1.75 TOG |
| Standard UFH limit | 2.5 TOG |
| Heat pump target | under 1.5 TOG |
Cormar Primo Plus is rated 1.1 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 2.75. The UHMA rule subtracts 1 TOG because tests showed real in-situ resistance runs about a TOG below the paper sum, giving 1.75 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.
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