InsightSpecification guideHot-climate designVRF systems
T1 and T3 capacity: how to read TCL VRF ratings for hot climates
A VRF unit’s headline capacity is rated at standard conditions. In hot climates the T3 figure is lower, and the gap is large enough to change the model you pick.
TCL HVAC Middle EastPublished 4 min read
The capacity printed on a VRF outdoor unit is almost always the T1 figure. It describes how much cooling the unit delivers when the outdoor air is 35 °C. A Gulf rooftop in July is a different place, so the number that matters for sizing is the one rated for a hotter condition.
What T1, T3 and T4 mean
TCL’s datasheets state the standard condition as 27 °C dry-bulb indoor and 35 °C dry-bulb outdoor, labelled T1. The same sheets for hot-climate markets also publish capacity under the headings T3 and T4. Where TCL gives the exact test temperature for those conditions on the sheet, use it; where it does not, ask TCL before assuming a value.
How much capacity is lost: TMV6 Master
| Model | T1 | T3 | Difference |
|---|---|---|---|
| 8 HP | 25.2 | 23.1 | −8.3% |
| 12 HP | 33.3 | 30.9 | −7.2% |
| 16 HP | 45.0 | 40.0 | −11.1% |
| 20 HP | 56.5 | 51.0 | −9.7% |
| 24 HP | 68.0 | 61.5 | −9.6% |
| 30 HP | 85.0 | 77.5 | −8.8% |
Source: TCL TMV6 Master specification sheet. Percentages are calculated from the published kW values.
What this changes in selection
- A system selected on T1 capacity can fall short of the design load on the hottest days. Check the T3 column first.
- Efficiency also drops: the TMV6 Master 20 HP is rated EER 4.08 at T1 and 3.17 at T3, so electrical input rises for less cooling.
- Ambient limits are separate from capacity ratings. The TMV6 Master is listed for cooling from −15 to 56 °C; the TMV6+ ECOC cooling-only series is listed up to 60 °C.
A short checklist
- Take the design cooling load for the building.
- Compare it with the T3 capacity of the outdoor module, not the T1 figure.
- Confirm the cooling ambient range printed for that model covers your site.
- Ask TCL for the latest datasheet before issuing the submittal.
