Vendor Teardown 06 — HVAC / Cooling

Source: 02_dehum_hvac.jpeg + 07_pricing_offer.pdf

This is the single biggest technical finding in the whole document review. Of the €82 584 vendor offer, the HVAC line is where the customer's crop actually lives or dies.

Equipment spec (the low number)

Pricing offer (the actual number)

The equipment-spec / pricing-offer discrepancy

Equipment spec says 10.5 kW per flowering room; pricing offer delivers 15 kW nameplate (UCHA60-TDC) per flowering room. Reading these charitably together, the vendor has already applied derating — they sized nameplate at 15 kW to hit a target of ~10.5 kW effective after the 35 °C ambient derating hit (~70 % of nameplate in Malta summer).

That's actually sophisticated of them, if true. But it only closes half the gap.

UCHA60-TDC — what is it?

"UCHA" is not a mainstream European HVAC brand. Based on the naming convention and the 15 kW capacity + €3 200 price point, this is a Chinese commercial ducted split — likely:

• A Gree, Hisense, or Midea commercial OEM line rebranded
• Or a direct Chinese commercial brand (e.g. Haier, TCL, or a smaller OEM)

At €3 200 for a 15 kW commercial ducted split, the vendor is ~40–50 % under European commercial benchmarks. Daikin / Mitsubishi / Toshiba equivalents at 15 kW cool run €6 000–9 000 each. The €3 200 price point is consistent with:

• Chinese origin
• 1-year manufacturer warranty (commercial grade is typically 3–5)
• Single-phase power (check — 15 kW on single phase is a lot of current and may not be legal in PL/Malta)
• R32 or R410A refrigerant
• Limited parts availability in Malta (spares shipped from CN, 4–6 week lead time)

Ask the vendor for the full UCHA60-TDC datasheet, COP rating, nominal capacity at 35 °C ambient, and Maltese F-gas certification paperwork. Without those the unit is a black box.

Heat balance re-done

Load per flowering room:

• Lighting electrical input = 100 % sensible heat: 11.76 kW
• Motors, pumps, relay heat, sensor power: ~0.5 kW
• Dehumidifier sensible reject (276 L/day × 0.7 kWh/L ÷ 24 h): ~8 kW — unless the hot side is ducted outdoors (not clarified in offer)
• Solar gain through roof and south wall (Malta summer, sealed room): ~1.5 kW

Best case (dehu ducted out): ~13.7 kW sensible Worst case (dehu reject inside): ~21.7 kW sensible

UCHA60-TDC effective capacity at Malta peak

• Nameplate: 15 kW
• 38 °C outdoor ambient derating: × 0.75 → 11.25 kW
• Sensible Heat Ratio 0.75 (the unit wastes some capacity on latent the dehu already removed): × 0.85 (partial SHR discount since dehu already handles most latent) → ~9.6 kW effective sensible at peak

Verdict

Either way, the vendor's flowering HVAC is insufficient at peak Maltese ambient. In the best case (dehu ducted) the customer lives with uncomfortable canopy temps and mildly reduced yield; in the worst case (dehu reject inside), they lose a crop every July/August heatwave.

The vendor's air duct line

Each flowering room gets "Air Duct 4 m at €115" — one 4 m duct run per room. This is almost certainly the supply duct from the UCHA60 indoor unit into the room ceiling, not a dehumidifier exhaust duct to outdoors. So the worst-case reading (dehu reject inside) is more likely. A dehu exhaust duct to outside would be a separate line (longer run, insulated, weatherproof terminal), not "4 m air duct at €115".

Wider facility HVAC

The non-flowering rooms are reasonably sized. The failure is concentrated in the two flowering rooms — which is also where the crop value is.

Additional risk — single point of failure

Each flowering room has ONE UCHA60-TDC. If that unit fails in week 5 of flower:

• Indoor coil stops condensing → temperature rises 1 °C per hour from just the lights
• Canopy temp reaches 35 °C within 5 hours
• Crop experiences irreversible heat damage; terpenes volatilise off
• Commercial service tech in Malta for a Chinese rebadged commercial unit: 3–7 days lead time
• Replacement unit: 4–6 weeks from China

Risk-adjusted outcome: losing one UCHA60-TDC = losing one full crop cycle = €15 000–30 000 lost revenue, on a €3 200 unit that saved maybe €2 000 vs a European brand.

This is the single strongest argument for the DIY counter-proposal's N+2 split AC approach — see diy_proposal/02_hvac_splits_diy.md.

Confirmations still needed from vendor

1. Exact UCHA60-TDC / UCHA24-TDC manufacturer datasheet with COP, nominal capacity at 35 °C, and 38 °C ambient capacity.
2. Refrigerant type and Maltese F-gas certified installer arrangement.
3. Warranty term and spare-parts lead time from Malta.
4. Is the dehumidifier hot side ducted outdoors?
5. What is the redundancy / failover plan when a 15 kW unit fails mid-cycle?
6. Single-phase or three-phase power feed for the UCHA60-TDC?