What Is a Constant Temperature and Humidity Unit?
A constant temperature and humidity unit is an integrated environmental-control system designed to regulate temperature and relative humidity within defined limits. Unlike a conventional dehumidifier, whose primary function is moisture removal, or a conventional air conditioner, whose primary function is temperature control, a constant temperature and humidity unit combines several functions so that both conditions can be managed as part of one system.
The appropriate temperature and humidity setpoints depend on the room, process, product and applicable requirements. For this reason, a constant temperature and humidity unit should be selected from the actual project conditions rather than from room size alone.
How Does a Constant Temperature and Humidity Unit Work?
A constant temperature & humidity unit (also called a precision climate unit or constant-temp & humidity unit) is an integrated system that controls temperature and relative humidity together, within tight tolerances, around the clock. Where a refrigeration dehumidifier only condenses moisture and an AC only moves temperature, this unit manages four functions in one package:
- Cooling (refrigeration)— removes heat and condenses excess moisture out of the air.
- Reheat (electric)— lifts temperature back to set point after cooling, so you are not left cold and dry.
- Humidification (electrode)— adds moisture when the room runs too dry.
- Circulation (indoor fan)— pushes conditioned air through the space and keeps it uniform.
The result is a room that sits at, say, 22 °C and 50 % RH instead of swinging between 18 °C / 65 % and 26 °C / 40 % as the day changes. The LT-CTH line is built as a split system — an indoor unit plus an outdoor unit — with electric reheat and electrode humidification.
Inside the LutaAir LT-CTH Series
The LT-CTH series is a split-type constant temperature & humidity line spanning compact rooms to large production spaces. Nine models cover it:
- Temperature control:18–30 °C at ±1.0 °C
- Humidity control:40–70 % RH at ±5.0 %
- Air circulation:1,000–13,000 m³/h
- Cooling capacity:2–60 kW
- Heating capacity:3–36 kW
- Refrigerant:R22 / R407C / R410A
- Operation ambient:5–35 °C
- Heating mode:electric · Humidification mode: electrode
- Power:220–240 V / 50 Hz / 1-phase (LT-CTH5) or 380 V / 50 Hz / 3-phase (LT-CTH9 and above)
That 40–70 % RH band with ±5 % accuracy is the sweet spot for most “keep it stable, keep it dry-ish” rooms — pharmaceutical storage, food factories, labs, cleanrooms, and archives. For deeper drying or low dew points, see the [desiccant rotor dehumidifier line]
LT-CTH Full Specification
| Model | Cooling (kW) | Heating (kW) | Airflow (m³/h) | ESP (Pa) | Power supply | Rated power (kW) | Indoor unit D×W×H (mm) | Indoor net wt (kg) |
| LT-CTH5 | 5.2 | 3 | 1,000 | 80 | 220–240 V / 1-ph | 1.5 | 620 × 580 × 1,750 | 120 |
| LT-CTH9 | 8.5 | 6 | 2,300 | 80 | 380 V / 3-ph | 3.10 | 800 × 580 × 1,900 | 180 |
| LT-CTH12 | 12 | 8 | 3,000 | 90 | 380 V / 3-ph | 4.10 | 850 × 580 × 1,900 | 200 |
| LT-CTH20 | 19.5 | 9 | 4,300 | 90 | 380 V / 3-ph | 5.80 | 1,195 × 580 × 1,900 | 240 |
| LT-CTH25 | 25.5 | 16 | 5,000 | 100 | 380 V / 3-ph | 7.70 | 1,300 × 740 × 2,050 | 300 |
| LT-CTH30 | 30 | 18 | 6,200 | 150 | 380 V / 3-ph | 4.5 × 2 | 1,300 × 740 × 2,050 | 300 |
| LT-CTH40 | 40 | 25 | 8,000 | 200 | 380 V / 3-ph | 5.8 × 2 | 1,550 × 740 × 2,250 | 350 |
| LT-CTH50 | 49 | 27 | 13,000 | 200 | 380 V / 3-ph | 7.4 × 2 | 1,650 × 740 × 2,250 | 450 |
| LT-CTH60 | 60 | 36 | 10,000 | 300 | 380 V / 3-ph | 9.4 × 2 | 2,200 × 1,480 × 1,850 | 500 |
Why “Sensitive Rooms” Need Both Held
Controlling only one variable leaves the other free to drift — and drift is what ruins product. A few rooms where this matters:
- Pharmaceutical storage.Empty hard-gelatin capsules and many APIs are hygroscopic; supplied storage guidance commonly cites roughly 15–25 °C with 35–65 % RH to avoid softening, brittleness, or clumping. Treat that as an application guideline to confirm with QA, not a LUTA specification — but the LT-CTH 40–70 % RH range covers the middle of it comfortably.
- Food factories.Spicy-instant-noodle lines, seasoning powders, and wrappers need steady humidity to stop caking and quality swings at volume.
- Labs and metrology.Calibration and sensitive instruments want a climate that does not move with the weather.
- Cleanrooms and archives.Process consistency and artifact protection both depend on a held band, not a daily swing.
The point: a sensitive room usually fails on the variable nobody was watching. Holding temperature and humidity together is cheaper than scrapping a batch.
How to Size an LT-CTH Unit for Your Room
A quick, non-final checklist before we engineer it:
- Airflow first.Estimate room air changes per hour, then match the model’s circulation (1,000–13,000 m³/h). CTH5 fits a small chamber; CTH50 moves 13,000 m³/h for a big space.
- Load second.Add up heat load (equipment, people, lighting) and moisture load (infiltration, process, occupancy) — that sets cooling and reheat demand.
- Check accuracy.±1.0 °C / ±5.0 % RH is the LT-CTH standard; confirm it meets your spec.
- Check external static pressure.ESP runs 80–300 Pa across the range — size ductwork to it.
- Check power.CTH5 is single-phase 220–240 V; CTH9 and above are 3-phase 380 V.
Final selection must be confirmed against your room volumes, loads, and local code — send us the numbers and we size it properly.
FAQ
What is the difference between a dehumidifier and a constant temperature & humidity unit?
A dehumidifier only removes moisture. A constant temperature & humidity unit controls temperature and humidity together, with electric reheat and electrode humidification, and holds both to a tight tolerance.
Can the LT-CTH reach very low humidity like a desiccant rotor?
No — by design it covers 40–70 % RH. For below 40 % RH or a low dew point, use a desiccant rotor dehumidifier . Choose by the RH or dew point your process requires.
Does it need an outdoor unit and drainage?
Yes on the split design — each model pairs an indoor unit with an outdoor unit (dual units on CTH30 and above). Operation ambient is 5–35 °C. Confirm drainage and piping details with our team for your layout.
What refrigerant does the LT-CTH use?
R22 / R407C / R410A.
Get a Free Climate Assessment
A sensitive room is only as stable as the unit holding it. Tell us your room size, the temperature and humidity band each zone needs, your loads, and we will size the right LT-CTH units and confirm the layout.
Get a free constant-temperature & humidity assessment →
