LTHW cassette heater for suspended ceilings
The CurveVector Cassette Heater is an LTHW cassette heater that fits a standard 600 x 600 mm suspended ceiling grid, so only its round white grille shows in the room. Room air is drawn in through the perforated centre of the grille, warmed by a hot water coil and discharged evenly through 360° at a fixed 45° angle. Choose a 3-row coil for heat pumps and condensing boilers, or a 2-row coil for conventional boiler water temperatures.
Supplied by SPC (S & P Coil Products Limited), the CurveVector Cassette Heater suits commercial and public buildings where walls and floors need to stay clear for furniture, displays and storage, from schools, offices and shops to libraries, museums and healthcare waiting areas. It can also be fitted in plasterboard ceilings with access panels, or hung freely below an open ceiling.
Fits a 600 mm grid
Recessed into a standard 600 x 600 mm ceiling tile
360° air discharge
Even air in every direction at a fixed 45° angle
Heat pump ready
3-row coil option with outputs published at 45/35°C
Supported by SPC
Selection, technical support and a local Area Sales Manager
2.9 to 4.1 kW
Heating output at 45/35°C water for heat pumps: 3-row coil, low to high fan speed, 18°C room.
6.3 to 8.4 kW
Heating output at 82/71°C water: 2-row coil, low to high fan speed, 18°C room.
300 mm
Height above the ceiling, for a unit measuring 570 x 572 mm in a 600 x 600 mm ceiling tile.
1.8 to 3 m
Mounting height above the floor: 1.8 m minimum, 3 m recommended maximum.
What is an LTHW cassette heater?
An LTHW cassette heater is a fan-assisted heater, fed from a low temperature hot water system, that is recessed into the ceiling so it takes no wall or floor space. The CurveVector Cassette Heater has a heat exchanger of copper tubes and aluminium fins, a backward-curved fan with an EC motor, and a round grille that discharges air through 360°, so warm air spreads evenly across the room even at low fan speed.
An integral thermostatic valve and actuator on the return connection limits the discharge air temperature to 65°C. Two blanking plates are supplied to close up to two of the outlets, so the air can be directed away from a wall or window.
Inside the CurveVector Cassette Heater: air drawn in through the centre of the grille and discharged through 360°
What size is the CurveVector Cassette Heater?
The CurveVector Cassette Heater comes in one size for a standard 600 x 600 mm ceiling tile, with a choice of two coils.
| Dimension | CurveVector Cassette Heater |
|---|---|
| Ceiling tile | 600 x 600 mm |
| Unit (W x L x H) | 570 x 572 x 300 mm |
| Grille overall | 620 x 620 mm |
| Weight | 32 kg |
| Water content | 1.5 litres (2-row coil), 2.1 litres (3-row coil) |
| Pipe connections | 22 mm |
Read more in our launch article: CurveVector Cassette Heater: A New Circular-Grille Option for Ceiling-Mounted Heating. Planning heating for a school? Read Modern Heating Solutions for UK Schools and Educational Buildings.
Can a cassette heater work with a heat pump?
Yes. The CurveVector Cassette Heater is available with a 3-row coil for the low water temperatures of heat pumps and condensing boilers.
- 2.9 to 4.1 kW at 45/35°C water, low to high fan speed, 18°C room
- 4.2 to 5.9 kW at 60/40°C water for condensing boilers
- Also suits waste heat recovery and other low temperature heating circuits
How does a 360° cassette heater spread heat?
The CurveVector Cassette Heater recirculates room air through the coil and sends it out in every direction.
- Air is drawn in through the perforated centre of the grille
- It is warmed as it passes through the hot water coil
- It leaves through outlets around the grille, angled 45° downwards into the room
How loud is the CurveVector Cassette Heater?
The CurveVector Cassette Heater has three fan speeds, from NR 29 at low speed.
- NR 29 (low), NR 35 (medium) and NR 39 (high), based on Q=2, R=4 m, V=300 m³ and a 0.4 s reverberation time
- Airflow of 107, 134 and 158 l/s
- Specific fan power of 0.14 to 0.24 W/l/s from the EC motor
Full heating performance for both coils, including water flow rates and pressure drops, is in the CurveVector Cassette Heater brochure.
CurveVector Cassette Heater installation, controls and options
The CurveVector Cassette Heater hangs from threaded rods on the suspension profiles supplied, then is brought into line with the underside of the T bars and levelled. It can be fitted before or after the ceiling, and adjusted in any direction to line up with the grid.
- Two suspension brackets supplied as standard
- Rotatable grille, fitted after the unit is hung
- 22 mm flow and return connections on the side of the unit
- Electrical box reached from the side of the unit
Step-by-step instructions are in IOM 103 in the downloads.
CurveVector Cassette Heater in a 600 x 600 mm suspended ceiling
The CurveVector Cassette Heater can also go into a plasterboard ceiling, or hang freely where there is no ceiling grid.
- Plasterboard: cut an opening larger than the unit (570 x 572 mm) but smaller than the grille (620 x 620 mm)
- The suspension rods carry the weight, not the plasterboard
- Access panels are needed in a plasterboard ceiling for maintenance
- Free-hanging units use the same suspension method
CurveVector Cassette Heater hung below an open ceiling
CurveVector Cassette Heater controls are remote, and each control option is supplied with its own wiring diagram.
- Remote thermostats: on/off, change speed and proportional
- Remote switches: on/off, change speed and summer/winter
- Adjustable low water temperature cut-out, which switches the unit off when hot water is not available
- Remote thermostats are best mounted on a wall at about 1.5 m, away from heat sources and direct sunlight
Choose the CurveVector Cassette Heater coil to suit the water temperatures on your project.
- 3-row coil (H3): for heat pumps and condensing boilers
- 2-row coil (H2): for conventional boiler water temperatures
- Grille in RAL 9016 white as standard, with other RAL colours on request
- Zinc-plated steel casing with internal sound-absorbing insulation
Project support from SPC: from survey to commissioning
SPC supplies CurveVector Cassette Heaters for installation by your M&E contractor, and supports the project from the first survey to handover.
Site surveys
We visit site to check mounting positions and ceiling types for each room.
Selection
We choose the coil for your water temperatures and the controls for each space.
Technical support
Our technical team answers coil, control and installation questions.
Area Sales Managers
A local ASM supports you from specification to delivery.
Specifying the CurveVector Cassette Heater
Free help to select units and plan the installation.
Get a unit selection
Send us your room sizes, heat losses and water temperatures, and we will select the number of CurveVector Cassette Heaters, the coil and the controls for each space.
Technical drawings and IOM
Download the brochure for technical drawings and full performance data, and IOM 103 for suspension, pipework, wiring and maintenance details.
Where is a CurveVector Cassette Heater used?
CurveVector Cassette Heaters suit commercial and public buildings where the walls and floor need to stay clear, including schools, colleges and universities, offices and reception areas, shops and showrooms, libraries, museums, banks and healthcare waiting areas. The images show typical settings.
Schools, colleges and lecture rooms
Libraries, museums and public buildings
Shops and showrooms
CurveVector Cassette Heater specification summary
| Feature | CurveVector Cassette Heater |
|---|---|
| Type | LTHW cassette heater for recessed ceiling installation (suspended T bar or plasterboard), or free-hanging |
| Ceiling tile | 600 x 600 mm |
| Unit dimensions (W x L x H) | 570 x 572 x 300 mm (300 mm above the ceiling) |
| Grille overall | 620 x 620 mm |
| Weight | 32 kg |
| Mounting height | 1.8 m minimum above the floor, 3 m recommended maximum |
| Coil options | 3-row coil (H3) for heat pumps and condensing boilers; 2-row coil (H2) for conventional boiler water temperatures |
| Heat exchanger | Copper tubes and aluminium fins |
| Heating output (18°C room, low to high fan speed) | 3-row coil: 2.9 to 4.1 kW at 45/35°C, 4.2 to 5.9 kW at 60/40°C. 2-row coil: 5.5 to 7.3 kW at 80/60°C, 6.3 to 8.4 kW at 82/71°C |
| Discharge air temperature limit | 65°C, set by an integral thermostatic valve and actuator with remote sensor on the return connection |
| Air discharge | 360° through the grille perimeter at a fixed 45° angle; two blanking plates supplied to close up to two outlets |
| Fan | Backward-curved centrifugal fan, aluminium casing and impeller, three speeds |
| Motor | External rotor EC motor with sealed for life ball bearings, IP44, auto-reset thermal overload protection |
| Airflow | 107, 134 and 158 l/s (low, medium, high) |
| Specific fan power | 0.14, 0.19 and 0.24 W/l/s |
| Noise | NR 29, 35 and 39 (low, medium, high), based on Q=2, R=4 m, V=300 m³, 0.4 s reverberation time |
| Electrical supply | 230 V, 1 phase, 50 Hz; 155 W maximum fan power; 1.6 A maximum current |
| Pipe connections | 22 mm compression, flow and return on the side of the unit |
| Casing | Zinc-plated sheet steel with reinforcement and internal sound-absorbing insulation |
| Grille | Rotatable plastic grille with removable perforated centre and filter; RAL 9016 white as standard, other RAL colours on request |
| Controls | Remote on/off, change speed and proportional thermostats; on/off, change speed and summer/winter switches; adjustable low water temperature cut-out |
| Supplied with | Grille, two suspension brackets and two blanking plates |
| Maintenance | Filter and internal surfaces cleaned through the grille; electrical box reached from the side |
| Supplied by | SPC (S & P Coil Products Limited) |
Discuss your cassette heater project
Planning ceiling heating for a school, office, shop, library or other commercial or public building? Tell us about your project and we will help you specify CurveVector Cassette Heaters. Call 0116 249 0044 or email spc@spc-hvac.co.uk.
Frequently Asked Questions
Yes. LTHW (low temperature hot water) and LPHW (low pressure hot water) are two names for the same kind of wet heating system, so an LTHW cassette heater and an LPHW cassette heater do the same job. The CurveVector Cassette Heater runs on hot water from a heat pump, condensing boiler or conventional boiler, with the coil chosen to suit the water temperature.
A water-fed cassette heater is a type of fan convector built to recess into the ceiling. Like a fan convector, the CurveVector Cassette Heater uses a fan to pass room air over a hot water coil, but it sits in a 600 x 600 mm ceiling tile and discharges through a round grille in every direction, leaving the walls and floor free.
Choose the 3-row coil (H3) for the lower water temperatures of heat pumps and condensing boilers, for example 45/35°C or 60/40°C. Choose the 2-row coil (H2) for conventional boiler temperatures, for example 82/71°C or 80/60°C. Our team can select the coil for your water temperatures and heat losses.
Yes. The CurveVector Cassette Heater uses the same suspension rods and profiles in a plasterboard ceiling as in a suspended grid. Cut the opening larger than the unit (570 x 572 mm) but smaller than the grille (620 x 620 mm), let the rods carry the weight, and include access panels in the ceiling for maintenance. The unit can also hang freely where there is no ceiling.
Yes. The CurveVector Cassette Heater is supplied with two blanking plates that can close up to two of the outlets around the grille, so less air is sent towards a nearby wall, window or obstruction.
Each CurveVector Cassette Heater needs a 230 V single phase supply with an earth. A dedicated fused or switched spur within 1.5 m of the unit is recommended, kept accessible for servicing. The unit is protected by a 1.6 A fuse, and power and control wiring connect to a terminal block in the electrical box on the side of the unit.
Clean the inside of the CurveVector Cassette Heater with a vacuum cleaner nozzle at least every three months, or more often in dusty areas. Remove the central grille to reach the filter, which can be cleaned, dried and refitted. Check the filter regularly at first to find how often your building needs it. Never clean the inside with water, and isolate the power before opening the grille.
The CurveVector Cassette Heater grille is RAL 9016 white as standard, and other RAL colours are available on request. Call 0116 249 0044 or email spc@spc-hvac.co.uk to discuss a colour for your project.
