Metropolitan Powered Trench Heaters are LTHW powered trench heaters from SPC, recessed into the floor beneath full height glazing to counter cold down-draughts. Low-power EC/DC fans draw room air across the heat exchanger and send the warmed air up the window, with fan speed set by a 0-10V signal from a BMS or room controller.
Manufactured in Leicester by S & P Coil Products Limited and independently tested to BS EN 16430, Metropolitan Powered Trench Heaters suit commercial, public and residential buildings with large glazed areas, including offices, reception areas, hotels and restaurants. They fit screeded or suspended floors, 110 mm deep, in four widths and 22 standard lengths, with bespoke sizes on request.
EC/DC fans
Low-power fans with 0-10V speed control
Any floor
For screeded or suspended floors, 110 mm deep
BS EN 16430
Performance independently tested to BS EN 16430
Made in Leicester
Manufactured and supported by SPC in the UK
470 to 3,551 W
Heat output per unit at 80/60°C water, 20°C room air and medium fan speed, across all four widths. Outputs are published for lengths up to 3,100 mm
110 mm deep
One unit height in four widths (180, 225, 260 and 300 mm) to suit shallow floor build-ups
0-10V control
EC/DC fan speed set by a BMS or room mounted controller, or by hand with the on-board rotary potentiometers
22 lengths
From 1,100 to 3,200 mm in 100 mm steps, joined with flangeless end plates for continuous runs
What are Metropolitan Powered Trench Heaters?
A Metropolitan Powered Trench Heater is a black powder coated steel casing set into the floor, holding a heat exchanger of copper tubes expanded into aluminium fins, low-power EC/DC fans and a roll-up grille that sits level with the finished floor. Each unit runs on a 230 V supply, and the heat output is controlled by the speed of the fans.
The unit is installed close to the glazing with the heat exchanger on the window side. The fans draw room air into the trench, blow it across the heat exchanger and send the warmed air up the window, where it counters the cold down-draught before circulating around the room.
Metropolitan Powered Trench Heaters beneath the windows at 42 Park End Street, Oxford
What sizes do Metropolitan Powered Trench Heaters come in?
Metropolitan Powered Trench Heaters are 110 mm high in four widths, in 22 standard lengths from 1,100 to 3,200 mm in 100 mm steps. Longer runs are made by joining units end to end with flangeless end plates.
| Width (mm) | Height (mm) | Width at feet (mm) |
|---|---|---|
| 180 | 110 | 230 |
| 225 | 110 | 275 |
| 260 | 110 | 310 |
| 300 | 110 | 350 |
Bespoke widths, heights and lengths, curved sections and grilles, and corner kits with angled sections and mitred corner grilles are available on request.
Planning trench heating for a glazed building? Read our guides: Why Trench Heating is Ideal for Modern Buildings and How Do You Stop Cold Down-Draughts from Full Height Glazing? You can also see the full SPC trench heating and cooling range.
How do Metropolitan Powered Trench Heaters perform?
Output depends on the width and length of each unit and the fan speed, so a run of Metropolitan Powered Trench Heaters can be sized to the heat loss along the glazing.
- Outputs published at 80/60°C water, 20°C room air (ΔT 50°C) and medium fan speed
- Up to 3,551 W from a 300 mm wide unit, 3,100 mm long
- Sound pressure level below 30 dBA at 2 m, at medium fan speed
- Heat exchanger pressure tested to 22 barg, air under water, before fitting
Where can powered trench heaters be installed?
Metropolitan Powered Trench Heaters suit indoor spaces with large glazed areas, as single units or continuous runs.
- Screeded (concrete) or suspended floors, with levelling screws at each corner and adjustable support feet
- Each unit needs its own 230 V supply, plus control wiring for a BMS or room controller
- Grilles suit occasional foot traffic, not point loads such as chair legs
- Not for doorways or areas of constant footfall, or outdoors
Full heat output and water pressure drop data for every width and length is in the Metropolitan Trench Heating and Cooling brochure.
Metropolitan Powered Trench Heater grilles, controls and options
Metropolitan Powered Trench Heaters are supplied as standard with an anodised aluminium roll-up grille and a matching trim for the edge of the casing. The double-T profile blades give a free area of 60%.
Grilles and trim come in satin silver, black and a range of Anolok bronze, gold, umber and blue-grey finishes. Stainless steel grilles are available on request (grille trim is not available in stainless steel). Roll-up grilles suit occasional foot traffic, but not point loads such as chair legs.
Metropolitan Powered Trench Heaters use EC/DC fan motors, so the heat output is controlled on the air side by fan speed. Water side valves can also be supplied where the project calls for them.
- 0-10V control: fan speed is set by a 0-10V signal from the building management system (BMS) or a room mounted controller
- Manual setting: fan speed can be set on site with the on-board rotary potentiometers
- Room thermostats: SPC supplies a range of wall mounted room thermostats, including SPC Modulo
- Zones: several units can follow one thermostat or BMS signal, with each unit wired to its own power supply
- Water side: 2-port valves and actuators can be added to the control strategy
- Connections: flexible hoses with integral quarter turn isolating valves are available
Metropolitan Powered Trench Heaters can be adapted to the building, with bespoke widths, heights and lengths, curved sections and grilles, and corner kits with angled sections and mitred corner grilles. Contact SPC to discuss project-specific requirements.
Each unit arrives fully assembled, with transverse bracing and a protective cover to keep in place while the floor is finished. The grille and trim are packed separately and fitted once the unit is installed. In a screeded floor, the pipework and the power and control cables are brought into the casing before the screed is laid.
Project support from SPC: from survey to commissioning
SPC manufactures and supplies Metropolitan Powered Trench Heaters for installation by your chosen mechanical and electrical contractor, and supports the project at every stage. Our Trench CPD is CIBSE approved and can be booked for your practice.
Site surveys
SPC can visit site to review trench positions, dimensions and layout before order.
Selection and layout
Send us your drawings and design conditions and SPC will select unit widths and lengths.
Trench CPD
Our CIBSE approved CPD, Design Considerations for Trench Heating, can be delivered to your practice.
Area Sales Managers
Your local SPC Area Sales Manager is on hand for questions, site visits and installation queries.
- Ready for site: each unit is labelled with its serial number, model reference and site reference, and arrives with a protective cover to keep in place until the grilles are fitted.
- Installation, operation and maintenance: IOM 78, the Metropolitan Powered Trench Heaters manual covering installation, commissioning, maintenance and fault finding, is supplied with every unit.
Specifying Metropolitan Powered Trench Heaters
Unit selection from SPC and a free BIM object for your model.
Get a unit selection
Send us your drawings and design conditions and SPC will select Metropolitan Powered Trench Heater widths and lengths for your project.
Download BIM objects
Add Metropolitan Powered Trench Heaters to your BIM model. The BIM object is free to download from SPC on bimstore, alongside the rest of the SPC range.
SPC trench heating in UK projects
SPC trench heating has been installed beneath full height glazing in buildings across the UK, including offices, schools, libraries, museums, hotels, restaurants and visitor centres. Metropolitan Powered Trench Heaters were chosen for 8 Salisbury Square in London, 42 Park End Street in Oxford and the Museum of Two Halves in Wrexham, and other SPC trench heating projects include Hanley Library in Stoke-on-Trent, 244-254 Cambridge Heath Road in London, The Grand York Hotel, The Orangery at Aynho Park, Berkhamsted Sixth Form, Archway Tower in London and the Midlands Goods Shed at King’s Cross. See SPC’s projects.
Metropolitan Powered Trench Heater specification summary
| Detail | Spec |
|---|---|
| Type | Fan-assisted (powered) LTHW trench heater with EC/DC fans |
| Widths | 180, 225, 260 or 300 mm (width at feet 230, 275, 310 or 350 mm) |
| Height | 110 mm |
| Lengths | 22 standard lengths from 1,100 to 3,200 mm in 100 mm steps; longer runs joined with flangeless end plates |
| Heat output | 470 to 3,551 W per unit at 80/60°C water, 20°C room air (ΔT 50°C) and medium fan speed, depending on width and length; outputs are published for lengths from 1,100 to 3,100 mm |
| Fans | Low-power EC/DC fans; speed set by a 0-10V signal from a BMS or room mounted controller, or by on-board rotary potentiometers |
| Sound | Sound pressure level below 30 dBA at 2 m, at medium fan speed |
| Electrical | 230 V AC supply to each unit, with a BMS connection point |
| Heat exchanger | Copper tubes expanded into aluminium fins, in galvanised sheet steel tubeplates, with a vent plug; pressure tested to 22 barg, air under water |
| Water connections | 15 mm plain copper, front or side entry |
| Casing | Minimum 1.2 mm mild steel, black powder coat, with knock-outs for pipework and cables, levelling screws at all four corners, adjustable support feet, transverse bracing and a protective cover |
| Grilles | Anodised aluminium roll-up grille with stainless steel springs and plastic spacers, 60% free area, with matching trim; stainless steel grilles on request |
| Grille finishes | Satin silver, black and a range of Anolok bronze, gold, umber and blue-grey colours |
| Floors | Screeded (concrete) or suspended floors |
| Controls | Air side by fan speed; optional 2-port valves and actuators, wall mounted room thermostats including SPC Modulo, and flexible hoses with integral isolating valves |
| Bespoke options | Bespoke widths, heights and lengths, curved sections and grilles, corner kits with angled sections and mitred corner grilles |
| Testing | Independently tested to BS EN 164301 |
| Manufactured | Leicester, UK, by S & P Coil Products Limited (ISO 9001:2015) |
1 EN 16430: European performance test standard for trench convectors and fan assisted convectors.
Full heat output and water pressure drop data for every width and length is in the Metropolitan Trench Heating and Cooling brochure.
Discuss your trench heating project
Send us your layout for a Metropolitan Powered Trench Heater selection for your office, reception, hotel, restaurant or public building, request a site survey or book the Trench CPD. Call +44 (0)116 249 0044, email spc@spc-hvac.co.uk or use the form below.
Frequently Asked Questions
Natural trench heaters, such as Metropolitan Natural Trench Heaters, have no fans: air moves through the heat exchanger by natural convection alone. Fan-assisted (powered) trench heaters, such as Metropolitan Powered Trench Heaters, are trench heaters with fans that move room air across the heat exchanger. SPC makes both types, as well as Metropolitan HC trench heating and cooling, and can advise which suits your project.
Yes. LTHW (low temperature hot water) and LPHW (low pressure hot water) both describe the wet heating systems Metropolitan Powered Trench Heaters connect to. SPC’s trench literature uses LPHW, and publishes Metropolitan Powered outputs at 80/60°C water, 20°C room air and medium fan speed.
Each unit needs a 230 V AC supply, and an on-board power supply runs the EC/DC fans. Every unit needs its own supply, even where several units follow one thermostat, and each unit must be earthed. If the unit is set in a screeded floor, the power and control cables must be brought into the casing before the screed is laid.
Yes. Fan speed is set by a 0-10V signal, which can come from the building management system (BMS) or a room mounted controller, and each unit has a BMS connection point. Alternatively, fan speed can be set by hand with the on-board rotary potentiometers. Water side valves can be added, though control by fan speed is recommended.
Metropolitan Powered Trench Heater roll-up grilles are suitable for occasional foot traffic. They should not take point loads such as chair legs, and trench heaters should not be fitted directly in front of doorways or in areas of constant footfall, where there is a risk of damage and debris from footwear.
Install Metropolitan Powered Trench Heaters close to the window or wall they protect, with the heat exchanger on the window side and the flow and return pipework on the left hand side when looking from inside to outside. IOM 78 gives the recommended distances from the glazing and the clearances needed around the casing in a screeded floor.
Clean the heat exchanger with a vacuum cleaner or compressed air, more often in dusty areas. Clean the fans and fan housings with air or a dry cloth only, never water or spray, as the motors contain electronic parts. The casing and grille can be cleaned with a dry or damp cloth and mild detergent, keeping moisture away from the electrical section. The fans have sealed for life bearings, and the heating water should be treated with an inhibitor that is compatible with copper. Full guidance is in IOM 78.
Yes. A Metropolitan Powered Trench Heater BIM object is free to download from SPC on bimstore. Dimensional drawings for every width are in the brochure.
