How to choose a concealed cistern and frame
Concealed cisterns cost from £65 ex VAT for a plastic kit to about £340 on a frame; flush plates are extra. The pan decides the type: frameless behind a floor standing pan, on a frame behind a wall hung pan.
Floor standing or wall hung pan
A floor standing pan, such as a back to wall pan, takes a frameless cistern fitted inside the wall or duct behind it. A wall hung pan needs a frame, which carries the pan and holds the cistern. Send us the pan code and we will check it suits the frame; the pans themselves are in commercial toilets and commercial wall hung toilets.
Full height or low height frame
Full height frames are 1120 to 1150 mm tall and adjust by up to 200 mm, on the KWC DVS and Dolphin sheets. Where the duct is lower, an 820 mm low height frame takes a pneumatic plate only, as the infrared plates do not suit its cistern; for a floor standing pan at a low duct there is a low height frameless cistern; ask us about its plate.
Wall build and fixing
Frames stand in front of a masonry wall and are finished in plasterboard or a light wall, tested to a 400 kg load, on the Dolphin sheets; the installation frames on the KWC DVS sheets are self supporting steel for dry lining, fixed to wall and floor, with pan elbow, hose and bolts included, described as TÜV tested. Both makers line or insulate their frame cisterns against condensation.
Pneumatic or infrared flush plate
Pneumatic cisterns take a pneumatic flush plate, which needs no power: pressing it sends air down a flexible tube to the cistern. Infrared plates flush as the user moves away, so nobody touches them; they are hardwired to a 240 V supply, with no battery option, and work only with the electronic cisterns from the same maker.
Some plates come powder coated in a RAL colour or ceramic coated as well as brushed steel, and the RAL pneumatic plate has a minimum order of 16. For a toilet with no cistern, see flush valves.
Concealed cistern kits
Where budget matters most, the plastic concealed cistern kits cost least, from £65 ex VAT. Each has a 6 litre ABS cistern, a WRAS approved side entry valve, a 1.5 or 2 inch flush pipe and a back to pan connector.
The vertical kit sits on a bracket, set 700 mm high on the KWC DVS instructions; the others fix to the wall. The kits' parts lists include no flush button or valve, so ask us what will flush them.
Accessible toilets
For a wheelchair accessible toilet, choose the barrier free installation frame, about £250 ex VAT, and put the flush plate on the transfer side, as Approved Document M asks. Accessible pans are in disabled toilets.
What the price buys
A frame, cistern and pneumatic plate together start at about £320 ex VAT, and an infrared plate costs more than the cistern it fits. Delivery takes 1 to 3 working days. Call 020 4571 5856 if you are unsure which cistern suits your pan.
Compare the types
The rows are the cistern types by the pan and duct they suit, with the height and wall depth each needs and its flush plate; the plastic kits have no row, as their sheets print none of these.
Concealed cisterns and frames compared, from the makers' data sheets
| Type | Height (mm) | Wall depth (mm) | Flush (litres) | Flush plate | Price from (ex VAT) |
|---|
| Frameless, for floor standing pans | 530 to 745 | 126 to 150 | 6/3 | Pneumatic or infrared | About £190 |
| Cisterns on full height frames | 1120 to 1350 | 126 to 170 | 6/3 or 4/2 | Pneumatic, infrared or controller | About £220 |
| Low height frame cistern | 820 to 1020 | 150 to 170 | 6/3 | Pneumatic | About £280 |
| Barrier free frame and cistern | 1120 | 155 | 4/2 | Pneumatic or controller | About £250 |
Regulations and standards
Three rules apply: the Water Regulations cap the flush volume, EN 14055 and WRAS approval cover the cistern and its inlet valve, and Approved Document M sets where the flush plate goes in an accessible toilet.
In England and Wales, paragraph 25 of Schedule 2 to the Water Supply (Water Fittings) Regulations 1999 limits any single flush to 6 litres, and the lesser flush of a dual flush cistern to two thirds of the greater. The Dolphin cisterns give 6 and 3 litres, adjustable to 4.5 and 3 or lower, and the KWC DVS kits fill to 6 litres. The KWC DVS AquaFix cisterns can be set to 7.5 and 4.5 or 4 and 2 litres: set 4 and 2 for new work, as 7.5 litres is over the limit.
The Dolphin frameless and framed cisterns comply with EN 14055 Class 2 and have a WRAS approved inlet valve to BS 1212-4:2016 and an AUK1 backflow arrangement, on their sheets. The KWC DVS concealed cistern kits come with a WRAS approved side entry valve. The AquaFix installation instructions carry the marking EN 14055-CL1-6/9-NLI-VRI.
Approved Document M Volume 2, which applies to buildings other than dwellings in England, asks for the flush of a toilet used by wheelchair users to be on the open or transfer side, whichever way the room is handed (paragraph 5.10). In its Diagram 18 the front of the pan sits 750 mm from the back wall: the 750 mm Dolphin Doc M wall mounted pan fits the low height frame, or the full height frames with Dolphin's strengthening brackets. The KWC DVS AquaFix frame for accessible toilets is called barrier free on its sheet.
Where they are used
Offices ask what the cisterns use and report, hospitals ask for a flush nobody touches and a cubicle that meets the accessible layout, and public washrooms ask for nothing within reach but the plate.
Offices and workplaces
Where a facilities team tracks water use, the infrared plates can report uses, half and full flushes and estimated water use to an app or building management system, on the Dolphin sheets. For a frame, cistern, plate and pan in one order, the WC sets are in commercial wall hung toilets.
Hospitals and care homes
For touch free toilets, the infrared plates have hygiene flush settings and a cleaning mode that stops the flush while the plate is wiped. For accessible cubicles, the barrier free frame puts the cistern behind a wheelchair accessible pan, and the pans are in disabled toilets.
Public washrooms
A concealed cistern leaves only the flush plate within reach, and a pneumatic plate needs no power. Where the supply can deliver at least 1.2 litres per second at the pan, a pressure flushing valve with no cistern becomes an option: see flush valves.
