66 HPM 0416

HPM-04-APR-2016

Got a story? Ring us on 01732 748041 or e-mail twood@unity-media.com UNDERFLOORHEATING UFH: comfortable, even warmth Underfloor heating (UFH) is an affordable solution for many homeowners and housebuilders and, as Nigel Sanger, technical manager at JG Speedfit, explains, installing a UFH system in a screeded floor is both easy and cost-effective... Underfloor heating (UFH) provides the most comfortable, even warmth of any heating system and the long-term running costs are lower than any radiator-based alternative. UFH matches the preferred room heating profile, which concentrates maximum heat at floor level, a slightly lower heat at head height, with the lowest temperatures at ceiling height. This is the precise opposite to conventional radiator or warm air systems, which see hot air rising wastefully to ceiling level. With UFH, there are no cold spots or hot ceilings. For the installer, UFH allows pipework to be installed, filled and tested in one operation. The system consists of a manifold, which distributes the heating water to each UFH circuit and allows the isolation and flow rate setting of each; a control pack connected to the manifold to regulate the flow temperature and pump water to each circuit; barrier pipe, a pipe fixing system and a heating control system. Maintenance requirements are minimal as there are few moving parts within the system and pressure testing is carried out before installation. A STEP-BY-STEP TO A TROUBLE-FREE INSTALLATION 1. Preparation: With a solid floor, it is essential to ensure sufficient floor depth is available and suitable insulation specified. Insulation depth is determined by design or building regulations which require that any downward heat loss does not exceed ten watts per m² in accordance with BSEN1264. When installing the system, special consideration should be paid to areas of high heat loss which may affect the performance of the system. 2. Preparing the floors: Floor insulation should be fitted to a flat sub-base and joints securely taped over. An expansion strip is required around the perimeter of the room to accommodate the expansion which will occur within the screeded area as the system heats up. BX EN 1264 Part four requires a protective membrane to be placed over the insulation layer to prevent contamination of the insulation by the screed. 3. Choosing the pipe layout: There are several ways to lay pipe, depending on pipe spacing, room layout and fixing method. Serpentine is a simple up and down circuit pattern, especially suited to irregularly shaped rooms or small areas such as kitchens and utilities. Counterflow, or spiral, pattern achieves an even floor temperature with alternating flow and returns, with a typical WWW.HPMMAG.COM pipe spacing of 200mm. Both can be combined to suit the shape of the room and in rooms requiring multiple circuit areas, counterflow and serpentine can be used to good effect. 4. Installing the manifold and pump pack: The manifold consists of two rails, one for the flow and one for the return, complete with ball valves and drain/filling valves. Some manifolds, such as those by JG Speedfit, are supplied complete with pre-fitted brackets and vibration isolation mounts. The manifold is fitted to the wall, allowing enough height to accommodate the insulation and screed depth, pipework and conduit elbows. Pipework is then connected to the manifold and run to the room to be heated. If it passes through other rooms, use conduit to prevent the pipework influencing heat in those rooms. 5. Installing the pipe: Using the screed as a heat diffuser, you can choose between a staple system and a mounting rail for pipe installation. Staples should be attached at approximately 500mm apart and a guage will keep the designed pipe centres even and help the installation process. Mounting rail, especially suitable for large regular shaped areas, provides ready-made pipe spacing and can be fixed to insulation which is too thin for staples. In either case, begin by connecting the pipe to the manifold and start the first circuit 75mm from the perimeter. 6. Filling and testing: Ensure the water is forced around the UFH loops one at a time to prevent short circuiting from one manifold rail to the other. If there is the possibility of freezing conditions, suitable antifreeze should be added to protect the pipework. Once the system has been filled, a hydraulic pressure test should be carried out on all loops in the system. 66 APRIL 2016 HEATING & PLUMBING MONTHLY 7. Applying the screed: The screed should be laid as soon as possible after the pressure test and the system should be left under pressure during screeding. Low thickness pumped screeds are available and work well with UFH. Screed drying times will vary, typically 28 days for a sand/cement screed and UFH systems should never be used to speed up the drying process. 8. Start-up and commissioning: Following the manufacturer’s instructions for start-up, the initial water flow temperature on screeded floors should be maintained at 25°C for three days. On day four, it can be increased gradually in increments of 5°C per day until the maximum design temperature is reached. This must then be maintained for a further four days. enquiry number 144 One Two Four Three Five Seven Six


HPM-04-APR-2016
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