General
The specialist underfloor heating company should carry out the design, supply, manufacture, installation and commissioning of the underflooor heating system.
The underfloor heating contractor should be a member of the Underfloor Heating Manufacturers Association (UHMA).
The underfloor heating contractor should provide relevant insurances including Employers liability, Public liability, Product liability, design indemnity and PI Insurances. In addition the contractor shall have a full Health & Safety Policy and relevant skill cards to evidence company competence at all levels.
The underfloor heating contractor should provide examples of specific projects and installations to demonstrate relevance of overall management strategy of this specialist discipline appropriate to the project being undertaken.
The examples should include fully substantiated design information. References of previous projects should be submitted to demonstrate a track record of a minimum of ten years.
The underfloor heating contractor should submit a copy of their Environmental Policy which will include evidence to substantiate all statements made.
The underfloor heating pipework to be used should fully support the “Environmental & Performance Characteristics of Polybutylene Pipe” document (cf pdf file).
Pipework
The underfloor heating pipework should be 20mm polybutylene tube. The polybutylene tube (PB) should be a five layer co-extrusion with an integral oxygen barrier. The barrier is to prevent oxygen ingress into the system and should therefore be fully protected against site damage by being sandwiched between the inner and outer layers of polybutylene during the manufacturing process. The pipework should be covered by a 50 year guarantee, be fully recyclable and conform to the environmental policy submitted.
Joints
Joints in the slab or screed or in any underfloor heating installation should not be not permitted. The underfloor heationg circuits must be installed in one continuous length without any joints. In the event of accidental damage to the polybutylene pipewrok post installation then the pipework should be repaired using specialist repair couplings. Only fusion weld couplers manufactured in polybutylene should be permitted. The fusion weld joints should be made using specialist fusion welding machinery. No other form of repair should be permitted as the future system integrity and performance may be compromised.
Insulation
The insulation should be a “Tacker” insulation panel with a patterned, laminated fabric polythene re-enforcing foil. The foil should be water resistant and should be provided with overlaps on two sides in order to cover the adjacent panel. Each Tacker floor panel should be taped and sealed on all sides to accept the liquid screed.
The Mechanical Services Sub-Contractor should be responsible for the co-ordination between the underfloor heating specialist and the principal contractor to ensure that floor insulation levels are maintained and that the underfloor system is not left unprotected after laying.
Due to the recent changes in legislation the insulation specified by the underfloor heating contractor may not meet the current building regulations and should be checked with the architect for conformity, for both thermal properties and point loading characteristics.
Coils
The underfloor heating coils should be designed specifically to meet the heat losses required. The length of the coils will be determined by the room size and the outputs. No jointing should occur in the running length.
The heating coils should be 20mm PB pipework , spaced 200 – 300mm centres throughout and installed in a “Reverse Return Pattern”. The coils should be fixed to the insulation panel by way of a Tacker gun, which secures the pipework with staples to prevent lifting within the screeding process. The pipework should terminate at the appropriate wall mounted manifold locations.
Manifolds
The manifolds should be provided complete with isolating and regulating valves, temperature and pressure gauges, air vents, drain cocks, wall brackets with rubber isolating inserts and flow indicators. The Mechanical Services Sub-Contractor should include Unistrut support frames and the supply and fixing of same. This should all be co-ordinated with the underfloor heating floor specialist.
Controls
The underfloor heating actuators should be supplied by the underfloor heating manufacturer. However all the electrical wiring should be provided by the control specialist. Tamperproof or adjustable room thermostats should be supplied by the control specialist for connection to the manifold circuit actuators.
The control strategy should allow for each individual room to be controlled separately by way of manifold circuit actuators and room thermostats.
Pressure Testing
Upon completion, the system must be filled with water and pressure tested to a minimum of 1.5x the anticipated working system pressure. The system should be left under pressure test until the screeding process is completed.
Ecoscreed over Underfloor heating
click image to enlarge
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