• What are the requirements for a loft installation?
• Can I fill a system with softened water?
• Why is system flushing important?
• Do I need to fit a bypass?
• Can I fit a new boiler onto an existing "one pipe system"?
What are the requirements for a loft installation?
Boiler installations in roof spaces should comply with the following additional requirements:-

•	Enough vertical clearance should be provided to satisfy the static head requirements for an open vented system
•	Fixed flooring should be provided under and around the boiler for servicing, also from the entry point in the loft
•	A permanent means of access to the roof space should be provided e.g fixed, retractable loft ladder
•	Fixed lighting should be provided
•	A guard should be provided to prevent contact between stored articles and the appliance
•	The exit from the roof space should be provided with a guard rail to prevent anyone falling
•	Isolation of gas, water and electricity should be possible without entering the roof space

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Can I fill a system with softened water?
Water supplied via a water softener should not be used to fill any central heating system unless a corrosion inhibitor specifically formulated for the purpose has been added.

Because the chemical composition of softened water is very variable, we recommend that filling a system with it should be avoided by turning off the softener whilst the system is filled, if possible.

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Why is system flushing important?
Flushing of a central heating system in accordance with BS 7593 is carried out to remove contaminants such as flux residues, grease, jointing compounds, oxides produced by the corrosion process, bacteria and in hard water areas limescale.

If they are not removed, these contaminants form a harmful sludge in the system which reduces the efficiency of the system, causes noise and could potentially reduce the useful life of the appliance.

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Do I need to fit a bypass?
On open vented models, a bypass circuit, 3m long and incorporating an automatic bypass valve will be required.

On combi and sealed system models that are supplied with an integral bypass, an external automatic system bypass may still be required if there is any doubt that the minimum flow rate as specified in the installation instructions will be maintained at all times.

The above requirements are in line with CheSS best practice.

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Can I fit a new boiler onto an existing "one pipe system"?
A 'one pipe system' is not suitable for installation with Glow-worm HE boilers. The design of such systems makes them difficult to balance and generally had old fashioned 'gravity' hot water. Discuss your installation with your installer and upgrade to a modern and efficient 'two pipe system'.

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