BSRIA's Librarian Stephen Loyd shares the answers to the more frequent technical enquiries from BSRIA Members.
Electrical system inspection rates
How frequently should electrical installations be inspected and tested in non-domestic buildings?
There is a table in IEE Guidance Note 3 Inspection and testing that gives recommended frequencies of inspection.
Routine checks should be made annually and are basically visual, looking for damage, deterioration, signs of overheating, missing parts, adequate labelling, and operation of switches, and test buttons on residual current devices.
The maximum period between inspections and testing is three or five years depending on building type. Recommended tests are listed in Guidance Note 3, and should be carried out by a competent person.
Refrigerant leaks and boiler air
What guidance exists on the separation of DX condensing units charged with R407c refrigerant and an adjacent gas-fired atmospheric boiler plant?
The concern in this case are the DX condensing units located in a lightwell, from which the combustion air for the boilers is being drawn. If a refrigerant gas leak occurs, then the gas could be sucked through the grille and burnt.
There does not appear to be any categorical guidance on this issue, other than the over-arching risk assessment under the Construction Design and Management (CDM) Regulations.
R407c is an entirely safe, non-toxic and non-combustible refrigerant. However, care must be taken to ensure that the units are in an area sufficiently large enough to avoid an excessive concentration of refrigerant in the unlikely event of a serious leak in the system.
This means the maximum concentration of refrigerant that can be dealt with quickly and without damage to the person. The maximum recommended system charge for R407c is 0.31 kg/m3 of room volume.
Magnetic water softeners
Do magnetic water softeners work on pipework systems?
The answer is sometimes, depending on the water chemistry.
There are two sorts of magnetic device, one using permanent magnets and the other using electromagnetic fields. Magnetic water softening devices don't soften the water as such but encourage the precipitation of scale as particles rather than as an impermeable layer on heat transfer surfaces.