MCS have published a revised version of MCS020- the noise standards for heat pumps if they are to qualify for permitted development rights. It seems that this may be in advance to a change in PD rules, so is not yet in force.
In many ways it is better than the previous version and offers greater clarity. However I think it still suffers from a lack of precision, and (IMHO) does not meet the level of precision which would be expected of a document that is effectively part of the body of law. For that reason I would urge those interested in standards and/or precision or who rely on these as installers to read it and comment.
I have made the following comment:
I wish to draw your attention to the following matters which I think may be editorial issues with MCS020(a) as published on your website on 23/4/2025
On page 14 the text reads as follows:
"Barrier (Type 1) – a solid brick/masonry wall or a solid fence that is at least 18mm thick. There should be no cracks or gaps in the barrier. The barrier should extend horizontally by 1m or more from either edge of the heat pump.
Barrier (Type 2) – a solid fence that is less than 18mm thick. There should be no cracks or gaps in the barrier. The barrier should extend horizontally by 1m or more from either edge of the heat pump "
The meaning of 'The barrier should extend horizontally by 1m or more from either edge of the heat pump.' is unclear, and your help desk appears not currently able to offer a definitive interpretation. The meaning of this phrase needs to be unambiguous as it appears that it will become part of the body of the law of the land.
Also on page 14 the formula for calculating the sound pressure at the attenuation position is defined as
Ab is defined in the table on the same page, and in all cases is either negative or zero. The formula thus results in an increase in the calculated sound pressure at the attenuation position when a barrier is present, not a decrease. I refer you also to the example on page 18 which is inconsistent with the calculation and table on page 14.
I trust that you will consider this representation and, if appropriate, upissue the document with the necessary amendments.
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