ASHP noise assessment

This is off topic but here goes:

I’m sure that many “energy efficient” systems are designed that way but that should be the extreme exception, not the rule. My system normally ranges from 24°C to 28°C. On a particularly cold morning it might exceed 30°C. My home it not super insulated and I didn’t change any radiators.

I wouldn’t bother trying to find any other value for heat input requirement if you have a PHPP calculation but unfortunately PHPP is not approved for any government work or grants. I was lucky to find an installer that accepted my figures. It saved them the hassle of doing it themselves.

So just a quick update on this (ASHP nose assessment) job in Manchester. In the end the noise from the ASHP was a little over (non-compliant with) the MCC planning and noise criteria for night-time but compliant with the daytime value. We submitted a report stating these levels and the council deemed that this was “satisfactory” for the purposes of discharging their planning condition relating to noise. A good result for the project but we are still unsure what a consistent set of noise criteria might be.

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My (limited) understanding of this is that a system designed at 40C will only operate at that temperature at -5C, the rest of the year it’ll run at much lower temperatures as you describe.

There’s nothing to prevent you from designing a system to lower than 40C, but it may mean changing more radiators for larger ones. The more HPs we install, the more real world data we get in the UK climate, the better and more accurate our heat loss calculations can become :slight_smile:

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It’s like the EPC assessments. Assumptions of temperature and occupancy are made based on a restricted set of data. The accuracy and variance in results depends greatly on the assumptions made by the assessor.

I don’t know how I managed to get my figures accepted but they reduced our heat pump size considerably, however in the event of an ice age we will be needing supplementary heating, or more insulation.

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I’m working on heat pump size but it has been sidelined by planning permission and even a smaller heat pump would not have got me over the line.
However I have today had a minor breakthrough having proposed the following (again) I’ve had a tentative go ahead for this approach:

  1. Withdraw planning application.
  2. Install fence to top of wall to obstruct the view of the neighbours window.
  3. Commission new MCS 020 report.
  4. Install ASHP under permitted planning having passed MCS 020.

The fence would have to be more than 1m from the ASHP (it will be) otherwise it would be deemed a reflective surface. Look like I may get to proceed after all with zero help or thanks to Manchester Planning Department.


Whether it is deemed a reflective surface would depend on the orientation? Are you saying that the neighbouring property would be able to “see” the reflective side of the fence? If that were the case then it would also be able to see the ASHP anyway?
I guess what would be more relevant would be the arbitrary 1m (from stie boundary) rule. The latter is something that the government may revoke anyway (I think this is going through consultation).

I must admit the ‘reflective’ part did confuse me a little. The fence (I’m guessing about 600mm high on top of existing wall) would be at 90 degrees to the heat pump and create a visual barrier. Any reflective noise would be back at our property. It would be over 1m from the front of the heat pump. All seems a bit odd to me, the nearest neighbours window (and subject to all this debate is at 90 degrees to the wall and heat pump so wouldn’t see the heat pump anyway, although I appreciate this is about noise not visual pollution.

Yes so the barrier would potential affect the Q (of the ASHP as a noise source) in the MCS noise calc but not constitute a reflector that would direct the sound towards the receiver.

For me the Q factor will be the same (the fence will not add a reflective surface within 1m) but the fence would allow for a correction under ‘Note 5’.
I’ll have to go over my MCS again to check but I’m sure I was within a few of Db of a pass so this would work. I may make the fence higher to be sure to get a -10Db attenuation:

Note 5: Barriers between the heat pump and the assessment position (STEP 5)

A correction will be necessary if an installer is unable to see an assessment position from the top edge of the air source heat pump.

Use the following instructions to determine whether a correction is appropriate:

For a solid barrier (e.g. a brick wall or a fence) that completely obscures an installer’s vision of an assessment position from the top edge of the air source heat pump attenuation of -10 dB may be assumed;

Where a solid barrier completely obscures an installer’s vision of an assessment position from the top or side edges of the air source heat pump, but moving a maximum distance of 25cm in any direction to the air source heat pump allows an assessment position to be seen, attenuation of -5 dB may be assumed;