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.
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
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.
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:
Withdraw planning application.
Install fence to top of wall to obstruct the view of the neighbours window.
Commission new MCS 020 report.
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;
Thanks. This is the same as I worked out and indeed Octopus have agreed so the install is now going ahead under permitted development!
Just have to spend time working out once again the heat loss as I’m still convinced they have specified an ASHP far too big (16Kw).
Don’t worry about the heat pump being too big. It will stand you in good stead in the next ice age.
Generally heat pumps can modulate down to about 30% of their rating. For less output it will start cycling with is wasteful on energy and adds wear and tear. Autumn and spring will be your difficult periods.
Hi @Jonathan_Keenan, I’ve just found this thread as i’m approaching getting a heat pump.
I’m in a mid-terrace and having trouble siting the unit. I’ll likely be <1m away from the boundary but may be able to meet the MCS 42dB limit. In your correspondence with Manchester planning, did they say anything about being absolutely outside of this 1m requirement?
Hi @Samuel_Seabrooke
We are just 50% into the instal this week! So a little too early to say other than I’ve been happy with the Octopus installer and any issues have been of the sort that any expanding company like them would have; things like unannounced pre-deliveries and someone turning up to cap off gas when it had already been done. Nothing bad just the result of the complications in pulling together a complicated project.
My main concern has been the usefulness and accuracy of the initial survey. I feel that too many assumptions on air/heat loss are made and too much trust subsequently placed on their report. I may just be suffering from having just enough knowledge to question things but not enough to argue the case or know if I’m right. Time will tell. I ran out of time to get an air loss survey done as they ended up booking in the install very quickly once we bottomed out the planning issues.
Regarding them; I’m no expert and have been keen to forget as much as possible as planning is always a frustrating nightmare but my main advice would be to get within permitted planning requirements at all cost. Octopus did seriously let me down by recommending getting planning permission (which tbf should have been easy but turned out to be an expensive waste of time).
My understanding is that for permitted development " All parts of the air source heat pump must be at least one metre from the property boundary". As ours is above that it wasn’t a topic of conversation with them. If you could manage >1m all you’d need is to pass the ‘MCS020’ test which is about noise levels to your nearest neighbours window. Is it possible to wall mount an ASHP somewhere so it is outside of 1m from your boundary? If not there may still be hope for you if the distance from the nearest neighbours habitable room window or door is far enough away to pass the MCS020. I assume you will be requiring a smaller ASHP than the giant we have and therefore quieter one. You’ll need the specs for whatever pump unit your installer is proposing to use. Once you know that doing your own MCS020 is pretty easy so you could do some of the early assessment work yourself.
Hope this helps a little (but suspect not much).
Best of luck!
Kitchens, utility rooms, bathrooms, toilets, hallways, landings, corridors and lean to sheds are not habitable rooms. Living rooms, dining rooms and bedrooms are.
I believe that it has to be the nearest openable window of a habitable room in line of sight.
Edit: standing next to my heat pump I can’t hear it. The rules are very out of date.
Odd then that the rule applied in my case despite the fact the neighbouring building isn’t even completed or occupied so the position of the ‘assessment position’ (their window) is just a guess as to what lay behind it.
Surely if a heat pump is very quiet it would have no problem passing MSC020? Although I guess the 1m rule is the issue that’s been rendered out of date by tech improvements.
As probably noted elsewhere in the forum, the planning restriction that heat pumps need to be one metre from a neighbour’s property has been lifted, it seems.https://www.bbc.co.uk/news/articles/c3e5plqke3no
