ASHP noise assessment

Our ASHP installation prospects have ground to a halt as planning have requested noise assessments. These would be before and after, and presumably again once any mitigating recommendations were put in place. This would add up to almost as much cost as the ASHP installation itself! I’m looking into ways to bring the installation within permitted development but the can of worms is now opened… Anyone any access to any gear that would allow diy assessment that would be acceptable to planning?

This looks like an antiquated requirement. Modern heat pumps are really quiet. Yesterday I was in my garden and thought the pump was off until I walked past it and felt the cold air blowing from it.
Won’t the council accept noise level figures published for the planned unit?

If you do end up needing an assessment then avoid really cold days as the unit makes more noise the harder it works.

Unfortunately the manufacturers spec for the unit the installers want to use put it at the borderline for requiring planning permission which the installers told me to do and Manchester Planning have decided they want noise assessment both before and after, then a 3rd one if any mitigation works are done. This could be as much as £1k per assessment which is enough to kill the project altogether.

If you proceed as you outline you run the risk of having to rip it all out again, at even more cost, if the tests fail. And you wouldn’t get your BUS grant, so all the expense would fall to you.

You are certainly in an untenable position. I would go back to the installer and tell them you want another model (or another installer). There are loads of heat pumps from varying manufacturers with overlapping capacity. If you have plans to continue improving your fabric then try aiming for a slightly smaller machine. Generally smaller corresponds to quieter. In a manner of speaking you have up to £3000 available to find a quieter HP or you could find one for £3000 less to cover the cost of testing. Unfortunately cheaper are often noisier, so that one may not be workable either.

Have you checked the installer’s heat loss calculations? I know of one person that had a heat loss presented to them that exceeded their entire electric and gas usage for the year. Common sense says NO.

Thanks. What you say is roughly what I have concluded but summed up neatly so I can make decisions.
I do need to check through the calculations and have my suspicions that a couple of important measurements were also wrong (distance too neighbour window for example). I assume that the fact the neighbours window is in a building that has never been inhabited and ‘under construction’ for well over 10 years is irrelevant?
I’m pretty sure the specified Daikin EDLA16DA3V3 is over spec for us so spending time on checking the calcs may be time well spent. This is an Octopus Energy install which has mixed reviews however the quote is VERY competitive to the point it would be worth getting a smaller unit (or paying a bit more for alternative) and potentially replacing the unit in the future if it doesn’t work out (not a great plan). I do however suspect that Octopus have been cheap because they have secured good prices on a limited selection of ASHP units and would walk away from anything that complicates the install or is perceived to put them at risk of liability for a poor specification and install. Seems I have a weekend of wandering about with a tape measure ahead of me.

Is it a habitable room? Kitchens, utility rooms, bathrooms, wet rooms, store rooms, garages and more don’t count.

That’s huge. I take it you live in a tent, or maybe your windows aren’t glazed.

Octopus seem to quote for a direct boiler replacement. This covers them for less informed users running them at high temperature for short periods and then complaining about the cold and running costs. My heat pump is ¼ the rated output of my boiler and perfectly adequate. That also means that I could probably have had a much smaller boiler but no one seems to think of that.

The neighbours room is most likely intended to be a bedroom although it is a shell having never been finished. It is a conversion of an old stables attached to the bigger house and has progressed very little over the last 10-15 years. Windows went in about 5 years ago and almost nothing done since. It has certainly not passed any final building control or planning permissions.
I did also think this was a huge ASHP which is why I started looking into doing my own calculations. We have a fairly small combi boiler and never struggle to heat the house even though it was installed long before an extension that effectively added 2 double bedrooms. Our boiler is now faulty and overdue replacement but I really don’t want to invest in a new gas boiler, especially when the Octopus quote bring the cost to near what a new boiler installation would be.
You reflect what I have been thinking about Octopus. I’m glad they have put a lot of effort and funding into to rolling out a heat pump program and was happy with the approach the engineers that came took but do worry that at extremes of house size they may just be tending towards the old gas boiler installer trick of just over specifying to cover themselves as you say. My hope is they will be open to a suggestion to downsize should my calcs work out that way. I don’t want them to walk away at this point.

Octopus rejected my house at the application stage as too difficult. This seems to be their standard reason for rejection if you believe the appropriate thread on the Octopus forum. In “difficult” they seem to include “tedious”. My house has different wall structures and is not a quadrilateral.
Back in 2017 I had an assessment for a NIBE heat pump but couldn’t afford the recommendation, however I did get a valuable lesson in energy efficiency which I used to supplement my ongoing fabric efficiency work. It also meant that I wouldn’t accept any future survey that matched or exceeded the NIBE one.

When I restarted my quest for a heat pump four years later I did indeed have surveys that said my enhancements (mainly airtightening) had increased my energy requirements by 50%. Those suppliers were promptly dumped.

I chose Daikin because they were recommended by Ethical Consumer Magazine and before I knew what they offered, other than ethics, I contacted their sales office who put me in touch with a supplier. When they sent round a surveyor I told them what my heat loss was (rounded down) and persuaded them to agree. I then needed to choose between air to air or air to water. The price after BUS on the wet system was almost identical.

Thanks for the info Tim. I’m now about half way through surveying using www.heatpunk.co.uk to see what numbers come out. I’ll also have a go at the ‘rule of thumb’. Then it’s back to Octopus with my fingers crossed I guess.
I also got a ‘No’ from them a year or so ago. I think they (understandably) were going for the low hanging fruit of quick and easy installs when they first started. I seem to have eventually made it up the list once they had built up the teams and they got back to me. I’m now very much in danger of falling in to the ‘tedious’ category but will hope they have enough sunken costs by now to stick with it. We’ll see.

As an aside, you will need to fine tune your new system to perfection to make a significant monetary saving, due to the price differential between electricity and gas. Making an energy/GHG saving is very much easier.

Do you have access to a low cost electricity tariff? Octopus do have a tariff that claims to be for heat pump owners but I disagree. It is more suitable for an electric boiler or direct electric heating. A heat pump needs to be on (but not necessarily running) practically the whole winter, day and night, with small temperature offsets as required.

With this and a soon to be delivered EV I bought into Ripple Energy’s last scheme which was a solar farm so will get some discounted electricity back through that. If we can afford to I will invest in their next project as well. I think we have a notional 45 percent of our annual electricity use covered but that was pre EV and pre ASHP. The EV is not going to be high mileage but still a significant factor. If Vehicle to Grid becomes an actual practical thing then who knows what possible savings could be made…?
I am anticipating changing our Octopus tariff so will need to work out what is best for a house with an EV now and possible ASHP in the future. I believe swapping tariffs is fairly easy as long as you fit the criteria. They are coming next week to put in a smart meter with all this in mind.

Hi Jonathan.
I won’t be trying to sell a service here, but my day job is noise assessments and acoustic consultancy at Acoustic Consultants and Noise Assessment Services in Manchester, UK - Azymuth Acoustics UK.
We have done a few noise assessments of (multiple) ASHPs installed as part of area schemes for housing associations following the almost impossible requirements set out by Manchester City Council.
One specific job of this type is coming to a close this week with some final acoustic testing on a sample of ASHPs that are being installed on a new housing scheme. This will be an interesting exercise because it will test how the (city council) noise criteria work (or don’t work) in practice. In theory the ASHPs will NOT comply with the criteria and we together with the city council will be forced to determine how to interpret such “non compliances”. The key here will determining whether the assessment is for the very closest point at the receptor location(s) and whether the ASHPs need to tested at full rated output or a more typical “just ticking along” output level.

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Thanks, that’s very interesting. It would be good to know how that pans out. The council seem to be out of step with future requirements, especially given the phasing out of gas boilers and their own declaration of a climate emergency. No one wants to try to sleep next to someones noisy heat pump but they do seem to have taken a fairly extreme position. I’m looking into getting under the level for permitted development as I think the pump may be over specified and too big. Also the original assessment has inconsistencies in the distance from the neighbours window and in its calculations (it has a measurement of 6m to the window yet uses 5m in the report. I want to re-measure as I think it’s more like 8m). In short, avoiding planning seems the best option.

I agree with the comments about Octopus. They simply want to roll out as many HPs with as few complaints from customers. Swap out the boiler for a similarly sized heat pump then get them on the HP tariff to try and get the running costs down.

Heat loss calculations are interesting, but I am coming to the conclusion that there is no substitute for real world data. We replaced our 20 year old warm air heating system with a gas system boiler. A bit of distress purchase as we had a baby coming in the winter and our house was very cold. Now we are very comfortable and using about 10% less gas than before. The system was designed for a 55 deg C flow temperature and it regularly runs at that, so the engineer did a good job there. Every bit of pipework insulated too. I have estimated our heating demand and it is about a third of what Passivhaus Planning Package predicts!

Octopus’s heat pump tariff is called “Cosy”. The peak and off peak periods correspond roughly with gas demand from a boiler. Clearly if you have a grossly oversized heat pump then you can run it at full pelt during their off peaks and rest it during the peaks. Maybe you would save on running costs compared with a gas boiler but you could do so much better with a suitably sized heat pump with a reasonably priced flat rate tariff.

Edit: For those that can afford it a battery sized for heat pump consumption enables the HP to run all day on overnight cheap rate electricity.

Edit 2: I thought I’d check the description and rates (as per central Manchester).


Hi, I had a similar problem. I had problems from being at least 1m away from the boundary and meeting the noise requirements at the same time. My solution is hopefully to wait until they change the permitted development rules so you can put an ASHP within 1m of the boundary. The consultation on this closes on 9th April and is currently here:

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IMO the biggest problem with waiting is that I can fully imagine the government grant will disappear in the not too distant future.

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On the other hand without prices being skewed by the grant there will be a wider range of options.

Government grants rarely achieve the nett savings one might expect as everyone in the supply chain increases their price to get a slice of the benefit.

I agree to an extent. The EV subsidies were mainly a cash grab by the manufacturers. Prices did go down after the grants ended but that most likely has more to do with economy of scale and big reductions in raw material costs. I agree that this may well apply to ASHP but don’t think prices will fall as much as the current grant for quite some time. I think the grants serve a useful purpose in nudging early adopters and helping create the critical mass required to start to drive down prices. If the timing is right the transition could be seamless but as solar feed-in tariffs showed it is also possible for the transition to go off a cliff and adoption remain low for quite some time until global manufacturing costs and events like Ukraine pick up interest again. The trick will be not to be caught needing to replace a boiler during the trough between grant disappearing and market forces pushing prices down. In short I don’t trust our government to do this well.

I’m a fine one to comment. I got my heat pump with a BUS grant but I don’t think I got anything near full value for it.