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Planning Permission for Air Source Heat Pumps
Hi, my name is Tony and I'm new to this forum, having just discovered the very useful and information Home Farm videos. Whilst I've thought about installing an heat pump for a couple of years, initially a ground source and later an air source I've finally decided to take the plunge as we're renovating our house and now is the perfect time to install underfloor heating and a new heating system (the current one looks like it dates back to 1980's or even earlier).
As I'm installing the Caernarfon 18KW from Global Energy which is the same make and model that has been installed in Home Farm so I'm interested in the following from anyone else who has installed this model
1) How are the noise levels in reality? How far away from the unit do you need to move before you no longer hear the unit? What is the ambient noise level in the location when the unit is not operating?
2) The manufacture quotes efficiencies of 320%+ depending on the surrounding temperature and the required water temperature. I noticed in one article on Home Farm installation the efficiency was much lower at 266%. Is this due to the installation being 20m from the water tanks and hence there's heat loss in the pipes between the two and also energy required to pump the hot water between the ASHP and tanks?
3) Has anyone had experience of the Octopus Energy Agile tariff? This charges you a rate set each 1/2hr tied to wholesale prices and varies between 6p/kWh and 26p/kWh over the course of the day but can be as low as 2p removed link I have signed up for this but after 8 months I'm still waiting for them to arrange a new meter to be installed. Has anyone managed to get a Agile meter installed and if so has it reduced your costs?
Thanks
Tony
I am also waiting for the smart meter install from Octopus and now time frame of when it will be fitted, I actually have solar and battery at moment so would great benefit from having the smart meter install. I wait with hope 🙂 Mars who set the hub up will be able to give you much better detail on the air source heat pump noise levels (which from what ive read previously arent that bad but he has created a wall of wood around it to help offset the sound). he did fully insulate the pipes to ensure that any heat loss was minimised from the location of the heat pump to inside his house. I know it was a major pipe/tubing that the hot water and cold water pipes are connected to and that turn is very well insulated and buried underground for protection.
Welcome to the forums Tony.
First and foremost, since you're going ahead with Global Energy Systems, let's start by saving you some money. You can use this promo code with them GESRFAF000160 and you'll get £200 of your installation. Full disclosure, we'll get some Amazon vouchers.
Noise levels. We don't think that the noise is that bad from the unit, but we've not been able to compare it other ASHPs. While we can hear it on quiet days (when we've gone outside) it's but no means an invasive sound/noise. But that is a subjective opinion. I've touched the pump when it's been on max, and the vibrations are minimal.
If you haven't done so already, you can jump to around 26:30 of this video where we show you the noise next to the machine and from a few metres away:
You can also ask Mike H his opinion who has the same model - I will drop him an email and ask him to comment here. This is Mike's review of the same model: https://renewableheatinghub.co.uk/caernarfon-18kw-review
Where are you going to be positioning your unit Tony?
Our COP, as you have correctly pointed, is 2.7. There are a lot of factors that come into play, but I don't believe that the distance of our pump from the house is one of them. I think it has more to do with the fact that we're running at 45C and that the defrosts impact the performance.
I think, and I can be corrected on this, but COPs are measured at 35C as an industry standard, so they're factoring in well insulated houses. I would rate our insulation as being good, not excellent, so we run our heat pump at 45C, hence the lower COP. I've attached a photo from our unit's plate that shows this.
What's your insulation like Tony?
I still think that the Caernaforn 18kW is a good heat pump. Since you're getting a new model, you'll also be benefitting from a better positioned filter and I believe that the distribution pump is now cited inside the heat pump chassis.
Please let me know if you have any other questions about the pump - I'll be happy to answer them.

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Hi Mars,
I am surprised that you are still running your ASHP with a water flow temperature fixed at 45C, I would have thought that it would be more efficient to allow the temperature of the water to be adjusted to match the heating load.
Did you get your problem of cold radiators resolved?
@derek-m, we're getting our rads sorted in the weeks ahead. There have been a lot of developments - big video update coming up.
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Thanks Mars,
In terms of positioning we're looking to site it behind our front porch as this is the closest point to our basement which is where the tanks will be. Our neighbours have raised noise concerns with the council, hence the questions on the noise levels in reality. Having done some testing with a microwave (that generates roughly the same noise levels) we can can't hear the ASHP in the hallway of our house so I'm not overly concerned. I'd rather not go to the expense of siting the unit away from the house given the pipework seems reasonable expense to buy (£60/m?) and install (our drains run across the line where the pipework would have to be laid).
As the house was built around 1890 our current EPC ratings is F i.e. terrible but we're renovating the property and the projected EPC rating is D, although I think it will be better than this as it doesn't take account of the MVHR unit we are planning to install (more about this below). We will be replacing all our radiators and pipework (which looks to date back to the 1970s) and also install underfloor heating on the ground floor which I believe does not require as higher temperature as radiators so works well with the ASHP?
Have you looked at a MVHR unit? I've installed one in a property we have in the French Alps and they are excellent for removing dust and damp from the property. It also seems to reduce the temperature you need to heat the house to in order for it to feel warm. Obviously they work best in new build houses but as we're replacing our windows and doors as part of the renovation we should be able to seal the house reasonable well. We also have a wood burner which needs to have an external air supply and the flue sealed to prevent airflow up the chimney. So quite a lot of effort to get the property changed to make the most out of a MVHR but in my experience they are great for improving air quality and the comfort level within a property whilst also being green in terms of significantly reducing hear loss within a property,
Thanks
Tony
Does one need planning permission? If the answer is yes then I need to get a move on!
Retrofitted 11.2kw Mitsubishi Ecodan to new radiators commissioned November 2021.
14 x 500w Monocrystalline solar panels.
2 ESS Smile G3 10.1 batteries.
ESS Smile G3 5kw inverter.
@morgan, we didn’t need planning permission. Interested in hearing other people’s experiences and feedback.
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You shouldn't need pp as it will normally fall within permitted development rules. If you'r in a conservation area you need to check if there are any Article 4 directions (these are extra restrictions that override permitted development rules). I know this because we are in a conservation area and had to check. Link below. Remember it's you and not your installer/builder who is responsible for all of this!
https://www.planningportal.co.uk/info/200130/common_projects/27/heat_pumps/2
Retrofitted 11.2kw Mitsubishi Ecodan to new radiators commissioned November 2021.
14 x 500w Monocrystalline solar panels.
2 ESS Smile G3 10.1 batteries.
ESS Smile G3 5kw inverter.
Hi,
You need planning permission for ASHP where the compressor unit is over 0.6m3 which for the Caernarfon 18Kw it is, irrespective of whether you are in a conservation area or not. Check the restriction on the planning portal as there are other restrictions.
I was told by Stafford County Council Planning department I didn't need it as ASHP fall under Permitted development but this isn't correct. Global Energy were very helpful in guiding me here.
I wouldn't underestimate the frustration of the planning process. Not only do the council not seem to know the rules I've have to have numerous conversations with my neighbours about the noise levels.
Before you apply to planning make sure you've got a MCS survey done (which establishes whether the noise levels are within the required standard) and I would advise speaking to any of you neighbours and educate them as to the noise levels.
You also need to provide block and location plans as well as elevations. I was lucky I could re-use these from a recent planning application my architect did for an extension I'm doing. My planning application (which I started 2 months ago) is here (keyVal=QN4S5ZPSK8I00) if you're interested in looking at the level of detail you need to give and the sort of responses I've had from the council and my neighbours.
@chaplito, thanks for explaining the planning permission. Global Energy Systems were meticulous with our paperwork and we were never requested to apply for planning permission. Is this a county regulation?
How close is the pump going to be to your neighbours?
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