hi
we are currantly transforming an old wooden bungalow into two storey chalet that is sufficently insulated to meet building reg standrds. It will have 4 bedrooms and one large living area.
We are keen on ASHP but worry the noise will upset the neighbours.(next door is 3ms away) I have read the ASHP produces around 49db but how long each day will the ASHP be on ? The system we are planning will also have solar and a wood burner feeding into the hot water tank so the ASHP will not be needed all year round. The wood burner will not be lit every day in the winter more when we have the time or inclination!

Thanks allot

Alex

How long depends on your buildings thermal response time/levels of insulation and the temperature difference between inside and outside. Look up Degree Days for your area.

The Decibel scale is logarithmic (base 10 I think).

Is sound (in still air) inversely proportional to the square of the distance, so you have to know the distance that they measured the ASHP.
Also when it comes on is important. During the night it may get a bit annoying but during the day it may be fine. Regular maintenance my also help as this may stop some small rattles developing into a terrible racket, like my old washing machine, upset the neighbours no end.

Oftec provide advice on noise level from oil boiler flues. It includes advice on working out how close a window can be. You need to know the noise level produced by the boiler/flue at 1 meter.

http://www.oftec.org/documents/Noise_emissions.pdf

For example: If it produces 55db (measured at 1 meter) and the noise contains "tones" then you add 5db to make 60db and look up the distance on chart 1 to give a minimium distance of 3.5 meters.

Noise is very subjective. For example white noise might be more acceptable than one with several tones in that beat horribly even though the loudness is the same.

I get the impression from the distance the neighbour is away that it's going to be basically just across a drive / double path between the 2 houses, with the ASHP on the OP's wall facing directly at the neighbours house. In this situation the noise will basically bounce off the walls of the 2 houses and be really annoyingly loud in any rooms on either house that have windows opening onto the drive/passageway.

the passageway could also act to essentially direct sound outwards in the direct of either end of the passageway in a relatively directional manner, so neighbours to the front or rear could also be affected more than you'd think from the diagrams supplied by the manufacturers, particularly if they had their bedroom in the line of fire.

Having had my bedroom in my first year at uni about 10 meters across an alleyway from an air conditioning unit, I can fairly confidently say that your neighbours are going to hate you if you install this in this setting.

Well, roughly, you'll lose about 6dB every time you double the distance from the source - but you need to add on say 3dB at the receiver end for refection

That's simplistic of course, and a window will have a reasonable insertion loss.

Pick a unit that's say 50dB at 1m, then you should be OK

Be aware however that the noise can be quire tonal - and persistent - so they are very easily heard of an evening

As a quick test, get your neighbour to start up the car outside the garage and leave it ticking over - how does it sound from your gaff

You can put fencing elements around the HP condenser to "extend" the noise path as a reasonably simple fix

Regards

Barney

Noise is very subjective, we found our ashp quite noisy to start with but quickly got used to it. It was our own noise so we were probably more tolerant of it than if someone else was making it. Some of our family are light sleepers so noticed it more than the deaf/snoring people did...

The outdoor units of ashps are very similar to the air conditioning systems they are derived from. If you look round the back of many office/retail/hotel/restaurant units, there will be a unit very similar to the one you are considering. Stand appropriately far from it and see how you feel about it.

If the ASHP is sized to exactly match your daily heating needs, then it will have to run all of the day/night. Chances are it will be oversized, espc on mild days, so you can run it at more acceptable times, or run it at a lower rate at night, many of them have this function available.

Or, try and convince your neighbour to go down the same route

I guess it depends what type of unit and what you want it to do, e.g. heating, cooling, water heating only, A2A or A2W each may impact differently regarding running time etc.

My Toshiba R32 ducted heating unit has a sound pressure on start up of 48dB; lower as the indoor unit modulates and senses room temp up to the required setting. Nuisance noise is all a bit subjective, can you somehow mitigate with shrubbery planting?