@elton, @kenbone has a lot of Samsung ASHP experience and knowledge. Maybe he can cast some light.

Hi, Bit of an update. I bought a decibel meter and monitored the sound for an evening. It was one of the warm days so I put the thermostat to 22 as room was at 20.5 anyway. At 19.40 temp was 20.5, and at 22.17 it had got to 21.6 - external temp was not much less than 20 so that seems a bit lame to me anyway. Samsung 8k is rated at 48db. During that period of 2.5 hours I measured the noise with the meter 1 metre from front and 1 metre from side. Front reading varied from 49 to 56, and side from 46 to 50 ( although I perceive sound from side angle to be worse). It did go down suddenly to 37 dB just before I turned the thermostat down and went to bed. That was noticeably quieter but unfortunately I could still hear it from inside, whining and speeding up and down so i think the heat pump is just in a stupid place. Next morning it did a DHW cycle and measured 49db 1 metre from side and 54 dB at the front. 

I think the majority of the downstairs noise is the pump noise coming in through the window and patio doors (dg and closed). Upstairs I think vibration in the pipes is being amplified as they go through stud in bathroom and carrying. Also think the tank is making a noise during DHW cycle.

Installers have now decided I need to get a gravel tray installed for them to put the unit on (why they didn't say before is a mystery) before they come back and finalise position of pump, go through my queries, and register it with Samsung.

So, any thoughts on those decibel readings? If you move the heat pump away from the house, what are the disadvantages and limits for pipe runs of flow and return?

@lokisam  Hi, Yes.

First thought - sound meter. Did you buy a class 1 or 2 sound meter? I bought a meter (data logger) off ebay for £50 and found it didn't match one on my iphone. I was a bit suspicious and wanted proper recordings so I shelled out £200 on a class 2 one. Env Health use class 1 but I couldn't afford that. Turns out, using my class 2 one, my iphone app "decibel meter" was far more accurate than the £50 ebay one. Its good as it has a data logger so does it over time.

Second thought - known issues with declared noise levels. There is some debate about sound power level measurements and whether they are actually properly represented by manufacturers. See DESNZ report page 13:

So in essence the 63dB(A) sound pressure/SPL figure may be untrue - and under-reported.

I'm not sure if this feeds into the declared sound pressure levels (SWL) or whether SWL is tested independently but, unless you have  reflective surfaces, the heat pump is faulty, the dB(A) meter is inaccurate or the assessors have botched the assessment, the declared SWL should pretty much be reasonably accurate. You probably need to work through the issues above to discount them until you are down to one.

@editor @kenbone 

Thanks, I would be very interested to hear if you have any thoughts on the Gen 6 noise levels and qualities please Ken or whether noise levels & properties are pretty much the same as any eg Vaillant, Veissmann, Mitsubishi?

@lokisam, with the 20C outside air temperature I would think that the ASHP would not be working too hard so it is concerning that your readings are still above the rated figures. My pump is only doing DHW runs at the moment with air temperatures between 17C and 23C and it is certainly a lot quieter than during the colder months.

@elton that's interesting about your iphone app being more accurate than the ebay sound meter. I had discounted using a phone app as a sound meter as I had no way of calibrating it and also I didn't think the microphone would be suitable. I have had poor results trying to record the ASHP noise with a phone so assumed that the microphone might be tuned for a speaking voice and couldn't resolve the full range of frequencies in the noise and the tonality you mentioned previously. Thinking about it now, the problems with recording might have been to do with the recorder app's compression rather than the microphone and I should try again with lossless raw PCM 🤔 

@sjn yes, when they come back I want to check if they have it on weather dependent. I read that decibel apps work well on iPhone because mic is at a set level, but can be variable on android. I put two apps on my android and they gave massively different readings so I bought a cheap meter off amazon, supposedly accurate to +_ 2db.