Enclosure or longer piping run for split ASHP system

[Jonshine]

Hi,

 

In the simplest possible form, which will give the most energy-efficient (and lowest-running-cost) outcome for a split ASHP system, and will the difference in efficiency be large or small:

 

Option One: Eight metres of external refrigerant piping plus an enclosure (specified to back static air pressure of no greater than 20 Pascals) around the ASHP (like this one Heat Pump Enclosure - there is a similar grating on the other side, and an 'S' bend between them, with the unit in the middle of the 'S', with the top of the 'S' being the exhaust and the bottom of the 'S' being the intake.)

 

Option Two: Sixteen metres of external refrigerant piping without an enclosure, in a position surrounded by two outbuildings, a fence, and a hedge, with a couple of metres space in front of the fans and on one side, and a few tens of centimetres clearance on the other (meeting and slightly exceeding the manufacturers recommended distances.

 

Thanks!

 

Yours,

 

Jon

[Marvin]

Hi @Jonshine

 

This might need you to do a rough sketch or two, however, the shorter distance between the ASHP and the heat demand the better. Secondly I would insulate any pipwork outside the building thermal envelope as thick as possible.

 

More info would be helpful, like the floor area of the building, the expected peak heat requirement on a cold day, what choices you are considering regarding hot water in summer and winter, will there be PV,  what part of the world the building is in, is it a referb or newbuild, what the thermal emmiters are (radiators or underfloor heating or what), is this your long term home (some people refer to them as homes for life but they are rearly designed that way). What is your calculated heating energy use for a year

 

IMHO let me explain why I think this info is important:  You indicate your desire to have a low-running cost (don't we all!) ASHP system.

 

We run an ASHP system that uses about 30kWh per year per square meter of floor area.

 

This was acheived by intergrating various alternatives and designing our refurbishment to be long term efficent to suit our needs.

 

We had space problems and our ASHP is on the garage flat roof. The external pipework is about 1 meter each way. The pipework to the hot water tank is about 4 meters each way.

 

We cut down the running cost by installing good insulation and good airtightness and the use of an MVHR system. Short term pain, long term gain.

 

You may not have the budget or the inclination for all this, and thats fine.

 

However, as for 1 or 2 ASHPs, what would you gain having only one on? When do you expect to use two? Will you need the heating on all year round or only for 6 months?

Were you thinking of one large and one small to cover the hot water only during the summer?

 

I leave you to cogitate.

 

Good luck

 

Marvin

 

PS. What are the stand by energy uses of the ASHPs. 45 watts per hour standby is how much per year?

 

Oh yes about 400kWh a year..... !!!

 

 

Edited June 8, 2023 by Marvin

[DanDee]

59 minutes ago, Marvin said:

Hi @Jonshine

However, as for 1 or 2 ASHPs, what would you gain having only one on? When do you expect to use two? Will you need the heating on all year round or only for 6 months?

Were you thinking of one large and one small to cover the hot water only during the summer?

 

I leave you to cogitate.

 

Good luck

 

Marvin

 

PS. What are the stand by energy uses of the ASHPs. 45 watts per hour standby is how much per year?

 

Oh yes about 400kWh a year..... !!!

 

 

 

I think he said option 1 or 2(A vs B), there's no mention of option1(A) being a single HP and option 2(B) being 2 HPs

[Marvin]

9 minutes ago, DanDee said:

 

I think he said option 1 or 2(A vs B), there's no mention of option1(A) being a single HP and option 2(B) being 2 HPs

Your quite right apologies. I was thinking of the extra cost of a second ASHP.  M.

Edited June 8, 2023 by Marvin

[JohnMo]

Do you need a split at all? Certainly on option 1, a monobloc could do that service. Saves the complication of refrigeration engineers. For your info I'm running a monobloc about 12m from my UFH manifold and another 8m to the hot water cylinder. Everything runs on the ASHP package circulation pump, except cylinder heating where I have a boost pump in the return line, pulling 33W only when cylinder heating is active.

 

Bigger impact to option 1 or 2 maybe the balance of the rest of the system in house.

[Jonshine]

Hi,

Yes, Dandan is correct, and no worries it was not clearly written! I should be clear, we already have this system, but our immediate neighbours aren't happy with the noise of the exterior unit, and we've decided to move or enclose it (I was a little embarrassed to admit this at first). It is a single ASHP with variable speed/power depending on need, either:

 

Option A: Next to the house, with an enclosure. 

 

or

 

Option B: At the bottom of the garden without an enclosure but with an extra eight metres of external refrigerant (not water) piping.

 

As it happens, Option A and Option B have similar upfront costs for us.

I'm in Britain, in a reasonably mild part of it. Hot water is via a tank at 50-degrees-centigrade (boosted to 65-degrees once-a-week using an immersion heater to kill bacteria), central heating is through radiators running at about 37-degrees-centigrade, both using a heat exchanger unit in the loft that moves heat from the refrigerant into the water. There's about eight metres of external refrigerant piping to get from the exterior Heat Pump to the loft already. There are also air conditioning wall boxes which run directly off the refrigerant, but we don't use them very much.

 

The house is about 100m^2 and reasonably modern. We're using about 5000kWh of heating and about 3000kWh of hot water (we have toddlers toddling around, so the house is kept quite warm at the moment, and there are lots of baths, but that won't continue to be the case). It's probably fair to use the suggested 3000kWh figure over the long run. 

 

There's solar PV panels, and we don't seem to be using much electricity from the grid in summer, but - being in Britain - they don't generate much electricity in winter. The house is well insulated (we had more added as part of this installation) and not drafty as such but we have to maintain a certain level of ventilation because Radon gas leaks out of the ground in Britain. We're expecting to be here a good long time, so spending more upfront to get a better result isn't a problem.

 

Thanks for all the help and hope that that information helps!

 

Yours,

 

Jon

[DanDee]

3 minutes ago, Jonshine said:

Hi,

Yes, Dandan is correct, and no worries it was not clearly written! I should be clear, we already have this system, but our immediate neighbours aren't happy with the noise of the exterior unit, and we've decided to move or enclose it (I was a little embarrassed to admit this at first). It is a single ASHP with variable speed/power depending on need, either:

 

Option A: Next to the house, with an enclosure. 

 

or

 

Option B: At the bottom of the garden without an enclosure but with an extra eight metres of external refrigerant (not water) piping.

 

As it happens, Option A and Option B have similar upfront costs for us.

I'm in Britain, in a reasonably mild part of it. Hot water is via a tank at 50-degrees-centigrade (boosted to 65-degrees once-a-week using an immersion heater to kill bacteria), central heating is through radiators running at about 37-degrees-centigrade, both using a heat exchanger unit in the loft that moves heat from the refrigerant into the water. There's about eight metres of external refrigerant piping to get from the exterior Heat Pump to the loft already. There are also air conditioning wall boxes which run directly off the refrigerant, but we don't use them very much.

 

The house is about 100m^2 and reasonably modern. We're using about 5000kWh of heating and about 3000kWh of hot water (we have toddlers toddling around, so the house is kept quite warm at the moment, and there are lots of baths, but that won't continue to be the case). It's probably fair to use the suggested 3000kWh figure over the long run. 

 

There's solar PV panels, and we don't seem to be using much electricity from the grid in summer, but - being in Britain - they don't generate much electricity in winter. The house is well insulated (we had more added as part of this installation) and not drafty as such but we have to maintain a certain level of ventilation because Radon gas leaks out of the ground in Britain. We're expecting to be here a good long time, so spending more upfront to get a better result isn't a problem.

 

Thanks for all the help and hope that that information helps!

 

Yours,

 

Jon

 

I would vote for the enclosure and the move is not really far away and it may very well still be audible for the neighbour. 

[Jonshine]

Hi,

 

We're confident that the result will be good for the neighbour either way (from the moved position, the garage - which is separate - will be between the ASHP and the neighbour's house). The other neighbours are also well-screened from that position.

 

All else being equal, we would go for the enclosure, but we're nervous that the air will have to flow around both sides of the 'S' bend. For these purposes let's say it's costing us about £1,000 a year to heat the house - so over the 20-year horizon we're considering sending our energy costs up by 20% or so is painful but manageable, but if they doubled we'd have to make some other change.

 

Yours,

 

Jon

[sharpener]

I think the psychology of moving it where the neighbour cannot see it is more likely to have the desired effect.

[JamesPa]

9 hours ago, DanDee said:

 

I would vote for the enclosure and the move is not really far away and it may very well still be audible for the neighbour. 

As a matter of relevant interest

 

• how far is the pump from your neighbours living/bed room(s), what's the visibility
• what does the MCS calculation say is the noise pressure at the assessment point()
• what pump model is it
• is the area you are in rural and quiet, urban and noisy ore in the middle

 

There is still dispute over whether the permitted development noise standards 'work', certainly the Environmental Health Officer at my LPA doesn't believe in them, and DEFRA have launched an investigation.  God help us (and the planet) if the outcome is to make them tighter mind you!

 

 

[DanDee]

21 minutes ago, JamesPa said:

As a matter of relevant interest

 

• how far is the pump from your neighbours living/bed room(s), what's the visibility
• what does the MCS calculation say is the noise pressure at the assessment point()
• what pump model is it
• is the area you are in rural and quiet, urban and noisy ore in the middle

 

There is still dispute over whether the permitted development noise standards 'work', certainly the Environmental Health Officer at my LPA doesn't believe in them, and DEFRA have launched an investigation.  God help us (and the planet) if the outcome is to make them tighter mind you!

 

 

 

We need a split with only the evaporator with the fan outside, the compact compressor+bits inside. Basically a split AC installed vice versa.

[JamesPa]

32 minutes ago, DanDee said:

 

We need a split with only the evaporator with the fan outside, the compact compressor+bits inside. Basically a split AC installed vice versa.

sorry the question was meant for @Jonshine

[JamesPa]

10 hours ago, Jonshine said:

we already have this system, but our immediate neighbours aren't happy with the noise of the exterior unit,

As a matter of relevant interest

 

• how far is the pump from your neighbours living/bed room(s), what's the visibility
• what does the MCS calculation say is the noise pressure at the assessment point()
• what pump model is it
• is the area you are in rural and quiet, urban and noisy ore in the middle

 

There is still dispute over whether the permitted development noise standards 'work', certainly the Environmental Health Officer at my LPA doesn't believe in them, and DEFRA have launched an investigation.  God help us (and the planet) if the outcome is to make them tighter mind you!

[Jonshine]

Hi,

 

The ASHP was installed under Permitted Development rights, so it meets the MCS standard. But it is close to the maximum permitted volume at the assessment point. The pump is a Samsung something-or-other.

 

The neighbour hasn't made a formal complaint about the noise at all (yet), but, what they've indicated to us is that they think it is a noise nuisance under the Environmental Protection Act 1990, not a planning issue. We've decided to make one of these two changes rather than contest this further. We live in a reasonably dense suburban area that's relatively quiet at the moment, but increasingly noisy as it's not finished being built yet (well, it's noisy during the day because of construction, but quiet at night when they stop working - but as more houses and roads are finished, there are more people and more traffic so the night noise level is creeping up too).

 

It would be nice if DEFRA et al can sort this out for the future! Either we shouldn't have been allowed to install this in the first place (in which case we'd have done something different), or our neighbours shouldn't potentially have grounds for a complaint. This bait-and-switch benefits nobody.

 

(There was a planning complaint made that the air-cooling exceeded the Permitted Development rights. The wall boxes were an add-on to the original ASHP central-heating-and-hot-water installation, and were entirely internal changes. The installer indicated to us that this meant they were not considered 'development' of any kind in a planning sense. The council planning enforcement officer didn't contradict this, but they did ask us to put in a retrospective planning application for the air cooling function. They gave us a two-week deadline to do that, then made themselves unavailable for those weeks (first on holiday, then in court) so we were unable to ask for any clarification. Rather than miss the deadline, we chose to take the simple option of putting in the retrospective application, which is currently under consideration).

 

That's... more for the benefit of people in the future than for us, I suppose.

 

Our main query is more about which of these two solutions for the noise issue will be more energy efficient.

 

Yours,

 

Jon

[sharpener]

1 hour ago, Jonshine said:

Our main query is more about which of these two solutions for the noise issue will be more energy efficient.

 

I would guess the enclosure, because assuming the 20Pa back pressure criterion is met there will be little or no additional power required whereas the heat losses on the extra pipe run will be small, but very real (and quantifiable). But I doubt anywhere near the 20% you mention upthread.

 

Can you provide a link to the specific enclosure you have in mind? Do they warrant its performance with your particular HP and what dB reduction do they state it will achieve? Also how does it vary across the spectrum?

[JamesPa]

10 hours ago, Jonshine said:

Hi,

 

The ASHP was installed under Permitted Development rights, so it meets the MCS standard. But it is close to the maximum permitted volume at the assessment point. The pump is a Samsung something-or-other.

 

The neighbour hasn't made a formal complaint about the noise at all (yet), but, what they've indicated to us is that they think it is a noise nuisance under the Environmental Protection Act 1990, not a planning issue. We've decided to make one of these two changes rather than contest this further. We live in a reasonably dense suburban area that's relatively quiet at the moment, but increasingly noisy as it's not finished being built yet (well, it's noisy during the day because of construction, but quiet at night when they stop working - but as more houses and roads are finished, there are more people and more traffic so the night noise level is creeping up too).

 

It would be nice if DEFRA et al can sort this out for the future! Either we shouldn't have been allowed to install this in the first place (in which case we'd have done something different), or our neighbours shouldn't potentially have grounds for a complaint. This bait-and-switch benefits nobody.

 

(There was a planning complaint made that the air-cooling exceeded the Permitted Development rights. The wall boxes were an add-on to the original ASHP central-heating-and-hot-water installation, and were entirely internal changes. The installer indicated to us that this meant they were not considered 'development' of any kind in a planning sense. The council planning enforcement officer didn't contradict this, but they did ask us to put in a retrospective planning application for the air cooling function. They gave us a two-week deadline to do that, then made themselves unavailable for those weeks (first on holiday, then in court) so we were unable to ask for any clarification. Rather than miss the deadline, we chose to take the simple option of putting in the retrospective application, which is currently under consideration).

 

That's... more for the benefit of people in the future than for us, I suppose.

 

Our main query is more about which of these two solutions for the noise issue will be more energy efficient.

 

Yours,

 

Jon

This is really interesting as it confirms what I had begun to suspect namely that installation under PD rights may not give protection from an action under environmental health legislation.  Clearly this is a legislative trap which, as you say, needs to be sorted.

 

Does the complaint arise from winter use when presumably your neighbours have their windows closed, or from summer use.  I have argued that an argument can be made for allowing ashps to emit noise above a relatively quiet background, which the pd rules do, on the grounds that they are noisiest when it's cold and people will be indoors with the windows closed.  However this argument is invalid in summer when the ashp may still be in use for dhw.

[Jonshine]

Hi,

 

Here's a link to a case study on their website: https://www.environ.co.uk/projects/residential-air-source-heat-pump/  which indicates a 20dB reduction. I've previously downloaded a brochure from there as well, but I couldn't find it again. I do have some more specific noise reduction information including a spectrum but the email I was sent it in has some 'may be confidential' boilerplate text at the bottom so I'd better be safe and not share it. We're completely confident this enclosure would resolve the problem, certainly.

 

Yours,

 

Jon

[Jonshine]

51 minutes ago, JamesPa said:

This is really interesting as it confirms what I had begun to suspect namely that installation under PD rights may not give protection from an action under environmental health legislation.  Clearly this is a legislative trap which, as you say, needs to be sorted.

 

Does the complaint arise from winter use when presumably your neighbours have their windows closed, or from summer use.  I have argued that an argument can be made for allowing ashps to emit noise above a relatively quiet background, which the pd rules do, on the grounds that they are noisiest when it's cold and people will be indoors with the windows closed.  However this argument is invalid in summer when the ashp may still be in use for dhw.

 

Unfortunately, it turns out to be both.

 

The MCS noise standard for permitted development only covers the heating and hot water, so whilst we could've tried to defend that, it wouldn't have protected the air cooling use. With either of these solutions, we should be basically able to use what we want when we want without disturbing anyone. If it had been just the air cooling, we might've managed that by, say, only using it when the neighbours were out or on Heatwave Alert days. And if we only had the central heating and hot water, we might've decided to legally defend our use of it. But the combination of those things made it more appealing to get the resolution in the physical world rather than the legal space.

 

Tangentially, even though anyone could come along at any time and install what we've installed, if the neighbours decided to sell, it probably would at the moment put some buyers off their house (people do not, presently, seem to be thinking 'when that neighbouring house has a heat pump where will it go and what will the effect on the property I'm considering buying' but they would consider the heat pump we've actually installed) which could affect the sale price, which would then become the benchmark price for the value of our house since we're on an identikit estate. 

 

If you're genuinely getting into this with either the council environmental health department under Section 80 of the Environmental Protection Act 1990, or a direct private prosecution under Section 82, I would suggest a consultation with a solicitor. I did speak to one and they thought there was at least a presentable case that using the central heating and hot water didn't constitute a noise nuisance (even if you wouldn't have been allowed to, say, play music at that volume). It's a broadly-drafted piece of legislation and context matters. But you definitely shouldn't take secondhand legal advice from me!

 

[sharpener]

2 hours ago, Jonshine said:

Hi,

 

Here's a link to a case study on their website: https://www.environ.co.uk/projects/residential-air-source-heat-pump/  which indicates a 20dB reduction. I've previously downloaded a brochure from there as well, but I couldn't find it again. I do have some more specific noise reduction information including a spectrum but the email I was sent it in has some 'may be confidential' boilerplate text at the bottom so I'd better be safe and not share it. We're completely confident this enclosure would resolve the problem, certainly.

 

Yours,

 

Jon

 

Promising, looking at what they say 20dB sounds about right and if it already complies with MCS then would reduce level to 17 dB which is really quiet.

 

Would you mind telling us what they quoted you? We might need something similar for a Vaillant two-fan 12kW, depends if the window next door is a "habitable room". Also I imagine of interest to @JamesPa who as you have gathered has a similar issue.

[Jonshine]

The enclosure may do a bit less at important low frequencies, but it will still be in that regime. If the council were to insist on a BS4142 assessment or similar, there would also likely be a tonality penalty ('this compressor is more annoying than an equivalent volume of bird-cooing...' said someone who doesn't have doves nesting under their solar panels) of about 7dB. But the background here, even at night, seems to be around 30dB. Besides, unlike in the MCS assessment BS4142 (et al) are about actual noise so the nighttime quiet-mode operation can be considered. On the other hand, it's quite a dense estate so the sound is probably being funnelled and reflected by garages and houses that aren't considered in the MCS assessment. Swings and roundabouts, really. We're confident the enclosure will solve the problem - equally, so would the other solution (essentially, fencing off a section of our garden for the heat pump using this panelling https://www.ikoustic.co.uk/products/acoustic-fences/noistop-essential-acoustic-fencing/ - this is a cheaper solution but hurts the value of the house more).

 

It's, well, there's no easy way to say this, the quote is for about four-and-a-half thousand pounds, delivered either assembled or flat pack, and including VAT. The original heat pump installers have agreed to do the installation as part of the normal servicing. I should say this is bundled into a broader agreement with the neighbours and we'd be happy with that outcome. I had a quote for a similarly performing but slightly smaller enclosure from Germany which was several thousand pounds more. Environ also offer a louvred enclosure, but that was only £1,200 cheaper and doing 6dB of attenuation instead of 20dB (although it was also smaller). 

 

Also, because of the size of the enclosure and the fact that it just edges onto the drive, it will be visible from the street so we think we will need planning permission, for the enclosure, as a structure (nothing to do with the Heat Pump except that the Heat Pump will be inside it). We'll be submitting that soon (the above has reassured us a bit that it's not going to double our heating bills or anything over the next eighteen years, which would've run into the tens of thousands of pounds), but we probably won't have an outcome for a couple of months - so we may very likely have the chance to revisit our decision in light of DEFRAs consultation outcome (thanks for making us aware of this, very helpful)!

[sharpener]

15 minutes ago, Jonshine said:

It's, well, there's no easy way to say this, the quote is for about four-and-a-half thousand pounds, delivered either assembled or flat pack, and including VAT.

 

That sounds atrocious! Can you not put some ikoustic fencing in front of it where it is currently? That looks a reasonable product to try in the first instance.

 

Edited June 9, 2023 by sharpener

[Big Jimbo]

If i fit ASHP to my new property, i obviously hope it will comply. However, i really hope it annoys the hell out of my neighbour.

[Jonshine]

46 minutes ago, sharpener said:

 

That sounds atrocious! Can you not put some ikoustic fencing in front of it where it is currently? That looks a reasonable product to try in the first instance.

 

 

Unfortunately not. We could fence off an area in our garden it would go in. But... if you think about two otherwise identical houses, but one has a noticeably better garden but it costs say three and a half thousand more, that would seem like a perfectly reasonable price to pay, and viewed that way we feel a bit better about it. (It also wouldn't be appropriate to kiss-and-tell as to what's bundled into the, well, we haven't actually agreed anything yet, but it'll be part of a broader agreement with our neighbours).

 

35 minutes ago, Big Jimbo said:

If i fit ASHP to my new property, i obviously hope it will comply. However, i really hope it annoys the hell out of my neighbour.

 

So... yeah.

1. It's important to be sure it complies with the MCS, because the MCS is at a level that may generate complaints and you'll have to prove compliance otherwise the council planning authority will probably take action against you.

2. If you want the air cooling as well, you probably need to put in the planning application for that (as a use - you can be clear the physical installation and heating purpose is under Permitted Development). The law is unclear enough you might get enforcement action taken against you otherwise.

3. It's probably worthwhile to wait until the DEFRA consultation results are released, at least before signing the agreement for the Heat Pump, you can do the pre-installation stuff - seems like that will be at the end of the summer.

4. You should try to get on with your new neighbours! We got on well with these neighbours prior to this, and we hope to do so again afterwards. It's a tough situation, and it's really Parliament's fault for creating a situation of competing rules at differing levels. If it were clearly allowed for a Heat Pump to be this noisy, I think the neighbours could've learned to accept it or maybe offered to pay for the entire cost of the enclosure themselves. And obviously, if it clearly weren't allowed we would've done something different in the first place.

5. It's been really good and successful for us and we're very happy with it. One thing to note is that because ours is a split system - there is a heat exchanger between the refrigerant and the water, and that sits in our loft. It's not noisy-noisy, but you wouldn't normally have something loud up there because the ceilings are very thin. If I'd know it was going to be quite as loud as it is, we'd probably have put some sound-insulation sheets down in the loft under and around it. Also, worth lagging the interior pipework for the same reason, even if it isn't really hot enough to need it for thermal purposes (I guess that last applies to a monobloc system too).

[markocosic]

I'd go option 2.

 

Losses from refrigerant lines won't kill the performance. Vacuuming the gas down into the outdoor unit and extending the lines is child's play.

 

 

Option 3.

 

Something more premium than an old Samsung split If the indoor unit is annoyingly noisy AND the outdoor unit is annoyingly noisy...perhaps you should ask to see other units in operation?

 

Separates perhap? A quiet monobloc delivering the heating and hot water directly using water; plus a more basic air to air for cooling? Only the latter requires planning/can be objected to. If it's used in summer daytime whilst windows are closed for the heat anyway it's less likely to annoy neighbours. The PD / MCS monobloc there's less they can complain about especially if the hot water is timed during noisy hours. (generally the unit should only be audible at higher compressor frequencies whilst preparing hot water)

[JamesPa]

10 hours ago, markocosic said:

Losses from refrigerant lines won't kill the performance.

Can you clarify a bit the rationale.  My simple physics says that the refrigerant line post compression must be hotter than the water flow temp so thermal losses are greater, but I must be missing something otherwise what's the point of splits?