ASHP acoustic cover

[rbw]

5 hours ago, puntloos said:

@Moonshine and @IanR - can you explain why this is a big problem?

 

Clearly, having a warmish water flow in a pipe that needs to cross 10m of garden in the middle of winter is less ideal than something stapled to your heat envelope. But insulation is surprisingly good, and wrapping say 10m outside pipe in say 200mm worth of insulation.. surely that would only drop temp "a bit"?

 

Can someone perhaps compare the 2 situations Tony listed, e.g ,simplifying for calculation purposes, and assuming the ASHP runs for an hour in both cases

 

B/ ASHP is stapled to the wall, so let's assume "0m" of piping, hot water entering house is 35C

C/ ASHP center garden, needs 10m external piping buried 500 mil deep, with say 200mm insulation

 

-> the question is - how warm will the water in C be for various cases, (-10? 0? +10)

 

We are faced with a similar positioning conundrum, though in our case driven more by aesthetics rather than noise. Wherever we choose to position our ASHP it will not be up against the house so our plan is to use Mibec pre-insulated pipe (likely their Primo Duo product). Mibec’s brochure has heat loss graphs on page 37, one of which I have copied below. Hopefully here with the requisite knowledge will likely be able to translate these into temperature losses for given flow/return/ground temperatures and distance. 

[IanR]

6 hours ago, puntloos said:

Clearly, having a warmish water flow in a pipe that needs to cross 10m of garden in the middle of winter is less ideal than something stapled to your heat envelope. But insulation is surprisingly good, and wrapping say 10m outside pipe in say 200mm worth of insulation.. surely that would only drop temp "a bit"?

 

I was told by the Installers the recommended Max distance from (a mono block) ASHP to UVC (not just the distance outside the house) is 10m.

 

I assume the manufacturers' COPs and SCOPs etc. are based on that Max.  I put my UVC quite central in the house so had a 20m pipe run, 15m of which is under the slab to the ASHP. To mitigate the extra length I used a pre-Insulated twin-pipe duct from Rehau - the Rauvitherm SDR DUO 32+32/150 with a claimed U Value of 0.26 W/m-K

A quick hand calc suggests that with a flow temp of around 50°C and a ground temp of 8°C (I've used the twin-pipe duct for the underground portion of the run) the energy loss is around 11W/m (7.25W/m for a 35°C flow temp)

 

For your 10m run that suggests quite a small 110W loss when heating the cylinder, and less when space heating (assuming lower flow temp). So with a worst case COP of 2.5 that shouldn't be costing you more than 44W extra electricity into your ASHP. A small loss, but with you for the entire life of the installation.
 

Edited August 4, 2021 by IanR

[puntloos]

5 hours ago, IanR said:

 

I was told by the Installers the recommended Max distance from (a mono block) ASHP to UVC (not just the distance outside the house) is 10m.

 

I assume the manufacturers' COPs and SCOPs etc. are based on that Max.  I put my UVC quite central in the house so had a 20m pipe run, 15m of which is under the slab to the ASHP. To mitigate the extra length I used a pre-Insulated twin-pipe duct from Rehau - the Rauvitherm SDR DUO 32+32/150 with a claimed U Value of 0.26 W/m-K

 

Somewhat counterintuitive for me that the U-values go up with bigger pipes, but I guess more radiation surface = more loss rather than that the thickness of the actual insulation makes things better..

 

5 hours ago, IanR said:

A quick hand calc suggests that with a flow temp of around 50°C and a ground temp of 8°C (I've used the twin-pipe duct for the underground portion of the run) the energy loss is around 11W/m (7.25W/m for a 35°C flow temp)

 

For your 10m run that suggests quite a small 110W loss when heating the cylinder, and less when space heating (assuming lower flow temp). So with a worst case COP of 2.5 that shouldn't be costing you more than 44W extra electricity into your ASHP. A small loss, but with you for the entire life of the installation.
 

 

*I summon the power of my highschool physics!@#*

 

OK maybe not. But. The thing I'm missing is - you say 44W extra usage, but presumably an ASHP isn't running all day, and it isn't 8C every day either, so I assume you're not saying this is effectively having a permanent 24/7 44W load on my electrical bill, but in that case:

 

Could you put this into money(or kwh) terms? Option A costs X per year, and option B (10m extra outside) costs X+... per year?

Obviously I intend to also have PV to run most of this.. but you know..

 

In my actual current design I have about a 8m run from the ASHP location to the house (perhaps the foundations start a little earlier), a further 10m through foundation into the service shaft, and then perhaps 8m up into the loft where most of the plant is.  

 

Obviously 25m is quite the run, so I am wondering which of the components would make a major difference to put on the ground floor. For example, I could put the UFH manifold and the DHW cylinder (with ASHP coils) on the ground floor, but I doubt I could fit the hot and/or cold buffers there, and definitely not the chiller coils and MVHR

[IanR]

28 minutes ago, puntloos said:

Somewhat counterintuitive for me that the U-values go up with bigger pipes, but I guess more radiation surface = more loss rather than that the thickness of the actual insulation makes things better..

 

Larger pipes for same duct size means less insulation = higher U Value = higher energy losses.

 

28 minutes ago, puntloos said:

OK maybe not. But. The thing I'm missing is - you say 44W extra usage, but presumably an ASHP isn't running all day, and it isn't 8C every day either, so I assume you're not saying this is effectively having a permanent 24/7 44W load on my electrical bill, but in that case:

 

Correct, the notional extra 44W is when the ASHP is heating the DHW Cylinder. So not for very long each day ie. 1 - 2 hours perhaps. A lower wattage, depending on flow temperature, for when the ASHP is supplying heat for Space heating, which may run for more hours per day depending on your property heat losses.

8°C is the ground temperature, which is fairly constant all year at 8°C - 10°C

 

28 minutes ago, puntloos said:

Could you put this into money(or kwh) terms? Option A costs X per year, and option B (10m extra outside) costs X+... per year?

Obviously I intend to also have PV to run most of this.. but you know..

Not without knowing you DHW usage and Space Heating demand, and doing a long calculation. But, for every hour the ASHP is running the loss is around 0.5 pence.

 

PV will contribute, but you can't run an ASHP solely on PV. (unless the array is very large and supported by battery backup)

 

28 minutes ago, puntloos said:

Obviously 25m is quite the run,

 

It is a long run, you need to insulate well, or perhaps choose a split system ASHP, where the losses are less due to small bore pipe, however this brings a part of the ASHP in to the house, which while it is quieter than a Gas-combi boiler, is not as quiet as having the whole unit outside.

Bring the UVC and UFH buffer as close to the ASHP as you can
 

28 minutes ago, puntloos said:

... but I doubt I could fit the hot and/or cold buffers there, and definitely not the chiller coils and MVHR

 

Hot & cold buffers and chiller coils, sounds complicated, are you installing offices and heating/cooling via air?

 

Edited August 4, 2021 by IanR

[puntloos]

For some extra clarity, here are my "4 options"

 

- A is the furthest away from everybody's houses. 

- B is near neighbours and our terrace

- C is much better but we might run into various planning issues and it will impede the view from the bottom right room (and noise?)

- D is perhaps a comprimise, it shortens the direct run from 18 to 13m, but suddenly we're bothering perhaps ourselves but mostly our neighbours?

 

I strongly prefer A but if someone can tell me how many kwh I have to buy or generate per year to pay for it, I'd love to have an idea!

 

 

[puntloos]

13 minutes ago, IanR said:

8°C is the ground temperature, which is fairly constant all year at 8°C - 10°C

 

Does it matter if we dig a 1m deep trench or a 50cm one?

 

13 minutes ago, IanR said:

Not without knowing you DHW usage and Space Heating demand, and doing a long calculation. But, for every hour the ASHP is running the loss is around 0.5 pence.

 

Good rule of thumb.

13 minutes ago, IanR said:

PV will contribute, but you can't run an ASHP solely on PV. (unless the array is very large and supported by battery backup)

 

Will certainly have a decent PV array, 16x 420wP panels. Probably a battery too.

 

13 minutes ago, IanR said:

It is a long run, you need to insulate well, or perhaps choose a split system ASHP, where the losses are less due to small bore pipe, however this brings a part of the ASHP in to the house, which while it is quieter than a Gas-combi boiler, is not as quiet as having the whole unit outside.

My current plan is the Daikin Altherma 3, which I think indeed is a split device

https://www.daikin.co.uk/content/dam/dauk/document-library/Brochures/Heating/Heating Installer brochures/Daikin Altherma 3 H HT_767.pdf

 

 

13 minutes ago, IanR said:

Bring the UVC and UFH buffer as close to the ASHP as you can
 

So my DHW location as indicated might be a good idea? How much space does the UFH buffer and manifolds etc need?

13 minutes ago, IanR said:

Hot & cold buffers and chiller coils, sounds complicated, are you installing offices and heating/cooling via air?

 

Well, we want a meaningful cooling setup.. hot buffers help preventing spin up/down/up somewhat and I imagine cold does the same.. would you not want those?

[IanR]

44 minutes ago, puntloos said:

My current plan is the Daikin Altherma 3, which I think indeed is a split device

 

If you are running a split system ASHP rather than a mono block, then this discussion regarding energy losses via the pipes run between the ASHP and the UVC (and buffer) are not relevant to you, at least not the calcs. and losses discussed here. There are much lower losses with the small bore pipes that run between the 2 units of a split system, hence they are recommended for installs where the ASHP is up to 50m from the indoor unit.

 

48 minutes ago, puntloos said:

Well, we want a meaningful cooling setup.. hot buffers help preventing spin up/down/up somewhat and I imagine cold does the same.. would you not want those?

 

You can achieve that through the UFH and a single buffer that is either heating or cooling at anyone time. But I assume you plan to provide heating and cooling simultaneously, via large bore ducting.

[Tony K]

11 hours ago, Moonshine said:

 

You are incorrect in the 42 dB applying to the host dwelling and this is actually applied at the nearest house, so in effect you don't need to worry about the noise level at your house if you don't need to.

 

Is the ASHP going in as PD or under your planning application? if under your planning application then you won't need a MCS020 certified installation which will save you money. 

 

Your local authority may ask for a noise assessment to be done for planning, but this is easy and when i did mine just followed the methodology set out in MCS020, and submitted that (there is a MCS020 noise tab in the following spreadsheet)

 

https://mcscertified.com/wp-content/uploads/2019/09/MCS-Heat-Pump-Calculator.xlsm

 

For option B or the variant of it, it seems that the neighboring properties are over 20m away with a fence acting as a barrier, so a unit with a sound power of 57 dBA will be fine for planning.

 

The issue of noise is really reducing the impact on your own home and garden and isn't a concern for the planners. 

 

your red dot does seem the most logical place to put the unit on the facade, but will have more of an impact on the garden than the location of the green dot, though the green dot is just outside the main bedroom. is the build masonry or timber frame?

 

The acoustic enclosures do work to a degree, but i have not found one that reduces the noise by a level as claimed, and i haven't found one that looks 'nice'. 

 

Thanks @Moonshine. The GPDO regs (Class G Permitted Development) don't specify which windows noise must be measured from (or refer to noise at all), they just rely on the MSC standards. I have read a guide to those standards which seemed not to discriminate between host windows and neighbouring ones, but haven't read the actual standards themselves, so I'll take your advice, thanks.

 

I don't think it really makes a lot of difference in this instance - I will be looking to reduce noise as far as I can for my own sake and for the neighbours. The nearest neighbours windows are some 7 metres away from position B, but my new house is located between those windows and position B, so I would be surprised if 42db were to be recorded. 

 

The ASHP was not explicitly shown on my planning application, so I'll be using GPDO Class G rights. I note the GPDO does not require prior notification, or submission of evidence that the MSC standards are met, only that they are. This gives me a little leeway in practice - I will install the pump in position B, see what it sounds like when it is up and running, and if it drives me mad then I'll look at an acoustic enclosure for it, thereby following advice from @IanR. I can't imagine that the heavy industrial acoustic enclosures on the link you provided have any great magic to them - surely I can achieve something worthwhile by attaching sound insulation to the inside of a timber lean-to / log store, and placing that around the ASHP? This would affect noise emissions and also provide some thermal insulation around the pump, which I understood to have functional benefits. 

 

My SB has a masonry frame. @PeterW suggested that there were benefits to locating the ASHP perpendicular to the house wall, but has not yet explained his thinking on that front. Would I be right to presume that a perpendicular position would reduce the extent of sound echo off of the house wall?

 

I will also have a quite densely green garden once it matures, including some of the plants on the list @joe90 provided!

 

Edited August 4, 2021 by Tony K

[PeterW]

27 minutes ago, Tony K said:

My SB has a masonry frame. @PeterW suggested that there were benefits to locating the ASHP perpendicular to the house wall, but has not yet explained his thinking on that front. Would I be right to presume that a perpendicular position would reduce the extent of sound echo off of the house wall?

Correct !! 

[puntloos]

21 minutes ago, IanR said:

 

If you are running a split system ASHP rather than a mono block, then this discussion regarding energy losses via the pipes run between the ASHP and the UVC (and buffer) are not relevant to you, at least not the calcs. and losses discussed here. There are much lower losses with the small bore pipes that run between the 2 units of a split system, hence they are recommended for installs where the ASHP is up to 50m from the indoor unit.

 

OK, will have to keep it in mind. I'd love to see the pro/con in this setup:

A/ monobloc, costs AAA quid per day extra, noise is far away, near-irrelevant

B/ split, costs BBB quid per day extra, a XYZ db device in my understair cupboard makes ZZZdB noise at 1m

 

21 minutes ago, IanR said:

You can achieve that through the UFH and a single buffer that is either heating or cooling at anyone time. But I assume you plan to provide heating and cooling simultaneously, via large bore ducting.

Not sure if I want to heat&cool, of course it's helpful to be able to heat more hot water, even in a hot day where the primary climate function is cooling. 

Is such a scenario common? My family's needs are fairly modest but don't want to be 'sad in retrospect'

 

[SteamyTea]

As odd as this may sound, if you are 'digging trenches', have you considered a GSHP.  The actual unit does not have to be in the house, can be in a brick box or similar.

[puntloos]

53 minutes ago, SteamyTea said:

As odd as this may sound, if you are 'digging trenches', have you considered a GSHP.  The actual unit does not have to be in the house, can be in a brick box or similar.

 

Absolutely but a topic in this area have more or less brought me down from GSHP saying that in short the ground in UK does not conduct heat fast enough so you run into freezing the ground all the time.

 

But - my M&E team was planning to give me quotes for both... 

[SteamyTea]

6 hours ago, puntloos said:

Absolutely but a topic in this area have more or less brought me down from GSHP saying that in short the ground in UK does not conduct heat fast enough so you run into freezing the ground all the time.

Again, like an ASHP, properly designed, sized and installed, freezing is not a problem.

(ground heave is usually because the pipes are too short and too shallow)

[Marvin]

1 hour ago, SteamyTea said:

Again, like an ASHP, properly designed, sized and installed, freezing is not a problem.

(ground heave is usually because the pipes are too short and too shallow)

There are currently about  30,000 GSHP being installed per year in the UK.

What puntloos has read about is a system installed that is not fit for purpose.

 

You cannot say my mini is s*** because I can't tow my caravan. My mini works perfectly well.

 

Correct that the outside ground will freeze but only if there is too much drain of heat in that area. This would be a result of incorrect sizing of system or too much pipe per square meter or too shallow a trench.

 

There is too much information calculated and evidence to refute that installed GSHPs work, as with ASHPs.

I await the contradictions from the 30,000 people who had systems installed in 2019.

 

M

 

[Marvin]

More info on above

 

 

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.geothermal-energy.org/pdf/IGAstandard/WGC/2020/01018.pdf&ved=2ahUKEwjK7a_3ppnyAhUTgVwKHeAUCb0QFnoECAYQAg&usg=AOvVaw3CtNYvl34E6GpgqL14rNoJ

[SteamyTea]

MCS have this about ground pipe lengths.

http://www.gshp.org.uk/pdf/MIS_3005_Ground_loop_sizing_tables.pdf

 

Personally I think an ASHP, correctly designed and installed, won't be a problem, but worth looking at other options and balancing them all up.

 

8 minutes ago, Marvin said:

There is too much information calculated and evidence to refute that installed GSHPs work, as with ASHPs.

Still trying to get my head around this.

[Marvin]

16 minutes ago, SteamyTea said:

Still trying to get my head around this.

That's one of the problems with GSHP systems: The design and installation are critical.

Unlike a hot water tank which usually has a fairly swift recovery rate (unless your covered in s*** and waiting to have a bath) the ground can take a lot longer to recover its original temprature. 

[Marvin]

As far as I understand if an ASHP installation is to be covered under PD then the heat exchanger unit has to be no more than 10m from the buffer/hot water tank.

 

[Tony K]

2 hours ago, Marvin said:

As far as I understand if an ASHP installation is to be covered under PD then the heat exchanger unit has to be no more than 10m from the buffer/hot water tank.

 

 

I haven't read the MCS standards, but I presume that is where you are getting the 10m distance from? 

 

Many will have included the ASHP in their planning application and so whilst they will need to ensure compliance with any relevant planning conditions, will not need to worry about complying with the terms of the General Permitted Development Order (the Act which brings Permitted Development rights into law, and sets out the detailed regulations).

 

Those of us relying on PD rights may already appreciate that the GPDO requires that 'the air source heat pump complies with the MCS Planning Standards or equivalent standards' along with a series of other, clearly set out constraints and conditions. 

 

It's not unheard of for the GPDO to refer to other Acts (the definition of a 'caravan' in the GPDO is as per the Caravan Sites and Control of Development Act 1960 for instance), but reliance on a standards document 'or equivalent' is unusual. I presume this part of the GPDO accommodates the idea that ASHP technological development may be fast moving, as will knowledge around the subject and best practise therefore. Therein lies an issue I would advise awareness of. 

 

The GPDO does not currently require you to register the presence of your PD ASHP with the planning dept either in advance or after installation, but anyone wishing for the peace of mind that comes with formal confirmation, in advance of any works onsite, that their Council agrees their ASHP is covered by PD can apply for a certificate of lawfulness. 

 

However - a certificate of lawfulness can only confirm that the subject operation (installation of a ASHP in this case) would have been lawful on the day you applied for the certificate, not the day the certificate was issued and certainly not on the day you get around to installing the ASHP. A certificate of lawfulness has an ever-depreciating value in that way. If the regs, and in this case the guidance, moves on between the date of your application and the date you install it, you need to accord with the regs and guidance as they exist on the latter, even if that means doing things differently than you said you would when you applied for the certificate. 

 

How much all this matters depends entirely on how quickly and significantly the MCS Planning Standards or equivalent standards move on, and how much difference any change in them makes to your proposal, but given most of us planned for an ASHP a long time before we ever installed it, it is worth looking at the MCS standards once again before installation. 

 

Edited August 5, 2021 by Tony K

[Marvin]

3 hours ago, Tony K said:

haven't read the MCS standards, but I presume that is where you are getting the 10m distance from? 

Yes.

https://www.planningportal.co.uk/info/200130/common_projects/27/heat_pumps/2

 

More distance between ASHP and item to be heated/cooled equals more inefficient.

[puntloos]

@Marvin the discussion started around here: 

Obviously I take care not to take one-random-internet-dude (m/f)'s opinion as canon, which I also apply to you, of course.

But in general:
 

- I only have a smallish garden (unless I can put slinky/pipes under my foundation?) - effectively about 10x15m. 

- Boreholes, I'd be fine with them, but the ground I have is dense clay, so as I understand it, the heat/cold needs to be drawn from the local area and can't travel/radiate away.

 

It seems that the calculations have to be done carefully, as with everything.. my sense just is that with ASHPs you can always add more, or more powerful devices, where with GSHP once you've designed your setup and it runs into trouble you're basically up a certain creek with a certain lack of paddles.

 

@saveasteading Any comments on this thread so far? ?

Edited August 5, 2021 by puntloos

[puntloos]

2 hours ago, Marvin said:

Yes.

https://www.planningportal.co.uk/info/200130/common_projects/27/heat_pumps/2

 

More distance between ASHP and item to be heated/cooled equals more inefficient.

 

Would it be acceptable to have the GSHP "device" sit in a loft? Since with that technology you're bringing even more noise into your house and all..

[saveasteading]

22 minutes ago, puntloos said:

@saveasteading Any comments on this thread so far?

I am reading and learning. Nothing much to add since my original.

 

We have dug test holes and have fast draining sand, so the ground is dry and little replacement heat will be available.

Even a borehole specialist tells us to use air source.

 

The heat loss along a supply pipe could be significant. I once put in ASHP with 20m pipes. As well as the super expensive proper insulation, we surrounded it with surplus PIR filled cladding, before backfilling. Worked fine.

 

No to machines in the loft. The noise will reverberate through the joists. I put in a relatively small shower pump at home, on rubber pads, and it is audible in all adjacent rooms.

[Tony K]

Regarding noise reduction, this is interesting, though I am not sure I understand the claim to have reduced the noise from an ASHP 'by half', when the graph shows a 3db reduction?

 

 

 

[Moonshine]

9 minutes ago, Tony K said:

Regarding noise reduction, this is interesting, though I am not sure I understand the claim to have reduced the noise from an ASHP 'by half', when the graph shows a 3db reduction?

 

Decibels are a logarithmic value, reduction of half the pressure is a 3 dB reduction (= 10 x log10(1/2))