Where best to site ASHP

[Marvin]

Our ASHP unit runs most of the time and in the morning when it is not running its about 5C warmer than the air or surrounding surfaces 

[Marvin]

9 minutes ago, joe90 said:

Not surprising as they look exactly the same!

Hope you've fixed your heating...

[SteamyTea]

2 hours ago, epsilonGreedy said:

 

Surely this confirms what people observe, namely the ground on the sunny side of a building can be frost free when the shaded north side suffers a multi day permafrost at this time of year.

But has (expletive deleted) all to do with the air temperature.

 

Meteorological stations the world over measure the temperature in the shade for a reason. Why a Stevenson screen is used.

[joe90]

45 minutes ago, Marvin said:

Hope you've fixed your heating...

Thanks, yes, turned out to be a duff (designed) bypass valve on the manifold letting too much cold water pass so could never get the loops up to temp. I am sure the manifold would work with a gas or oil boiler as the incoming water would be much hotter, blocked it off and plumbed a proper blending valve into the pipework.

[joth]

6 hours ago, ReedRichards said:

 If @jothis still finding big tanks ugly then it must surely be some decades before ASHPs fade from notice.

To clarify, I don't find them unusually or notably ugly. Just stating that, objectively, they are ugly.

In the entire history of houses, I don't think anyone every put a big oil tank in front of their house to add aesthetic charm or to enhance  the street-scene. So my conclusion is they are at absolute best aesthetically neutral, and on average will detracting from the visual appeal of the property.

 

[Marvin]

2 hours ago, joe90 said:

Thanks, yes, turned out to be a duff (designed) bypass valve on the manifold letting too much cold water pass so could never get the loops up to temp. I am sure the manifold would work with a gas or oil boiler as the incoming water would be much hotter, blocked it off and plumbed a proper blending valve into the pipework.

?

[SteamyTea]

14 minutes ago, joth said:

To clarify, I don't find them unusually or notably ugly. Just stating that, objectively, they are ugly.

In the entire history of houses, I don't think anyone every put a big oil tank in front of their house to add aesthetic charm or to enhance  the street-scene. So my conclusion is they are at absolute best aesthetically neutral, and on average will detracting from the visual appeal of the property.

 

How about putting stickers on them.

"I am saving the planet"

 

Bit like those "I am a key worker" ones, or "Thank You NHS".

 

Virtue signalling makes all the difference.

[joe90]

Actually I find solar panels on a roof ugly and would not want them on my pretty cottage, I had planning for them on my garage roof but would still not like the look. an ASHP is not very big and can easily be hidden behind some timber screening as long as air flow is maintained.

[SteamyTea]

7 minutes ago, joe90 said:

Actually I find solar panels on a roof ugly and would not want them on my pretty cottage

Would you notice roof integrated ones much? I can't remember which side of your roof faces the most south.

 

As my house foundation is a good 6 foot higher than the road, I can hardly see my roof.

[Ralph]

It's low down on the priority list but our white Daikin ASHP stands out like a sore thumb against our nearly black house.

 

In general I don’t think there has been much thought on the aesthetics of any of them, they all look like commercial air con systems.

 

Daikin do a “low sound” cover in what looks like black aluminium that I may go for. There is also someone on Etsy who does them in composite aluminium, prices seem decent. https://www.etsy.com/uk/shop/ASGAbdeckungen?ref=simple-shop-header-name&listing_id=1058466884

 

[joe90]

9 minutes ago, SteamyTea said:

Would you notice roof integrated ones much?

Better and saves slates.

11 minutes ago, SteamyTea said:

I can hardly see my roof.

My roof is very visible from all angles.

[joe90]

1 minute ago, Ralph said:

our white Daikin ASHP stands out like a sore thumb against our nearly black house.

Get it wrapped, talking to a car owner at a show and was surprised to learn his car was wrapped rather than painted and half the cost of a respray. You can buy the film on EBay and mostly flat panels so a doddle to do DIY, or a few cans of spray paint, can’t be that hard.

[Chanmenie]

22 hours ago, ProDave said:

Right at the front of the side wall would be my choice, i.e. facing about south west.

 

I think sun does make a difference, certainly here, when we get a cold spell the north side of the house becomes a permafrost in winter but the south side is definitely very much warmer, so probably less defrosting issues.

 

And although it may seem controversial to put it almost in the front garden (actually the side garden I am proposing)  people tend not to spend time in their front gardens so it keeps any noise away from yours and your neighbours back gardens.

Yes @ProDave that would be my preferred location, it’s 6m from the boundary with the neighbour and they don’t use that side of the garden.

Their oil fired boiler is that side and it’s pretty noisy, I’m sure it’s far noisier than an ASHP 

[epsilonGreedy]

5 hours ago, SteamyTea said:

But has (expletive deleted) all to do with the air temperature.

 

Meteorological stations the world over measure the temperature in the shade for a reason. Why a Stevenson screen is used.

 

Well yes indeed because they require a consistent reading not affected by the sun popping out from behind clouds. Your post in effect confirms how influential direct sun light is at warming things up.

 

The benefit derived by an ashp situated with a southerly aspect will depend on how many heating demand cycles per hour and the duration of a cycle. As you indicate ambient air temp will eventually determine whether the internals of an ashp get to the frosting point but an ashp bathed in sunlight will start with a higher temp advantage. You also seem to dismiss any warming of the air mass on the southern side of a property.

 

The onus is really on you to disprove human intuition and life experience on this matter since we all know that sitting in the shade is usually chilly in the UK.

[SteamyTea]

4 minutes ago, epsilonGreedy said:

The onus is really on you to disprove human intuition and life experience on this matter since we all know that sitting in the shade is usually chilly in the UK.

OK, here is how it is proved.

Sit in the shade with a thermometer and take several air temperature readings, then sit in the sun and do the same, but make sure that the thermometer is not affected by sunlight.

 

Or, tell me how an ASHP can only take air from a shaded area, when it shifts several tonnes of it a day, how can it 'know' that it is in the shade, and the air it is drawing is in the shade.  Air has a habit of moving about, luckily.

Also, how do ASHP perform effectively at night?  Not as if the CoP drops drastically.

Also, the metal case would only hold a few kJ of energy, hardly a measurable amount, especially as the external heat exchanger has refrigerant gas expanding into it at about -23°C.

 

Do you actually know how an ASHP works?

[epsilonGreedy]

25 minutes ago, SteamyTea said:

Also, how do ASHP perform effectively at night?  Not as if the CoP drops drastically.

 

 

This would be a persuasive point if true when an ashp is located with a southerly aspect.

 

32 minutes ago, SteamyTea said:

 

Also, the metal case would only hold a few kJ of energy, hardly a measurable amount, especially as the external heat exchanger has refrigerant gas expanding into it at about -23°C.

 

 

I was predicting a continuous process where the metal case warms a few degrees above ambient temp then radiates some heat into the ashp mechanics. The case heat capacity is not the significant measure.

[Iceverge]

3 hours ago, epsilonGreedy said:

The onus is really on you to disprove human intuition and life experience on this matter since we all know that sitting in the shade is usually chilly in the UK.

 

ASHP simply move too much air to make much use of relatively small localised warm air pockets.

 

A 10kw heat pump moves up to 3000m3/hr. Say you were to allow an hour for each airchange to gain meaningful heat in a nice suntrap that was sheltered up to 10m high with 300m2 ground area .Then put the heat pump in the middle. On a still day it would make a measurable difference to the performance of your ASHP.

 

 

However you’d be better off just putting the entire house in the said suntrap instead!

 

 

I wager a better ASHP location would be as close to the house as possible to reduce pipe heat losses and in a naturally windy area so the fans don’t need to work so hard. 

[SteamyTea]

7 hours ago, Iceverge said:

in a naturally windy area so the fans don’t need to work so hard. 

Until the direction reverses.

I suspect that if the ASHP is close to a house then the windspeed is significantly reduced, especially at ground level.

[Iceverge]

1 hour ago, SteamyTea said:

Until the direction reverses

Yes didn't think about this. One could probably do an analysis of wind direction Vs heating load to get an optimum direction to point the fan. 

 

Then put the ASHP on the apex of their roof to maximize wind flow 

[joe90]

9 hours ago, Iceverge said:

However you’d be better off just putting the entire house in the said suntrap instead!

? this is why I faced the back of our house south with a large conservatory across the whole 12m, black tiles on the floor above insulation and large bifolds into the house. I think this contributes a massive amount of heat into the house fir a lot of the year. The heating rarely comes on even mid winter on clear sunny days. Even our Jeremy with all his extensive knowledge and calculations didn’t realise the impact of the microclimate in his location, he ended up needing more cooling than heating.

[Iceverge]

I think this merits further study. Pull out some real data. Have you any simple thermometer to keep an eye on temps for us @joe90

 

I get the feeling it might be a very useful element of low energy building. All the benefits of massive glazing without the heat loss or overheating. 

 

"The selective use of solar gain through manually operated glazed appendages on domestic housing"

 

Or a conservatory m8. ?

[SteamyTea]

33 minutes ago, Iceverge said:

One could probably do an analysis of wind direction Vs heating load to get an optimum direction to point the fan. 

I did that about a decade ago.  Just for my location though.

Basically A NE wind, gentle, colder, but sunshine, SW wind, strong, warmer and cloudier

[Iceverge]

I suspect that'd probably be similar to the south of Ireland. What is the optimum fan direction then, blowing the same way as the prevailing wind? 

[SteamyTea]

17 minutes ago, Iceverge said:

I suspect that'd probably be similar to the south of Ireland. What is the optimum fan direction then, blowing the same way as the prevailing wind? 

I am really not sure.

Common sense say fan blows same way as wind, but it may cause over speeding of the fan (though I doubt it).

I would have thought that there is really little difference, and putting the ASHP in a sheltered position is best, but not shaded as that may encourage mould to grow.

Shall have to see if I can find any north facing ASHPs and see what they look like.

[epsilonGreedy]

12 hours ago, Iceverge said:

However you’d be better off just putting the entire house in the said suntrap instead!

 

I wager a better ASHP location would be as close to the house as possible to reduce pipe heat losses and in a naturally windy area so the fans don’t need to work so hard. 

 

 

No one is suggesting positioning a new build house elsewhere on a plot so that an ASHP gets the prime sunny location. Likewise there has been no discussion of remote siting of an ASHP in the sunny corner of a plot.

 

The matter of debate is: given equally viable ASHP locations on a north or south facing wall what advantage will be gained on the southern wall. Putting aside the summer chilling function I think we all accept there is a theoretical advantage on the southern wall but is it a 0.1% reduction in heating cost or 5%?

 

It would help if you and @SteamyTeacould concur on the volume of air drawn through an ASHP. @SteamyTeasays "several tons a day" and you are claiming "up to"  3.7 tons an hour.

 

Anyhow the real point of interest is ASHPs that are prone to frosting. Let's not forget the COP of an ASHP in defrosting mode is negative 1.0 or is it negative infinity? The worst outcome is an ASHP that spends so much time defrosting there is not enough time left to maintain the required internal house temp. Someone reported such a case here recently. Would a southerly aspect help such edge cases?