location of ASHP

stickybookmark

Hi all, is there an optimum location for an Air Source heat pump (air to water heat pump) should it be located at a certain side of the house to face prevailing winds/warmer winds etc to increase efficiency? Or does it not matter where you put it?

Gumbo

stickybookmark wrote: »

Hi all, is there an optimum location for an Air Source heat pump (air to water heat pump) should it be located at a certain side of the house to face prevailing winds/warmer winds etc to increase efficiency? Or does it not matter where you put it?

What does the manufacturers instructions say?

Any i see are almost always just out the back door to one side.

gooseygander

stickybookmark wrote: »

Hi all, is there an optimum location for an Air Source heat pump (air to water heat pump) should it be located at a certain side of the house to face prevailing winds/warmer winds etc to increase efficiency? Or does it not matter where you put it?

I was told by my installer that they can be placed anywhere EXCEPT facing prevailing wind. Now I don't know the reason or science behind this, anyway mine is put on the north facing wall of the house and I did question this at the time citing that this will be the coldest face of the house and this is when I was informed they can be faced anywhere except towards prevailing winds.

BarneyMc

Mine will be just outside the back door on an east facing wall and will be very sheltered. Not sure if the way it faces affects efficiency (doubt it) but it certainly should improve its longevity. Sitting in the prevailing winds & rain could not be good.

Calahonda52

Lets look at the science here:
the ASHP is trying to extract heat from air so the warmer the air, the better.

As to the issue of prevailing wind, then windchill is the risk so look at this
http://www.nws.noaa.gov/om/winter/windchill.shtml

"Bright sunshine may increase the windchill temperature by 10 to 18 degrees F."

The project here is trying to predict skin temp but the principles still apply so my view is that location does matter: the unit needs to be shelter from driving wind and rain but needs plenty air flow around it so stuck up against the north facing wall, restricting the airflow across the fins because its too close to the wall, is not the right location.
My guess is the actual location is driven by the desire to minimise the pipe runs ( between the compressor and the outside unit etc) and a fair bit of aesthetic input by she who must be obeyed: I don't want that yolk on my patio

stickybookmark

Calahonda52 wrote: »

Lets look at the science here:
the ASHP is trying to extract heat from air so the warmer the air, the better.

As to the issue of prevailing wind, then windchill is the risk so look at this
http://www.nws.noaa.gov/om/winter/windchill.shtml

"Bright sunshine may increase the windchill temperature by 10 to 18 degrees F."

The project here is trying to predict skin temp but the principles still apply so my view is that location does matter: the unit needs to be shelter from driving wind and rain but needs plenty air flow around it so stuck up against the north facing wall, restricting the airflow across the fins because its too close to the wall, is not the right location.
My guess is the actual location is driven by the desire to minimise the pipe runs ( between the compressor and the outside unit etc) and a fair bit of aesthetic input by she who must be obeyed: I don't want that yolk on my patio

AFAIK the compressor is in the outside unit ?

stickybookmark

BarneyMc wrote: »

Mine will be just outside the back door on an east facing wall and will be very sheltered. Not sure if the way it faces affects efficiency (doubt it) but it certainly should improve its longevity. Sitting in the prevailing winds & rain could not be good.

I think this is a summary of irish wind direction
http://www.birdwatchireland.ie/Default.aspx?tabid=276

Wind from the north is cold
Wind from the east is cold and dry
Wind from the south is warm
Wind from the west is warm and wet

So based on that it wouldn't seem a good idea to have it facing east as the wind is cold. However I'm told Ireland experiences wind from the east very rarely. The prevailling wind is south west so it's good that it's not facing into that. Mine will be on the east side of my house but the actual front of the unit will be facing south. I was also told that having it on the north side of the house wouldn't be a problem

Calahonda52

It depends on the design.
The outside piece at a minimum has to be the coil that the refrigerant passes through and evaporates as it passes through the coil, absorbing the heat from the air, this piece generally called the evaporator.
The piece that is usually inside is the condenser where the gas that has been compressed by the compressor gives up its heat and condenses into a liquid.

[See the attached schematic which is for a ground source to hot air heat pump but I use it when teaching as its pretty clear: just follow the refrigerant.]

in a ASHP there are three elec motors:

1. the fan driving the warm air through the evaporator fins
2. The pump passing the water through the condenser.
3. The compressor.

There are therefore three choices for what pipe work comes from outside in

1. the hot water: flow, return
2. the compressed gas: flow, return
3. the liquid : flow, return

thatslife

Calahonda52 wrote: »

There are therefore three choices for what pipe work comes from outside in

1. the hot water: flow, return
2. the compressed gas: flow, return
3. the liquid : flow, return

of the 3 choices, which is best option?

Calahonda52

thatslife wrote: »

of the 3 choices, which is best option?

Different ideas abound, one being your tolerance for noise from the 3 elec motors, the fan and the compressor: which also gives off heat so having as much of the kit indoors would reduce heat losses.
Some air to water models may have heat recovery from the compressor
At the domestic level you may not get a choice: