Off the wall question on Air Source Heat Pumps

TutuKaka

Just going to throw this one out there.

From my limited knowledge of Air Source heat pumps the performance decreases as the air temperature drops so I think it is safe to assume that in the current conditions the nation's heat pumps are working overtime.
Today I happened to call to a friend who has a polytunnel in his backgarden. Despite the snow and cold conditions outside, the temperature in the tunnel was comfortable.

So (assuming you had the space etc) would it make any sense to have your heat pump collector in a polytunnel type structure?

Condenser

TutuKaka wrote: »

Just going to throw this one out there.

From my limited knowledge of Air Source heat pumps the performance decreases as the air temperature drops so I think it is safe to assume that in the current conditions the nation's heat pumps are working overtime.
Today I happened to call to a friend who has a polytunnel in his backgarden. Despite the snow and cold conditions outside, the temperature in the tunnel was comfortable.

So (assuming you had the space etc) would it make any sense to have your heat pump collector in a polytunnel type structure?

It would need to be huge. An average size unit would move 5000m3 of air an hour which would short cycle back through the coil repeatedly in a small tunnel getting colder and colder on each pass. It couldn't replenish the energy as quick as it was taken out so you'd end up with very low temps very quickly.

sydthebeat

TutuKaka wrote: »

Just going to throw this one out there.

From my limited knowledge of Air Source heat pumps the performance decreases as the air temperature drops so I think it is safe to assume that in the current conditions the nation's heat pumps are working overtime.
Today I happened to call to a friend who has a polytunnel in his backgarden. Despite the snow and cold conditions outside, the temperature in the tunnel was comfortable.

So (assuming you had the space etc) would it make any sense to have your heat pump collector in a polytunnel type structure?

its not a mad question and one i have pondered before.

the most common answer i got was that the volume of air needed to be drawn into the system would be such as to make the poly tunnel extremely cold.
basically the structure outside would have to be of a size large enough to ensure that the in coming air has time to warm up before being drawn into the system. If you consider that some systems can draw as much as 8000m3 an hr it gives you an idea of size

also your exhaust stale air would need to be exhausted to somewhere else, longer pipe runs meaning more pump power required means lower efficiencies.

TutuKaka

So unless you happen to live next door to a steel furnace and you can pump the excess heat into the containment structure its a no go:)

Back to the drawing board then...