Heat pump tumble dryer - do they create condensation and how long is a typical program for fully dry

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Rheumatoid said:

I'm thinking about getting a heat pump drier but it would need to go in the garage and mainly be used in the cold months. Does this have any impact on their efficiency?

We have our HP in a unheated* attached garage.

Worked fine for years although no records of ambient temps.

Recenty added power meter and temp/humidity to monitor consumption of both washer and dryer under different conditions.

We were away during the recent cold spell(no heat from opening the door) lowest recorded day was 0.5c-1.1c
under 5c min for 10 days 
under 5c max for 7days

I suspect most winters we never got to freezing for an extended period.

The recorded drying cycles so far have been 8c-11c.
No noticeably different on the small sample set.
Tandem drying did result in a observable reduced energy use for the second load(sample size 1so far).

You can get hybrid HP dryers that also have heaters to speed up cycles and probably would be useful to kick-start the HP in cold conditions.

As HP only need a power supply and a 60c footprint they can go just about  anywhere.



* single skin brick, drylined inc ceiling with insulation over, pitched roof, up&over doors no draft strips.