I'm a bit confused, since, initially, you mentioned dehumidifying.
However, I'm getting the impression that the heat pump in this case is entirely internal to the machine, which is not what I had in mind when mentioning heat pumps (thinking of their coefficient of performance of 3-4) [1]. Were I aware of these machines, I would have specified:
It's not as if modern dryers are using a heat pump with an outdoor source to raise the temperature of the clothing instead of burning gas or "burning" electricity with resistive heating.
That said, a 2x efficiency gain, by whatever method, is more than I expected, though still falling into what I would categorize as "not much room", especially if the gain comparison always assumes the oldest, least-efficient 5kW model only ever running at its highest setting. The other key assumption in all these comparisons is that all these dryers can finish the same sized load in the same amount of time, which can't possibly be true in the real world.
If my $40-to-repair machine already has some efficiency tweaks such that its worst-case is only 4kW, the $500 machine's worst-case is 2.5kW, but my actual behavior averages out to running them at 70% power, I'm saving barely over a kilowatt per hour, and I'm back up to 3500 hours to break-even at $.12/kWh electric rates. $1800-for-1kW is nearly 14k hours, or nearly 18 hours a week over fifteen years, and I don't do that much laundry.
[1] If this is so, it strikes me as odd to call it that, just as it would strike me as odd to call out a free-standing dehumidifier having a "heat pump", even though that's the crucial to the device functioning.
However, I'm getting the impression that the heat pump in this case is entirely internal to the machine, which is not what I had in mind when mentioning heat pumps (thinking of their coefficient of performance of 3-4) [1]. Were I aware of these machines, I would have specified:
It's not as if modern dryers are using a heat pump with an outdoor source to raise the temperature of the clothing instead of burning gas or "burning" electricity with resistive heating.
That said, a 2x efficiency gain, by whatever method, is more than I expected, though still falling into what I would categorize as "not much room", especially if the gain comparison always assumes the oldest, least-efficient 5kW model only ever running at its highest setting. The other key assumption in all these comparisons is that all these dryers can finish the same sized load in the same amount of time, which can't possibly be true in the real world.
If my $40-to-repair machine already has some efficiency tweaks such that its worst-case is only 4kW, the $500 machine's worst-case is 2.5kW, but my actual behavior averages out to running them at 70% power, I'm saving barely over a kilowatt per hour, and I'm back up to 3500 hours to break-even at $.12/kWh electric rates. $1800-for-1kW is nearly 14k hours, or nearly 18 hours a week over fifteen years, and I don't do that much laundry.
[1] If this is so, it strikes me as odd to call it that, just as it would strike me as odd to call out a free-standing dehumidifier having a "heat pump", even though that's the crucial to the device functioning.