Mitsubishi air source heat pumps

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Someone asked for link:
https://www.mitsubishicomfort.com/benefits/hyper-heating


There has to be a catch.  How can they efficiently extract heat from
such cold air?  I'm eager to learn details and see evaluations.
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On 22 Mar 2021 at 11:33, Willie via EV wrote:

> How can they efficiently extract heat from such cold air?  I'm eager
> to learn details and see evaluations.

They can indeed extract heat, but I'm not so sure "efficiently" necessarily
applies.

I have a Mitsubishi Mister Slim M series mini-split.  It's supposed to
produce 100% of its rated output at 5 deg F and significant heat to -13F.  
Anecdotally, that seems to be the case.  Certainly there is still plenty of
output.  However from what I've read the COOP falls apppreciably at those
temperatures.  Generally when temperatures fall into the single digits F, I
switch over to separate resistive baseboard heat to give it a break.

David Roden, EVDL moderator & general lackey

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They can't, I don't care what they say. The laws of physics still apply.
The "heat" that is being discharged might be 60F which is hot compared
to 0F. They would have to circulate thousands of cubic yards of 0F air
to obtain even a tiny amount of "heat".

> Someone asked for link:
> https://www.mitsubishicomfort.com/benefits/hyper-heating
>
>
> There has to be a catch.  How can they efficiently extract heat from
> such cold air?  I'm eager to learn details and see evaluations.
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> On Mar 22, 2021, at 7:17 PM, EVDL Administrator via EV <[hidden email]> wrote:
>
> On 22 Mar 2021 at 11:33, Willie via EV wrote:
>
>> How can they efficiently extract heat from such cold air?  I'm eager
>> to learn details and see evaluations.
>
> They can indeed extract heat, but I'm not so sure "efficiently" necessarily
> applies.
>
> I have a Mitsubishi Mister Slim M series mini-split.  It's supposed to
> produce 100% of its rated output at 5 deg F and significant heat to -13F.
> Anecdotally, that seems to be the case.  Certainly there is still plenty of
> output.  However from what I've read the COOP falls apppreciably at those
> temperatures.  Generally when temperatures fall into the single digits F, I
> switch over to separate resistive baseboard heat to give it a break.

…and if you look at the accessories Mitsubishi offers for that line of air handlers, like the very first one is a supplemental resistive heating insert.

                               -Bill

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On Mon Mar 22 16:57:39 PDT 2021 [hidden email] said:
>They can't, I don't care what they say. The laws of physics still apply.
>The "heat" that is being discharged might be 60F which is hot compared
>to 0F. They would have to circulate thousands of cubic yards of 0F air
>to obtain even a tiny amount of "heat".

Just depends on the system involved.  0F is WAY above absolute 0.
It's quite possible to make a heatpump that works with a large temperature difference.
It's not going to get a 20x factor like most, but I'm quite sure that you can make one that is > 1.



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John Lussmyer via EV wrote:
> Just depends on the system involved.  0F is WAY above absolute 0. It's
> quite possible to make a heatpump that works with a large temperature
> difference. It's not going to get a 20x factor like most, but I'm quite
> sure that you can make one that is > 1.

Bingo! :-) I think that's the right answer.

"Efficiency" is a measure of how close to the ideal you can get. So you
can have a heat pump that is very efficient at pumping heat up a large
gradient (like from 0 deg.F to 70 deg.F). It's not going to have a COP
of 20; but more like 2.

Still, that would be better than a resistive heater with a COP of 1.

Lee Hart

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just playing; they're experimenting, building and learning. That's
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Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com

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On 3/22/21 12:33 PM, Willie via EV wrote:
> Someone asked for link:
> https://www.mitsubishicomfort.com/benefits/hyper-heating
>
>
> There has to be a catch.  How can they efficiently extract heat from
> such cold air?  I'm eager to learn details and see evaluations.


Here is one explanation:
Mitsubishi's Hyper-Heating H2i®

Mitsubishi's hyper-heating H2i® compressor motor signals that a burst of
heat is needed when the temperature gets below 40°F. Depending on the
temperature, the motor revs up accordingly and the system absorbs the
additional heat thrown off the compressor magnets. After the extra heat
is absorbed, it's funneled to the back of the blower.

That process supercharges your heat output. That's how Mitsubishi's
hyper-heating H2i® inverter compressor matches the heat that's needed
and quickly responds to the dropping temperature outside.

Also with Mitsubishi's “flash injection” bypass circuit, you avoid the
problem of decreasing amounts of refrigerant at sub-zero temperatures.
Flash injection helps increase the amount of the refrigerant circulating
between the indoor and outdoor units.

Refrigerant flow is increased when refrigerant is bypassed to the
compressor. It gives the system more stable and continuous heating -
even down at extreme temperatures. That's why Mitsubishi's hyper heat
systems can provide 100% of their rated capacity all the way down to 23°
F when other heat pumps can't.

https://gotductless.com/blogs/mitsubishi/hyper-heat-feature-review

So sounds like they add more refrigerant to compensate for cold weather,
and also use some excess heat form the compressor motor to pre-heat
things.

Jay
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Thanks for the VERY informative information!  "Hyper heat" seems to have
become a common label applied to air source heat pumps that can produce
heat down around zero F; other brands than Mitsubishi offer them.

I have the unconfirmed impression that the "hyper heat" heat pumps are
better at low temperature heat production than the resistive heat add ons.

On 3/23/21 10:40 AM, Jay Summet via EV wrote:

>
> On 3/22/21 12:33 PM, Willie via EV wrote:
>> Someone asked for link:
>> https://www.mitsubishicomfort.com/benefits/hyper-heating
>>
>>
>> There has to be a catch.  How can they efficiently extract heat from
>> such cold air?  I'm eager to learn details and see evaluations.
>
>
> Here is one explanation:
> Mitsubishi's Hyper-Heating H2i®
>
> Mitsubishi's hyper-heating H2i® compressor motor signals that a burst of
> heat is needed when the temperature gets below 40°F. Depending on the
> temperature, the motor revs up accordingly and the system absorbs the
> additional heat thrown off the compressor magnets. After the extra heat
> is absorbed, it's funneled to the back of the blower.
>
> That process supercharges your heat output. That's how Mitsubishi's
> hyper-heating H2i® inverter compressor matches the heat that's needed
> and quickly responds to the dropping temperature outside.
>
> Also with Mitsubishi's “flash injection” bypass circuit, you avoid the
> problem of decreasing amounts of refrigerant at sub-zero temperatures.
> Flash injection helps increase the amount of the refrigerant circulating
> between the indoor and outdoor units.
>
> Refrigerant flow is increased when refrigerant is bypassed to the
> compressor. It gives the system more stable and continuous heating -
> even down at extreme temperatures. That's why Mitsubishi's hyper heat
> systems can provide 100% of their rated capacity all the way down to 23°
> F when other heat pumps can't.
>
> https://gotductless.com/blogs/mitsubishi/hyper-heat-feature-review
>
> So sounds like they add more refrigerant to compensate for cold weather,
> and also use some excess heat form the compressor motor to pre-heat things.
>
> Jay
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On 3/23/21 12:11 PM, Willie via EV wrote:

>
> I have the unconfirmed impression that the "hyper heat" heat pumps are
> better at low temperature heat production than the resistive heat add ons.
>


Heat pumps are almost always more efficient that a restive heat element.
  However, when the temperature gets cold enough outside, they may not
be able to produce as many BTU's as your house needs (lack of supply),
so they turn on the "emergency" resistive heating elements to keep up
with the demand.

Jay
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