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Old Today, 04:34 AM   #2041
Steve
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Originally Posted by marting View Post
Depends. It removes moisture from the inside air in cooling mode. In the heating mode it removes moisture from the outside air and only warms inside air. That's for air based source/sinks. Some use buried or pond sink/sources. These also can remove water vapor from the indoor air when they are cooling depending on humidity levels.
Well,

"When the heat pump is working in cooling mode, the room will automatically dehumidify. In heating mode, there is no need for the heat pump to dehumidify. The warm air that circulates around the room removes the moisture:.


https://www.heatandcool.co.nz/faqs/w...ng%20system%3F

There a numerous other sources that say the same thing. Heat pumps actually dry the air to some degree in either mode.
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Old Today, 05:11 AM   #2042
jadebox
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Originally Posted by Steve View Post
Well,

"When the heat pump is working in cooling mode, the room will automatically dehumidify. In heating mode, there is no need for the heat pump to dehumidify. The warm air that circulates around the room removes the moisture:.

Where does the moisture go? :-)



Warm air doesn't remove the moisture. It is less dense than cold air, so it can contain more moisture. So, warming the air will reduce the relative humidity, not the actual amount of moisture.



What effect, if any, that would have in the virus or your ability to catch or spread it is beyond me.
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Old Today, 05:46 AM   #2043
Steve
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Originally Posted by jadebox View Post
Where does the moisture go? :-)



Warm air doesn't remove the moisture. It is less dense than cold air, so it can contain more moisture. So, warming the air will reduce the relative humidity, not the actual amount of moisture.



What effect, if any, that would have in the virus or your ability to catch or spread it is beyond me.
Very basically, during the heating cycle, moisture from the outdoor air is condensed on the outside surface of the coil where it gathers and runs off. The air that the heat pump heats and pushes into the house is less humid than the outside air. Given sufficient infiltration/exfiltration due to pressure imbalances the humidity of the indoor air will become uniformly lower than outdoors.

There is much technical info that is easily searchable if you remain curious.

re the virus - this is just a bit of thread drift. I am content to drop it.
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Old Today, 07:06 AM   #2044
marting
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Originally Posted by Steve View Post
Well,

"When the heat pump is working in cooling mode, the room will automatically dehumidify. In heating mode, there is no need for the heat pump to dehumidify. The warm air that circulates around the room removes the moisture:.


https://www.heatandcool.co.nz/faqs/w...ng%20system%3F

There a numerous other sources that say the same thing. Heat pumps actually dry the air to some degree in either mode.
That's correct as far is it goes, but heat pumps in the warming mode are no different from regular gas/electric heaters that warm the air. Conventional HVACs do exactly the same thing.

Buildings in colder climates are typically more insulated and usually have less outside air mixing because of efficiency concerns. This re-cycled, relatively dry air is what makes for an ideal environment for Covid-19 airborne virus to accumulate. So these regions can have higher spreads as fall/winter approaches.
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Old Today, 07:16 AM   #2045
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Originally Posted by marting View Post
That's correct as far is it goes, but heat pumps in the warming mode are no different from regular gas/electric heaters that warm the air. Conventional HVACs do exactly the same thing.

Buildings in colder climates are typically more insulated and usually have less outside air mixing because of efficiency concerns. This re-cycled, relatively dry air is what makes for an ideal environment for Covid-19 airborne virus to accumulate. So these regions can have higher spreads as fall/winter approaches.
Which answers the point. The claim was the the heat pump dries the air differently than the wall heater.
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Old Today, 04:54 PM   #2046
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At long last we may soon have a definitive answer on droplets and aerosols: https://www.theguardian.com/world/20...ive-in-the-air
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Old Today, 06:23 PM   #2047
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Originally Posted by The Atheist View Post
At long last we may soon have a definitive answer on droplets and aerosols: https://www.theguardian.com/world/20...ive-in-the-air
I don't care how long it survives. I only care how long it can still make people sick. Those are two different specs.
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Old Today, 06:38 PM   #2048
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Originally Posted by The Atheist View Post
At long last we may soon have a definitive answer on droplets and aerosols: https://www.theguardian.com/world/20...ive-in-the-air
Interesting. However, the only way to suspend aerosols between two rings using electrostatic fields is to imbue the aerosol particles with a charge, and that charge would create a significant electric field at the surface of the particle. The smaller the particle, the larger the field. I have no idea how that would affect the virus's stability but it's certainly not a normal condition in aerosols as any tiny particle with a net charge will strongly attract to nearby surfaces. Much bigger effect than gravity at aerosol sizes.

What work have they done to verify that these aerosol particles with a net charge remain as viable? If this has been tested, it might be a great way to test SARS-CoV-2.
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Old Today, 06:43 PM   #2049
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What's usually done and could be done in this case is put minks in cages at various distances and expose them to aerosols of various droplet size.
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Old Today, 07:20 PM   #2050
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Possible Herd Immunity in Manaus, Brazil
https://www.medrxiv.org/content/10.1...787v1.full.pdf

Quote:
Here we show that the transmission of SARS-CoV-2 in Manaus, located in the Brazilian Amazon, increased quickly during March and April and declined more slowly from May to September. In June, one month following the epidemic peak, 44% of the population was seropositive for SARS-CoV-2, equating to a cumulative incidence of 52%, after correcting for the false-negative rate of the antibody test. The seroprevalence fell in July and August due to antibody waning. After correcting for this, we estimate a final epidemic size of 66%.
An interesting data point is that IgG levels fell quickly in succeeding months:

Quote:
Excluding extreme negative samples (<0.4 S/C), the median assay signal fell steadily from May onwards: 3.9 (May), 3.5(June), 2.3 (July) and 1.7 (August)
This suggests serological surveys in regions strongly hit in the first wave may understate the percentage of the population actually immune.

From the Discusson:
Quote:
Our results show that between 44% and 66% of the population of Manaus was infected with
SARS-CoV-2 through the course of the epidemic. The lower estimate does not account for
false-negative cases or antibody waning; the upper estimate accounts for both. The elevated
mortality and the rapid and sustained drop in cases (Figure 2A and S4) suggest population
immunity played a significant role in determining the size of the epidemic in Manaus.
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