COVID 19 and HVAC....problem ?

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Old 04-08-20, 04:25 PM
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COVID 19 and HVAC....problem ?

Let's say someone in our house has active virus, confirmed via a test and is quarantined in a room or basement or whatever. It is cold and heat pump is running. If airborne particles via a cough or sneeze get to a return vent and is cycled back into the house......is that a problem ?
 
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04-09-20, 05:11 AM
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Is it possible to transmit the COVID-19 virus via indoor air circulation systems?
This question has come up a lot with my customers over the last month.
The answer is yes.
However, it isn’t easy for the molecules of the virus to make it completely through the system and make it out alive to infect others. The chance of infection in this manner is very low.
At an average size of 0.12 microns the germ is easily small enough to make it through average air filters. And it’s not feasible to use ultra restrictive HEPA style air cleaners in (most) equipment.
If at all possible, if someone is a known positive, get them out of the house to another location to quarantine.
If this is not possible put them in a closed room and make sure the room is cleaned and sanitized regularly. Tape cheap filter material to any returns in the room and treat the material with disinfectant (NOT bleach).
But, if the person has been living in the space with others, and then starts showing symptoms, it’s likely already become contagious and been spread to others in the household. The virus is contagious without showing symptoms.
Being in the hvac field, and working in hospitals, health clinics and other “ground zero” type areas during this outbreak, I’ve been taking my temperature twice daily to try and catch it early if I were to contract it. I have small children at home that I don’t want exposed.
 
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Old 04-08-20, 06:09 PM
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In theory, yes. In reality, I don't think so. The CDC tells us to say 6' apart. That tells me that the airborne particles can only stay airborne for a short time.
 
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Old 04-09-20, 03:20 AM
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I don't agree. Actually I do agree but not for the same reason. In a forced air heating system the air particles are being swept along with air currents. An open sneeze in room travels about 4 -5 feet with no air currents. With flowing air they are swept along with the current.
This where a decent filter can play a big part in controlling air born particles.
If a family member has the virus or possibly is a carrier, make sure no fans are being used as the weather begins to warm up.
 
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Old 04-09-20, 05:11 AM
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Is it possible to transmit the COVID-19 virus via indoor air circulation systems?
This question has come up a lot with my customers over the last month.
The answer is yes.
However, it isn’t easy for the molecules of the virus to make it completely through the system and make it out alive to infect others. The chance of infection in this manner is very low.
At an average size of 0.12 microns the germ is easily small enough to make it through average air filters. And it’s not feasible to use ultra restrictive HEPA style air cleaners in (most) equipment.
If at all possible, if someone is a known positive, get them out of the house to another location to quarantine.
If this is not possible put them in a closed room and make sure the room is cleaned and sanitized regularly. Tape cheap filter material to any returns in the room and treat the material with disinfectant (NOT bleach).
But, if the person has been living in the space with others, and then starts showing symptoms, it’s likely already become contagious and been spread to others in the household. The virus is contagious without showing symptoms.
Being in the hvac field, and working in hospitals, health clinics and other “ground zero” type areas during this outbreak, I’ve been taking my temperature twice daily to try and catch it early if I were to contract it. I have small children at home that I don’t want exposed.
 
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Old 04-09-20, 06:01 AM
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Transmission through ventilation ducts and HVAC systems has been suspected on several of the cruise ships with COVID so I have to assume it's possible at home as well. I think public officials are afraid of making this statement too loudly as home care is really the only option for most patients.
 
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Old 04-09-20, 06:07 AM
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I'm not an expert in either the virus or HVAC systems but it does seem that there's at least a possibility of spread. That being the case, just eliminate the possibility by closing the supply vent in the room or area. There's products available but, given the situation, you can cover the supply vent with a piece of cardboard and some tape if it can't be closed in any other way.

Keep in mind, though, that systems are balanced so you should be mindful of this. Perhaps someone can comment on whether it's necessary to close one or two return vents, as well. I don't believe that's the case under most circumstances.
 
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Old 04-09-20, 06:15 AM
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PD, I think you're spot on with your assessment of why not much has been mentioned.

Locally we have skilled nursing and subacute rehabilitation facility for residents living with a diagnosed condition or requiring medical supervision. That facility has been breached and almost all the staff and residents are affected. I can't believe that they did not take action early on. My son was in that facility when he was in rehab for his stroke. Security in terms of who and when a person could enter was very relaxed.
 
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Old 04-09-20, 09:20 AM
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I'm pretty lucky. Our house has a master suite that can be easily closed off to create an isolation ward. I also have a two hose portable air conditioner that can be pressed into service for the quarantine suite so I can close that area off to the house's HVAC. Unfortunately I don't think many people are so lucky.
 
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Old 04-09-20, 10:26 AM
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Although the virus could be spread thru the HVAC systems.... I would think that if there was an infected person within a home....there would be a good chance all would have the virus.
 
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Old 04-09-20, 11:14 AM
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Yes PJ, it's almost inevitable.
The question becomes paramount in places other than a home. An office, a store, an airplane, prisons, hospitals. Any place where air is recirculated and put back into the public breathing area. One would expect to catch the virus or any virus at home via close contact or recirculated air. But few of us think about public places that most likely has recirculated air. Especially an air conditioned place.
 
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Old 04-09-20, 11:20 AM
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One final way to assist with flu and coronavirus prevention is to install a MERV 13 rated air or furnace filters,

Pretty pricey!
 
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Old 04-09-20, 12:25 PM
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One final way to assist with flu and coronavirus prevention is to install a MERV 13 rated air or furnace filters,

Pretty pricey!
So it makes one question is it cost effective. Most likely not in the home, assuming no other underlying respiratory problems. But now is it cost effective in public enclosures? And most assuredly the cost would trickle down to all our products and services.
 
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