I am not one of those guys with a lot of letters behind my name. All of what you are about to read are my own thoughts on the subject based on my thirty years of experience in the field of HVAC distribution and you are getting exactly what you are paying for. I have to generalize a bit so your particular HVAC system may not be described in full – the universe is simply too large. Even if you follow this advice, you still might get covid. Forward.
There have been a lot of articles recently about the virus and how it transmits and moves around in air currents, in particular the ones that are created by HVAC systems in your domicile or your place of work. Some of these articles have been pretty decent, and a lot of them pretty dismal. Below are my thoughts on the virus. A lot of this is based on our past experience in the industry when anthrax was all the rage.
There are three main ways to lower your chances of meeting the virus up close and personal, as relates to HVAC systems. These are in my order of preference:
1. Dilute it
2. Zap it
3. Trap it
1. Dilute it – everyone knows you are “safe” if you are outside, even if you don’t wear a mask. Why is this? Because covid needs a bunch of “them” to get into “you” and if you are outside, there are naturally fewer of “them” around because there is so much free air diluting “them”. The fewer of “them” that can get into “you”, the lower your chance of getting the disease. In most single family dwellings, fresh air isn’t introduced enough. In the energy conserving decades of the seventies and eighties, we tightened up our structures and this practice continues to this day. While saving energy, the same stale air circulated through your house eventually is actually quite bad for you, and if you toss in the off gassing of new carpets or floors or drywall, it is even worse. Energy Recovery Ventilators and Heat Recovery Ventilators are code in some parts of the country, but not in most. These devices introduce fresh air into a house, exchanging the heat or air conditioning and exhausting the stale air. Very good items to have, but expensive. If you live in a residence I would highly recommend one if practical. Also, LEAVE YOUR BLOWER ON 24 hours a day. Most modern HVAC systems don’t consume all that much energy and your air filtration equipment simply doesn’t work if there is no air moving over it. In commercial buildings with rooftop units, the economizer is what brings in fresh air into a structure. Many times the economizers are broken and never fixed. Sometimes they are. If you live in a high rise, you have fewer options. If you can, open the windows. Obviously in extremely hot and cold climates, it is harder to make air exchange energy efficient or opening windows practical. In other words, you can’t bring zero or one hundred degree air into a structure for pretty much any reason, to keep it short.
2. Zap it – There are two main ways to kill covid in an HVAC system. I put both of these in the “zap it” category. You can put a UV light in the air stream (again, it doesn’t work if you don’t have your fan on) or put in a bipolar ionizer. UV lights are pretty self explanatory – they have been proven to work on heartier viruses than covid but not actually tested against covid. Also, as you can imagine, demand is intense right now. The other technology is bipolar ionization – on a simple level, these machines create ions that attach themselves to the virus and deprive it of hydrogen so it dies. Demand is also very strong for these. The commercial versions have been tested against covid and are effective.
3. Trap it – I have seen articles in the MSM about MERV 13 filters. The articles are, amazingly, mostly correct, with one very large problem. They are correct in the fact that MERV 13 filters (to keep it simple, MERV is an efficiency rating) will trap the virus (and it will die in a day or two after sitting on that filter). The problem is that demand right now for MERV 13 filters is so high that it is unlikely that you can find one. I work with four filter vendors and as of this writing, their lead times stack up like this:
Company 1 – not taking orders, back orders fulfilled in 12-16 weeks
Company 2 – taking orders, lead time 12 weeks
Company 3 – taking orders, lead time 12 weeks
Company 4 – not taking orders, back orders fulfilled maybe next year
We are recommending our customers who want MERV 13 filters to purchase a full years supply at once and store them. The issue is that the same companies that make the media for PPE are the companies that make media for MERV 13 filters and sell it to the filter manufacturers. Guess what is getting priority?
That is basically it and I am sure I have left out a lot as the HVAC universe is large. You really have nothing to fear from your HVAC system. Face to face contact is a far greater concern. I will attempt to answer any specific questions you may have in the comments. Keep it civil, as I freely delete nasty or insulting comments.