Air Exchangers 101 - An Introductory Guide to Residential Air Exchangers
Do I NEED an air exchanger for my home?
If you want to:- Save money on home heating and cooling costs
- Breathe clean, fresh, and safe air in your home all year round
- Reduce the likelihood of developing dangerous mold and bacteria growths
Then the answer is definitely YES, you need an air exchanger in your home. No matter whether you live in an apartment, condo, row house, or standalone home, your home, wallet, and, most importantly, your health, will all benefit from the installation of a modern residential air exchanger.
How does a residential air exchanger work?
Older buildings used to leak stale inside air to the outside and would simultaneously allow in fresh outside air, creating a sort of natural ventilation throughout your home. However, modern houses, condos, and apartments built to much higher standards than previously are much more air tight and as such, modern homes don’t ‘breathe’ on their own anymore. Thus, you need an air exchanger to exhaust stale indoor air and replace it with fresh, high-quality outdoor air.
To get a better understanding of the flows through an air exchanger, let’s take a closer look at the visual example below.
During the heating season, fresh air from outside (#2) is drawn into the air exchanger core, where it meets with stale air from inside the home (#3). Inside the core, energy and/or heat is transferred from the warm, stale air to the incoming cool, fresh air, warming the cooler air before the next step. The fresh air is then distributed throughout your home (#4) through your ducting and/or your forced-air heating/air conditioning system. The now-cooler, stale air is exhausted to the outside (#1).
What are the types of residential air exchangers?
There are two main types, or designs, or residential air exchangers available on the North American market. The most common for across Canada, and colder regions in general, is the Heat Recovery Ventilator, or, HRV for short. The other design is the Energy Recovery Ventilator, or, ERV.
Both types fulfill the same basic air exchanging function but they do differ significantly in how they exchange energy or heat in the core of the exchanger. This also impacts the control of humidity levels inside your home.
Do I need an HRV or an ERV?
This is THE most common question we get regarding residential air exchangers. And, understandably so! This isn’t as straightforward a question to answer as it would first appear. Let’s start with the basics of how an air exchanger works, and then we will work towards which type you need.
What is the difference between an HRV and an ERV?
A HRV and ERV both exchange the air in your home, and have similar designs – on the outside. The REAL differences between the two designs is in HOW they exchange heat, or energy, inside the core of the air exchangers.
The core in Heat Recovery Ventilator allows for the transfer of heat from the outgoing stale, warm air to the incoming cooler, fresh air. However, the core in a HRV will not allow the transfer of moisture, or humidity, between the two air streams. Thus, if you have high humidity in your home, this excess moisture is expelled with the outgoing stale air.
The core in an Energy Recovery Ventilator works in much the same way as for the HRV, but instead of just allowing the transfer of heat energy across the core, the ERV core also enables the transfer of a high percentage of heat and moisture between the incoming and outgoing air streams.
In both cases the transfer of energy or heat between the outgoing and incoming air streams will lessen the loads on your home HVAC (heating, ventilation, and air conditioning) system.
The three below images, compliments of Venmar, help to visualize this process for us.
Heat & Moisture transfer inside a Venmar HRV Core
I live in _______ - do I need a HRV or an ERV?
Multiple manufacturers, such as Aldes and Lifebreath, provide a generalized map to recommend an ERV or a HRV based solely on geographical location (see images below), but, THIS IS NOT your only consideration when deciding which to go with!
Why choose a Heat Recovery Ventilator (HRV)?
HRVs are best suited for homes in dry and cold climates with excess humidity during the heating season. HRVs enable the removal of that excess moisture, thus preventing the build-up of moisture in your home and significantly reducing the chances of dangerous mold and bacteria growths.
Why choose an Energy Recovery Ventilator (ERV)?
An ERV is best used in either colder climates where there is no excess moisture in the home during the heating season, or, in homes located in warmer climates where the outside humidity levels are high.
What size of an air exchanger do I need?
Residential air exchangers are rated based on the maximum provided volume of airflow, measured in CFM (cubic feet per minute). Our offered air exchangers can all run at variable speeds, meaning if you buy a 130 CFM air exchanger, the maximum air flow will be 130 CFM while the unit can also run at lower speeds to provide only the required amounts of air.
If you are not making (major) changes to your homes HVAC or ventilation system, you can often times get away with replacing your old unit with a similarly sized new unit. However, if there have been changes in your system (think of home additions or renovations), there is a good chance you require a different sized air exchanger.
Still not exactly sure what size or model you need? Don’t hesitate to contact our team! Contact us online 24/7, or give us a call Monday through Friday during standard business hours and we will be glad to help.
Additional Information about Air Exchangers
Most major manufacturers have substantial amounts of information available on their websites to help you better understand residential air exchangers and your options. Some of our favourite references are here: