Home ERV Air Exchanger FAQs

Air Exchanger

Home ERV Air Exchanger FAQs

Do I really need an ERV home air exchanger?

To ensure proper indoor moisture levels, every home needs to bring in fresh air to replace stale air.  In older homes, there is enough air leakage through the walls and around the windows to replace the air in the house.  Newer, more energy efficient homes, are much tighter and do not leak as much air.  In these homes, an ERV home air exchanger will ensure a healthier and more comfortable indoor environment. Some states are changing their building codes requiring that air exchanger systems be used.

Is an ERV air exchanger an expensive home improvement?

It all depends on the model, size and features of the air exchanger, and how complex the installation will be. Costs, which range from $1000 to around $2500, are lower when included in the building of a new home, and understandably higher to retrofit.

Is an ERV air exchanger expensive to operate?

An ERV air exchanger needs electricity to run the fans but, it also recovers some of the heating/cooling that would normally be lost.  Estimates to run a home ventilation system range from $80 – $90 per year.  Using an ERV air exchanger adds about $100 to your overall utility bill.

What features should I look for? 

First decide if you want a ventilator or if you want to use an ERV air exchanger.  Ventilators, because they do not have the equipment to transfer the heat between the air streams, tend to be more inexpensive.  These units may offer single or multiple speed controls, pollutant sensor controls and variety of filtering options.  ERV air exchangers tend to offer additional features such as humidity regulation, and pre-heaters to prevent ice buildup.

How do I compare different models?

Ventilation systems are typically tested and rated for performance.  Look for a certification from an independent laboratory such as the Home Ventilation Institute (HVI).  Typical specifications to look at when comparing models include:  airflow capacity (usually measured in cubic feet per minute – CFM), recovery efficiency of the recovery core, sone level of the fans, and warranty coverage on parts such as fans, cores, and controls.

How does an ERV air exchanger work?

The incoming fresh air is moderated in the energy recovery core.  The core is typically made up of a series of thin plates of aluminum or plastic.  In a warm climate, An ERV air exchanger transfers cold exhaust air temperatures to incoming warm air temperatures and visa versa in cold climates.  Unlike a  HRV, an ERV also transfers incoming humidity to the outgoing airstream in warmer climates.  In this way, humidity levels are maintained by a rotating wheel or with desiccant material.

Do I still need kitchen and bathroom exhaust fans?

In typical homes, you would still want to use kitchen and bathroom exhaust fans.

Will I still need to use a dehumidifier?

If the air exchanger that you rare installing provides humidity regulation, then you may not need a dehumidifier. Remember though that an ERV air exchanger works on your entire home, and if you have areas in the home that are especially damp (like a basement), then the system may not be able to handle the load and you may still need to use a dehumidifier.

What size ERV air exchanger should I get?

Most new building codes require a minimum airflow of 15 CFM/bedroom plus an additional 15 CFM.  So for a four bedroom house you would want to get a system that has a minimum capacity of 75 CFM.  Additional ventilation may be needed for special needs such as bathrooms and kitchens or in homes with damp basements.

What routine maintenance will I have to perform?

Always check your owner’s manual but for most systems you will need to clean or replace air filters about once every 1 – 3 months.  Check that the ducts are not blocked at least once every year. For ERV air exchangers, you will need to clean the recovery core and drain mans about every 6 months.  Finally, you need to make sure that the system is properly balanced, and for that you should hire a professional, at least once every 12 – 18 months..

Do I really need fresh air in my home?

Humans are unable to detect low levels of contaminants in their air.  So even though the levels in your home may be small, over time they may represent a significant health hazard.  So to be safe, it makes sense to simply ensure that the minimum amount of fresh air required for good health is provided at all times.

How much fresh air is needed in a home?

Current building codes require that all the air in a home be exchanged 3-4 times every hour (ACH). Because modern homes are built tighter (a term that indicates a smaller rate of ACH), air has to be introduced mechanically to meet code.  To figure out exactly how much air is needed, requires a blower door test should be performed by a professional. The alternative is to simply provide enough air to safely exceed the code requirement. There is after all, no such thing as getting too much fresh air.

What are the negative health effects of not enough fresh air in a home?

Everyone is different.  Some people may experience health effects from indoor air pollutants immediately while others may not notice any symptoms for years.  Pollutants in indoor air can cause irritation of the eyes, nose, and throat, headaches, dizziness, and fatigue.  These symptoms are usually short and can be treated by simply removed the pollutants from the air.  Other diseases, such as asthma, hypersensitivity pneumonitis, heart disease, and cancer fever, may take years to develop but when they do occur they are much more difficult to treat.

Air Exchanger

Please continue reading my ERV – 3 product review and visit my ERV Store.  Also see my other review posts for this green living product: 

Fifteen best features of an ERV.

How an ERV works.

Ten reasons why an ERV is green.

Tips and tricks for ERVs.

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