ERV requirements
Russell Cooke| Posted inMechanicalson
I am starting process of researching ERV for my Northern FL home. Have 1400 sf ranch, central AC/heat. Return is a single (centrally located) location. Home built in 2005, so reasonably insulated but definitely nothing exceeding minimum code for insulation. My air handler is out in garage in closet like many FL homes, so space is somewhat of an issue. Can you make sizing recommendations? There are two occupants as well as two small dogs.
Will likely be upgrading the air conditioning system in entirety in next few years (salt air kills the outdoor compressor units) but I don’t want to wait for that eventuality. Thanks, Russ
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Replies
Russell,
Here is a link to an article that will help answer questions about your ventilation system:Designing a Good Ventilation System.
According to ASHRAE 62.2 (the best-known residential ventilation standard), a 1,400-square-foot home requires a ventilation system rated at 57 cfm if the house has 2 residents; or 65 cfm if the house has 3 residents; or 72 cfm is the house has 4 residents; or 80 cfm if the house has 5 residents.
It sounds from your question as if you assume that a ventilation system needs to be connected to your air conditioning system. But providing ventilation is not the same as providing cooling, so in many cases, these two systems -- the ventilation system and the cooling system -- are entirely separate.
What lead you to the conclusion that you need an ERV now? Before worrying about how big an ERV needs to be, make sure that the symptoms you hope to correct are attributable to inadequate ventilation. If the symptoms are actually a result of excessive unintentional ventilation (usually called infiltration), than an ERV won't help.
You might try purchasing a portable CO2 meter to see what your typical CO2 level is in the house. (CO2 is a surrogate for other indoor air quality metrics.) Then, run a bathroom fan continuously for awhile and see how much that changes the CO2 levels. There are a lot of factors that influence short term CO2 levels, so you would want to repeat the experiment quite a few times before drawing conclusions.