ERV unit

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nizak

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I am being told by the general contractor that I work for that he will no longer be using whole house ERV units.

He is telling me that his HVAC contractor is going to utilize the bath and laundry exhaust fans to accomplish this.

I asked what I need to do since I supply and wire the fans.

He said nothing on my end. His HVAC guy will take care of it.


The HVAC contractor doesn't even know what size or type units I'm installing.

What am I missing here?
 
nizak said:
I am being told by the general contractor that I work for that he will no longer be using whole house ERV units.

He is telling me that his HVAC contractor is going to utilize the bath and laundry exhaust fans to accomplish this.

I asked what I need to do since I supply and wire the fans.

He said nothing on my end. His HVAC guy will take care of it.


The HVAC contractor doesn't even know what size or type units I'm installing.

What am I missing here?
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bet he don't do that for very long... as houses get tighter and tighter, the need for mechanical ventilation increases. Expecting regular ol bath fans to provide that ventilation on a tight house is like expecting your wife's hair dryer to work with a completely blocked intake. It just won't work and he'll figure it out after the first lawsuit or two...
 
Sounds to me like all that means is HVAC guy is taking care of fresh air needs - may not be ERV type of application though. Fresh air inlet into HVAC system is certainly a start on this, but at same time if you bring air in some has to go out....

Same with your bath ventilation to some extent. Pull air out, some has to come in, tighter sealed the building is the more important it is to pay attention to this. Even the laundry vent would need make up air if house is tight enough.
 
OK, I'll bite.

I always call an Energy Recovery Unit an ERV. Are you guys talking about something completely different?

If not, how could an exhaust fan do energy recovery?
 
Poking around Google I see that ERV's are typically integrated with the HVAC system, but they are not just exhaust fans. I don't think the GC is fully up to speed here.
 
steve66 said:
OK, I'll bite.

I always call an Energy Recovery Unit an ERV. Are you guys talking about something completely different?

If not, how could an exhaust fan do energy recovery?
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It doesn't. Op never said they won't be ventilating structures, just that there wouldn't be ERV's. Don't know any more details though.

If there is energy codes to comply with, and they are being enforced, ERV may be a requirement to have if you are using such ventilation.
 
An ERV exhausts air, and brings in makeup air. It also transfers energy (heating or cooling) from the exhaust air to the makeup air. So the fresh air being brought in is tempered, and isn't the same as the outdoor temperature. Exhaust fans only do 1 of those 3 things.

So it seems to me that the statement:

"We don't need ERV's anymore -We are going to use exhaust fans instead"

makes about as much sense as saying:

"We don't need electrical anymore, We are going to use plumbing instead."

They are apples and oranges.
 
steve66 said:
An ERV exhausts air, and brings in makeup air. It also transfers energy (heating or cooling) from the exhaust air to the makeup air. So the fresh air being brought in is tempered, and isn't the same as the outdoor temperature. Exhaust fans only do 1 of those 3 things.

So it seems to me that the statement:

"We don't need ERV's anymore -We are going to use exhaust fans instead"

makes about as much sense as saying:

"We don't need electrical anymore, We are going to use plumbing instead."

They are apples and oranges.
Click to expand...

 
I think the point is that depending on the climate and on the cost of installing an ERV, an exhaust-only ventilation strategy using a bath fan can be cost effective.

Cheers, Wayne
 
steve66 said:
An ERV exhausts air, and brings in makeup air. It also transfers energy (heating or cooling) from the exhaust air to the makeup air. So the fresh air being brought in is tempered, and isn't the same as the outdoor temperature. Exhaust fans only do 1 of those 3 things.

So it seems to me that the statement:

"We don't need ERV's anymore -We are going to use exhaust fans instead"

makes about as much sense as saying:

"We don't need electrical anymore, We are going to use plumbing instead."

They are apples and oranges.
Click to expand...
Oranges and and grapefruits maybe. They both are there to exhaust air. The ERV does temper the air hence the "energy recovery" in it's name. If house is so tight that makeup air can't get in - then exhaust fan doesn't really exhaust either. Especially the typical low power bath fans. Put a 25 HP grain aeration blower in and you might find some makeup air the little bath fan can't suck in. Might have hard time opening or closing doors or windows while running also.:cool:
 
I believe 600 cfm is a magic number for exhaust hoods. Don't know how big a high end kitchen with a fancy hood would draw, but I have heard talk of make up air being needed in some tight high end homes.
 
GerryB said:
I believe 600 cfm is a magic number for exhaust hoods. Don't know how big a high end kitchen with a fancy hood would draw, but I have heard talk of make up air being needed in some tight high end homes.
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An ERV is simply drawing in about same amount of fresh air as it is exhausting. some may be ducted to take air out of bathrooms as you often want air drawn from there anyway, but certainly woulnd't have to be. They are about bringing in fresh air more then they are about exhausting anything specific, and happen to be designed to exchange heat between incoming and outgoing air to lessen HVAC needs. They don't recover 100% but still helps compared to direct inlet and outlet.
 
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