Heat Recovery Ventilator / Energy Recovery Ventilator

johns · 10/14/2006, 10:06 AM

Can anyone explain the differences to me between a Heat Recovery Ventilator and an Energy Recovery Ventilator and how they work?

H20ENG · 10/17/2006, 08:33 PM

An HRV simply transfers sensible heat from the exhaust air to theincoming air. Most small units use a stacked corrugated plastic in alternating directions.

An ERV uses a dessicant based media to also transfer some of the moisture (latent heat) fromt he exh air to the supply air.
It also works in reverse in the summer- cool air is not wasted, it absorbs heat from the incoming air as they pass each other.

Larger units use a rotating wheel that interfaces with both airstreams.

HTH
Chris

johns · 10/17/2006, 08:40 PM

An ERV uses a dessicant based media to also transfer some of the moisture (latent heat) fromt he exh air to the supply air.

So you're saying the ERV actually adds humidity to the air coming into your house?

I've heard it mentioned in a thread or 2 that ERVs work best in areas where it is more warm all year, and HRVs work better in area where it gets cold during parts of the year. From what you've said, I dont think I understand why this would be. But is this the way you would describe the conditions of their uses as well.

H20ENG · 10/17/2006, 08:44 PM

Sorry, I should have explained further. It will only try to equalize the latent and sensible heat of both airstreams. So, if the outside is freezing and dry, but inside is humidified and warm, the exhaust will transfer some of its "energy" (latent and sensible heat) to the incoming air, so that it uses less energy to condition the incoming air.

Likewise in summer when the conditions are reversed, the "energy" will flow the opposite way.

Make more sense?
Chris

johns · 10/17/2006, 09:58 PM

Yes. Makes sense. In either case, outside air coming into the house is 'conditioned' to be somewhat more like the inside air. And that's what I was thinking before anyway.

But are you talking specifically about an HRV, ERV or both. When I read their descriptions, they both appear to be doing the same thing. And then there is the question of whether one or another should be used in areas where it gets cold. I cant seem to understand why one would be better than the other in any particular case. Thats where most of my confusion lies.

DocApoc · 10/18/2006, 08:42 AM

an ERV recovers more energy when the outgoing air is damp.

It condenses some of the moisture in the air, which warms the incomming air.

This would seem to benefit a fish room system.

johns · 10/18/2006, 10:04 AM

I'm starting to remember some of the arguments against an ERV in our fish room applications...

One thing I've heard is that the air is so damp in our applications that the dessicant gets used up very very quickly. Seems to make sense.

Is there any truth to this?

And is there any truth to the statements that ERVs dont work as well in areas where is gets very cold for at least part of the year?

Here, I finally found one of them. SOme comments on ERV vs HRV can be found here:

http://www.reefcentral.com/forums/sh...5&pagenumber=2

Can anyone provide specific info as to why one would work better than others in various settings to help decide between the 2?

H20ENG · 10/18/2006, 06:33 PM

Good site with a map of what to use where:
http://www.fantech.net/hrv_erv.htm

More:
http://hvac-talk.com/vbb/showthread....6&pagenumber=2

http://diy-zoning.sourceforge.net/Ho...s/faq.html#hrv

http://www.renewaire.com/New%20Web%20Files/ERVvsHRV.pdf

RicGio · 10/19/2006, 06:19 PM

outstanding explanation H2OEng... HRV's work better in warm/damp rooms.

johns · 10/19/2006, 07:34 PM

outstanding explanation H2OEng... HRV's work better in warm/damp rooms.

Actually (just to point out how confusing all this is) most of those links provided by H2OEng are saying that an ERV works better at removng moisture than an HRV. Read through the Reneweaire thread and HVAC-ralk thread. Most every explanation I see says the same thing: ERV = better moisture reduction.

I also got off the phone with a guy who sells Reneweaire, and he maintains that ERVs work better for this application as well. Keep in mind, Renewaire only sells ERVs and not HRVs. But his arguments sounded quite sensible.

Double-J · 10/19/2006, 08:21 PM

H20ENG- whats the difference between this model
http://www.rewci.com/faairexveae.html
and the model that you have posted. The price seems to be much less. is it the same thing as an ERV

Thanks

rayjay · 10/20/2006, 08:44 AM

This is my HRV I had to install because of the humidity in my house that wrecked my window and doors and some drywall over the years.
The HRV works best in my climate, the ERV works best in warm climates where temps might occasionally get down to freezing but primarily stay above 5 degrees Celsius.

10/14/2006, 10:06 AM	#1
johns Premium Member Join Date: Nov 2003 Location: Wisconsin Posts: 2,684	Heat Recovery Ventilator / Energy Recovery Ventilator Can anyone explain the differences to me between a Heat Recovery Ventilator and an Energy Recovery Ventilator and how they work? __________________ Visit my Reefkeeping Tank of the Month: http://reefkeeping.com/joomla/index.php/component/zine/article/4 Current Tank Info: 190G Custom Starphire Peninsula, External Overflow, 30G Sump, 70G GrowOut, 2x400W MH + 4x54W T5 over peninsula, 1x250W DE HQI over GrowOut, Octo Pro 300 skimmer, Eheim 1262 return w/ Wavysea, 2xTunze Streams + 2 Nano Streams, Neptune ACIII controller

10/17/2006, 08:40 PM	#3
johns Premium Member Join Date: Nov 2003 Location: Wisconsin Posts: 2,684	An ERV uses a dessicant based media to also transfer some of the moisture (latent heat) fromt he exh air to the supply air. So you're saying the ERV actually adds humidity to the air coming into your house? I've heard it mentioned in a thread or 2 that ERVs work best in areas where it is more warm all year, and HRVs work better in area where it gets cold during parts of the year. From what you've said, I dont think I understand why this would be. But is this the way you would describe the conditions of their uses as well. __________________ Visit my Reefkeeping Tank of the Month: http://reefkeeping.com/joomla/index.php/component/zine/article/4 Current Tank Info: 190G Custom Starphire Peninsula, External Overflow, 30G Sump, 70G GrowOut, 2x400W MH + 4x54W T5 over peninsula, 1x250W DE HQI over GrowOut, Octo Pro 300 skimmer, Eheim 1262 return w/ Wavysea, 2xTunze Streams + 2 Nano Streams, Neptune ACIII controller

10/17/2006, 09:58 PM	#5
johns Premium Member Join Date: Nov 2003 Location: Wisconsin Posts: 2,684	Yes. Makes sense. In either case, outside air coming into the house is 'conditioned' to be somewhat more like the inside air. And that's what I was thinking before anyway. But are you talking specifically about an HRV, ERV or both. When I read their descriptions, they both appear to be doing the same thing. And then there is the question of whether one or another should be used in areas where it gets cold. I cant seem to understand why one would be better than the other in any particular case. Thats where most of my confusion lies. __________________ Visit my Reefkeeping Tank of the Month: http://reefkeeping.com/joomla/index.php/component/zine/article/4 Current Tank Info: 190G Custom Starphire Peninsula, External Overflow, 30G Sump, 70G GrowOut, 2x400W MH + 4x54W T5 over peninsula, 1x250W DE HQI over GrowOut, Octo Pro 300 skimmer, Eheim 1262 return w/ Wavysea, 2xTunze Streams + 2 Nano Streams, Neptune ACIII controller

10/18/2006, 08:42 AM	#6
DocApoc Registered Member Join Date: Sep 2006 Location: Seattle Posts: 36	an ERV recovers more energy when the outgoing air is damp. It condenses some of the moisture in the air, which warms the incomming air. This would seem to benefit a fish room system. __________________ -Jamie Marshall Current Tank Info: 24 Aquapod reef tank

10/18/2006, 10:04 AM	#7
johns Premium Member Join Date: Nov 2003 Location: Wisconsin Posts: 2,684	I'm starting to remember some of the arguments against an ERV in our fish room applications... One thing I've heard is that the air is so damp in our applications that the dessicant gets used up very very quickly. Seems to make sense. Is there any truth to this? And is there any truth to the statements that ERVs dont work as well in areas where is gets very cold for at least part of the year? Here, I finally found one of them. SOme comments on ERV vs HRV can be found here: http://www.reefcentral.com/forums/sh...5&pagenumber=2 Can anyone provide specific info as to why one would work better than others in various settings to help decide between the 2? __________________ Visit my Reefkeeping Tank of the Month: http://reefkeeping.com/joomla/index.php/component/zine/article/4 Current Tank Info: 190G Custom Starphire Peninsula, External Overflow, 30G Sump, 70G GrowOut, 2x400W MH + 4x54W T5 over peninsula, 1x250W DE HQI over GrowOut, Octo Pro 300 skimmer, Eheim 1262 return w/ Wavysea, 2xTunze Streams + 2 Nano Streams, Neptune ACIII controller

10/17/2006, 08:33 PM	#2
H20ENG Pro builder/aquarist hack Join Date: Jul 2002 Location: NORCAL (Vacaville, CA) Posts: 5,125	An HRV simply transfers sensible heat from the exhaust air to theincoming air. Most small units use a stacked corrugated plastic in alternating directions. An ERV uses a dessicant based media to also transfer some of the moisture (latent heat) fromt he exh air to the supply air. It also works in reverse in the summer- cool air is not wasted, it absorbs heat from the incoming air as they pass each other. Larger units use a rotating wheel that interfaces with both airstreams. HTH Chris

10/17/2006, 08:44 PM	#4
H20ENG Pro builder/aquarist hack Join Date: Jul 2002 Location: NORCAL (Vacaville, CA) Posts: 5,125	Sorry, I should have explained further. It will only try to equalize the latent and sensible heat of both airstreams. So, if the outside is freezing and dry, but inside is humidified and warm, the exhaust will transfer some of its "energy" (latent and sensible heat) to the incoming air, so that it uses less energy to condition the incoming air. Likewise in summer when the conditions are reversed, the "energy" will flow the opposite way. Make more sense? Chris

10/18/2006, 06:33 PM	#8
H20ENG Pro builder/aquarist hack Join Date: Jul 2002 Location: NORCAL (Vacaville, CA) Posts: 5,125	Good site with a map of what to use where: http://www.fantech.net/hrv_erv.htm More: http://hvac-talk.com/vbb/showthread....6&pagenumber=2 http://diy-zoning.sourceforge.net/Ho...s/faq.html#hrv http://www.renewaire.com/New%20Web%20Files/ERVvsHRV.pdf

10/19/2006, 06:19 PM	#9
RicGio Registered Member Join Date: Oct 2002 Location: NJ Posts: 658	outstanding explanation H2OEng... HRV's work better in warm/damp rooms.

10/19/2006, 07:34 PM	#10
johns Premium Member Join Date: Nov 2003 Location: Wisconsin Posts: 2,684	outstanding explanation H2OEng... HRV's work better in warm/damp rooms. Actually (just to point out how confusing all this is) most of those links provided by H2OEng are saying that an ERV works better at removng moisture than an HRV. Read through the Reneweaire thread and HVAC-ralk thread. Most every explanation I see says the same thing: ERV = better moisture reduction. I also got off the phone with a guy who sells Reneweaire, and he maintains that ERVs work better for this application as well. Keep in mind, Renewaire only sells ERVs and not HRVs. But his arguments sounded quite sensible. __________________ Visit my Reefkeeping Tank of the Month: http://reefkeeping.com/joomla/index.php/component/zine/article/4 Current Tank Info: 190G Custom Starphire Peninsula, External Overflow, 30G Sump, 70G GrowOut, 2x400W MH + 4x54W T5 over peninsula, 1x250W DE HQI over GrowOut, Octo Pro 300 skimmer, Eheim 1262 return w/ Wavysea, 2xTunze Streams + 2 Nano Streams, Neptune ACIII controller

10/19/2006, 08:21 PM	#11
Double-J Premium Member Join Date: Sep 2005 Location: IA Posts: 1,061	H20ENG- whats the difference between this model http://www.rewci.com/faairexveae.html and the model that you have posted. The price seems to be much less. is it the same thing as an ERV Thanks

10/20/2006, 08:44 AM	#12
rayjay Registered Member Join Date: Oct 1999 Location: London, Ontario, Canada Posts: 3,969	This is my HRV I had to install because of the humidity in my house that wrecked my window and doors and some drywall over the years. The HRV works best in my climate, the ERV works best in warm climates where temps might occasionally get down to freezing but primarily stay above 5 degrees Celsius. __________________ Seahorses. Culture nanno, rotifers and brine shrimp. Current Tank Info: Seahorses