I'm sure this question has been discussed in this forum before, but the search engine does not appear to be working.

I'm building a timber frame in climate zone 6 and I'm ready to buy an HRV.

For an additional $160 I can upgrade to an ERV.

I don't mind spending the additional money if I can benefit from the ERV, but most everything I read tells me I only need an HRV.

The timbers are wrapped in 6" polyurethane wall SIP's and 8" roof SIP's.  The walkout basement is constructed of ICF.

Requesting opinions on the subject.

Thanks for your input!

Will you have a significant need for air conditioning? Do you have particularly cold and dry winters(ever need to use a humidifier)? That is when you would need an ERV IMO...

I'm struggling with the same question for my NorCal coastal property (Marine Zone 4)

I googled the question and read quite a bit about the difference between the 2 types and am still not sure what I should install. I'm leaning towards an HRV only.

I found this link on this very site https://www2.buildinggreen.com/article/choosing-between-erv-and-hrv

My problem is that my area is pretty humid, but doesn't need AC in the summer. However, the heat pump I will be installing won't dehumidify the air. Fresh air coming in is naturally moist, especially in the mornings and at night (when I will be calling for heat). Winter morning temps in this Marine zone 4 can get down to 30 degrees f and that is also the time of the year when the most rain falls. Summer morning temps are typically 45-55 degrees f, so I will still be calling for heat on those mornings and the air at that time of the day is moisture laden. I don't want excess humidity in the house and I'm unsure a good HRV can eliminate enough of the excess humidity in the incoming fresh air. I know that colder air doesn't hold the humidity as well as hot air, but I still get concerned about too humid of air (mold, mildew, etc).

Not to derail your thread, but if anybody has any thoughts about my climate zone (Marine zone 4), I'm all ears. Everything I've read about HRV vs ERV differences, indicate ERV's can remove some of the humidity (but from warmer moist air during summer months) and are primarily recommended for systems that use air conditioning cooling in the summer. While my system can be an AC (it's a heat pump), I will primarily be using it as a heater (mornings year round and winter days). It rarely even gets to 80 in the summer/early fall (summer typically highs 70-75, lows around 50-55) in Trinidad, CA. On those rare days that reach 80, most people open a few windows in the afternoon.

Do a search on Google and you'll find plenty to read and maybe your climate zone will fit the description of the recommended climates for an ERV or HRV. My climate zone doesn't fit neatly in the recommendations.

My understanding is that ERVs typically use more energy, depending on how it is used and the type of ERV design.

In your Trinidad CA an HRV is the way to go. Neither your summertime nor wintertime average outdoor dew points warrant the moisture exchange. (Don't conflate "rainy" with "humid"- it's not the same thing until/unless it's raining at temperatures above 65F outdoors.) Your wintertime ventilation air is already in a human-healthy & comfortable range, as is your summertime ventilation air. Pull up a dew point graph:

https://weatherspark.com/#!dashboard;q=trinidad%20ca

The mean summertime high dew point is 56F, which at 75F indoor temps translates to 52% relative humidity. That's at the high end for those susceptible to dust mites, but it's otherwise very comfortable and healthy. That's the mean high dew point. On 99 out of the 100 days of summer you'd be able to dry out the house to below 50% RH by cranking up the ventilation, no need for mechanical dehumidification or air conditioning.

The mean wintertime low dew point is 35F. which at 68F indoors becomes 29.5 % RH, which is at the dry end for human health & comfort. On those rare cold snaps where the dew points dive below that for a few days you can always dial back the ventilation rates if need be if the interior air gets too dry.

The energy use is about the same for either HRV or ERV, but the lifecycle of ERV cores are generally shorter than HRV cores, and it doesn't provide appreciable comfort or health benefits.

+1 The relative humidity of an air mass changes with temperature. IE: As you heat that outside air you are bringing in(move it's temperature farther away from the dewpoint), it's relative humidity decreases. I live farther north, but in a borderline marine environment. As an example, it has been pretty cool with low clouds and rainy today. looking at my WX station, outside it is currently 49F @99% RH. Inside my well ventelated(leaks like a sieve) home, it is currently 72F @47% RH... Same air but with a 22F temp increase...

As mentioned in one of my sentences, I knew that colder air temps don't hold moisture as well as warmer air temps, and dew points (relative humidity to air temp ratio) play a role in that (or more accurately are a measure of that). But I was still concerned that fresh moist air coming into the house through an HRV/ERV, might "stay" in the house. It can get quite soggy outside there and I probably unduly get concerned about it.

Thank you Dana for those figures...they put me at ease.

My house is pretty tight. Currently R24 walls; R30 subfloor in crawl space, completely air sealed envelope, R38 attic (not presently installed) high R value and low infiltration windows (Alpen series 7) and doors. I do get nice solar heat gain in the afternoon, as the long side of the house faces the south west and that is where most the windows are. I don't live there yet and I've not stayed over night since I've insulated the walls and sub floor, so I'm interested to see how long the solar heat gain lasts until I lose that gain (air handler and heat pump are not installed yet, but hopefully by late this year). I will find out in late April when I spend a week on the property and again this summer when I spend 3 weeks working there.

I do have a wood burning fireplace (which was my source of heat last summer and will again be this summer). I'm sure I always lose a little heat up that chimney, even when the flu is closed.

HRV it is for me. Now I just need to research the various brands and models.

After consulting with the engineer that did my manual J calculations, I purchased a Broan ERV140TE energy recovery ventilator.  It's manufactured by Venmar and private labeled for Broan.

Posted By Boyne on 16 Feb 2016 11:05 AM
After consulting with the engineer that did my manual J calculations, I purchased a Broan ERV140TE energy recovery ventilator.  It's manufactured by Venmar and private labeled for Broan.

Why?

Hi Badger,

Why? Just following the advise of a professional.

Why did he specify the ERV? Where are located? What type of construction?