Remote Living > Heating
HRV vs. ERV (or both)?
jlsoaz:
Hi - does anyone have strong views on HRV vs ERV for achieving goals of both fresh healthy air in a residence (or commercial building) along with not using more energy than needed to keep the air at a comfortable temperature? Generally this is seen as a question of which climate a person is in, no?
I'm at 3500 feet altitude, and there are wide swings in temperature. Even though generally this is a very hot area in summer (Arizona), I find myself expending a lot of energy to keep the place warm in winter. Is there such a thing as having both types of unit installed, and then switching between them, depending on the season?
DamonHD:
In the UK ERV is considered rarely necessary, where you are moreso:
https://forum.buildhub.org.uk/topic/12734-no-condensate-from-mvhr/?tab=comments#comment-213746
Rgds
Damon
bigrockcandymountain:
Ok so here is my experience.
I have an ultimate air 200dx ERV and I have just ordered a Venmar e15 ecm HRV to replace it.
It is about -10f. -25 celsius here and has been for the last week. We are having trouble keeping the humidity down. It is around 50% and sometimes 60%. In your climate, i think an erv would be fine, but not here. (Saskatchewan, Canada)
We are also off grid so we don't like to run the erv wide open for long periods. It is always on though and doesn't use much power. It is amazingly efficient at heat transfer. I am expecting the hrv to be a little less efficient that way. Our house is passive house airtight and we are a family of 4 always cooking, showering etc.
The people that sell hrv / ervs like to make it seem simple but it really depends on a lot of factors. Namely, your climate, your airtightness of your envelope, and the habits of the people living in the house.
I will add that the ultimate air erv works differently than most erv's. I believe it returns more moisture than other erv's.
If anyone wants a good used Ultimate Air 200dx ERV i will be selling mine. They are a good unit, just not for our situation.
jlsoaz:
Thanks for the responses so far, very much to the point.
jlsoaz:
--- Quote from: bigrockcandymountain on January 16, 2020, 05:12:38 PM ---Ok so here is my experience.
I have an ultimate air 200dx ERV and I have just ordered a Venmar e15 ecm HRV to replace it.
It is about -10f. -25 celsius here and has been for the last week. We are having trouble keeping the humidity down. It is around 50% and sometimes 60%. In your climate, i think an erv would be fine, but not here. (Saskatchewan, Canada)
We are also off grid so we don't like to run the erv wide open for long periods. It is always on though and doesn't use much power. It is amazingly efficient at heat transfer. I am expecting the hrv to be a little less efficient that way. Our house is passive house airtight and we are a family of 4 always cooking, showering etc.
The people that sell hrv / ervs like to make it seem simple but it really depends on a lot of factors. Namely, your climate, your airtightness of your envelope, and the habits of the people living in the house.
I will add that the ultimate air erv works differently than most erv's. I believe it returns more moisture than other erv's.
If anyone wants a good used Ultimate Air 200dx ERV i will be selling mine. They are a good unit, just not for our situation.
--- End quote ---
Hi - thanks for running through these points. Some things here for me to think about. I guess I'll need to try to understand the humidity points better. I'm in an area where people usually go for ERV, but I'm told by the concrete dome builders that de-humidification is more something they emphasize, so I'm not sure that fits with my getting something that might make it more humid inside. Also, when buying coolers around here, over the years folks have opted for air conditioning or evaporative coolers. One of the reasons the EVAP coolers have somewhat lost the battle is they do not work when it gets humid. Around here they work most of the time, but once in awhile it is rainy and then they don't work.
The tight envelope of your passive house sounds a bit similar to mine. I think my main question for you would be whether there is such a thing as retaining your ERV and running it some of the time, but then switching over to HRV for other times. Temps here range from over 100 or 105 F in summer to a bit below (not sure exactly how much) 32 F in winter. Within a day, there can be a (somewhat) wider swing than some folks are accustomed to, as one might expect in (somewhat) high desert. These are temps in formally reported terms, but then I tend to see slightly different temps if checking other sources, such as occasionally seeing 110 F on my car dashboard.
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