ERV VS HRV

PLUMBARIS

Going to install an hrv or an erv for a clients new home.I put an erv in my own home 20+ years ago but have read that ervs are only worth the extra cost in severe climates. Were in nortern Indiana, ASHRA low temp of +5 what are some of the opionions out there.

Brad White_202

ERV versus HRV

ERVs are "Energy Recovery Ventilators and recover total heat (temperature plus latent or moisture-based energy). These are also known as "Enthalpy" devices.

HRVs just recover temperature and pass moisture right on through.

The above I think you know. The application goes to what you are trying to achieve. In the south and gulf states, where AC rules, you want enthalpy or ERV performance. In Canada, or any cold dry climate with 3.2 beer and year-round hockey, ERV's tend to frost up as the moisture is exchanged, so HRV's rule there.

In similar temperate climates where you are adding humidity, the ERV looks better than HRVs would.

Short answer...

PLUMBARIS

Summer Usage

My client plans on using this year around and we get pretty humid around here so in that case an erv is the answer. I am planning on hooking the bath fans directly into the unit so unless its running there would be no vent. Most ervs also have a defrost mode dont they.

Brad White_203

Defrost Mode

Wasn't that a band from the '80's?

Most but not all ERV's (and some HRV's too let's be clear here) have a defrost mode. HRV's can frost over too, especially if the outgoing air has concentrated humidity.

ERV's "take it harder" because the desiccant coatings absorb and retain so much more moisture that the freezing can occur on both sides of the exchanger.

Defrost modes vary in type. Some bypass untempered exhaust air into the incoming air stream to warm it- strictly by code, you cannot do this, recirculate exhaust back into the incoming airstream. Some have an "off cycle" to allow defrosting to take place passively. Some ramp down the speed and lessen the incoming air rate... depends on the type, but bypass seems most common. For general exhaust (for whole-house exchange versus toilet exhaust), this is often just fine.

The question is, how cold does it get?

The folks at Lifebreath and Fantech have zone maps which expand on the basics above.

Rich L.

Band from the 80's...

"Wasn't that a band from the '80's? " LOL! Thats hilarious!

I live in Iowa and installed an HRV in my home. I use mine year round. (bath and laundry rm fans tied in) I wanted to be able to get rid of the excess humidity in the heating season. With radiant heat I've found my winter indoor air to be too humid without an air to air heat exchanger. Even with high quality windows I was getting condensation before installing and using my HRV.

I went with a Lifebreath unit. It has a defrost bypass mode, built in humidistat, five operating speeds, and is easy to clean. I put remote 20, 40, 60, buttons in the bathrooms and kitchen for high speed operation during showers. I believe mine is the model 160 but don't recall for sure.

Best regards, Rich L

Steve_168

ERV core

I was told by the ERV people to use an HRV core[aluminum] during our winters[L.I.N.Y.]to prevent condensation damage to the ERV "paper"core.