ERV/HRV vs Dehum - What’s the difference?

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[coasttal]

Matt, as a mechanical engineer, I only want one item in a very tight home bringing air into the house. Therefore I spec an ERV for that. I also recommend dehumidifiers for the interior of the home that are fixed in the home and drain to the plumbing system, but do not connect the air stream to the exterior. Also, I pull air from all bathrooms, kitchen, and peak of vaulted ceilings and exhaust them through the ERV. I put the fresh air into the large common areas where no one will sit, since that air may be a bit cooler or warmer than the air in the house. This strategy has worked well in design and works well in my own home. I do engineering in the southeast US.

[StevePatak]

Matt, Would love to see a video that involves retrofitting a system into an existing home with multiple HVAC zones that goes through the considerations and complications of trying to make something fit with existing equipment.

[anando]

Glad to see this video. Recently put an ultraire dehumidifier in my house because my builder didn’t despite having unvented attic and entire house is spray foamed.
I will say in last day or so we noticed we are much comfortable at 73-74 as opposed to having to keep temps at 70 prior to installing the dehumidifier

I’ve learned a lot from your videos and helped me make sure my builder wasn’t taking short cuts.

[chadwhite]

Great video Matt. We build in Northwest Arkansas and have all four seasons with times of high humidity. It was not until we spent three years in Arizona that I understood Comfort was not tied to temperature but rather humidity. We would leave our AC at 78° and be more comfortable than 70° in a high humidity area.

[megacleancab]

I live in Central Florida. I just had the insulation 2.0 system and the UltraAire 98. Dropped my bill by 1/2. We work from home and were very worried about indoor air quality. Glad I watch you and this old house.

[carterdjohnson]

Matt, we recommend installing the ERV/HRV and taking the bathroom air back to the unit with a UV light in the airstream before the coil. Some people in the area like to add the dehumidifier also, however that is on higher-end homes where more space for mechanical is available. In mid-range to low-cost housing, we generally use the A/C system as the dehumidifier like in a car as the retrofit in the controls package, changing the humidity levels based on air-changes and base temperatures. This can work for home and commercial systems.

[KJSvitko]

Many homes have just too much air leakage.
All new homes and all remodels need to have a blower door test and seal up air leaks first.
I wish all builders / remodelers did blower door tests as standard practice. It makes the home more comfortable and saves energy / utility bills on heating and cooling.

[bchilva]

How do you install both systems? Are they on a separate duct system together? Would like you to do a video on how these are both installed

[compactc]

Watching your videos has convinced me that I'll likely have to build my house to get what I want. One of the big items is the HVAC, I think my personal preference leans towards radiant ceilings and some kind of ducted system to circulate purified outdoor air to keep the IAQ controlled. I have terrible allergies, hate high humidity, and love feeling cold.

[PaulyDownUnder]

Matt, if running both, an ERV and Dehumidifier, how would you duct them? Would you keep them complete separate or join them together, does the ERV feed the Dehumidifier or vice versa?

[austinselleck]

Northwest Arkansas- I’ve seen humidity in the single digits when it gets cold for awhile in the winter. During the summer that’s a different story. Not uncommon for humidity outside to be over 90%. In this case I like the idea of a dehumidifier

[pkla]

Thank you so much for going over this. I literally ran into a house today that the engineer advised putting ERVs in. The house already had humidity problems (it’s over 70%) and this is in Tropical climate (Miami area). I told the client exactly what you’re saying.

[jasontoolan]

Thank you Matt, for sharing how we can reuse conditioned air. On the path to a more regenerative future.

[fishbowl]

As a Realtor, love this channel for learning!

[superspeeder]

Great to see the building pros preaching ERVs over HRVs! ERVs were misunderstood for a long time, and most people in most places will benefit from an ERV over an HRV.
In a nutshell, any time the outdoor air's moisture content is greater than or lesser than the moisture content of the indoor air being exhausted, an ERV will temper the moisture content of the incoming air so it has less of a negative impact on your indoor humidity (compared to an HRV which just brings in the outdoor air as-is). AN ERV IS NOT A DEHUMIDIFIER, but it will slightly dehumidify the incoming air during hot humid months, which means less moisture indoors and lower humidity/higher comfort. It will also HUMIDIFY the incoming air during cold dry months and will result in less drying of indoor air compared to an HRV.
As Matt points out, there are cases where supplemental dehumidification will also be necessary, especially during periods of high outdoor humidity and low AC demand since the AC just won't run often enough to maintain low moisture levels indoors.

[chuckchrystak]

We just built a house and did a handful ourselves including the air sealing. I put so much detail to not miss anything and got our 3600sg’+ ranch with 10’ ceilings in main and an unfinished basement. Got the house to 1.30 ACH. We live in Nebraska so we can see everything from cold and dry and dry to high and humid. I am stuck on what to do. We also have Geothermal, with gas auxiliary heat. My goal with building was to not ever use the auxiliary heat except for if we lost power.

[ParabellumX]

Great explanation, Matt.
Thanks for the video!
You couldn't have been any closer to the truth when you said that every home down here in the south needs a dehumidifier. When I purchased mine, it was literally my best investment ever.

[keltonlowry]

Overall a pretty good video. Some really good information if homeowners are looking. You just are incorrect when you start talking about the refrigerant cycle. Outdoor units do not make refrigerant cold. Also you should use the term refrigerant and not Freon. Being you’re talking about D humidification obviously the unit would be running in the air condition mode. The line that you feel that is cooler is actually coming back from the indoor unit. Technically you cannot make cold you can only remove heat. The sub cooled liquid refrigerant hits the metering device at the indoor unit causing it to flash off and change state to a vapor. After leaving the metering device it’s now 80% vapor 20% liquid. The air moving across the indoor coil causes the rest of the refrigerant to flash off and now becomes a superheated vapor by absorbing heat from the air. The cool line that you are feeling by hand coming back to the outdoor unit technically is what is holding the heat from inside your house.

[mikeisnumber]

Thanks Matt. Love that you talked about how to use them in conjunction with each other.

[certificationtv]

The prerequisite before using the product is that no outside air enters the room.
Air gaps in windows and front doors can change the efficiency of the product.