Clearing the Air: Choosing Between Centralized and De-Centralized HRVs
/Next month, Small Planet Supply is hosting a webinar featuring our own Eric Fenno, discussing the difference between centralized and decentralized heat recovery ventilator systems and what to consider when deciding which type of system is best for your home or build. This is the first time that we’ve offered this webinar. We wanted to know more about the webinar and what will be covered, so we sat down with Eric Fenno to learn more about what he has planned.
Next month’s webinar is focused on centralized versus de-centralized HRV systems. Can you briefly explain what the difference is between these two types of systems?
No Heat Recovery Ventilators (that we know of) come with clear doors. But Eric Fenno will help webinar attendees have a clearer picture of what type of heat recovery ventilator is right for their home or project.
Sure! Central/Decentral is sometimes substituted with ducted/non-ducted if that’s easier to understand. It’s not 100% true, because sometimes they have ducts, and we don’t want to call them “ductless” because that’s more commonly referring to a different thing, but it gives you an idea.
A central heat recovery ventilator system will have one, usually larger, unit that moves air around the entire structure with a ducted distribution system. Often (and best-case usually) the distribution ducting is separate from any other duct work, and the unit is the only source of air movement through the building envelope. The centralized heat recovery ventilators tend to be a little more complicated and a little more powerful and feature rich. They’re also often a little more convenient, since generally you don’t mess with them or their settings much.
A de-centralized heat recovery ventilator is usually a smaller unit that ventilates by circulating air around a single room/space. The air can be moved into enclosed rooms by using transfer fans that exhaust air from say, a bedroom wall, and pulls fresh air through the gap, beneath the door. De-Centralized heat recovery ventilators are simple, easy to use, and easy to understand usually. The big tradeoff is that they often require the fan unit to be in a living space, and while they aren’t usually very loud, sometimes people just don’t like that. Occasionally these de-centralized heat recovery ventilators can use a duct or two to ventilate a different part of the house for a cascading effect, which is another reason we don’t call them “ductless” or “non-ducted.”
Your webinar will undoubtedly go into detail about these two types of systems. Are there currently misconceptions about centralized versus decentralized systems that can stand in the way of a homeowner or builder making the best choice for their specific situation?
Fresh-R Units are examples of de-centralized HV systems
There are a lot of different factors that can impact this, I tend to consider floor plan, new vs remodel, and size the most when I recommend one over the other. De-centralized systems are great in small to mid-sized open floor plans. Some of them also need a separate solution for bathroom exhaust as well.
In remodels, it’s usually advantageous to go with a de-centralized system unless you’ll be going down to the studs already. They save a lot of duct-running trouble/cost, even if maybe you need to add a second unit.
For new construction, since you’re not going to have to tear your sheetrock out, it can make a lot more sense to go with a central system for those mid-size to large projects.
You haven’t spent your whole career in building systems, what did you personally find surprising (if anything) about heat recovery ventilation systems when you first began selling them?
Having grown up in houses with forced air my whole life, it was sort of mind-blowing to think that you’d want something that moved air around but didn’t condition anything. As I got more into building science and my education, it finally clicked as I was really exploring the concept of air-tightness that, “oh, this is not a climate solution, this is a health solution which preserves climate for the sake of efficiency.” From that lens, a system that continuously exchanges air, scavenges conditioning, and provides a central filtration point, makes a ton of sense.
Who do you think will most benefit from this webinar?
Hopefully everyone! I am not alone in being confused by the concept of an HRV the first few times I tried to get my head around the idea, and they (HRVs) are, hopefully, going to be a household item in the coming years. It’s a concept that’s relatively new to the trades, and all new to most homeowners. We’ve been building homes tightly enough that some sort of mechanical ventilation is needed since 1998, and now we’re at a point with energy and building code where you really should have something like an HRV for almost all residential construction. In the webinar, we’ll talk about what these systems are and why they’re important and explore the situations where you might choose one system over another. I’ll also touch on how to design for them systems as well, so even if you’re knowledgeable in one area, hopefully there’s something to learn in another.
Don’t miss the chance to learn about centralized and de-centralized HRV systems on May 16. You can register by using the button below.
