ERV auto balancing importance
Hi All, I’ve never lived with an ERV or HRV, I’m currently trying to choose an ERV.
How convenient is the Auto/self-balancing on something like the Broan AI series. My understanding is it balances across the core. So if a register gets adjusted or closed somewhere in the house the unit will self balance the intake and exhaust. Does it provide other benefits?
My thinking is that after a couple of months of living with the ERV I will probably figure out exactly how I want all the registers set up and never mess with them again. Is the auto-balancing providing a benefit even if the registers are never messed with? Is it unrealistic to think that I’m not going to mess with the air flow at each register?
I’m trying to decide between the Broan AI and the Renewaire Premium L. I’m leaning towards the Renewaire but wondering if I’m going to regret not having the auto-balancing.
Thanks!
-Cedar
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
Depends on how your ERV is ducted. If it is connected to an HVAC system an autobalance unit will work much better as the flows won't change as the system ramps up/down.
If fully ducted, auto balance won't get you much except it is easer to commission, so if you are paying for tech time, it is usually worth it.
Oh yeah that is important information I left out. It's going to be fully ducted, Also I a doing all the work my self, building my own house and doing all the systems.
Auto balance will help adjust for clogged filters or windy days adding back pressure to your exterior exhausts or intake ports as well as prevent your house from being negatively pressurized which is very important. Being slightly over pressurized is much preferred over negative. I think it is important to have this feature and not a ton of extra money.
Ok interesting, I hadn't thought about clogged filters or wind. that is a good consideration.
Yeah the price is about the same. It seems like the renewaire is slightly more efficient and doesn't have a defrost mode. Both of these things are leaning me towards the renewaire.
Which Broan model specifically? Sensible efficiency does seem higher on the Renewaire but the wattage looks higher than comparable Broan 140 CFM models. For example, the Broan B160E75RT uses 105-112 watts (winter-summer) @ 125 CFM while the Renewaire EV Premium L uses 184 watts at 256 CFM (128 CFM in/out). If I did the math correctly, that is like $2569 per year if running for 6 hours a day at the national average kWh cost of $16.26/kWh. The better way to do this is to run a BEOpt model (it's free) and see how much of an energy penalty the extra latent heat would be since the Broan is slightly less efficient. You can run two BEOpt cases, one with the Broan and one with the Renewaire and see which one lowers the overall operating cost and compare that against the upfront price differences between the units to establish an ROI.
Thanks for the info. I was looking at the B210E75RS. I am sure over sized for my needs but, it seems like the bigger the more efficient. It's going in a crawl so physical size doesn't matter to me. I will hardly ever be running it at full power, more like 50-70cfm continuous with boost at times.
It does look fan efficiency is better on the Broan so that is a good point. Jeeze it's hard to find all the details on these things, every manufacture seems to show the data slightly differently. But even just the spec sheet shows the Premium L is rated at 2.7W/cfm and the Broan 210 is raited at 2.2W/cfm.