Residential ventilation requirements and systems are poorly understood by many professionals, including municipal building inspectors. Yet, the next iteration of the Ontario Building Code comes out in 2017 requiring heat recovery in ventilation systems. It’s time we get it right for balanced ventilation systems like Enthalpic/Energy Recovery Ventilators (ERV) and Heat Recovery Ventilators (HRV). Will we be ready?
We test a number of high-end renovations and new residential construction projects and often, the balanced ventilation systems gets shockingly short shrift from builders and municipal inspectors. Some ventilation systems we’re asked to commission, but some systems we just happen to see glaring issues and feel morally compelled to say something to the builder or owner. Below are a series of photos taken of mechanical systems installed after 2014 in the Municipality of Toronto. The common issues we see in the field include:
- HRV with no condensate connection: Yes, it’s true that ERVs don’t require a condensate connection but HRVs do require a connection.
This HRV’s condensate nipple would have ensured 1.5″ of water under the core before it drained out… onto the floor.
You can see if from a mile away, there’s no condensate drain hose under that HRV.
- E/HRV’s with the “fresh” air intake adjacent to 3 combustion appliances: cooking, hot water and forced air furnace.
This composite image is of a wall section on a house. Yes, the flapperless brown grill (1st from the left) shows the ERV’s sucking air between the DHW, furnace and kitchen range exhaust. Stunning on a house built in 2015. See below for the close up.
HRV fresh air intake between a rock and a hard place. Trades and municipal inspectors need better training to avoid making these glaringly obvious mistakes.
- E/HRV’s with no insulation on the Fresh air Intake and a few other issues.
While prepping for a duct leakage test, I noticed the fresh air intake was uninsulated…. OK that’s not all, in fact this unit didn’t have a stale air exhaust connected and all the punch-outs were still in place. A very incomplete install. I couldn’t believe my eyes. See accompanying image below.
All metal knock-outs still in place, and the two back wall foam knock-outs are also still in place… With only one pipe, was this really inspected?
- E/HRV’s with excessively long or small diameter ducts to outside. For the record, most residential grade E/HRV don’t have much static pressure and therefore the duct runs that connect the unit to the outdoors are always large diameter (starting at 8″ID), run through short (ie less than 12′), hopefully smooth walled ducts. The cumulative duct length below is about 45′ each leg. About 60′ in total if you include the sections of corrugated flex duct. Adding insult to injury, the 4″ID lengths are sure to choke the flow down to a trickle. Note that the fresh air intake should be insulated all the way.
Coming off the HRV, two flex duct lengths joined to two bare metal, straight galvanized ducts. Continued next frame along steel beam.
Fresh air intake of bare, smooth metal ducts as they pass along the steel beam transition to a smaller diameter duct and turn to go out the wall. Continued below.
Diameter reduction in metal pipe with two elbows as the metal transitions to a 10′ length of flex duct.
The stale air exhaust pipes terminating outdoors with a diameter reduction in metal pipe with two elbows as the metal transitions to a 10′ length of flex duct.
- Insulated ducts: Why do we have to wait for this simple technology to make it to North America. Please let’s do get long, insulated and nearly seamless pipes!
This is what I call getting your ducts in a row: insulated, easy to air-seal and fewer seams. Available through Pinwheel Builds!
Pro Tip: Sleeve your walls early and use a seamless section of pipe to prevent in-wall condensation, especially if you have deep walls.