ERV
ERV — Energy Recovery Ventilator
London Ontario
An ERV (Energy Recovery Ventilator) transfers both heat and moisture from outgoing exhaust air to incoming fresh air — unlike an HRV, which transfers heat only. For most London Ontario homes, an HRV is the correct choice because the climate is cold and dry and the goal is to remove excess indoor humidity. An ERV is the right choice for a specific subset of London Ontario homes: those with consistently very low winter indoor humidity (below 25–30% RH), ultra-tight new construction where occupant-generated moisture needs to be preserved, or homes with humidity-sensitive contents. Hawana assesses your home's actual humidity conditions at every estimate visit and recommends the right unit — not the more expensive one. TSSA certified. BBB A+. 138 five-star reviews.
How an ERV Transfers Both Heat and Moisture
The ERV does everything an HRV does — and one thing more. The enthalpy core transfers moisture vapour between the two airstreams in addition to heat, using a hygroscopic membrane that water molecules can pass through.
ERV Enthalpy Core — What Transfers in Winter
21°C indoor air
0 to +5°C after core
High RH indoor
Some moisture retained
CO2, VOCs, odours
Pollutants exhaust outside
The Enthalpy Membrane — How Moisture Transfers Without Air Mixing
The key physics of an ERV: the enthalpy core uses a hygroscopic material — either a static membrane panel or a rotating enthalpy wheel — that allows water vapour molecules to pass through it by adsorption and desorption, while blocking air and larger molecules. The two airstreams never mix — the exhaust air and fresh intake air flow on opposite sides of the core. Heat transfers by conduction across the membrane (same as in an HRV). Moisture transfers by the vapour pressure gradient: higher humidity on the exhaust side drives vapour through the membrane to the lower-humidity intake side.
Winter Mode — Moisture Retention
In winter, warm moist indoor exhaust air passes over one side of the enthalpy core. Cold dry outdoor intake air passes over the other side. Heat transfers from warm exhaust to cold intake (as in any heat exchanger). Moisture vapour also transfers from the higher-humidity exhaust side to the lower-humidity intake side — delivering some of the indoor humidity back into the home in the fresh air stream. Result: the incoming fresh air is both pre-warmed and pre-humidified.
Summer Mode — Humidity Reduction
In summer, the process reverses. Outdoor humid air passes its moisture to the drier indoor exhaust air — the ERV acts as a passive dehumidification step for incoming fresh air. London Ontario summers are moderately humid (June through August), so this benefit reduces the AC dehumidification load modestly. This summer benefit is real but secondary to the winter moisture retention benefit for most London Ontario ERV installations.
What the ERV Does NOT Transfer
The enthalpy membrane blocks air molecules, odours, CO2, VOCs, and biological contaminants. The two airstreams never mix. The ventilation function — continuously replacing stale indoor air with fresh outdoor air — is identical to an HRV. The ERV does not introduce outdoor odours or pollutants into the home any more than an HRV does.
5 Situations Where an ERV Is Better Than an HRV in London Ontario
Most London Ontario homes need an HRV. These are the specific situations where an ERV is the correct choice — with the reasoning for each.
💧 Consistently Low Winter Indoor Humidity
The clearest indicator that an ERV is appropriate. If your home runs below 25% RH in winter despite normal occupancy and cooking activity — causing dry skin, static electricity, cracking wood floors, or wood furniture separation — an HRV is exhausting more moisture than your home can afford to lose. An ERV retains 40 to 60 percent of that moisture. Dray K.'s review below describes exactly this scenario in a 2020-built ultra-tight South London home.
🏠 Ultra-Tight New Construction (ACH50 < 1.0)
Extremely well-sealed homes (air changes per hour at 50 pascals below 1.0) have virtually no natural infiltration. All moisture exchange happens through the controlled ventilation system. In these homes, occupant-generated moisture is the only indoor humidity source, and exhausting too much of it through an HRV can push indoor RH below comfortable levels in London Ontario winters. An ERV preserves a larger fraction of occupant-generated humidity.
🎸 Humidity-Sensitive Contents
Natural wood, vintage instruments, artwork, and wine collections require stable relative humidity between 40 and 60% RH year-round. In a London Ontario winter, an HRV can push the surrounding environment below 25% RH, causing cracking, warping, and damage. An ERV, by retaining moisture, helps maintain the 40 to 50% RH range that protects these materials. Flint T.'s home recording studio situation is a direct example — vintage guitars were developing cracks at 18 to 22% RH.
🏠 Respiratory or Skin Conditions Requiring Stable Humidity
Several respiratory and skin conditions worsen significantly in low humidity. Below 30% RH, nasal mucous membranes dry out, reducing their ability to filter airborne particles. Eczema and psoriasis typically flare in dry conditions. For households where these conditions are present, maintaining indoor RH above 35% in winter is medically beneficial — and an ERV helps achieve this without running a humidifier continuously. Gorse B.'s review below describes this exactly.
🏠 Condominium or Multi-Unit Residential
High-rise and mid-rise condo buildings commonly specify ERVs in their mechanical systems because the sealed-envelope construction and high-occupancy conditions mean indoor humidity can drop significantly in winter without moisture retention. Individual suite ERV replacements should match the building's original specification. Hawana assesses and installs ERVs in condo suites across London Ontario.
✗ When an ERV Is NOT the Right Choice
- Homes where window condensation appears every winter — excess indoor humidity already present; ERV would worsen it
- Homes with visible mould growth — retaining additional moisture makes the problem worse
- Homes where indoor winter RH is already above 45% without a humidifier running — ERV not needed for humidity retention
- Older homes built before 1980 with significant natural infiltration — HRV is appropriate and less maintenance-intensive
- Homes where you have not measured winter indoor humidity — call Hawana for an assessment before deciding
Indoor Humidity in London Ontario Winters — What the Numbers Mean
The ERV vs HRV decision ultimately depends on your home's actual winter indoor humidity. Here is how to interpret the readings.
How to measure your winter indoor humidity: An inexpensive digital hygrometer ($15–$30 at any hardware store) measures relative humidity. Place it in the main living area, away from bathrooms and kitchen. Read it on a cold day in January when outdoor temperatures are below -10°C. If it consistently reads below 30% RH with normal occupancy and cooking activity, your home is losing too much moisture through ventilation — an ERV assessment is warranted. Call Hawana at (647) 550-4220 for an on-site humidity assessment.
ERV vs HRV — Which Is Right for Your London Ontario Home?
| Attribute | HRV — Heat Recovery Ventilator | ERV — Energy Recovery Ventilator |
|---|---|---|
| Core type | Aluminium or polypropylene cross-flow core | Hygroscopic enthalpy membrane or rotary wheel |
| Heat transfer | Yes — 70–85% efficiency | Yes — similar efficiency |
| Moisture transfer | No — humidity exits with exhaust | Yes — 40–60% moisture retained |
| Best for London Ontario winters | Homes with normal or high indoor humidity — most homes | Homes with chronically low indoor humidity (<30% RH) |
| Condensation risk management | Better — removes excess humidity | Not appropriate if condensation already present |
| Core cleaning method | Washable with water — simple | Vacuum or damp wipe only — no detergents (destroys hygroscopic treatment) |
| Filter cleaning | Every 1–3 months | Every 1–3 months |
| Summer benefit | Heat recovery only — no humidity management | Modest humidity reduction on incoming air |
| Price (integrated with forced-air) | From ~$1,200 | From ~$1,300 |
| Recommended for most London Ontario homes | ✓ Yes — default recommendation | Specific use cases only |
Hawana's approach: Every ventilation estimate visit includes a humidity assessment and an honest recommendation — HRV if that is right, ERV if the home genuinely has low winter humidity. An ERV is not upsold as a premium product. If your home's winter RH is above 35%, an HRV is correct. If it consistently reads below 25 to 30%, an ERV is the appropriate choice. Gorse B.'s review below is an example of the assessment approach — actual humidity measurements, not a preference guess.
ERV Core Maintenance — What You Must Not Do
The enthalpy core requires different care than an HRV core. Using the wrong cleaning method destroys the hygroscopic treatment permanently.
💧 ERV Enthalpy Core — Correct Maintenance
- Vacuum gently with brush attachment to remove loose dust and debris
- Wipe with a lightly damp cloth if more cleaning needed
- Allow to dry completely before reinstalling
- Do NOT use detergent, soap, or harsh cleaners of any kind
- Do NOT submerge or spray water directly on enthalpy cores
- Detergents strip the hygroscopic coating — the core becomes an HRV core permanently
- Inspect annually for physical damage and coating degradation
- Replace if moisture transfer efficiency has declined significantly
🔌 HRV Aluminium Core — For Comparison
- Remove and wash with warm water — fully washable
- Mild soap acceptable if needed
- Rinse thoroughly and allow to dry completely
- Core inspected annually but rarely needs replacement
- Much simpler maintenance than enthalpy core
- Polypropylene cores in some models — same washable approach
- Filters on both intake and exhaust sides: clean every 1–3 months
- Core lasts the life of the unit if properly maintained
The most common ERV maintenance mistake: Treating the enthalpy core like an HRV core and washing it with soap and water. This permanently destroys the hygroscopic treatment that enables moisture transfer. The core then functions as a heat-only exchanger — you have paid for an ERV but are now running an HRV. Flint T.'s review below specifically mentions this maintenance guidance — his previous unit had the core washed improperly and lost its moisture transfer capability. Hawana provides written maintenance instructions with every ERV installation.
ERV Installation Cost — London Ontario 2026
Integrated with Forced-Air System
ERV supply connected to furnace return air duct. Dedicated exhaust grilles in bathrooms and kitchen. Commissioning and balancing to OBC ventilation rates included.
Standalone — Dedicated Ductwork
For homes without forced-air. Dedicated supply and exhaust duct runs. Commissioning and balancing included.
Slightly higher than HRV due to enthalpy core cost. Final ERV installation cost depends on home size, duct run complexity, and the specific unit required to meet OBC ventilation rates. Written quote before installation. Call Hawana at (647) 550-4220.
Your ERV & HRV Specialist — London Ontario
Abdullah Ghzail — Lead HVAC Technician & Founder
Abdullah installs ERVs and HRVs across London Ontario and Southwestern Ontario since 2018 — with an actual humidity measurement at every ventilation estimate because the right ventilator depends on your home's actual conditions, not a preference guess; an ERV recommended when indoor winter RH is consistently below 25 to 30 percent because that is when the moisture retention benefit is real and meaningful; and written enthalpy core maintenance instructions with every ERV installation because the most common ERV mistake — washing the enthalpy core with soap — permanently destroys moisture transfer capability. TSSA certified. BBB A+. 138 five-star reviews.
ERV Reviews — London Ontario
138 five-star reviews — 2020 ultra-tight South London home at 20% RH resolved (Dray K.), home recording studio vintage guitar humidity crisis fixed (Flint T.), eczema sufferer humidity assessment and ERV recommendation (Gorse B.). Read all ↗
"Called Hawana after our third winter in our 2020-built South London home. Indoor humidity was consistently below 20% from December through February — static electricity constantly, hardwood floor developed a small crack, humidifier running almost continuously. Hawana explained why an ERV made more sense than an HRV: we needed to retain the moisture our household was generating rather than exhausting it. ERV installed and integrated with our Carrier forced-air system. First winter: indoor humidity stayed between 35 and 45% without running the humidifier constantly. Floors have stabilised."
"We have a basement recording studio and needed stable humidity for vintage guitars. Our old HRV was exhausting too much moisture — we were seeing 18 to 22% RH in the basement in January, which is damaging for wooden instrument bodies. Hawana recommended an ERV and explained that the enthalpy core retains a portion of indoor moisture. The Venmar ERV has kept humidity consistently above 35% through winter. The technician also explained that you cannot wash the enthalpy core with soap — it destroys the hygroscopic treatment. Our previous unit had that done improperly."
"Replacing our 18-year-old HRV and asked Hawana whether to replace with another HRV or upgrade to an ERV. My wife has dry-skin eczema that worsens significantly in dry environments. The technician checked our humidity readings — we were averaging 28% RH in winter. He explained that 28% is borderline: an HRV would keep us in that range or lower, while an ERV would help maintain 35 to 45%. Given my wife's condition he recommended the ERV, based on our actual measurements. Lifebreath ERV installed, winter humidity now 38 to 42%. My wife's skin is noticeably better from December through February."
ERV Installation — Southwestern Ontario
ERV FAQ — London Ontario 2026
How an ERV works, who should get one, ERV vs HRV, enthalpy core maintenance, humidity thresholds, installation cost, OBC compliance, switching from HRV, brands, and condos.
ERV or HRV? — Find Out With a London Ontario Assessment
Hawana measures your home's actual winter indoor humidity and recommends the right unit — HRV if that is correct, ERV if your home genuinely has low winter humidity. Venmar, Lifebreath, Broan-NuTone. Commissioning and balancing to Ontario Building Code included. TSSA certified. BBB A+. 138 five-star reviews.
More Air Filtration & HVAC Services
💨 HRV — Heat Recovery Ventilator
Recommended for most London Ontario homes. Removes excess winter humidity.
💧 Whole-Home Humidifier
Works alongside HRV or ERV to maintain 40–50% RH. Paired with furnace.
🔌 Air Filtration Services
HEPA, UV, and media filtration. Works with ventilation system.
🔌 Ductwork Services
Duct assessment and sealing. Required for ERV forced-air integration.
📋 Maintenance Plans — $149/yr
Annual ERV and HRV inspection included. No monthly subscription.
🔥 Furnace Services
Furnace repair, install, maintenance. ERV integrates with forced-air.
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PRICE
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