If you own a two-flat in Evanston or a rented single-family in Glenview, your heating system is not just a comfort item — it’s a habitability requirement with dates and temperatures attached. Tenants know it, inspectors enforce it, and the cheapest version of compliance is almost never the cheapest over five years.
This is a practical guide for small landlords: what you’re actually obligated to provide, where the citations come from, and which HVAC choices reduce your risk and your calls. We do this work for owners across the north suburbs, and the pattern is consistent.
The Core Obligation: Heat, During Heat Season
Illinois municipalities set their own heat ordinances, but they follow a common shape. Through the cold months — typically mid-September through the end of May or early June — a landlord must supply heat capable of maintaining a minimum indoor temperature in every habitable room, measured a few feet off the floor at the center of the room. Daytime minimums generally land in the upper 60s, with a slightly lower overnight minimum.
Two details catch owners out:
- “Capable of maintaining” is the standard, not “the furnace runs.” An undersized or badly ducted system that can hold 62°F in a back bedroom during a cold snap is a violation even though the equipment works.
- If the heat is tenant-controlled and tenant-paid, you still own the equipment’s ability to perform. Shifting the gas bill to the tenant doesn’t shift the capacity obligation.
Because the exact dates, temperatures, inspection triggers, and penalty structures differ between Evanston, Skokie, Glenview, and unincorporated Cook County — and because they get amended — verify the current numbers with your municipality’s property standards or building department before you rely on them. We’ll tell you what your equipment can deliver; your village tells you what it must deliver.
Where Landlord HVAC Citations Actually Come From
In our experience the write-ups cluster into six areas, and only the first is about temperature.
1. Insufficient heat in one room
Usually a duct problem, not a furnace problem: a closed-off addition, a crushed flex run, a return-air path that was drywalled over during a remodel. Fixes are often a few hundred dollars of duct work rather than new equipment. If the imbalance is between floors, zoning is the real answer.
2. No CO alarm near a fuel-burning appliance
Illinois requires carbon monoxide alarms within a short distance of every sleeping area in homes with fuel-burning appliances or attached garages, and smoke alarms are now required to be sealed 10-year units in most cases when replaced. In a two-flat with a shared basement mechanical room, this is the single most frequently missed item. It’s cheap to fix and expensive to ignore.
3. Unsafe venting or a shared flue problem
Replace a furnace in an older two-flat with a high-efficiency condensing unit and the water heater is left alone on an oversized masonry chimney it can’t warm. That’s an orphaned appliance, it backdrafts, and it’s both a CO hazard and an inspection failure. Budget the chimney liner or the water heater changeout as part of the furnace job — not next year.
4. Unit-to-unit conditioning shared across a duplex
One furnace ducted to both units of a two-flat is a maintenance and billing problem, and in some jurisdictions a code problem, because heat can’t be independently controlled by each tenant. Separating systems is real money but it also raises rent ceilings and resale value.
5. Missing combustion air or a blocked mechanical room
Tenant storage piled around a furnace, a louvered door removed, a laundry room enclosed around the water heater. Inspectors write this up on sight.
6. No maintenance record
If a tenant complains and you have no service history, you own the dispute. A documented annual visit is the cheapest defense you can buy. That’s most of why our maintenance agreements are popular with landlords: they generate paperwork with dates on it.
Equipment Decisions That Lower Landlord Risk
| Decision | Landlord-friendly choice | Why |
|---|---|---|
| Furnace type | Mid-range two-stage, sealed combustion, name-brand parts availability | Fewer emergency calls; parts on the truck; avoids the ultra-premium boards that strand you in January |
| Thermostat | Commercial-grade with adjustable limits, or a lockable cover | Stops the 85°F-in-February gas bill and the “off all winter” frozen pipe |
| Cooling | Standard efficiency AC, or ductless heads in units without ducts | Ductless avoids window units, tenant damage, and a lot of duct work |
| Metering | Separate systems and separate meters per unit wherever feasible | Tenant pays their own usage; removes the shared-cost argument entirely |
| Water heating | Right-sized tank per unit, not one oversized shared tank | One failure no longer takes out both units; simpler cost allocation |
| Filters | 1-inch filters at an accessible return, not a buried media cabinet | Tenants can actually change them; blower failures drop |
Typical Costs for Rental HVAC Work (2026, North Suburbs)
| Job | Installed cost |
|---|---|
| Furnace replacement, single unit | $4,200 – $8,500 |
| Furnace + AC replacement | $8,500 – $16,000 |
| Chimney liner for an orphaned water heater | $950 – $2,600 |
| Ductless mini-split, one head | $4,200 – $7,500 |
| Duct repairs / adding a run to a cold room | $450 – $2,800 |
| Separating HVAC between two units | $9,000 – $28,000 |
| Smoke + CO alarm compliance package, per unit | $350 – $1,200 |
| Annual maintenance agreement, per system | $220 – $480 / year |
The Turnover Window Is Your Best Friend
Everything above is dramatically cheaper and faster with an empty unit. No scheduling around tenant work hours, no notice requirements, no drop cloths through a furnished living room, no emergency premium. If you have a unit turning over in the next 60 days and the furnace is over 15 years old, that’s the moment — not the first 10°F night with a tenant in place.
Frequently Asked Questions
Can I require the tenant to pay for heat?
Generally yes when the unit is separately metered and the lease says so clearly. You remain responsible for equipment that can meet the required temperatures. Check your municipality’s disclosure requirements for who pays what.
Am I required to provide air conditioning?
Illinois habitability rules center on heat, not cooling. But if you advertise or supply AC, you generally must keep it in working order — and some local ordinances add cooling requirements for common areas. If you provide it, maintain it.
A tenant says the apartment is cold. What should I do first?
Document a temperature reading in the middle of the room, at about 3 feet, with exterior doors closed. Then get the system checked. A written service record and a measured temperature settle most of these before they become complaints.
Do you work with property managers?
Yes — we handle HVAC, electrical, and plumbing under one roof, which means one call and one invoice for a mixed-trade turnover punch list. See our commercial and multi-unit work.
What about heat pumps in rentals?
They can be excellent, especially ductless in unducted units, and dual fuel in ducted ones. The caution is tenant education and backup heat staging — a tenant who doesn’t understand the system will report it as broken. We size and configure with that in mind. Details on our heat pump page.
Serving Landlords in Evanston, Glenview, and the North Suburbs
We work with owners of two-flats, small apartment buildings, and single-family rentals throughout Evanston, Glenview, Skokie, Wilmette, Morton Grove, and Des Plaines.
Talk to MMDS
MMDS handles HVAC, electrical, and plumbing under one roof across the north and northwest suburbs. Call (847) 221-6280 or request a visit here. Financing is available through Sunbit and PowerPay, so a repair or upgrade can be spread into monthly payments instead of one hit to the bank account.