A tankless water heater in the right Chicago home is transformative: endless hot water for back-to-back showers, 20 – 30% lower gas bills, 20+ year service life (vs. 8 – 12 for tanks), and a compact wall-mounted unit that reclaims the 3 × 3 foot footprint of your old tank. But a tankless is only as good as its installation. Do it wrong — undersized gas line, wrong venting, no condensate drain, no isolation valves — and you end up with poor performance, error codes, frozen pipes, and premature failure. Plumbers 911 Chicago does tankless right. We install Rinnai, Navien, Noritz, Rheem, and Takagi tankless systems across Chicago and 245 surrounding cities, and every install includes: proper BTU sizing for Chicago's cold incoming water (37 – 42°F in winter), gas line upgrade to 3/4" or 1" for adequate fuel supply, correct intake and exhaust venting (concentric or twin-pipe, always stainless or PVC per manufacturer spec), condensate drain routing with neutralizer where required, electrical connection, isolation valves and service ports for annual descaling, pressure test, gas leak test, and Chicago permit with inspector sign-off. The result: a unit that performs flawlessly from day one and lasts 20+ years. Call 833-758-6911 for a free site assessment. For related pages: tankless water heater repair, water heater repair, water heater installation, gas line services, and whole house repiping.
Is a Tankless Water Heater Right for Your Chicago Home?
Tankless is not automatically the right choice for every home. Here's how to decide.
Great Candidates for Tankless
- You run out of hot water regularly — large family, multiple simultaneous showers, fills a soaking tub
- You have space constraints — tight mechanical room, finished basement, or want to reclaim the tank footprint
- Your gas tank is failing and you're going to replace anyway (upgrade to tankless while you're at it)
- You want long-term hold and lower energy bills — payback is 5 – 10 years, then 10+ years of savings
- You have an adequate gas supply (or are willing to upgrade the gas line)
- You value reduced flood risk — no 40 – 80 gallons sitting in a tank that could fail
Not Great Candidates
- Single bathroom, low usage — a standard tank is fine and cheaper
- Extremely limited budget — tankless costs more upfront; tank is cheaper for first install
- Gas service can't be expanded (very rare, but worth checking in old multi-flats)
- You plan to sell the home within 3 years — payback timeline won't hit
Cost vs. Performance Trade-off
- Tank water heater: $1,400 – $3,000 installed (see water heater installation); 8 – 12 year life; up to 50 gallons on standby
- Tankless water heater: $3,500 – $7,500 installed; 20+ year life; unlimited capacity at rated flow
- Hybrid heat pump tank: $2,500 – $5,000 installed; 10 – 15 year life; electric-based for certain applications
We help you pick the right option based on your usage, budget, and home layout. No bias — just analysis.
Correctly Sizing a Tankless Water Heater for Chicago
The #1 reason tankless installations underperform is incorrect sizing. Here's how we do it right.
The Two Critical Variables
- Flow rate — how many gallons per minute (GPM) of hot water the unit must deliver simultaneously
- Temperature rise — the difference between incoming water temperature and desired output temperature
Chicago Incoming Water Temperature
- Winter (December – March): 37 – 42°F
- Spring/Fall: 48 – 55°F
- Summer: 55 – 65°F
Desired Output Temperature
- Standard: 120°F (code-compliant safe temp for residential; prevents scalding)
- Higher for commercial / high-hardness dish: 125 – 140°F
Typical Required Temperature Rise (Chicago Winter)
- 120°F output − 40°F incoming = 80°F rise in winter
Flow Rate Demand
Calculate peak simultaneous demand for your household:
- Shower: 2.0 – 2.5 GPM
- Kitchen faucet: 1.5 – 2.0 GPM
- Bathroom faucet: 1.0 – 1.5 GPM
- Dishwasher: 1.0 – 1.5 GPM
- Washing machine: 2.0 – 2.5 GPM
- Soaking tub: 4 – 8 GPM (huge, requires largest tankless)
Example: Chicago 3-Bedroom, 2-Bath
- Scenario: one shower + kitchen faucet + washing machine running simultaneously
- Demand: 2.5 + 1.5 + 2.0 = 6.0 GPM at 80°F rise
Example: Chicago 4-Bedroom, 3-Bath
- Scenario: two showers + dishwasher + kitchen faucet
- Demand: 4.0 + 1.5 + 1.5 = 7.0 GPM at 80°F rise
Manufacturer Flow at 80°F Rise
- Rinnai RU160iN (160K BTU): ~4.0 – 5.5 GPM at 80°F rise
- Rinnai RU199iN (199K BTU): ~5.5 – 7.5 GPM at 80°F rise
- Navien NPE-210A2 (180K BTU): ~5.5 – 7.0 GPM at 80°F rise
- Navien NPE-240A2 (199K BTU): ~6.5 – 9.0 GPM at 80°F rise
- Noritz EZTR50 (180K BTU): ~5.5 – 7.0 GPM at 80°F rise
Sizing Conclusion
For most Chicago homes, a 199,000 BTU condensing tankless is the right size. For small homes with 1 bath and low simultaneous demand, 160,000 BTU may be enough. For large homes or commercial applications, we may recommend a pair of units installed in parallel (manifolded) for 12 – 18 GPM capacity.
Important: manufacturer GPM ratings are often at a modest 50°F rise. For Chicago winter's 80°F rise, de-rate GPM by about 30 – 40%. We always size for worst-case (coldest winter day) so you have adequate capacity year-round.
Gas Line Upgrade: Why Your Tankless Probably Needs Bigger Gas
Tankless water heaters require significantly more gas than tanks. Old gas lines that worked fine for a tank water heater are almost always undersized for a tankless.
The Math
- Tank water heater: 35,000 – 50,000 BTU
- Tankless water heater: 180,000 – 199,000 BTU
- Ratio: tankless needs ~4x more gas
Existing Gas Line Sizing in Chicago Homes
Most pre-2005 Chicago homes have 1/2" gas line from the meter to the water heater. At typical Peoples Gas pressure (7" WC) and typical run distance (20 – 50 ft), a 1/2" line handles about 120,000 BTU max.
A 199,000 BTU tankless needs:
- 3/4" line for runs under 50 ft
- 1" line for runs over 50 ft or when shared with other appliances
Gas Line Upgrade Options
- Upsize the existing line to 3/4" or 1" from the meter
- Run a new dedicated line for the tankless (sometimes easier if the existing line is buried in walls)
- Upsize only from the tee, not the meter — possible if the main trunk is already 3/4" or 1"
Cost to Upsize
- Short run (basement, accessible): $500 – $1,200
- Medium run (some wall opening): $1,200 – $2,500
- Long run or complex routing: $2,500 – $5,000
This is a required investment for a tankless installation. Anyone who tells you they can install a tankless on your existing 1/2" gas line is setting you up for poor performance, error codes, and premature failure. See our gas line services page for details.
Gas Pressure Measurement
Before finalizing the install, we measure gas pressure at the unit under load. Required: manufacturer-specified inlet pressure (typically 4 – 10.5" WC for natural gas). If pressure drops below spec under fire, the unit will short-cycle and throw error codes. The fix is either upsizing the line (already done in most installs) or coordinating with Peoples Gas to upgrade the meter regulator.
Venting: Concentric vs. Twin Pipe, PVC vs. Stainless
Venting is the most-commonly-miscommitted part of a tankless install. Wrong venting causes recirculation, CO issues, and regulatory violations.
Condensing vs. Non-Condensing Units
- Condensing (higher efficiency, most common modern installs) — produces cool exhaust that can be safely vented in Schedule 40 PVC. More efficient because it recovers latent heat from the exhaust.
- Non-condensing (older, some rural applications) — produces hot exhaust that requires Category III stainless steel venting. More expensive.
Concentric vs. Twin Pipe
- Concentric — single pipe containing both intake (outer ring) and exhaust (inner pipe). Simpler, single wall penetration. Max length typically 25 – 35 ft.
- Twin pipe (direct vent) — separate intake and exhaust pipes. More flexible for complex routing. Max length typically 50 – 100 ft depending on unit.
Chicago Installation Options
- Wall vent — horizontal termination through an exterior wall. Fastest install. Requires proper clearance from windows, doors, and soffits.
- Roof vent — vertical termination through the roof. Higher install cost but works when wall vent clearances can't be met.
- Dedicated chase — runs through multiple floors for units installed below the final termination.
Chicago Code Requirements
- Minimum clearances: 12" from operable windows, 4 ft from property lines, 3 ft from gas meters
- Exhaust termination: 12" above grade or snow line (Chicago snow depth)
- Condensate slope: 1/4" per foot back to unit for proper drainage
- Material listed by manufacturer: only vent material listed in the manufacturer's install manual is acceptable
- Neutralizer required for condensate from high-efficiency units venting into copper or cast iron drain
What Goes Wrong
- Vent too close to windows or intake vents — exhaust recirculates, CO risk
- Wrong material — using non-listed PVC shortens life and voids warranty
- Improper slope — condensate pools, freezes, causes errors
- Joints not properly sealed — leaks CO into mechanical room
We follow manufacturer spec and local code on every install. Every vent is tested with a manometer and CO detector after commissioning.
Condensate Management: The Often-Missed Detail
High-efficiency condensing tankless water heaters produce acidic condensate during operation (pH around 3 – 5). That condensate needs to go somewhere.
Condensate Production Rate
A 199,000 BTU condensing tankless running at full fire produces about 0.5 – 1.5 gallons per hour of condensate. In a busy home, 5 – 15 gallons per day of acidic water needs to drain somewhere.
Where It Drains
Options in order of preference:
- Floor drain — gravity drain to a floor drain in the mechanical room. Best option when available.
- Condensate pump — a small electric pump lifts condensate to a sink or laundry tub drain. Second choice.
- Sump pit — pump condensate to the sump pit for discharge with the sump pump. Works but adds chemical load to the sump.
- Laundry tub or sink — direct drop via air gap.
Neutralizer for Acidic Condensate
When condensate drains into copper or cast iron piping, the acidity slowly corrodes the pipes. A condensate neutralizer (a container filled with calcium or magnesium chips) raises the pH before discharge. Required by many jurisdictions for condensate draining into metal piping.
- Cartridge neutralizer: $50 – $120, replaceable every 12 – 24 months
- Neutralizer tank with check-volume indicator: $200 – $400, replaceable every 18 – 36 months
Freeze Prevention
In cold basements or exterior locations, condensate lines can freeze. Fixes:
- Keep lines in conditioned space whenever possible
- Insulate any exposed lines with foam tubing
- Heat trace in extreme cases
- Slope continuously so water doesn't sit
Documentation
We document the condensate routing, neutralizer type, and service schedule in your install paperwork so annual maintenance is straightforward.
Our Tankless Installation Process
A typical tankless install is a full-day project. Here's what happens.
Step 1: Pre-Install Site Assessment
Before scheduling the install, we visit the site to:
- Verify gas supply adequacy (measure existing line size, check run length)
- Assess venting options (wall vs. roof, clearances)
- Confirm electrical availability (120V dedicated or shared outlet)
- Evaluate mechanical space (wall mounting, clearances, access)
- Recommend specific model based on demand
Step 2: Quote and Schedule
Written quote covering: unit, gas line work, venting, condensate, electrical, permit, labor, disposal of old unit, first-year annual descaling. You approve the scope and we schedule.
Step 3: Permit Application
Pulled before install. Most Chicago tankless installs require both plumbing and gas permits.
Step 4: Install Day
- Morning: Remove old tank, cap old gas and water connections, haul away
- Mid-morning: Run new gas line (or upsize existing)
- Midday: Mount new tankless unit, connect water lines with isolation valves and service ports
- Afternoon: Install vent piping (intake and exhaust)
- Late afternoon: Install condensate drain with neutralizer
- End of day: Connect electrical, commission unit, run through all fixtures
Step 5: Pressure Test
Gas lines pressure tested to 1.5x working pressure for minimum 15 minutes with no drop. Documented on permit.
Step 6: Commissioning
- Set temperature
- Test ignition, flame, and error code clear
- Run hot water at every fixture, verify flow rate and temperature
- Set recirculation if equipped
- Configure smart features if Wi-Fi equipped
- Register warranty with manufacturer
Step 7: Chicago Inspector Visit
Inspector verifies: gas pressure test, venting per manufacturer spec, condensate routing, electrical, clearances, and overall install. We meet the inspector on site.
Step 8: Final Walk-Through
We show you how to:
- Operate the unit
- Adjust temperature
- Reset if an error appears
- Schedule annual descaling
- Locate and operate isolation valves
Step 9: Documentation
You receive: permit, inspection certificate, manufacturer warranty registration, manual, annual service schedule, and our invoice.
Step 10: Annual Service Reminder
We put you on our reminder schedule for descaling at the 12-month mark. See our tankless water heater repair page for service details.
Tankless Installation Cost in Chicago
Complete tankless installation pricing.
| Item | Typical Cost Range |
|---|---|
| Tankless water heater (Rinnai, Navien, Noritz, Rheem, Takagi) | $1,200 – $3,500 |
| Standard installation labor | $1,200 – $2,500 |
| Gas line upgrade (1/2" → 3/4" or 1") | $500 – $2,500 |
| Venting (wall termination, standard length) | $300 – $800 |
| Venting (roof termination or long run) | $600 – $1,500 |
| Condensate pump (if no gravity drain) | $150 – $350 |
| Condensate neutralizer | $80 – $250 |
| Electrical (if new outlet needed) | $150 – $400 |
| Old tank removal and disposal | $150 – $300 |
| Chicago plumbing permit | $150 – $400 |
| Chicago gas permit (if required) | $150 – $300 |
| First-year descaling (included in our installs) | included |
| Recirculation pump upgrade (if desired) | $500 – $1,200 |
Typical Total Ranges
- Straightforward install (sufficient gas line, adjacent wall vent, floor drain nearby): $3,500 – $5,000
- Standard install with gas upsize: $4,500 – $6,500
- Complex install (roof vent, long gas run, condensate pump, electrical upgrade): $6,000 – $8,500
- Pair of units in parallel for large home or commercial: $8,000 – $14,000
What Drives Cost Up
- Distance from gas meter requiring long upsize
- Roof venting requirements
- Finished mechanical room (drywall, tile access)
- Commercial or high-demand sizing requiring parallel units
- Code variances (permit complexity)
What Keeps Cost Down
- Existing 3/4" gas line (rare in older Chicago homes)
- Wall-vent feasibility (adjacent exterior wall)
- Floor drain within 6 ft for condensate
- Electrical outlet within 3 ft
Rebates and Incentives
- Peoples Gas rebate: $150 – $300 for high-efficiency condensing tankless (check current program)
- ComEd rebate (for electric tankless, less common): varies
- Federal tax credit: 30% up to $2,000 for qualifying heat pump models (check current IRS 25C rules)
We help you identify applicable rebates and provide the documentation to claim them.
Top Tankless Brands We Install in Chicago
We're certified installers for all the major brands. Here's how they compare.
Rinnai
- Market leader in the U.S. — highest install volume, broadest parts availability
- Most common Chicago install
- Typical models: RU160iN (160K BTU), RU199iN (199K BTU), Sensei RX model line
- Strengths: proven reliability, excellent dealer network, strong service support
- Typical cost: mid-range; unit $1,400 – $2,800
Navien
- Best-in-class efficiency — NPE-A2 series has built-in recirculation, up to 0.97 UEF
- Typical models: NPE-180A2, NPE-210A2, NPE-240A2
- Strengths: built-in recirculation pump, Wi-Fi connectivity, excellent winter performance
- Considerations: complex electronics (more to go wrong, but well-supported)
- Typical cost: premium; unit $1,800 – $3,200
Noritz
- Japanese engineering, widely respected
- Typical models: EZTR series, EZ98, EZ111
- Strengths: durability, quiet operation, good performance in cold climates
- Typical cost: mid-range; unit $1,400 – $2,600
Rheem
- Strong warranty (up to 12 years on heat exchanger)
- Typical models: RTGH-95DVLN, RTGH-95DV (condensing)
- Strengths: reliable, widely available parts, good warranty
- Typical cost: mid-range; unit $1,200 – $2,400
Takagi
- Compact design, often used in tight-space installs
- Typical models: T-H3, T-H3S, TK-540
- Strengths: high efficiency, compact footprint
- Typical cost: mid-range; unit $1,300 – $2,500
Which We Recommend for Most Chicago Installs
- Rinnai RU199iN — our most-installed unit. Right-sized for most Chicago 3-bath homes. Excellent reliability and service.
- Navien NPE-210A2 or NPE-240A2 — for homeowners who want built-in recirculation and top efficiency.
- Noritz EZTR — alternative for homeowners who prefer Japanese engineering.
We don't push one brand over another based on margin. We recommend based on your actual needs, home layout, and budget.
Chicago Winter Performance: Tankless in Extreme Cold
Chicago's incoming water temperature dips to 37 – 42°F in January. A properly sized tankless handles this fine; an undersized one struggles.
Winter GPM Derating
Manufacturer specs are usually at a 50°F rise (typical for southern markets). At Chicago's 80°F winter rise, real-world GPM drops 30 – 40%.
- Rinnai RU199iN: 9.8 GPM at 50°F rise → ~5.5 – 7 GPM at 80°F rise
- Navien NPE-240A2: 11.2 GPM at 50°F rise → ~6.5 – 9 GPM at 80°F rise
This is why proper sizing matters. A "6 GPM unit" in summer may only deliver 4 GPM in Chicago January.
Freeze Protection
Modern tankless units have built-in freeze protection: when the unit senses temperatures approaching freezing, it circulates water through internal heat traces to prevent heat exchanger damage. Requires:
- Constant power supply — battery backup or generator recommended
- Intake/exhaust vents clear of snow and ice (walk around after storms)
- Condensate line not frozen — insulate any line in cold zones
What to Do if the Unit Freezes
- Do not force the unit on
- Leave off, warm the space to 50°F+, wait 24 – 48 hours
- If water leaks from the unit body, the heat exchanger cracked and needs replacement
- Call 833-758-6911 for emergency service
See our frozen pipe repair and tankless repair pages for related cold-weather info.