Tankless Water Heater Installation

What a tankless water heater is and how it works

Unlike those big metal tank sitting in your basement or utility closet, a tankless water heater works around the clock — heating and reheating the same water whether you're home or not, whether you're using it or not. A tankless water heater flips that idea on its head. Instead of storing hot water and hoping you get to it before it cools down, a tankless unit heats water only when you turn on a faucet — and stops the instant you're done. No standby. No waste. Just hot water when you need it. And when it comes to space? These units are roughly the size of a carry-on suitcase and mount flat against the wall. That bulky tank taking up half your utility closet? Gone — replaced by something you'll barely notice is there.

How Efficient Are They?

Think about what your water heater is doing right now. Even if no one's home, even if it's 2 a.m., even if you're on vacation in Florida for two weeks — that tank is burning gas to keep 40 gallons of water hot, just in case someone eventually turns on a faucet. That's called standby heat loss, and you're paying for it every single day. Modern condensing tankless water heaters are built to eliminate that entirely:

• Condensing tankless: Delivers 93 to 96 cents of useful heat for every dollar of gas you spend
• Standard storage tank: Delivers only 50 to 60 cents per gas dollar — the rest escapes into the air around the unit, wasted

The difference adds up fast. Switching to a tankless unit saves most Northbrook homeowners around $100 per year on gas bills. That might not sound dramatic on its own — but over the 15 to 20 year life of the unit, that's $1,500 to $2,000 back in your pocket. For a lot of homeowners, that savings alone comes close to covering the difference in upfront cost between a tankless unit and a traditional replacement tank. You're not just buying a water heater — you're buying one that starts paying you back from day one.

How we size a tankless water heater for your Northbrook, IL home

Tankless water heater installation in Northbrook, IL begins with precise sizing. The following process determines the correct unit for your home.

First, we determine your climate zone and incoming water temperature. Northbrook, IL falls in approximately Zone 4 with a groundwater temperature of approximately 52°F. To reach a 120°F outlet temperature, the required temperature rise is approximately 68°F. A top-capacity 199,900 BTU/h condensing unit delivers 11.2 GPM at a 35°F rise but only 3.9 GPM at a 100°F rise — incoming water temperature is the single most important sizing variable. Performance also varies by season within the same region; sizing must account for worst-case cold-water conditions, not annual averages.

Then, we calculate your peak simultaneous hot water demand. Industry-standard flow rates: shower ~2.0 GPM, kitchen faucet ~1.5 GPM, dishwasher ~2.0 GPM, washing machine ~3.0 GPM, bathroom faucet ~1.0 GPM. Two simultaneous showers plus a kitchen faucet equals approximately 5.5 GPM of required capacity. Minimum activation flow is 0.4 GPM — very low-flow fixtures may not trigger the burner.

Finally, we ensure the demand to BTU capacity match and that peak demand does not exceed single-unit capacity.

Tankless water heater installation requirements

The installation of a tankless water heater in Northbrook involves infrastructure verification across four categories. Each must be confirmed before the unit is mounted.

Gas supply infrastructure

A tankless unit at full fire consumes up to 199,900 BTU/h — roughly 5× a conventional 40-gallon tank at 36,000–40,000 BTU/h. The entire gas system — meter, regulators, piping — must be verified. Insufficient supply can cause lockouts, improper combustion, carbon monoxide, or fire. Natural gas inlet pressure must fall within 3.5–10.5 in. WC. At a 0.3 in. WC pressure drop over 30 feet, a ½-inch gas line carries only 72 CFH while the unit requires approximately 200 CFH — upsizing to ¾-inch or 1-inch pipe is required in most situations. YesXpress Plumbing recommends connecting the water heater as the first appliance downstream of the gas meter.

Venting system

Modern condensing units use 2-inch or 3-inch PVC, CPVC, or polypropylene vent pipe — not metal. Maximum vent run: 70 feet (2-inch) or 150 feet (3-inch); each 90° elbow reduces the maximum length by approximately 5–6 feet. The unit must be vented separately from all other appliances — never through an existing chimney. Vent terminal clearances require at least 4 feet from operable windows or doors, 12 inches above exterior grade, and 3 feet from the gas meter. Horizontal sections must slope ¼ inch per foot upward toward the terminal.

Electrical requirements

120 VAC, 60 Hz is required — the unit cannot fire without power. Normal operation draws 85W; up to 200W with built-in recirculation or freeze protection active. Power must remain connected even when the unit is off — freeze protection requires continuous electricity, and freeze damage from power loss is not covered under warranty.

Water pressure and thermal expansion

Minimum operating pressure is 15 PSI; recommended minimum is 40 PSI. In closed water systems where a check valve or backflow preventer is present, a thermal expansion tank is required — without it, thermal expansion can cause rapid, dangerous pressure surges. Both hot and cold supply lines should be insulated from the unit to each fixture; the drain line and pressure-relief valve must never be covered.

Condensing vs. non-condensing tankless water heaters

Condensing tankless water heaters feature dual stainless steel heat exchangers and recover latent heat from flue gases, achieving a UEF of 0.93 to 0.96 — delivering 93 to 96 cents of useful heat per gas dollar. Condensing units use inexpensive PVC venting and produce acidic condensate (pH 3–5) that must be routed to a code-compliant drain.

Non-condensing units use a single copper heat exchanger with a lead/tin coating, achieve approximately 0.80 UEF, and require more expensive metal vent pipe. Higher exhaust temperatures in non-condensing models mean higher venting material costs.

YesXpress Plumbing installs condensing models from leading manufacturers across Northbrook, IL and the surrounding communities.

Cost: Tankless Water Heater Installation

Pricing for tankless water heater installation is driven by the unit size, gas line modifications, venting complexity, and electrical work — not by a generic flat rate.

Typical cost drivers for Tankless Water Heater Installations:

• Gas line upsizing from ½-inch to ¾-inch or 1-inch when existing infrastructure cannot supply 199,900 BTU/h
• Meter and regulator upgrades — the gas company may need to upgrade the meter
• Venting path length and number of elbows
• Electrical circuit addition if no 120 VAC outlet exists at the installation location

YesXpress Plumbing's starting price for tankless water heater installation is $2,090. YesXpress Plumbing provides a written scope summary and explains all cost factors before work begins so Northbrook homeowners can make informed decisions without surprises.

Annual operating savings: A condensing tankless unit consumes approximately 177–179 therms per year compared to approximately 269 therms for a standard tank — an estimated annual operating cost of approximately $193 versus $293 for the standard tank, saving roughly $100 per year. Over the 15–20 year expected life of the heat exchanger, cumulative savings amount to $1,500–$2,000, substantially offsetting the higher initial investment. For Northbrook homeowners protecting their home's long-term value, tankless water heater installation is a measurable investment in both efficiency and property quality.

Our tankless water heater installation process

Free in-home assessment — a YesXpress Plumbing technician inspects the existing water heater, gas supply (meter capacity, regulator rating, pipe sizing), venting path, electrical access, and water pressure.

Demand calculation and unit selection — we calculate peak simultaneous demand using industry-standard fixture flow rates and match it to the correct BTU capacity tier for Northbrook's groundwater temperature of approximately 52°F.

Gas line verification and upgrade (if needed) — we verify that the existing meter, regulator, and piping can deliver the required approximately 200 CFH at 199,900 BTU/h. Half-inch lines are evaluated for pressure and length constraints. Upsizing to ¾-inch or 1-inch is performed if necessary.

Professional installation — unit mounting, gas connection with pressure testing, water connection (¾-inch NPT), PVC vent routing, electrical connection (120 VAC, 60 Hz), and condensate drain routing.

Pressure testing and commissioning — the gas supply system is pressure-tested and leak-tested at normal operating pressures per ANSI Z223.1/NFPA 54; the unit is fired and outlet temperature is verified at multiple fixtures.

Homeowner walkthrough — we demonstrate the control panel (temperature adjustment, status display, error codes), explain maintenance requirements (annual heat exchanger flush, quarterly air filter cleaning, periodic inlet water filter rinse), and provide all permit documentation.

Common installation mistakes we prevent

Professional installation eliminates the errors that cause lockouts, unsafe operation, and premature failure:

Undersizing the gas line: A tankless unit at full fire requires approximately 200 CFH — a ½-inch line over 30 feet carries only 72 CFH. Installing without verifying gas supply causes burner lockouts, improper combustion, and carbon monoxide risk. YesXpress Plumbing verifies the full gas path from meter to unit before every installation.

Sharing an existing chimney for venting: Condensing tankless units must be vented separately from all other appliances using PVC, CPVC, or polypropylene — never through an existing metal chimney or shared flue. Mixing vent paths creates backdrafting and carbon monoxide hazards.

Skipping the thermal expansion tank: In closed water systems with a check valve or backflow preventer, thermal expansion from the heating cycle can cause rapid, dangerous pressure surges. YesXpress technicians verify system type and install expansion protection when required.

Ignoring freeze protection requirements: The unit's freeze protection system requires continuous 120 VAC power — even when the unit is turned off. Disconnecting power during winter or installing without a dedicated electrical connection voids the warranty and risks catastrophic freeze damage.

Uncontrolled recirculation: Running a recirculation pump continuously without a temperature shutoff (aquastat) dramatically accelerates heat exchanger wear and reduces the manufacturer warranty from 15 years to as little as 5 years.