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Harmonic Heating & Air Conditioning is here to take care of all your comfort system maintenance, repair and installation needs! Call us when you need comfort services!

Harmonic Heating & Air Conditioningstarstarstarstarstar5.0 / 5

216 Total Reviews /files//harmonic-logo-footer.png630-999-9008$10S187 Schoger Dr Suite #54, Naperville IL

ESC Direct Vent Cast Iron Gas Boilers

Ideal for installations where chimney venting is not possible' industry standard tapping locations permit ease of replacement for thousands of existing boiler installations.

  • Electronic ignition
  • Easy' intelligent IQ Control System™
  • Outdoor reset available – increases efficiency by 15-20%
  • Rear jacket panel of boiler is flat with no protrusions' simplifies transport and enables flush installations
  • Reliable' American-made cast iron heat exchanger can accept return water temps as low as 110°F
  • Intelligent Hydronic Control Combines aquastat' relay' and other ignition functions into a single module
  • IQ Option Panel Enables the easy plug & play installation of optional features such as outdoor reset' LWCO' and high limit
  • Optional Touchscreen LCD displays all boiler settings' diagnostics' and troubleshooting in sentences' not codes
MODELInput MBtuHOutput MBtuHAFUEDimensions
Water Content
ESC360.0 52.0 85.5 41x12.75x33 2.00 250
ESC491.0 78.0 85.4 41x15.5x33 3.00 300
ESC5121.0 104.0 85.3 41x18.5x33 4.00 350
ESC6152.0 130.0 85.2 41x21.5x33 5.00 410
ESC7182.0 156.0 85.0 41x24.75x33 6.00 460
ESC8212.0 180.0 84.5 41x27.75 7.00 510
ESC9243.0 206.0 84.0 41x30.75x33 8.00 560

Warranty Information

  • All Parts for 12 months -
  • Heat Exchanger - Limited Lifetime

Available Documents


We customize your comfort by making your home smarter, healthier and more efficient. Your peace of mind is as important to us as your comfort.

That's why every product us backed by warranties as robust and dependable as the products themselves.

Every piece of heating & cooling equipment is eligible for a 12-Year Parts Warranty, when you join the "Rock*Star Maintenance Program".

All other products are eligible for the 12-Year Parts Warranty.

Ask for details, terms, and conditions. All product warranties are registered by Harmonic within 30 days of purchase.

on all equipment repairs, indoor air quality & comfort items

Including humidifiers, air filters, air cleaners, thermostats and more! 12 year parts and labor warranty requires joining Rock*Star Maintenance Program. Ask for details, terms, and conditions.

The "Exclusive 12-year Parts & Labor Warranty" covers parts and labor cost from the time of purchase. "Exclusive 12-year Parts & Labor Warranty" requires annual maintenance to be performed by Harmonic Heating & Air Conditioning beginning immediately from the time of purchase. Maintenance must be performed annually during the initial 12-year coverage term in order to uphold warranty status. If annual maintenance is missed or not performed by Harmonic Heating & Air Conditioning, the "Exclusive 12-year Parts & Labor Warranty" becomes void immediately. Warranty coverage defaults to a 10 year part warranty and a 2 year labor warranty from the time of purchase. Warranty is registered to the purchaser and is not transferable.


when you purchase a Furnace or Air Conditioner from Harmonic!