Contact Us for Reliable Plumbing, Heating and Cooling Services

William G Day Company is your one-stop shop for heating and cooling and plumbing services.

Our Location

William G Day Company

1603 N. Jessup St #4
Wilmington, DE 19802
Phone: (302) 219-5591

Office Hours

Monday7:00 AM - 4:00 PM
Tuesday7:00 AM - 4:00 PM
Wednesday7:00 AM - 4:00 PM
Thursday7:00 AM - 4:00 PM
Friday7:00 AM - 4:00 PM

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HVAC Services

  • Air conditioning repair and installation
  • Heat pump, furnace and boiler repair and installation
  • Heating and cooling system tune-ups and preventive HVAC maintenance agreements
  • Indoor air quality solutions
  • Commercial HVAC services
  • Zoned systems
  • HVAC thermostats and controls
  • Packaged heating and cooling products
  • Mini-split air conditioners
  • Fan coils and evaporator coils
  • Ductless systems
  • 24/7 Emergency service
contact us today!

Call William G Day Company to Troubleshoot Your HVAC Unit

Call us for HVAC troubleshooting help before you schedule service. Sometimes the problem is something small that we can help you correct over the phone. It doesn’t hurt to try, and it might save you a service call.

Schedule a No-Cost Heating or Cooling Upgrade Consultation

If your furnace, heat pump, boiler or air conditioner is gobbling energy dollars, not keeping you comfortable and costing you a ton of money in repairs, you can start saving money on energy bills immediately when you upgrade to a high-efficiency replacement system. HVAC systems get less efficient with age, and new systems get more efficient every year.

It’s a safe bet that you’ll see a significant reduction in your monthly energy bills just by replacing your old unit with a new one. Call us to schedule a free in-home system upgrade consultation, and we’ll explore the options with you. Techs are on call on the weekend and will schedule on the next evening and/or weekend.

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License Numbers

  • Maryland HVAC 81535
  • City Of New Castle Business License 17000329
  • City of Newark HVAC 3914
  • City of Wilmington (Mech Contractor) 2503
  • Common Wealth of PA PA017110
  • New Castle County Master Contractor UT0778
  • State of Delaware Plumbing PL 0000466
  • State of Delaware HVAC HL0000001
  • State of Delaware Business License 1996103733
  • Maryland Plumbing 21340
  • New Jersey Plumbing 10631
  • Town of Elsmere L7-00099
  • Middletown HVAC & Plumbing 17-80486