This industry comprises establishments primarily engaged in the merchant wholesale distribution of plumbing equipment, hydronic heating equipment, household-type gas appliances (except gas clothes dryers), and/or supplies. Cross-References. Establishments primarily engaged in-- ? Selling and installing plumbing, heating and air conditioning equipment--are classified in Industry 238220, Plumbing, Heating, and Air-Conditioning Contractors; ? Merchant wholesale distribution of warm air heating and air-conditioning equipment--are classified in Industry 423730, Warm Air Heating and Air-Conditioning Equipment and Supplies Merchant Wholesalers; and ? Merchant wholesale distribution of household-type electrical appliances, room air-conditioners, gas clothes dryers, and/or household-type audio or video equipment--are classified in Industry 423620, Electrical and Electronic Appliance, Television, and Radio Set Merchant Wholesalers.