| Dunnill Mechanical Services - Littleburn Industrial Estate - DH7 8HJ |
| Eco Heat Systems - Unit 14 South Hetton Industrial Estate - DH6 2UZ |
| Efficient Heat - PO Box 183 - DH2 2WY |
| EHL U K - Unit G2/Unit/Morton Pk Way - DL1 4PJ |
| Fireplace Centre (Chester-le- Street) - 126 Front Street - DH3 3AY |
| Gas Services Northern Ltd - 80 Eastmount Rd Birch House - DL1 1LE |
| Heatparts - 85 Victoria Road - DL1 5JQ |
| Industrial & Commercial Heating (North East) Ltd. - Bowburn North Industrial Estate - DH6 5PF |
| J Chapman & Son - 437 North Road - DL1 3BN |
| Utili-Wise - Talltrees - DH3 3UQ |
| Whitfields Building Services Ltd - Whitfield House Front St Pity Me - DH1 5EA |
| Winsund Intrenational - Priory Farm - DH8 9DW |
| Yorkshire Thermal Technology Ltd - Durham Way North - DL5 6YZ |
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