- Cleveland Gas Service Engineers Ltd
- 01642 603922 - 14 Oxbridge Lane, Stockton-on-Tees, Cleveland, TS18 4DN
- Cleveland Gas Service Engineers Ltd
- 01429 269987 - 151 York Road, Hartlepool, Cleveland, TS26 9EQ
- County Durham Gas
- 01388 604556 - 46 Fore Bondgate, Bishop Auckland, County Durham, DL14 7PE
- Gas Services Northern Ltd
- 01325 489909 - 6b Oxford Street, Darlington, County Durham, DL1 1QZ
- Gascom
- 01740 622877 - 2 North Park Road, Sedgefield, Stockton-on-Tees, Cleveland, TS21 2AP
- T Taylor
- 01429 273481 - 25 Sandringham Road, Hartlepool, Cleveland, TS26 8PR
- EC Solutions
- 0191 4102737 - 56 Turnberry, Ouston, Chester Le Street, County Durham, DH2 1LR
- Gas Tech
- 01661 843107 - 158 New Ridley Road, Stocksfield, Northumberland, NE43 7EH
- Northern Boiler Maintenance
- 01207 561704 - 14 Handley Cross, Medomsley, Consett, County Durham, DH8 6TZ
- Neat Heat
- 01325 358596 - 9 Windermere Court, Darlington, Durham
- Expert Gas Services
- 01642 766006 - 1 Brougham Close, Ingleby Barwick, Stockton-on-tees, Cleveland, TS17 5GH
- Ltd Calibration Services
- 01642 470771 - Redcar, Cleveland, TS10 5AT
- Tacho-Grafix
- 01325 314422 - Groat Dv Aycliffe Indust Pk, Newton Aycliffe, DL5 6HY
- Ingleby Installations Limited
- 01642 762795 - 34 Lawrenny Grove Ingleby Barwick, Stockton On Tees, Cleveland, TS17 5EA
- ARA Plumbing and Heating
- 01388 766302 - 3 Brookside Cottages, Crook, County Durham, DL15 8JH
- M Smith Plumbing And Heating
- 07765 866782 - 35 Sandown Rd, Billingham, Cleveland, TS23 2BQ
- Chaumont Gas Services
- 01740 629337 - Turnpike Walk, Sedgefield, Durham, TS21 3NP