Ballycullen road,firhouse,dublin 24. Spend about €850 or less per bill. The cheapest in the range is the duo-tec 24 combi erp which typically costs £680 and the most expensive is the new ecoblue 33 combi erp at £1,735. Bord gáis energy will contact you to arrange booking and appointment time. Pour 1/2 cup baking soda, followed by 1/2 cup.