Installing an instant gas hot water heater:
Choose your unit based on the number of bedrooms and bathrooms and size of family using the system. Follow best gas practice recommendations for the placing of the unit near the bathroom away from windows and doors. Mount the unit by placing a random screw in the wall at the top-mounting bracket and swing the unit off this screw while you go ahead and place the main fixings into the wall to secure the unit. If into timber use either square drive or roofing screws to fix.
Once mounted proceed to provide the unit with a mains street pressure cold supply line. Sometimes this line may come off from under the house by way of a tee joint branched into a cold line. Or because it is best practice to mount the unit near the bathroom gain access through the outside wall to the underneath area inside the vanity cupboard and connect into the existing cold line with a brass tee or a poly tee as the case may be and a small flexi hose. Sometimes a hose tap can be wound out and a brass tee and brass socket fitted and the hose tap refitted to provide a cold line to the new unit. Do the same for the hot out flow line from the unit.
Also begin the process of removing the old hot water storage cylinder from its present position. Drain it down with a garden hose and disconnect the wiring as per instructions given under title Replacing a hot water storage cylinder:
Once the cylinder has drained remove it from the cupboard and disconnect the hot feed supply line pipe out of the cupboard and connect this point under the floor to the new gas hot water heater if you have not done so already under the vanity.
Please note: If the old hot water system used a header tank this will have to be disconnected from the mains street cold pressure line at the tank and blocked off.
Please note: When removing the header tank if you discover that the cold water feed for the shower was coming out of this header tank you will simply connect this branch line going to the shower mixer to the cold water mains pressure line coming into the tank to charge the shower mixer with equal hot and cold mains pressure.
Arrange for the gas bottles and gas line to be installed along with an electricity connection, and test.