Great Installation Prices on 135 Litre Gas Hot Water System Here are some of your options for a 135 litre hot water systems. If you have a Rheem stay with a Rheem. This applies to Vulcan and Dux as well. The reason is that the pipework layout is generally the same. This will keep the installation cost lower. Eliminating any extras. Rheem 135 Litre Gas Hot Water System Installed – Best Deals Vulcan 135 Litre Gas Hot Water System Installed –Best Deals Dux 135 Litre Gas Hot Water System Installed –Best Deals FAST Change Over Service. The old 135 litre hot water system will be removed as well as all associated rubbish.