I have a cess pit, not septic tank can i use this ? Other delivery options are available, please visit our. We offer a choice of regular boilers with a hot water cylinder or the ever popular combi boiler we can also explain how a heat recovery system could save as much as % of the energy that the boiler uses to heat the water we have the following systems available. What are your experiences of installing a new boiler? how much did you manage to save? let us know! A system boiler heats.