Gas heat exhaust

slamdvw

Looking to bid out a job to replace an old gas boiler with a new tankless water heater.



The existing boiler is sharing exhaust with a standard tank water heater, vented through gas chimney pipe.  Draft diverters on both the boiler and heater.



My question is, do I run a liner down (up ) the existing exhaust pipe or is it necessary since it's already rated for gas use?



My idea is to eliminate the tank heater and boiler - replacing with a tankless unit.



Thanks in advance



Robert Avery

Tim McElwain

Is the present

chimney a masonry or is it a double wall "B" vent? If it is "B" vent and the unit you are putting in is specified by the manufacturer for "B" vent installation you are all set. If however the vent is pressurized it will require special venting consideration typically side wall venting is the best solution.If it is a unlined masonry chimney you will have to have a liner installed in most cases.