Ventilation

[Anonymous]

The Chimney is 8 in. Dia. and 38 feet High. There are two water heaters (40 Gal each-37,000BTU’s each without power vented Fans) already vented into chimney with 3″ pipe. I need to put two more forced Hot water Heating systems into the same chimney (Both systems are 167000 BTU’s Each and have fan induction for Ventalation or blowers). I Need to how to get all 4 systems into the same Chimney, Being that the promlems are
1. The fans could blow out the pilots on the Water Heaters if both systems are on at the same time.
2. The size of the liner needed?
3. Whether I should use one 7″ liner for all or Seperate liners for each or just one for the Heating systems and leave the Hot Water systems as they are next to a smaller 3″ liner for the boilers.
Maybe someone has some advice and can help? If so you can contact me directly at my E-mail listed
Thank you Paul L. DerVartanain

[hjParticipant]

As far as blowing out the pilots, that is why you have back draft diverters on top of the water heaters. But if the chimney is not large enough, then the heater gases might not be able to enter the chimney against the blower’s pressure and then you would have the equivalent of a back draft with the heater gases spilling into the room. Your chimney’s area should be the same as the total area of all the flues connecting to it. You do not give the size of the heating unit flues but I would assume it would require at least an 8″ round liner. If you could find a fabricator, he might be able to create a 7″ square one which would have the same area but would slide into the 8″ chimney.

[SylvanLMPParticipant]

Paul I would strongly suggest you contact a local Master plumber or mechanical engineer to size this system. You should also think about the free air you will need for combustion for this new equipment. About using a 7″ square in lieu of the slightly larger round flue I hate down sizing flue piping and I don’t like mixing fan induced draft with natural.

You honestly should think about hiring a local professional, duly licensed.

[GuestParticipant]

You might ask your boiler dealer if there is such a thing as a high efficiency boiler, that doesn’t require connection to a chimney. I know there are high efficiency furnaces, which only require two pvc pipes run from the furnace to the outdoors(at basement level,) one for combustion air coming into the unit, and one for exhaust air leaving. You also might want to consider removing the hot water heaters all together, and getting boilers that will heat your heating and domestic hot water in one efficient unit.

[Author]

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