you are out of luck.....
you cant do that legally.
I had my water heater replaced last December with a Ruud PH2-40PF (the old one finally got a leak). I replaced my furnace and A/C about a month ago - the A/C died and the furnace was about 30 years old.
Anyway, the new furnace is a 95% direct vent model and all I have on the current chimney is the WH. At some point, I'd like to remove the chimney (the house is 50 years old - I think the current chimney is just metal vent pipe with no brick).
Is there any way to add a power vent to this model, or does the unit need to be replaced with one that was designed for a power vent from the factory? Thanks!
I will say right now that I had a draft vent unit installed since the old one was under home warranty and I couldn't afford the cost difference at the time. A new WH for $60 installed was a good deal in the winter.
The control and safety circuits for a power vent are so complicated that the cost to retrofit them to an existing furnace would likely exceed the cost of a new furnace. Also, because it would be impossible to get AGA or GAMA certification on a retrofitted furnace, there are legal, code, and insurance issues. There may be companies who tell you they can do this. I would not go there.
--Customers of plumbers: Never be afraid to ask for proof of licensure of the plumber servicing your equipment. A licensed plumber will be proud to show you his personal license.--
Looks like commercial stuff. I would stand by my comment that the cost to put this on a residential unit would be prohibitive. Probably need a new gas valve, because the typical water heater gas valve does not have any kind of interface connections necessary for the safety circuits.