Help with Venting Options

GregPD

Hello,



I am first-time home owner and looking for some advice. It is small (1000 square feet) 1931 Cape Cod House in the Hudson Valley, New York. It still has the original (I believe) boiler that was converted at some time from coal to fuel oil. It has one chimney on the side of the house with two unlined flues (one for a wood burning fireplace and the other for the boiler). It has cast-iron hot water radiators. I want to convert to natural gas. Here are my questions:



I was thinking of putting in a mod-con boiler as I thought it would not require lining the chimney (I could use some sort of PVC pipe?). But maybe this is not an option if the flue shares the chimney with another flue being used by a fireplace?



So, can I vent out the side of the basement? Is this a good idea?



Basically, I am wondering if I am going to have to get a steel liner for the chimney whichever way I go...



Thanks,

Greg

Jean-David Beyer

I am a homeowner with a Cape Cod in New Jersey.

So it is somewhat warmer here than where you are, but perhaps not all that much. My house is from 1950 and had a GE hot water boiler in it that was still working when I replaced it three years ago. I have copper tubing in the slab under the house downstairs and finned-tube baseboard upstairs. No basement. The boiler was and is in the attached garage with a single flue chimney in good repair. It was not big enough to run the intake and vent pipes in it, and you cannot run the flue through it (clay pipe lined brick chimney). So they ran PVC pipe up to the ceiling, and across the ceiling of the garage and out the side of the garage. That works OK for me. There is some question if you want to run the vent through PVC piping. A lot of question. There is a very long thread here at this site about that. You might wish to run a different plastic or stainless steel pipe.



http://www.heatinghelp.com/forum-thread/136409/Is-PVC-an-acceptable-vent-material-for-flue-gases



I am not a contractor, but I have seen brick chimneys with two and three separate flues in one overall structure. If yours is like that, I suppose you could run the flue up one of them, and use the other for whatever. With my W-M boiler they do not seem to like that because they want the vent and the intake to be pretty close to one another so the wind does not cause a pressure difference between the two. When picking a mod-con boiler, if you choose to do that, I suggest reading the installation manual to get the manufacturer's recommendation on venting and other installation issues. That might rule out some boilers.



As far as running a mod-con with baseboard, it is my impression that that is just fine if you have enough baseboard to run low temperature (less than, say, 130F) so you get adequate condensing. In my house, I raised the amount of baseboard in each of the two rooms in my upstairs from 3 feet to 14 feet to get enough heat at condensing temperatures. If you go mod-con, be sure to have outdoor reset connected. That way, even if you cannot run 130F or less in your baseboard all year long, you can probably do that some of the year and get some of the benefit. It is below the design temperature only about 2.5% of the time. And if you go mod-con, do not oversize the boiler at all, if you can help it.