[dmagor]

I have decided to decommission a basement fireplace, and I'm looking for sage advice so I don't overlook something important. It's a regular woodburning floor-level fireplace that had been converted to a gas fireplace insert some years ago. It vents via the original rooftop stack, and has a garden variety termination cap that doesn't appear to let in the weather. Gas has been disconnected, and my plan now is to frame the opening, board it up, and cover it with Gyproc. The Wise People next door say I should include a vent in the opening to deter moisture, but that's as much as I know. Any advice you can offer will be gratefully received. Thanks.

 

[Cherryville Chuck]

Check your heating system to see if there is air going into the basement and air coming back out. If not, you will have humidity and possibly mold problems. The vent up the old chimney will let air out but unless there is an air source feeding into the basement then the only way it will circulate is by becoming a lower pressure zone than the upstairs and sucking air downstairs. The cap on top of the pipe does not shut off any draft. That is done at the heater. How were you planning on keeping the basement warm if you are removing the heater?

 

[dmagor]

Thanks for your reply, Chuck. It's clear now that good venting is important, so I'll add a return air vent to the opening. Does 4" x 10" sound adequate? We have forced air gas heat in the basement, plus a portable electric unit, so the f/p insert was not really needed for heat. Do I need to do anything more for venting?

 

[Cherryville Chuck]

If you have a forced air furnace blowing into the basement then, if it was done properly, you should have an air return down there too. If you don't have one then I would ask a professional to look at it. It is easy to get the system working against itself. The vent you are suggesting might be useful in the summer when you have windows open. Whether it will draft on it's own is hard to say because the coldest air is at the bottom. In the winter you wouldn't want it open since hot air rises and it will form its own draft as well as creating a vacuum in the rest of the house which is bad for your furnace and gas hot water heater if you have one.

 

[dmagor]

Venting and heating the basement itself doesn't seem to be an issue. I am more concerned with venting the chimney stack itself, since it will soon be a big, vacant closed-in space. There is an aluminum vent stack that goes from the gas insert, straight up through the length of our brick chimney. I will close that off at the bottom; no problem there (I hope). The big vacant space that used to be a wood fireplace has had the flue and some of the brickwork removed when the gas f/p was installed. That is more my concern. Since there is going to be no heat source at all in there, do I have to worry about moisture collecting? It rains in BC (you might have heard that rumour), and no vent stack is 100% effective, so I guess some water might have sneaked in in the past (even though I can't find any evidence of it). Most of it would have been dispersed by the gas heat, so will I now have a problem with a little bit of rainwater? Do I need to cap the vent pipe at the chimney top as well?

 

[DaninVan]

Hey, Don; I'm not clear on why you abandoned the gas fp insert in favour of Hydro? (I'm also in B.C....Sunshine Coast). Hydro has skyrocketed...gas has gone down...Hydro is primed to rise even more.

We have an airtight Regency wood insert in our lower level masonry chimney, and pretty much depend on it during the Winter, to reduce our dependency on Hydro.
(It just occurred to me that someone may not make the connection between "hydro" and dam generated electricity, our major supply source here in B.C.)

I've ranted on earlier about my frustration at not having a built in combustion air supply to the fireplace. No shortage of venting here; the fp takes care of that! $$$$$$$

 

[dmagor]

Hey, Don; I'm not clear on why you abandoned the gas fp insert in favour of Hydro? (I'm also in B.C....Sunshine Coast). Hydro has skyrocketed...gas has gone down...Hydro is primed to rise even more.

We have an airtight Regency wood insert in our lower level masonry chimney, and pretty much depend on it during the Winter, to reduce our dependency on Hydro.
(It just occurred to me that someone may not make the connection between "hydro" and dam generated electricity, our major supply source here in B.C.)

I've ranted on earlier about my frustration at not having a built in combustion air supply to the fireplace. No shortage of venting here; the fp takes care of that! $$$$$$$

Thanks for replying, Dan. I have a long answer, but I'll give you the short one: replacement cost (old f/p insert is beyond repair) and wall space. We already have all the heat we need (brand new high-efficiency forced air gas furnace), so I'm not replacing Fortis with Hydro. And I need some room for my furniture.
Sunshine Coast is great; lived in Gibsons until 2 years ago, now on the north island.

I keep coming up with new questions: should I remove the vent pipe completely from my chimney? Maybe that's where I should be starting.

 

[Cherryville Chuck]

I may have the same Regency insert, I think there were only 2 models. Home for me is Cherryville in the North Okanagan. No Fortis, only hydro and wood. Part of me says cap it so that no possibility of rain water getting in, the other part of me says leave a vent opening in case you need summer ventilation, although you could run just the fan on the furnace. Maybe PM Richard (Gwizz), he was in the business.