Jump to content

Help with solid fuel and gas (LP) in same chimney


Recommended Posts

Hello folks. I have some questions for you involving how to safely vent both solid fuel and gas (LP) out of the same chimney.

I know this is not code, but a lot of people still do it and some of them are licensed plumbers with small children (I know two such cases).

(1) Can people give me some clarity as to what are the known (as in proven) hazards of doing such a thing and what (if any) precautions one can take to make sure nothing really bad happens from having a duel vent for wood and gas exhaust?

Background: basically we don't plan to use the propane boiler that much (located in basement)... and if we do use it we would make sure there is no fire going in the wood stove (first floor of house). The house is over 3 stories high (basement, 1st floor - 9ft high-, 2nd floor - 9ft high- and vaulted attic - over 12 ft high). I think we will have sufficient draft for either appliance - even without a sleeve (which is in the chimney right now because it's attached to the propane boiler exhaust). We plan to plug in a bunch of carbon monoxide detectors on all floors of the house and keep the chimney totally free of any debris or creosote build up.

(2) The propane boiler has a built in shut-off system that will stop gas from coming out if the lighting mechanism malfunctions.. this makes me think there would be no unspent gas fumes entering the chimney which would potentially meet with a spark a floor above, am I correct?

What are your thoughts on all this - thanks!

Link to post
Share on other sites

This is not allowed by code and is considered a safety hazard for a variety of reasons. Just called this out on an inspection yesterday. You should install two separate flues that are approved and designed for the intend use. Installing two separate flues will improve safety, ensurer proper drafting, prevent accidental ignition of unburned gases, etc.

Link to post
Share on other sites

Hello folks. I have some questions for you involving how to safely vent both solid fuel and gas (LP) out of the same chimney.

I know this is not code, but a lot of people still do it and some of them are licensed plumbers with small children (I know two such cases).

What's that got to do with anything? Plumbers? Children? huh?

(1) Can people give me some clarity as to what are the known (as in proven) hazards of doing such a thing and what (if any) precautions one can take to make sure nothing really bad happens from having a duel vent for wood and gas exhaust?

The hazard is that you'll be using the propane appliance when the exhaust gases flow into the house through the fireplace instead of out of the house through the top of the chimney. This would be bad because it could cause you to die from carbon monoxide poisoning. Even if that didn't happen, it would still be bad because it could make you sick. Even if that didn't happen, it could put a lot of water vapor into the indoor air, causing problems with condensation.

Even small changes in indoor air pressure could cause these gases to flow into the house. Exhaust fans in the kitchen, the bathroom, and the laundry room could do it, as could the clothes dryer. Gas venting relies on buoyancy, which, in turn, relies on remarkably small pressure differences.

The precaution that you would take would be to provide proper venting.

Background: basically we don't plan to use the propane boiler that much (located in basement)... and if we do use it we would make sure there is no fire going in the wood stove (first floor of house). The house is over 3 stories high (basement, 1st floor - 9ft high-, 2nd floor - 9ft high- and vaulted attic - over 12 ft high). I think we will have sufficient draft for either appliance - even without a sleeve (which is in the chimney right now because it's attached to the propane boiler exhaust). We plan to plug in a bunch of carbon monoxide detectors on all floors of the house and keep the chimney totally free of any debris or creosote build up.

Sounds good on paper. Want to bet your family's life on it?

(2) The propane boiler has a built in shut-off system that will stop gas from coming out if the lighting mechanism malfunctions.. this makes me think there would be no unspent gas fumes entering the chimney which would potentially meet with a spark a floor above, am I correct?

That's not really a risk. Propane is very heavy. If there's a leak, it won't rise at all; it'll fall to the floor and collect in the basement until something causes it to ignite. Then, it'll blow up the house.

What are your thoughts on all this - thanks!

Install proper venting.

And while you're at it, install one of these:

http://shop.iceassault.com/Gas-and-Prop ... ve-GS7.htm

Link to post
Share on other sites

Thank you all for your responses!

The two things I forgot to mention are... the house is very old and thus is really drafty (like a corn crib really!) and so I don't think there should be any concern for improper draft. (Re: Trent and Jim's notes).

We plan to install more plug-in carbon monoxide detectors that will read as low as 30 ppm. We also plan to install a few propane detectors.

Lastly, in response to Jim, our boiler has a built in propane gas detector and shut off valve and thus will not continue to release propane in the presence of a leak. Thus, there should be no unburned gasses present.

One last thought... so if propane sinks and we are testing for it.. and the boiler will not allow more propane to be release with the shut off valve, then how could there be any gas settling in the basement? Further more, if the fire is on the first floor and drafting up AND we never turn the boiler on when we're lighting a fire, how could there ever be an explosion?

Thanks for all your help! I don't have 500 or more dollars to spend to purchase and then install a side wall vent system and honestly have a lot of very dry wood to burn this winter... so I'm seriously considering firing up the wood stove after shutting off the boiler later this week. Please tell me what else I can do to be as safe as possible. In my humble opinion it's probably safer to do this than drive on the back roads in this snowy weather we're having at the moment [;)]

Link to post
Share on other sites

To the OP: Feel free to put you and your family at risk if you wish. Ignorance is bliss, until..........

Here's an option. When you want to use the gas fired equipment, install the vent/liner, but make sure it runs all of the way up to the top of the chimney. Then, when you wish to burn wood, pull out the liner, disconnect, and cap opening.

Link to post
Share on other sites

Plug in LP alarms ride about a foot above the propane on the floor. You need them right on the floor.

CO alarms listed to UL 2034 are junk. Yes, it may indicate as low as 30ppm but it won't sound the alarm at 69ppm for up to 30 days or 70ppm for up to 4hrs. They are unreliable and give a false sense of security. Get an unlisted CO monitor and install it within 15lf of any sleeping room between knee high and face level.

With so many codes and stds. telling you not to do what you're trying to do why do you insist on continuing? This is gross negligence and if anyone gets hurt in your home you could go to jail. How's that? A draft house in Wisconsin could be just as much or more of a drafting issue than a tighter one in a warmer climate--there's a LOT more to 'draft', which is a misnomer. What you really mean to say is 'flow'. Draft is just the presence of a negative vent pressure with respect to the air around the chimney.

You indicate there is a liner already in the chimney to the boiler. A liner for solid fuel must be insulated to meet the 2,100F listing of the liner. How do you propose to switch a liner back and forth? This is just ridiculous! Use the liner for the boiler and run an insulated listed solid packed chimney for the woodstove. Then have a pro perform a level II inspection.

If you blow up or burn down your house your insurance company will probably have an out and not have to pay up to the survivors. Bad idea in so many ways...

Link to post
Share on other sites

Thank you all for your responses!

The two things I forgot to mention are... the house is very old and thus is really drafty (like a corn crib really!) and so I don't think there should be any concern for improper draft. (Re: Trent and Jim's notes).

Doesn't matter. Might even make things worse.

We plan to install more plug-in carbon monoxide detectors that will read as low as 30 ppm. We also plan to install a few propane detectors.

You know, when inexpensive carbon monoxide alarms first started to become readily available, I thought that they were a great idea. A friend, though, told me that they were a terrible idea. "People will use them as an excuse to take stupid risks." I remember wondering whether or not people were really that dumb.

Lastly, in response to Jim, our boiler has a built in propane gas detector and shut off valve and thus will not continue to release propane in the presence of a leak. Thus, there should be no unburned gasses present.

That's good. Is the sensor located at the floor? Does it actually shut off the propane at a solenoid valve outside the house or does it just shut the boiler? You want it to shut the propane outside in case there's a leak at a fitting before the boiler.

One last thought... so if propane sinks and we are testing for it.. and the boiler will not allow more propane to be release with the shut off valve, then how could there be any gas settling in the basement?

Because the propane leak might occur before it reaches the boiler.

Further more, if the fire is on the first floor and drafting up AND we never turn the boiler on when we're lighting a fire, how could there ever be an explosion?

If propane were to leak in the basement, any spark could set it off. A motor, a light switch, whatever. Are you suggesting that it's ok to have a pool of explosive gas in your basement as long as you have a fire on the first floor? I don't follow the logic.

Thanks for all your help! I don't have 500 or more dollars to spend to purchase and then install a side wall vent system and honestly have a lot of very dry wood to burn this winter... so I'm seriously considering firing up the wood stove after shutting off the boiler later this week. Please tell me what else I can do to be as safe as possible. In my humble opinion it's probably safer to do this than drive on the back roads in this snowy weather we're having at the moment [;)]

I'm guessing that your car has anti-lock brakes and air bags. Given the way your brain works, as long as you have these safety devices, you can drive as fast as you want out there.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...