The code book in my country isn't based on hopes and dreams like yours I guess....
Originally Posted by gravity
I wasn't suggesting this so called chimney adapter. I believe a properly sized chimney liner in the masonry, then transitioning to b-vent to the furnace is the best and only way to go
And then tune the appliance with a combustion analyzer to its rated output so the chimney liner doesn't become a nice drain pipe from an underfired appliance.
Originally Posted by syndicated
A water heater is another example of an appliance that comes with a draft hood. That thing should be tossed in the trash and a barometric damper should be installed with a temperature switch for optimum safety.
I just wanted to respond to this part of your post. Yes, the gases cool off as they go up the chimney. And yes, a liner will seem to fix it but in reality is just a bandaid covering up a deeper problem.
Originally Posted by syndicated
If instead of installing the liner you removed the draft hood and piped the vent directly off the water heater, then installed a double acting barometric draft regulator, the problem would be fixed properly, no bandaid needed. Even if the flue is a 12 inch.
Draft hoods suck in 40-50% room air which dilute and cool the flue gases. If you remove the draft hood, the flue gases stay hot, the chimney stays dry and there is no need to line it (assuming it was inspected and is in safe condition). Draft hoods are dangerous, either low draft or high draft conditions can and do prevent the flue gases from venting.
Yes this is how I do my job. It is how things actually work in the real world. If an installation just passes code, that means it is the most dangerous installation you can legally get away with. I make appliances safe and exceed the code requirements.
Ah, but modifying an appliance, like removing a factory provided draft hood is against code.
Originally Posted by chuckcrj
Installing appliances into an improperly sized chimney is against code.
So throwing barometric dampers at anything burning gas isn't an option just because you think it's better isn't an option, atleast up here.
Any and every house I go to in my service area with a properly sized chimney (liners included) don't have condensation problems. If that we're the case rain caps would be plugging with ice every winter and the ones I remove would be corroded through.
What I have found, is that stand-by losses from most appliances, plus standing pilot lights keep the chimney warm enough to allow the flue gasses to pass without reaching their 140* condensation point.
In an oversized or unlined block chimney situation, we have seen stratification in side the chimney where the block literally sucks the heat out of the gas before it reaches the top, sandwiching and eventually sinking those gasses back down the chimney.
A block chimney has a lot of thermal mass, and are often not in great shape after 30+ years of service.
By putting the gas in a smaller (properly sized) pipe it can rise faster by staying hotter.
So what happen when the change of state occurs in the chimney and destroys the structure
a draft hood is against code. it retards the flow of exhaust gasses.
it does exactly what it's called.......diverts the draft!!
why do you put a barometric on an oil appliance? to control draft!
is it against the law to control draft on a gas appliance? NO!
Once you learn how to properly tune an appliance, throwing a barometric on it isn't just because it's better. It's so we can control draft, make an appliance safer, etc...
Just because something is code, it does not mean its safe and works as intended.
read the attachment i included a couple posts back