I notice HE furnaces have two pipes protruding from an exterior wall. Am I correct to assume the lower one is to bring outside air into the furnace (why?) and the higher one is to release the exhaust from the furnace? Also, how toxic is the exhaust fume (is it worse than car exhaust) and why can't it be released into a chimney like the older furnaces?
High Efficiency Furnace Questions
- Thread starter SkyRider
- Start date
Just had a new HE furnace installed after 20 plus years of reliable older HE furnace...both Carrier.
One pipe is intake, ie. does not suck air out of the house when the furnace is on; it's own intake (presumably) contributes to its efficiency.
Second pipe is exhaust and both pipes can be routed through your existing chimney.
This new multi-stage is incredible. The old furnace would just blast on and warm up the house. The new one quietly stages on and off and I can't tell when it's running other than the house is more consistently comfortable.
Pleasant surprise in technological advance.
One pipe is intake, ie. does not suck air out of the house when the furnace is on; it's own intake (presumably) contributes to its efficiency.
Second pipe is exhaust and both pipes can be routed through your existing chimney.
This new multi-stage is incredible. The old furnace would just blast on and warm up the house. The new one quietly stages on and off and I can't tell when it's running other than the house is more consistently comfortable.
Pleasant surprise in technological advance.
Correct, lower one is intake, furnace is burning gas and therefore requires air to do so, by bringing it in direct to the furnace it improves the functioning of your furnace as newer homes are becoming quite air-tight and even if they aren't often the furnace is tucked away in a utility room with poor ventilation to the rest of the house.
Because of the moisture, you cannot vent the furnace to an old chimney though - as has been said you can run the pipes up inside one. This will cost more hence why it is not routinely done.
Because of the moisture, you cannot vent the furnace to an old chimney though - as has been said you can run the pipes up inside one. This will cost more hence why it is not routinely done.
http://www.thefurnaceguy.ca/faq.html
My neighbour has only one pipe sticking out of his house and I have two pipes, what’s up with that?
Your Neighbour’s furnace is using the air within their home for combustion. This is robbing their home of air which has already been heated, used for combustion then exhausted to the outside.
Your two pipe system brings cold air from outside for combustion then exhausts it back outside without using any heated air from within the home. Some manufacturers will not honour the lifetime heat exchanger warranty unless a 2 pipe system is used.
Often furnace and laundry facilities are located in the same room. In a single pipe system the air being used for combustion is bringing with it fabric softeners and detergents that give off gases that are very corrosive to the internals of the furnace. Insist on a two pipe system where the intake and exhaust are piped to the outside.
You can use the old chimney for a new furnace , but I believe old chimneys are not built to handle the exhausts of newer furnaces, so the chimney would have to be lined with something to accommodate it. I believe it has to do with newer furnaces exhausting the same amount of water vapour, but as the exhaust is cooler, meaning more water can accumlate on the chimney walls causing all sorts of problems.
My neighbour has only one pipe sticking out of his house and I have two pipes, what’s up with that?
Your Neighbour’s furnace is using the air within their home for combustion. This is robbing their home of air which has already been heated, used for combustion then exhausted to the outside.
Your two pipe system brings cold air from outside for combustion then exhausts it back outside without using any heated air from within the home. Some manufacturers will not honour the lifetime heat exchanger warranty unless a 2 pipe system is used.
Often furnace and laundry facilities are located in the same room. In a single pipe system the air being used for combustion is bringing with it fabric softeners and detergents that give off gases that are very corrosive to the internals of the furnace. Insist on a two pipe system where the intake and exhaust are piped to the outside.
You can use the old chimney for a new furnace , but I believe old chimneys are not built to handle the exhausts of newer furnaces, so the chimney would have to be lined with something to accommodate it. I believe it has to do with newer furnaces exhausting the same amount of water vapour, but as the exhaust is cooler, meaning more water can accumlate on the chimney walls causing all sorts of problems.
As I understand it, most HE furnaces cannot be vented through a chimney as the temperature differential isn't sufficient to overcome the possibility of a vapour lock developing in the stack (heavy, moist air sitting in the vent above the exhaust, leading to dangerous situations).
using the chimney as a chase to route the new venting is fine, providing the total run distance etc is within allowable limit.
Ahhh Grasshopper, so many questions.
A hi-eff furnace is a condensing furnace (a secondary heat exchanger extracts the latent heat of the exhaust), so you get relatively cool exhaust gases which are mostly water vapour, trace amounts of CO2 (for a properly functioning furnace, about 9-25 PPM) and CO, and aldehydes. These aldehydes are slighty acidic, and that acidity will erode the masonry/lining of a conventional chimney, as well as condense even more in the cool chimney and form a big puddle coming out of the chimney cleanout.
You can run the exhaust & intake pipes up the old chimney, but there a re code requirements covering that (mainly, that the old chimney be dormant). So if dude still has a conventional water heater utilizing that chimney, it won't be happening (unless he gets a power-vent or tankless water heater).
Now, snatch the pebble from my hand......................
Yes, but if any work has to be done to them they will have to be converted. You should do periodic inspection to ensure the pipes are in good shape.
Thanks. I spoke to another neighbor and he said that the "black" pipes are grandfathered but good to know that any future changes will have to be "white".
the black pipes(ABS) were found to break down in time causing cracks etc & potential for co2 leaks, the white pipes have a higher temperature rating to overcome that. When I had my furnace installed last year they used white on the furnace and grey on the water heater, they claimed due to higher temperature exhaust. it apparently costs more and is noticeably heavier .
System 636 venting (the "white" stuff, can be either PVC or CPVC depending on the temperature rating) became code in Canada August 2007. If you existing venting fails, or if the appliance is being replaced, the venting must be brought up to new code. This applies to the exhaust venting only, intake pipes may still be ABS (the "black" stuff), or any non-636 plastic pipe, or 636 if you want to spend the money.
There are 2 companies in Canada that manufacture System 636 - Ipex and Royal Plastics. And guess what? Their products are not interchangeable. If you go with Ipex, everything must be Ipex: pipe, fitting, primer, glue. Otherwise the installation will not be considered as being to code.
Gentle Ben, maybe I'm reading your post incorrectly, but was your powervent water heater also replaced? If so, and if it was done after August 2007, that exhaust vent MUST be system 636, which is clearly marked on the pipe & all fittings. Also, did they claim the furnace exhaust was a higher temperature, or the water-heater exhaust??
both furnace & hot water heater were replaced last year (2010). the furnace was vented (intake & exhaust) with white and the water heater (exhaust only) was vented with grey. I recall the installer telling me they like to use the grey on the water heaters because of the higher exhaust temperature ( I assume due to being less efficient than the furnace)
the furnace venting is white 636 pipe class 11A 65 degree C, the hot water heater is grey system 636 class 11B 90 degree C and is noticeably "bulkier" fittings
My furnace (about 8 years old) is making a loud noise at startup, kind of a vibrating grinding sound (the sounds seems to lessen if I hold the black vent pipe when it is starting up). When the blower kicks in, the sound goes away.
I have no idea how to fix this type of thing. For repairs, is it recommended to go with a big name company (enbridge, direct energy, sears) or a smaller local firm? I live in Durham region so if anyone has any recommendations it would be appreciated.
I have no idea how to fix this type of thing. For repairs, is it recommended to go with a big name company (enbridge, direct energy, sears) or a smaller local firm? I live in Durham region so if anyone has any recommendations it would be appreciated.
I think that a power-vent water heater also vents through a pipe through the wall. How does a tankless water heater vent?
Tankless normally use concentric kits. Concentric kits draw freash air and release exhaust all in one pipe. Normally it is a 5 inch pipe with a seperate 3 inche pipe inside of it for exhaust and the 2inches surrounding the inner pipe draws your fresh air. Yes they are also vented through a wall same as 636.
If it lessons off when you hold the black ABS pipe, I am guessing your venter motor is just a little bit loose and is causing things to rattle around inside your furnace. Your venter motor is hooked directly in to one of your black pipes and I have seen my fair share of old/noisy/vibrating venter motors
