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High Efficiency Furnace Installations and Venting Info - Interesting Read

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Dec 23, 2003
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High Efficiency Furnace Installations and Venting Info - Interesting Read

Here is a good article in the Toronto Star about installations with High Efficiency Furnaces and venting.

http://www.thestar.com/article/578833

Image

When I think of our new high-efficiency gas furnace, I picture the Ricola cough drop commercial. You know, the ad with two Swiss mountaineers, one of them blowing an enormous alphorn, while the other calls, "Ricola!"

I could have had similar trumpets at the front of my house. I came close to getting them
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Jun 17, 2004
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Interesting. My friend just called me yesterday talking about replacing their furnace and asking whether I know the difference between 1 and 2 pipe installation.

I am just wondering if only one pipe is used instead of 2, does it mean the furnace is not installed properly or efficiently? Some company who sells Goodman hi-eff furnace told my friend that the Goodman furnaces can be installed with 1 or 2 pipes depending on the house structure according to the manufacturer's instruction. Is it true?

Thanks



hightech wrote:
Jan 31st, 2009 5:20 pm
Here is a good article in the Toronto Star about installations with High Efficiency Furnaces and venting.

http://www.thestar.com/article/578833

Image

When I think of our new high-efficiency gas furnace, I picture the Ricola cough drop commercial. You know, the ad with two Swiss mountaineers, one of them blowing an enormous alphorn, while the other calls, "Ricola!"

I could have had similar trumpets at the front of my house. I came close to getting them ? albeit smaller eyesores. It was a choice between freezing over the winter or swallowing my vanity over a pair of in-your-face furnace-venting pipes. But as the saying goes, you've got to shop around. Was I ever glad I did.

It began when A1 Air Conditioning & Heating arrived at our Oakville home (built in 1971) to clean our 20-year-old high-efficiency gas furnace. Although they replaced the heat sensor, they said the furnace was on its last legs. It was rusted inside and would kick in at about 15C, heat a bit, and cut out. My husband, Frank, doubted it would last the winter once the temperature went into deep freeze. So we looked into a high-efficiency furnace and decided to get another estimate.

The newer high-efficiency gas furnaces, as one furnace expert explained to me, are more energy efficient. They don't vent out the chimney like our old one or like mid-efficiency gas furnaces. Instead, two white PVC pipes, about two inches in diameter, come out of the house at grade level ? side by side ? and elbow up so that they're three feet above the estimated snow line. One vent takes the air to the furnace for combustion, while the other vents the furnace's exhaust.

We phoned another company (call it company B) and a sales rep came by. He examined the outside of our house for a place to mount the two pipes, but needed a one-foot clearance from the windows or doors and three feet from a gas metre. The only place he found was at the front.

I had suspicions about the pipes' appearance, so I asked Frank what they looked like. He took a flashlight, we put on our ski jackets and went vent hunting.

"Here," he said, flashing the light at the side of one house, "I think our neighbours have one." We were stumbling around in the dark. What if the neighbour was home and thought we were burglars? Geez. Shouldn't we just ring the doorbell? We went to the side and peered through the fence and bushes, but saw nothing.

Riding the bus home the next day, I passed a house with vent pipes at the side. They reminded me of those Ricola alphorns. Just smaller. More like a couple of periscopes or snorkels. I walked through the park moping, and then stood looking at our house , imagining how ugly the pipes would look once they sat plastered against my Georgian-style brick house.

I called A1 the next day and spoke with sales manager Jeff Smith.

"The sales rep at company B says that the only place the vent pipes can go is in the front," I told him, throwing down the gauntlet.

"Well, most of the time I can find somewhere to put them," he said, confidently. Smith mentioned another type of vent, a six-inch concentric model that resembles a stereo speaker. It's more aesthetically pleasing, but is more limiting to where it can be installed, he said.

When I arrived home the next day, my husband had good news: Smith had been by and was fairly confident that his team could install a concentric vent to the right of our garage door at the front or even at the back if they went through the garage. But he needed an engineering technician to confirm this.

We had made an appointment with one more company for an estimate. I mentioned the concentric vent to the representative at company C and yes, he said, they supplied it. He could come over to check out the placement.

Sunday morning he met with my husband. I returned from an appointment and asked Frank for the verdict.

"Oh, yeah. The concentric one won't do ? although he didn't give a reason. They'll have to use the traditional vent pipes. The only place is in the front, although he'll double check for us."

Back to calling A1 on Monday .

"Jeff, the guy at company C says the furnace can't be vented with concentric vents so we'll have to use the pipes and they'll have to go at the front!"

"Well," he again stressed, "we can usually find some spot, but I need to bring a tech over."

That evening a car pulled into our driveway and I met Smith. "You have some good news for me?" I asked. His face looked a bit sullen ? guilty, even. Oh dear.

He explained that he couldn't use the concentric vent, since the tech would have trouble installing it through the garage to the back. This would prove costly, since roofers would have to be called in. Plus the roof's slope near the garage didn't allow the disc to be mounted to the right of the garage at front.

But they did find one unobtrusive spot after combing every inch of the exterior ? at the left side of our house and to the right of our side door, near the mailbox. Our cedar bush would help hide it. They would have to use vent pipes, since the concentric vent needed to exit the building at least at the snow line. The only adjustment might require moving the water metre line over a bit, said Smith.

Okay. Hallelujah. Mission accomplished.

Our new high-efficiency gas furnace is now humming away. It has an ultraviolet germicidal air purifier, which inhibits the growth of contaminants on the furnace coil, plus we added a humidifier and an electronic air cleaner, to help filter dust, mites and mould. The price for the package wasn't cheap, but reasonable as appliances go ? $7,255.50, including taxes. Plus, we had an eco-ENERGY Retrofit assessment done prior. Under this program, homeowners can claim up to $5,000 in federal grants for making their homes more energy efficient.

Our heating package was cheaper than the alternative we considered ? tearing up the front lawn to install a ground-source heating system we estimated would cost at least $16,000, or building an addition over our garage to incorporate the vent and shouldering another mortgage.

Sometimes vanity does pay off.

Janice Bradbeer is an editor at the Star who loves her home but finds it a pain sometimes.
Sr. Member
Aug 25, 2005
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Some furnaces draw air for combustion from the inside. Thus, they only need one vent for exhaust.

Drawing fresh air from outside does have some benefits. If you end up finishing your basement, you won't need to worry about the furnace room having enough fresh air to feed the furnace -- if your furnace room is too small, you might even hear 'crackling' if there isn't enough fresh air.
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Mar 19, 2008
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It was my understanding that high efficiency was two pipes and medium efficiency was only one output pipe. Could be completely wrong though.
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Aug 25, 2005
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jjasond wrote:
Feb 1st, 2010 10:07 pm
It was my understanding that high efficiency was two pipes and medium efficiency was only one output pipe. Could be completely wrong though.
Some high efficiency furnaces have 1 exhaust pipe only. Buidlers like to use those units because they are CHEAP. My house has one.
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Jul 25, 2008
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I am looking into getting a new natural gas furnace high efficiency to replace my old oil furnace.

All the furnace guys I spoke to say they have to place the exhaust in the front.
just like the picture.

One furnace guy said they can use the chimney (3 levels+roof ) with a white pipe inside as there is no building code on this. Does anyone know the code that we can we do this?? :?:
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Dec 18, 2005
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redac wrote:
Feb 1st, 2010 8:35 pm
Some furnaces draw air for combustion from the inside. Thus, they only need one vent for exhaust.

Drawing fresh air from outside does have some benefits. If you end up finishing your basement, you won't need to worry about the furnace room having enough fresh air to feed the furnace -- if your furnace room is too small, you might even hear 'crackling' if there isn't enough fresh air.
+1. I've had a high efficiency Goodman furnace put into my previous place and it had the exhaust pipe leading to the outside, and the intake pipe staying in the furnace room drawing air for combustion. I previously asked a home inspector and a HVAC installer about whether both pipes should vent outside, and the answer they gave is it is not necessary, as long as the furnace room had no door or that the door is always left open so the furnace can draw air for combustion without any issue.

I did finally get someone to extend the air intake pipe outside so I could get fresh air, but I felt that it made the air blowing out of air vents when the furnace was running less warm, perhaps since the air coming in for combustion was icy cold and was mixed with the heated air from the furnace. Maybe someone who is familiar with high efficiency furnaces can comment on this.
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Jan 23, 2002
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I thought the concentrics were no longer permitted? I had my HE boiler installed in Dec 2008 and we had to go with the two pipes. As vanity goes, the concentric does look better.
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Jan 23, 2002
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jjtsl wrote:
Feb 27th, 2010 10:36 pm
... and the intake pipe staying in the furnace room drawing air for combustion. I previously asked a home inspector and a HVAC installer about whether both pipes should vent outside, and the answer they gave is it is not necessary, as long as the furnace room had no door or that the door is always left open so the furnace can draw air for combustion without any issue.

I did finally get someone to extend the air intake pipe outside so I could get fresh air, but I felt that it made the air blowing out of air vents when the furnace was running less warm, perhaps since the air coming in for combustion was icy cold and was mixed with the heated air from the furnace. Maybe someone who is familiar with high efficiency furnaces can comment on this.
Couple things to consider:

- I thought the intake on HE required an external vent. Without it your HE efficiency suffers

- the draw from the furnace will create a negative pressure drawing cold air into the house (also what about CO venting -- is this being drawn back in)?

Crack the basement door open when the furnace starts, do you feel a significant draft?
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Jan 11, 2007
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Just a tip for anyone with an unfinished basement that is considering finishing it... If your furnace room will not be on an outside wall and the venting will be boxed in as it passes through a finished area of the basement, make sure you have the white pvc venting and not the black abs.

If you need to replace your furnace and/or water heater in the future, you will have to replace the black abs venting with the white pvc to meet current codes and that will likely mean ripping out drywall and possibly some framing if your furnace room is not on an outside wall.

It will be much less expensive and less hassle to replace the venting before the basement is finished, rather than after and have to deal with breaking up the ceiling and then putting it all back together again.

(Shameless self promotion: If you have replaced a furnace and/hot water heater and need to have the ceiling repaired or other drywall repairs due to venting and live in the GTA, check out my website at www.randydrywall.com )
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May 24, 2003
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venice_it wrote:
Feb 28th, 2010 8:17 am
Just a tip for anyone with an unfinished basement that is considering finishing it... If your furnace room will not be on an outside wall and the venting will be boxed in as it passes through a finished area of the basement, make sure you have the white pvc venting and not the black abs.

If you need to replace your furnace and/or water heater in the future, you will have to replace the black abs venting with the white pvc to meet current codes and that will likely mean ripping out drywall and possibly some framing if your furnace room is not on an outside wall.

It will be much less expensive and less hassle to replace the venting before the basement is finished, rather than after and have to deal with breaking up the ceiling and then putting it all back together again.

(Shameless self promotion: If you have replaced a furnace and/hot water heater and need to have the ceiling repaired or other drywall repairs due to venting and live in the GTA, check out my website at www.randydrywall.com )
Actually you can still use the abs that is concealed. It is supposed to be pressure tested to check for possible leaks, and as long as it is okay, it is reusable. Thankfully, someone had enough brains to make this acceptable.

To be honest, there is nothing wrong with ABS piping for furnaces but according to the higher beings there is.
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Feb 25, 2010
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Just put in a high efficiency furnace. Here's a few things I learned:

The mid-efficiency models are no longer manufactured in Canada and cannot be imported. Once the stock runs out later this year, that's it. No more available anywhere. That means everyone with an older mid will eventually have to replace it with a high. Which means major venting in their basement unless they are lucky enough to have a furnace near an outside wall. Think of all the town homes that are screwed - vent out the front or back, no other option.

Mids vent out the chimney, highs vent out the side and cannot go up the chimney. Highs condense the water vapour which flows back into the system. That's why the vent pipes have to be at a certain angle to allow the water to drip back. We didn't have enough room for both intake and exhause so just the exhaust was put in. We added two air vents in the furnace room to give it enough fresh air. No problems yet.

Finally, make sure you get an energy audit before replacing the furnace. You'll save big time in rebates.
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Jan 20, 2007
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redac wrote:
Feb 1st, 2010 11:07 pm
Some high efficiency furnaces have 1 exhaust pipe only. Buidlers like to use those units because they are CHEAP. My house has one.

actually i think depends on the length of the intake run, as it can only go so far. though I'm sure it doesn't hurt that it saves the builder money too :)

personally I like it taking air from inside the house, helps force fresh air in.
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Dec 17, 2008
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jjtsl wrote:
Feb 27th, 2010 10:36 pm
+1. I've had a high efficiency Goodman furnace put into my previous place and it had the exhaust pipe leading to the outside, and the intake pipe staying in the furnace room drawing air for combustion. I previously asked a home inspector and a HVAC installer about whether both pipes should vent outside, and the answer they gave is it is not necessary, as long as the furnace room had no door or that the door is always left open so the furnace can draw air for combustion without any issue.

I did finally get someone to extend the air intake pipe outside so I could get fresh air, but I felt that it made the air blowing out of air vents when the furnace was running less warm, perhaps since the air coming in for combustion was icy cold and was mixed with the heated air from the furnace. Maybe someone who is familiar with high efficiency furnaces can comment on this.
The outside air is only used for the burning process, which happens in a closed chamber. It never mixed with the heated air, so the outside air temperature does not matter.
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May 24, 2003
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Taking air for the combustion process actually decreases the efficiency of the furnace as you are using heated air as combustion air. Its only a small <5% efficiency loss but it is still a loss.
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