What I'm Seeing Now

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This Is Deadly Air Being Drawn Into The House - In Northern Virginia?

There'e no other way to say it - this is deadly air in being drawn back into the house - in Northern Virginia?

Say it ain't so!

Well it is.

A high-efficiency condensing gas furnace is a wonderful and extremely efficient appliance.  I wish my furnace was this efficient.

Most gas furnaces, like mine, have a flue which expel their exhaust through a metal flue extending through the attic and roof.  I am losing huge amounts of heat through my roof!  And my furnace is only capturing, and using, a percentage of the heat generated by the furnace to send through the house.  For every dollar I am spending on natural gas I'm really only benefitting from a small percentage of every dollar toward heat.

The high-efficiency condensing furnace re-burns its exhaust so that what blows out is really very cool air, 105F or so.  At the same time it is drawing in fresh air, so it is an enclosed system and burns none of the oxygen in the house. 

The thermal image to the right shows the fresh, cooler air drawn in through the vertical purple tube on the left and the warmer air through the yellow tube on the right.  This system is operating as intended.

The exhaust has lesser carbon monoxide than a regular furnace would exhaust through the roof, but still its exhaust is laden with CO.

The two tubes, intake and exhaust, should terminate on the same side of the house and near each other, not near a window or door, and should look something like the configuration on the left.

Notice that the exhausted, warmer air is sent up and away. 

The fresh, cooler intake air is drawn in from below.

In this way the intake air and exhaust do not mix.

Seeing this the other day bothered me.

The longer tube is the exhaust for this condensing gas furnace.

The partially-hidden shorter one is the intake.

Do you see a problem with this too?

Steam was generated by the exhaust tube and you could actually see it being drawn back in through the intake tube.

It really is drawing in deadly air.

Now, surely, that dissipates throughout the air in the house. 

But why introduce that back into the home?

I did not see a carbon monoxide detector anywhere.  Certainly there should be a couple.

This furnace, and system, was installed in 1994.  That's pretty early in the history of this furnace type.  I have seen other systems installed in that time frame and do not remember seeing this before.  I don't think it was common practice for the intake and exhaust to have this configuration.

But it is a very easy fix and I highly recommended the buyers do!  Doing so would be a Best Practice!

My recommendation:  safety first.  Introducing carbon monoxide into the air can't be good.  Is it enough to be dangerous?  Who knows!  Over time maybe.  And some occupants of the house might be more susceptible to CO presence - like the elderly or very young.  So why introduce it in any quantity?

 

 

 

Jay Markanich Real Estate Inspections, LLC  

Based in Bristow, serving all of Northern Virginia.

Office (703) 330-6388   Cell (703) 585-7560

www.jaymarinspect.com


Comment balloon 35 commentsJay Markanich • November 17 2013 05:54AM

Comments

Hi Jay.

Where is the grill or screen for the furnace intake and exhaust? No exhaust under a window. The same as a sewer line vent.

I had a home yesterday that the PPM was 11 around the furnace exhaust. There were an are leaks.

The co detector never went off. The furnace is another story for another post.

Have a good day in Bristow.

Best, Clint McKie

Posted by Clint Mckie, Desert Sun Home, Comm. Inspection 1-575-706-5586 (Desert Sun Home, commercial Inspections) over 4 years ago

Good morning, Jay. Good catch! I strive not to over-analyze. I state the facts and move on. But then, because this is supposed to be a closed system the only thing I could see is bad combustion. Have the heat exchangers checked.

Posted by TeamCHI - Complete Home Inspections, Inc., Home Inspectons - Nashville, TN area - 615.661.029 (Complete Home Inspections, Inc.) over 4 years ago

The intakes can have a grill here Clint, but not the exhaust.  They can ice up and clog, so no screen is recommended.  Yikes with the air leaks!

Michael - and this has been like this for 19 years!  It's the same house as the stone staircase.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 4 years ago

Good morning Jay,

Thank you; another item for my check list.

Make yourself a great day.

Posted by Raymond E. Camp, Licensed Real Estate Salesperson Greater Rochester (Howard Hanna Real Estate Services) over 4 years ago

HA!  No doubt the present owners are walking around on their canes in a stupor from lack of oxygen.  Were they present to see if their lips were blue??

The cane??  Caused by taking a fall from the loose slab in the steps with no rail.

 

Posted by Lenn Harley, Real Estate Broker - Virginia & Maryland (Lenn Harley, Homefinders.com, MD & VA Homes and Real Estate) over 4 years ago

That looks like a really inexpensive fix.

Posted by Geoff ONeill (John L. Scott Medford) over 4 years ago
Good catch, and I'm glad that this is relatively simple to fix. - Debbie
Posted by Women of Westchester Working Together, Women helping Women get ahead (Women of Westchester Working Together) over 4 years ago

Raymond - keep your eyes peeled!  Actually I don't remember seeing this tubing arrangement before, so it is probably unusual.

Lenn - when the plants and hamsters start dying, there's a reason!

'Tis Geoff, 'tis.  PVC and a little Elmer's Glue.

OK, kidding about the Elmer's.

WOW Flooring Chick - it was easy to see with all the steam coming up!

 

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 4 years ago

Don't judge by plants.  They thrive on CO.  Hamsters?  Another story.  Maybe a canary would help some homes.

Posted by Lenn Harley, Real Estate Broker - Virginia & Maryland (Lenn Harley, Homefinders.com, MD & VA Homes and Real Estate) over 4 years ago

Lenn - I had always understood that CO kills plants as they need CO2.  But the canaries were used in mines as warning indicators,  I understand too.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 4 years ago

I'm curious, these are closed systems, how exactly is the exhausted air going to effect the occupants. I would believe the parameters set forth by the manufacturer are more to do with the function of the equipment with some exceptions. 

Posted by James Quarello, Connecticut Home Inspector (JRV Home Inspection Services, LLC) over 4 years ago

Jay we are having the same issues down here in South Florida not with heating systems but with Generators to close to windows or doors. It became a big issue when one family died because of improper installation.

Posted by Chuck Mixon, Cutler Bay Specialist, GRI, CDPE, BPOR (The Keyes Company) over 4 years ago

Great post Jay. The problem with being a consumer & not a trained inspector is; we have to trust the installers every time something is put in place in our homes. I wonder how we, as consumers, can be more proactive to make ourselves safer, & I know from experience, the reaction of installers if you question their methods...

Posted by Peg Barcelo, The FlufftasticStager from Summerland, BC (Fluff My House! Home Staging Inc. 250.486.6369) over 4 years ago

Common saftey practices must not have been required that day when when this was installed.

Posted by Suzanne Otto, Your Montgomery County PA home stager (Six Twenty Designs) over 4 years ago

Jay, this looks like one of those common sense things that a homeowner should be able to see! Intakes right next to the exhaust...bad idea! 

Posted by Tom White, Franklin Homes Realty LLC, Franklin TN (Franklin Homes Realty LLC (615) 495-0752 or www.FranklinHomesRealty.com) over 4 years ago

Jim - there are apparently a lot of these furnaces in Iowa, and many CO problems.   I read where Iowa State did a series of studies on what they called "older direct-vent furnaces," defined as 15 or older.  They attributed the CO problems to cracking in the vent tubes, a lack of combustion air, many cracked heat exchangers and venting issues where CO is drawn back into the house.  In this house the unit (1994) is in a small closet off the garage, along with one of the two heat pump air exchangers.  Starting with the venting I didn't like it overall, so it made the report hit parade.

Chuck - wow, don't open the window nearby!

You know what happens when we assume Peg.  But you're right, we have to have confidence in the professionalism of the installers.

Perhaps Suzanne, or the house was so spectacular they didn't think anyone would notice!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 4 years ago

Apparently all this time nobody noticed Tom.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 4 years ago

Jay - Unfortunately, common sense doesn't seem to be so common anymore.  They must have had the system serviced at some point in time since it was installed and you would think that any HVAC person would pick up on that.  Nice catch.

Posted by AJ Heidmann ~ CRS, YOUR Alexandria & Arlington, VA Real Estate Expert (McEnearney Associates, Inc.) over 4 years ago

Like Jim said above, AJ, this is a closed system and maybe in 1994 they didn't think that to be a problem.  To my mind, why take the chance?

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 4 years ago

Prertty easy fix on that one. Would highly suggest the change also. Kind of common sense. This is another reason to do home inspections.

Posted by Bill Reddington, Destin Florida Real Estate (Re/max Southern Realty) over 4 years ago

There was more to change than that Bill, but this would be a good start.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 4 years ago

Jay,

Our inspectors check that too. That one may be a closed system however I have seen direct vent furnaces installed (maybe by an amateur) that had the "makeup air" vented into the basement in close proximity to the burner bit NOT a closed system. In a case like that it should be several feet away from the exhaust.

Posted by Dana Basiliere, Making deals "Happen" (Rossi & Riina Real Estate) over 4 years ago

Hello Jay,

Have never run into one of these systems - I've learned something new, thank you!

Posted by Lisa Von Domek, ....Experience Isn't Expensive.... It's Priceless! (Lisa Von Domek Team) over 4 years ago

Great catch Jay!

Posted by Juan Jimenez, The Richmond Home Inspector (A House on a Rock Home Inspections LLC) over 4 years ago

Great observation. I agree that this looks like a fairly easy fix to extend the pipe up some distance.

Posted by Gerard Gilbers, Your Marketing Master (Higher Authority Markeing) over 4 years ago

There are things I want to know about and other I don't.  This is one of those I leave up to the expert like you to find. 

Posted by James Dray, Exceptional Agents, Outstanding Results (Fathom Realty AR LLC) over 4 years ago

Dana - on a new construction once I saw the exhaust line broken into two just before it got to the foundation wall, spewing its exhaust into the house!

They have been around for over 20 years Lisa.  But not in every area of the country.  They make no sense where you live.

Juan - wasn't too hard to see.  Look at my answer to Jim above in #18.  These older systems need to be looked at carefully when one thing isn't right.  It might be an indicator that other things aren't.  Haven't seen a post from you in a while.  Look forward to them!

It is easy Gerard, and cheap.

James - it was a kind of easy find.  Right in front and steaming!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 4 years ago

I have a direct vented boiler myself. An excellent technological improvement over atmospheric draft units.

Some of the issues you cite from the study could be found during an inspection. What they do not mention or you have not mentioned from the study is the proximity of the vents to one another. Some of these units actually incorporate a single vent where the exhaust and intake are contained in the one pipe. I have found issues with the location of the vent pipes when two are used relative to one another per manufactures specs, but that is a functional issue. That is, pulling the products of combustion back into the system to be used as combustion air. 

Now if the vent was installed near a window, closer than the standard, that to me is a potential CO issue.

Posted by James Quarello, Connecticut Home Inspector (JRV Home Inspection Services, LLC) over 4 years ago

That explains it...I moved South 25 years ago!

Posted by Lisa Von Domek, ....Experience Isn't Expensive.... It's Priceless! (Lisa Von Domek Team) over 4 years ago

That must be a fabulous system Jim - I have read about them.  Consumer Reports says the savings are huge.  I expect that's your experience.  As to the vent, if you are referring to the bell-shaped one, that is blowing directly away.  The vent thing and windows is confusing because the one in my photo has to be 4' or so from windows and doors and the bell one can be really near.  Not sure why. 

Lisa - your heating season needs to be longer than 3 or 4 days for these to make sense...  ;>)  Where Jim lives I bet a lot of people don't have air conditioning.  Can you imagine?

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 4 years ago

Yes, the cost to operate is very small, especially compared to oil. I have to agree, direct vents can be confusing. The only way to really know if its right is to check the manufacturers specs. 

Posted by James Quarello, Connecticut Home Inspector (JRV Home Inspection Services, LLC) over 4 years ago

Here, too, it's the local jurisdictions Jim.  One county allows this and another that.  The manufacturers all say what they say, but I get confused place to place!  I think the bell arrangement is the best - small, unobtrusive and efficient.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 4 years ago

Jay I don't understand the issue.  Isn't the intake only taking in air that will be used by the burner for combustion and aren't the combustion chambers designed so that no combustion products are "spilled" into the residence?  If this is the case, except for efficiency issues (CO doesn't burn), why is this really an issue?

What am I missing, besides the right half of my brain?  :)

Posted by Adam Mortensen over 4 years ago

Jay I don't understand the issue.  Isn't the intake only taking in air that will be used by the burner for combustion and aren't the combustion chambers designed so that no combustion products are "spilled" into the residence?  If this is the case, except for efficiency issues (CO doesn't burn), why is this really an issue?

What am I missing, besides the right half of my brain?  :)

Posted by Adam Mortensen over 4 years ago

Wow, Adam, to comment twice it must have challenged you greatly!

In one of my classes on this very furnace system, which challenged both sides of my brain, the class instructor pointed out a study by Iowa State U which was conducted on systems 15 years or older, like this one.  It determined that CO leaking was more prevalent over time as small gaps develop in the PVC due to such frequent expansion and contraction.  Changing the direction of the intake is a simple matter, that maybe eliminates the studied condition potential completely.

I'm just looking out for my client, as I always do.  And always will.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 4 years ago

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