Furnace Combustion Air Intake Question

[jinhuichiwow]

Hi guys,

I recently have 2 new American Standard 95% 60,000 and 80,000 BTU furnaces installed. I noticed that the combustion air intakes are not from outside of the house, but rather inside the basement. See the tube stops in the middle of the air. Will that be a problem? Wonder why the installation company didn't use the PVC pipes. Any ideas?

[syndicated]

Call them back.
The job isn't finished!

[pacnw]

I am going to assume, though I hate to do so, that the exhaust does go outside and JUST the intake is from the indoors/basement.

Some units do allow for this installation, provided enough air is available in that space.

However, they SHOULD have run both intake and exhaust outside for best benefit.

I would verify any paperwork description of the install and then call them back to run the intake outside.

[LibertyTree]

I may be wrong but I think many brands now approve single pipe applications. I always run both out unless its impossible or too difficult to do so (like a furnace that's in a basement in the middle of the house and you have to use the existing 4" B-vent stack as a chase for the single 2" PVC exhaust) What makes a high efficiency furnace different from an 80% efficient furnace that draws its combustion from the area its installed? Pro using AOP LOL

[heresjohnnyb]

Get the installers back there. Tell them to fix the drain too

[George2]

Were hi-efficiency, large filter (airflow) area filters recommended?

[motoguy128]

Most all unit can be installed this way as single pipe, but unless there a specific restriction on installation, it's just a shortcut. My upstairs unit in my attic was instaleld thsi way. When I repalced it this summer I had the combution air piped outside. You have the ability to make it totally sealed combustion and get combustion air from outside, why not just "do it right"? One of the major benefits of HE furnaces is that they are totally sealed combustion.


One interesting thing I've noticed lately, is that the intake often just feeds into the furance cabinet, not directly into a manifold/air box. That makes servicing easier, but it means that you need a screen to keep out bugs and critters and you'll always have soem dust. My tankless water heater is like thsi as well, but have a fine mesh screen that doe sa good job keeping stuff out.... but you need ot clean it every 3-6 months. I cleaned mine after 4 months and it was pretty bad. I could see a LOT of service calls within 1 year because of faults for combustion air as you get into winter and regularly use fully burner capacity because of cold incomming water.

[jinhuichiwow]

Get the installers back there. Tell them to fix the drain too

Thank you for your reply. What is the problem with the drain? Would you please tell me more?

[jinhuichiwow]

Were hi-efficiency, large filter (airflow) area filters recommended?

No. We were using the old filters. Didn't replace them.

[OldSchoolMech]

Is your front door hard to open since the install?
The house will be in a vacuum if the house is tight.
I always take fresh air from the outside

You are using old filters in a new unit? Please get new ones

[jtrammel]

Thank you for your reply. What is the problem with the drain? Would you please tell me more?

It looks like the furnace drain is not pitched we'll enough to adequately drain, but it could just be the way the pic looks.

[Chuck]

There is nothing wrong with either the venting or the drain. That furnace is approved for single pipe venting.

In fact, the burners will burn cleaner and be slightly more efficient with room temperature air instead of cold outdoor air in the winter.

I don't like drains run in front of furnaces from a service standpoint, but that setup will drain just fine.

That is a very restrictive return air drop and filter connection. I would want that redone if it was mine.

[second opinion]

It looks like the furnace drain is not pitched we'll enough to adequately drain, but it could just be the way the pic looks.

The way that it is piped if the drain line becomes clogged it will back up into the secondary heat exchanger and continue to fill into the inducer motor.

[ADillon]

There is nothing wrong with either the venting or the drain. That furnace is approved for single pipe venting.

In fact, the burners will burn cleaner and be slightly more efficient with room temperature air instead of cold outdoor air in the winter.

I don't like drains run in front of furnaces from a service standpoint, but that setup will drain just fine.

That is a very restrictive return air drop and filter connection. I would want that redone if it was mine.

x2

[motoguy128]

Is your front door hard to open since the install?
The house will be in a vacuum if the house is tight.
I always take fresh air from the outside

You are using old filters in a new unit? Please get new ones

Unless the house is hermetically sealed at every joint, I don't think a 50cfm ID fan will be able to create that much suction. I don't see many houses being that ultra tight... especially if they have operable windows.

But yes, it will make the home slightly negative.

[jtrammel]

Unless the house is hermetically sealed at every joint, I don't think a 50cfm ID fan will be able to create that much suction. I don't see many houses being that ultra tight... especially if they have operable windows.

But yes, it will make the home slightly negative.

X2

[jpsmith1cm]

Get the installers back there. Tell them to fix the drain too

Please review the AOP Forum rules before posting.

Those rules can be found here.

Thanks,

AOPC

[jinhuichiwow]

The installation company said they could do it for me, but gave me this warning -

Furnaces with fresh air intake from outside sometimes get junk (leaves and yard wastes) sucked from the outside and this problem is not covered by the warranty...

[George2]

The installation company said they could do it for me, but gave me this warning -

Furnaces with fresh air intake from outside sometimes get junk (leaves and yard wastes) sucked from the outside and this problem is not covered by the warranty...

It seldom happens, however, I put a "extended" hardware cloth screen on my intake because the exhaust and intake go out where my wall ivy is. I've never had a prob.

[pacnw]

X2

X3