HVAC

Have HVAC questions? Ask an HVAC Expert for answers

Ask an Expert,
Get an Answer ASAP!

We are getting condensation back into the heating area on the…

Customer Question
We are getting condensation back...
We are getting condensation back into the heating area on the outside of the 3in PVC. The 2in vent is surrounded by the 3 in PVC and then a 4in PVC through the roof. I need some details as to how the system operates in order to figure out my difficulties. The moisture system that removes condensation to the crawl space seems to be working correctly.
Submitted: 3 years ago.Category: HVAC
Show More
Show Less
Ask Your Own HVAC Question
Answered in 19 minutes by:
6/19/2015
HVAC Technician: Rick, HVAC Supervisor replied 3 years ago
Rick
Rick, HVAC Supervisor
Category: HVAC
Satisfied Customers: 24,609
Experience: 40+ yrs. experience as a licensed oil & gas technician.
Verified
Let's see if I understand your description. It sounds like you have a gas condensing furnace with a paired AC coil and you're getting condensation on the outside of the concentric 3" PVC vent/intake piping while you're running the AC. I have a theory as to what's happening. If your furnace has a sealed combustion chamber then my theory would be more viable.
Ask Your Own HVAC Question
Customer reply replied 3 years ago
It's not the AC it's the heating .
HVAC Technician: Rick, HVAC Supervisor replied 3 years ago
You have condensation on the outside of the vent piping when the furnace is firing?
Ask Your Own HVAC Question
Customer reply replied 3 years ago
Correct
HVAC Technician: Rick, HVAC Supervisor replied 3 years ago
I don't see how this is possible. The inner pipe which is the exhaust, will have exhaust gases that are moisture laden and which can condense into water liquid. The outer pipe only draws in air from outside for combustion. The air outside would have to be considerably colder and the air inside (where the condensation occurs) would have to be considerably warmer and humid for condensation to occur. During the winter the outside air is indeed much colder but I've never seen condensation on the outside of concentric piping even then.
Ask Your Own HVAC Question
Customer reply replied 3 years ago
There are 2 , 3in pic pipes from the furnace. The one that has the condensation problem has the 2in pvc inside . The other pvc goes straight up thru the ceiling in the proximity ( 4 in) of the other pvc. I've seen illustrations of this system and the 2, 3in pipes are joined by a 45' joint. In this case it would be above the ceiling line. The 2in vent and the 3in are encased by the 4" coming through the roof.
HVAC Technician: Rick, HVAC Supervisor replied 3 years ago
What's the model number of your furnace? If you have 2 3"PVC pipes connected to your furnace then 1 would be exhaust the other combustion air intake. If this is the case then you would not/should not have concentric piping (2" inside of 3") since this is only used when the intake and exhaust are piped together (not what you seem to be describing. Maybe some pictures of your installation, including where you're seeing condensation might help You can post a picture here by clicking on the paper clip icon in the tool bar at the top of this dialogue box. You can only post from a PC or a Mac not a phone or a tablet. If that doesn’t work for you then you can upload a pic to a file sharing service like https://photos.google.com/ OR https://www.dropbox.com and post the “share”link to your picture here or you can email the pic to customer service but the last option can take quite a while to get to me. Click on the CONTACT US link to contact customer service. http://ww2.justanswer.com/contact-us
Ask Your Own HVAC Question
Customer reply replied 3 years ago
The model number is ***** BWT. Nordyne. I'll try for some pics later today.
HVAC Technician: Rick, HVAC Supervisor replied 3 years ago
Ok
Ask Your Own HVAC Question
Customer reply replied 3 years ago
I went by the job site and opened the unit. No water condensation because the stat was turned down. The two 3" pvc have a 2" pvc pipes that run to the unit inside. The exterior roof penetration is 4" with a 3" and 2" inside. I've taken pics but don't know if I can get them to you successfully. If you Google the make and model you may pick up the drawings of the pvc details showing the pvc exiting the right hand side of the unit . When the 2 ,3" pvc enters the unit it goes back to 2"(both units). I'll try the pics but don't wait too long.
HVAC Technician: Rick, HVAC Supervisor replied 3 years ago
This is the first mention of 2 units (if I'm understanding you). Like I said before condensation inside the exhaust is normal. This type of config is pretty standard ( I did check the install manual). On the outside of a 3" concentric vent is not. You haven't given me any info so far that would inform me as to why this might be happening. I can only speculate that they aren't installed properly.
Ask Your Own HVAC Question
Customer reply replied 3 years ago
Should there be a 4" pvc on the roof penetration? Could this be the cause of the condensation of moisture at the 3" through the penetration of the roof. The top cap of the roof penetration looks to be designed for a 4"pic. The previous illustrations didn't include the 4" but showed the 45 degree transition between the two 3".
HVAC Technician: Rick, HVAC Supervisor replied 3 years ago
What you're describing isn't typical but that doesn't necessarily make it wrong but if the 4" is capped (has some type of weather cap)then it might be possible for the condensation to collect on the cap and run back down the outside of the 3"
Ask Your Own HVAC Question
Customer reply replied 3 years ago
Haven't heard from you in a couple of days and was wondering if you have come up with any phenomenal conclusions? The cap I mentioned was PVC which included the 4". it allowed the the 3" to breath and the 2" to vent to the outside. It was tent shape and allowed the 4" to be protected from the environment.
HVAC Technician: Rick, HVAC Supervisor replied 3 years ago
I gave you the only likely scenario based on the info you provided. Like a said before a picture might provide more insight into your situation
Ask Your Own HVAC Question
Customer reply replied 3 years ago
I'm not very computer literate regarding forwarding pics. I think that is not an option even though I have several good pics. Sorry about that.
HVAC Technician: Rick, HVAC Supervisor replied 3 years ago
Well, all I can do is answer based on the info you provide and all I can come up with (based on your description) is that the condensation is collecting under the 4" cap and running down the outside of the 3". The thing is that with this type of furnace the type of roof termination you describe is not typically used.
Ask Your Own HVAC Question
Customer reply replied 3 years ago
The e mail software doesn't cut it. Your conversations are not included. I'm at a loss on how to resolve the problem and keep the integrity of the ceiling and leaking with the condensation problem. Sorry about the pics.
HVAC Technician: Rick, HVAC Supervisor replied 3 years ago
Maybe if you contact customer service they can help you iron out your problems with the interface. I can't tell you specifically how to resolve your problem when I can't see what it is. All I can tell you is that it sounds like you have an atypical vent termination and it will probably have to be replaced with one that complies with the install instructions to resolve the problem.
Ask Your Own HVAC Question
Was this answer helpful?

How JustAnswer works

step-image
Describe your issueThe assistant will guide you
step-image
Chat 1:1 with a hvac technicianLicensed Experts are available 24/7
step-image
100% satisfaction guaranteeGet all the answers you need
Ask Rick Your Own Question
Rick
Rick
Rick, HVAC Supervisor
Category: HVAC
Satisfied Customers: 24,609
24,609 Satisfied Customers
Experience: 40+ yrs. experience as a licensed oil & gas technician.

Rick is online now

A new question is answered every 9 seconds

How JustAnswer works:

  • Ask an ExpertExperts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional AnswerVia email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction GuaranteeRate the answer you receive.

JustAnswer in the News:

Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.

What Customers are Saying:

You did one super job of explaining to me everything there is to know about this fridge. I'm looking forward to asking you questions in the future.

JimmyBagley, IA

Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help.

Mary C.Freshfield, Liverpool, UK

This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!!

AlexLos Angeles, CA

Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult.

GPHesperia, CA

I couldn't be more satisfied! This is the site I will always come to when I need a second opinion.

JustinKernersville, NC

Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around.

EstherWoodstock, NY

Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know.

RobinElkton, Maryland

< Previous | Next >

Meet the Experts:

Phil

Phil

Mechanical Engineer

7,634 satisfied customers

Retired HVAC/ Electrical & Boiler contractor. Industrial

Rick Mather

Rick Mather

HVAC Technician

3,133 satisfied customers

35 years experience, HVAC

Matthew

Matthew

HVAC Technician

2,014 satisfied customers

14 years experience in the HVAC field of service, installation, Manual J & D calculations

Brian HVAC Guy

Brian HVAC Guy

HVAC Technician

1,024 satisfied customers

I have been an HVAC/R mechanic/technician for 30+ years.

Kenton Guidry

Kenton Guidry

HVAC Technician

963 satisfied customers

12 years install/service experience.

Rick Ridley

Rick Ridley

UK Heating Engineer

871 satisfied customers

Retired But have had 30 years on the tools, Ex CORGI

Tom

Tom

HVAC Technician

770 satisfied customers

16+yrs HVAC/R service. Residential Commerical Industrial

< Previous | Next >

Related HVAC Questions
Brian, You helped me with drainage of a furnace a while ago,
Brian, You helped me with drainage of a furnace a while ago, maybe you can help with the venting of a new hot water heater going into my Mother's place... We had a high-efficiency furnace put in my Mo… read more
Billy
Billy
Journeyman Service Technician
State Licensed Mechanical Contractor
9,330 satisfied customers
My house has a heat pump with a propane backup. Last winter
My house has a heat pump with a propane backup. Last winter was very cold and on the worst days the unit would freeze up. The unit is in a utility area off the garage and the PVC vents go straight up … read more
Tim H
Tim H
Lead building engineer
Vocational, Technical or Trade Scho
1,922 satisfied customers
I have heating ducts for hot air in my basement. I would like
I have heating ducts for hot air in my basement. I would like to divert a small flow out of one duct to a PVC pipe to keep the pipe top open when it snows.… read more
Billy
Billy
Journeyman Service Technician
State Licensed Mechanical Contractor
9,330 satisfied customers
We have a heat pump system in our home. The main trunk line
We have a heat pump system in our home. The main trunk line and some of the ducts to the main floor are with a crawl space. The temperature outside is about 40 degrees at night and 60 degrees during t… read more
Phil
Phil
Mechanical Engineer
Degree, Mech Engr Technology
7,634 satisfied customers
I have a Trane 95% gas furnace SRX95 that was vented trough
I have a Trane 95% gas furnace SRX95 that was vented trough an old 6" galvanized B Vent stack that was left over from the last furnace. Is there going to be an icing problem when the temperature drops… read more
Billy
Billy
Journeyman Service Technician
State Licensed Mechanical Contractor
9,330 satisfied customers
When installing a 95% effiecient Furnace, in this case the
When installing a 95% effiecient Furnace, in this case the same furnace as before, how do you decide to use outside or inside intake venting. My furnace installation is in a walkup attice that is half… read more
Billy
Billy
Journeyman Service Technician
State Licensed Mechanical Contractor
9,330 satisfied customers
I installed an 80% gas furnace in a house with foam insulation
I installed an 80% gas furnace in a house with foam insulation on walls and under roof. So the envelope includes the attic. An engineer has suggested that I should have installed a 90% furnace with a … read more
Phil
Phil
Mechanical Engineer
Degree, Mech Engr Technology
7,634 satisfied customers
After a new roof the contractor said we had to pipe up the
After a new roof the contractor said we had to pipe up the new vent on the roof to exhaust fan. Now we get condensate dripping in the bathroom and kitchen vents. What can I do to fix this problem? Ins… read more
Electrifier
Electrifier
Owner - Contractor
Bachelor's Degree
147 satisfied customers
Hi-We are trying to isolate a problem with our heater. A small
Hi-We are trying to isolate a problem with our heater. A small amount of gas is getting into our air ducts, just as the gas valve cuts off. I understand from a chat with someone here last night that w… read more
Richard
Richard
District Technical Manager
Vocational, Technical or Trade Scho
1,416 satisfied customers
Over the summer, my heating contractor installed a new Armstrong
Over the summer, my heating contractor installed a new Armstrong 95% efficient gas furnace in my home. He insisted that he could not vent the furnace using the vent fro my original gas furnace and had… read more
HVAC_Doug
HVAC_Doug
Vocational, Technical or Trade Scho
I purchased an old house and my question is What are my options
I purchased an old house and my question is: What are my options to keep the crawl space humidity in check? It is now heated by forced air uninsulated main duct and the relatively big crawl space is o… read more
Tim H
Tim H
Lead building engineer
Vocational, Technical or Trade Scho
1,922 satisfied customers
My furnace blower will go on but no ignition occurs. My thermostat
My furnace blower will go on but no ignition occurs. My thermostat shows that my home needs heat. I had the thermostat replaced late last year but this problem keeps occuring. It does not happen const… read more
Matthew
Matthew
HVAC Technician
Bachelor's Degree
2,014 satisfied customers
I have condensation forming in my A/C ducks upstairs an
I have condensation forming in my A/C ducks upstairs and on the air handler cabinet, the unit is located just off one of two rooms upstairs and is only six years old--ducks are fully insulated and tap… read more
Patrick
Patrick
Bachelor's Degree
1,269 satisfied customers
My daughter has a Ruud Achiever 90 Plus which keeps freezing
My daughter has a Ruud Achiever 90 Plus which keeps freezing up the exhaust vent in cold weather. Any solution? Bruno… read more
Rick
Rick
HVAC Supervisor
24,609 satisfied customers
My current furnace is in my crawl space. The crawl space
My current furnace is in my crawl space. The crawl space is gererally dry. It has come timeto replace the HVAC unit, should I keep it in the crawlspace? or install in a closet inside the house? All th… read more
Rick
Rick
HVAC Supervisor
24,609 satisfied customers
Im a home inspector and yesterday found a Lennox Elite (Model
I'm a home inspector and yesterday found a Lennox Elite (Model G51MP-48C-090-07) condensing furnace installed in an attic over a new home. The attic is unconditioned space.(This home is in Boise, Idah… read more
Mario
Mario
Owner Of At Your Service Plumbing & Heat
High School or GED
672 satisfied customers
I have an a unit that is oil for heat and electrical for air.
I have an a unit that is oil for heat and electrical for air. I am not having any problems with the fairly new unit. My question is though. I seem to get the secretion of an oily substance that runs d… read more
Rick Mather
Rick Mather
HVAC Technician
Vocational, Technical or Trade Scho
3,133 satisfied customers
I have a high efficiency furnace that uses PVC as a flue exhaust.
I have a high efficiency furnace that uses PVC as a flue exhaust. The exhaust runs vertically through the roof, and at about 20 inches above the roof it terminates in a 135 degree PVC gooseneck. All o… read more
The Home Smithy
The Home Smithy
Home Improvement Repair Consultant
1,890 satisfied customers
Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Show MoreShow Less

Ask Your Question

x