furnace not venting properly

Reply

  #1  
Old 10-09-13, 05:30 PM
Member
Thread Starter
Join Date: Sep 2013
Location: usa
Posts: 56
furnace not venting properly

Hey guys ive got an older upflow gas furnace its made by york. Tried to fire it up for winter tonight. The furnace and water heater(gas) vent through same chimney. I started it up and I didnt fire. It usually takes a few times on first start of season, but it also pushed exhaust out of water heater flue. Ive had problems with furnace in the past but this is new. Ive had to clean flame sensor. Replaced control board last year. But the water heater has always had a draw when furnace was on. Im not sure why it didnt fire. Inducer starts igniter glows gas valve clicks. And I believe.that it was gas that I was smelling from the flue of water heater. Any ideas? Thanks
 
Sponsored Links
  #2  
Old 10-09-13, 07:02 PM
Member
Join Date: Dec 2007
Location: USA
Posts: 227
"Inducer starts igniter glows gas valve clicks." If there is no flame at all, is the gas valve to the furnace on?
 
  #3  
Old 10-09-13, 07:51 PM
Member
Thread Starter
Join Date: Sep 2013
Location: usa
Posts: 56
I think so it sounds like gas I flowing and smells like it from water heater. I didnt let it cycle to many times as it is late and I have children in house. Carbon monoxide. I will try this weekend to let cycle more
 
  #4  
Old 10-09-13, 08:21 PM
Member
Join Date: Dec 2007
Location: USA
Posts: 227
The furnace should have it's own separate gas valve, it may somehow been closed perhaps at the end of last winter.

Is there a pilot light?

If there are no flames, not even the pilot, it may be that the pilot light orifice is completely blocked and not permitting any gas to flow or not enough gas to reach the ignitor. I had an oven that would spark repeatedly but the pilot would not light, cleaning the orifice solved the problem.

If you know where the pilot light is you could try to ignite it with a long match or a barbecue lighter.
 
  #5  
Old 10-10-13, 08:59 AM
Member
Thread Starter
Join Date: Sep 2013
Location: usa
Posts: 56
Yes the furnace and water heater have thier own gas valves. The gas valve to furnace is on I confirmed that before starting. No pilot its a glow igniter that is beside burners.
 
  #6  
Old 10-10-13, 10:14 AM
Member
Join Date: Dec 2007
Location: USA
Posts: 227
Is it possible the orifice nearest the igniter is blocked with residue? A small mirror might help you inspect it.

If you place a flame from a long match or lighter near the orifice does the burner light up?
 
  #7  
Old 10-12-13, 12:59 PM
Member
Thread Starter
Join Date: Sep 2013
Location: usa
Posts: 56
Ok I let the furnace cycle a few times and it fired up. Let it run for a few mins and it still is pushing exhaust from water heater. Pics. Larger pipe going into "y" is furnace smaller goes to water heater. Other pic is water heater. That is where the exhaust is coming through. I tested draw with a cigarette when furnace is not on it draws fine when furnace comes on it pushes exhaust back into the room. Is there a backflow valve that I can install?
 
Attached Images   
  #8  
Old 10-12-13, 04:46 PM
SeattlePioneer's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Jul 2007
Location: Seattle, Wa
Posts: 5,503
Pull the metal fitting out of the chimney and check for debris that may be clogging the chimney. Usually that's mortar that has turned to sand and dropped to the bottom of the chimney, blocking the combustion gasses from entering the chimney.
 
  #9  
Old 10-14-13, 08:51 PM
user 10's Avatar
Member
Join Date: Mar 2004
Location: NA
Posts: 1,854
Likes Received: 15
If your chimney doesn't have a liner, it should. Unlined chimneys as far as I know are only good for natural draft appliances which put out very diluted exhaust. The moisture in undiluted exhaust can condense on the walls of the chimney and cause problems.

Even with a liner, I think an induced draft furnace should never be used on the same stack as a natural draft water heater due to the risk of spillage if the chimney gets blocked.

If major venting changes are required, you'll be better off switching to high efficiency, direct vented equipment.
 
  #10  
Old 10-14-13, 08:54 PM
user 10's Avatar
Member
Join Date: Mar 2004
Location: NA
Posts: 1,854
Likes Received: 15
Forgot to add, your furnace has a pressure switch which prevents it from firing if there isn't an adequate draft.
 
  #11  
Old 10-15-13, 07:42 PM
Member
Thread Starter
Join Date: Sep 2013
Location: usa
Posts: 56
Ok sorry for the delay guys. I pulled the pipe from wall. Of coarse it was rusted and had some holes in it. it also had lots of debris and a bird in bottom of chimney.vacuumed all that out. Looked into chimney with a mirror its clear. Draft from chimney is very strong. Updraft not downdraft. I installed new pipe. Reinstalled flues. Updraft is very good now. Untill the house fan comes on. Then there is a downdraft through water heater flue unless I either open basement/upstairs door or open a window in basement. I am assuming this means that I dont have enough return? Input btu/hr 100k output btu/hr 80k. Not sure what that means but house is approx. 1500 sq ft. With full basement with no registers. There are 8 registers upstairs with 2 returns the size of other vents and 1 a little larger and 2 floor joists "panned" for return.
Muggle- not familiar with "direct vent" water heater? Please explain. I just installed new water heater 2 years ago
If worse comes to worse I can probably leave door cracked to adjust for pressure/air flow difference. I would however like to get it fixed correctly
I forgot to add that there are 2 vents in the floor I thought that they were installed to allow heat transfer from woodstove. But now im thinking maybe to equalize pressure?
Thank you guys for all the info
 
  #12  
Old 10-16-13, 02:08 PM
user 10's Avatar
Member
Join Date: Mar 2004
Location: NA
Posts: 1,854
Likes Received: 15
The room doesn't have enough combustion air.

You need to install or enlarge a combustion air intake - ie vent between furnace room and rest of the basement.

Is the chimney lined? If not, the problem will recur and the chimney may need major repairs at some point. With mid efficiency equipment, you should have a liner.
 
  #13  
Old 10-16-13, 02:21 PM
user 10's Avatar
Member
Join Date: Mar 2004
Location: NA
Posts: 1,854
Likes Received: 15
Then there is a downdraft through water heater flue unless I either open basement/upstairs door or open a window in basement.

Read more: http://www.doityourself.com/forum/ga...#ixzz2hvFKU2Is
Which fan?

If it works okay until the main blower comes on, you have some major return air leakage.
 
  #14  
Old 10-16-13, 04:40 PM
Member
Thread Starter
Join Date: Sep 2013
Location: usa
Posts: 56
The furnace is in basement. It is unfinished no walls.

Main blower

Chimney is 8" clay? Flue tiles no liner
 
  #15  
Old 10-16-13, 04:54 PM
user 10's Avatar
Member
Join Date: Mar 2004
Location: NA
Posts: 1,854
Likes Received: 15
You have major return air leakage - when the fan comes on, the basement becomes depressurized.

To resolve this:

1. Seal return air duct joints with mastec (sp?) duct sealant or foil tape
2. Add at least a couple of supply runs to the basement to offset the return air leakage
3. Get the chimney lined. (check with a contractor first - code may or may not require it in your area)

If the furnace is 15+ years old, the best solution is to get high efficiency furnace put in (takes combustion air from outside and no chimney required) and have a small liner put in just for the water heater.

-----------------
100k input/80k output, btw sounds grossly oversized for a 1500 sq ft home unless there's no insulation. If/when you replace the furnace, consider downsizing.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes