FLUE DRIPPING CONDENSATE

bob young

What would cause a gas hot air furnace to drip from the flue connection. thirty foot horizontal run to chimney with fairly new [5 years] liner. condensate problem ongoing for five years since new replacement unit & chimney liner installed. small one family home approx. 100,000 btu unit.

Ironman

Several Things Could

1. Gas pressure too low.

2. Air flow too high.

3. Cycle rate too short.

4. Improper venting. Such as: 30 foot horizontal run to chimney.



Just to name a few.

KeithC

Flue

thirty feet!!



Your flue gasses are cold - that's a long run between the appliance and the thimble. I'd say to insulate the pipe and then insulate the chimney liner with vermiculite to try to warm up the exhaust beyond the wet temperature.



Make sure you've got CO alarms in that house.

ChrisJ

Insulating

30 foot horizontal appears to be acceptable but only if the vertical is at least 30 feet and I suspect this is only when using double wall pipe for the horizontal run as well as vertical so a uninsulated liner in a brick chimney isn't going to be quite as good.



I recall them also selling insulated liners as well as often installing undersized liners to improve draft with smaller appliances. What size liner is installed in the chimney?



As you recall I am not a pro, but I had a lot of chimney fun back in 2011 and perhaps I can be helpful even if only a little.

bob young

FLUE DRIPPING CONDENSATE

Thanx for the input gents. i do not usually do any hot air work but i was doing some misc. plumbing work for an elderly lady & she asked me to take a look at the furnace. unreal this heating outfit has been working on this issue five years. one patient client. if that was me  having done the job , i would have been arrested. don't even pay to get involved 'cause original guy already sucked every dime out of the job long ago. but fool that i am , i will probably play lone ranger once again & try to help an old lady. it never ends. at least its only a few blocks from my office !! if i can't fix it  she will probably sue me. i actually have a license !!  lol bob 

Bob Harper

code

At 30ft., code requires the chimney to be a min. of 40 ft. vertical (75%). Also, at 1/4" per foot, you'll need a min. 7.5" vertical vent rise from offset to breaching. You should have B-vent connector due to the high losses from the stack. That's also a lot of support needed. The furnace should be verified by combustion analysis for proper operation. A 3-4 min. post purge would go a long way. Insulating the liner may help a little esp. with an exterior chimney.  Combustion analysis should be considered with delta T, plenum temp., fan speed, firing rate.



Thirty foot offset is ridiculous. The furnace should be relocated or a CAT IV furnace should have been installed.

bob young

bob harper

than much ,bro.  top notch ananysis...as per usual. bob  young