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  1. #1
    Join Date
    Jan 2005
    Posts
    3
    My furnace was cutting in and out in the mibble of the heating cycle.I put my ear to the side of it and the induction fan was not sounding to healthy. Fist thing I checked was the flow of condesate through the trap - flowing to drain ok. Then I checked the the condesate tubes going to the trap one on the flue and one on the transition box. Both were clear. I then took the induction fan out tipped it over to find a bunch of water/condensate in it. My guess is the water was flying around in the fan housing and interferring with the singnal to the pressure switch which is designated for the induction fan. I cleaned every thing out checked the drain on the vent fitting on the flue which collects the condensate fired the furnace and every thing is working fine. Question, how the hell did all that condensate get into the ID fan housing ? Did the drain on the flue fitting overflow and run back into the ID fan ? I hear this can be due to an incorrect slop on the flue or a sag in the flue run therefore the condesate pools and eventally rolls back down the flue overflowing the flue drain and in to the ID fan. I checked the slop required and the slop that I have and it is ok. Required- 3.5" actual- 4.5". That said when I got the ladder out and checked the exhaust flue it was and always is very wet. Alot of water droplets on the roof of the plastic piping. Now let me through this out there. I set the 'swing' (differental)on my Lux progrmmable stat to 0.5 degrees c. Excellent room temp set point control. The furnace fires on low fire for 12min and if the call for heating is still there it fires on high fire. Room temp is 95% of the time satisfied during the 12min low fire stage. Question - is this flooding out my furnace due to the fact it dosen't stay on for very long. There is alot of condesate in the flue of a gas cond. furnace, do you have to have a higher heat rise setting in order to assist in drying out some of this condensate? Just one more ?? Furnace manual says to set thermostate anticipator to 0.1 is this the same as the swing setting?? Thangs in advance, Rich

  2. #2
    Join Date
    Feb 2004
    Location
    Ontario
    Posts
    700
    What's the make & model, and how long has it been installed? Worked properly before this?
    Question authority!

  3. #3
    Join Date
    Jan 2005
    Posts
    3
    Originally posted by jetstream
    What's the make & model, and how long has it been installed? Worked properly before this?
    Hi Jetstream, its a Heil H9MPT100J16A1. 3YRS this coming April. Yes the furnace has worked properly up until this incident. Can you comment on "condensate dwell" or "excessive wet time" are these related to incorect furnace heat rise or short firing cycles? Thanks.

  4. #4
    Join Date
    Feb 2004
    Location
    Ontario
    Posts
    700
    Not sure what you mean by those terms, but this is a condensing furnace. That's what it's supposed to do, produce condensate all the time it's running, and the unit is designed to be able to drain all that water away. I expect you've got a blockage, likely a plugged or kinked drain line somewhere.
    Question authority!

  5. #5
    Join Date
    Jan 2005
    Posts
    3
    Originally posted by jetstream
    Not sure what you mean by those terms, but this is a condensing furnace. That's what it's supposed to do, produce condensate all the time it's running, and the unit is designed to be able to drain all that water away. I expect you've got a blockage, likely a plugged or kinked drain line somewhere.
    I just read your response to vm020306's thread. I live just outside of Vanvouver B.C. and we also just went through a cold spell. Maybe my flue iced up, melted and the vent drain over flowed into my ID fan. Both drain hoses, flue and trsnsition box were clear. Is it normal for the flue exhaust pipe to be always wet? Rich

  6. #6
    Join Date
    Feb 2004
    Location
    Ontario
    Posts
    700
    Well it's the combustion air intake that might frost up from recirculation of the water vapour from the vent, (though it shouldn't), and yeah, while it's running the vent will be moist. That's no problem.
    Question authority!

  7. #7
    You have a condensing furnace and it sounds like it is working fine. Water vapor is normal in the flue gas. Make sure the furnace is close to level and keep the condensate drain lines clear of restrictions. Also make sure the combustion air intake is clear. If this is done and it still cuts in and out in the middle of a heating cycle you should have someone take a look at it.

  8. #8
    Join Date
    Apr 2004
    Posts
    7,680
    If its even relatively new, there would be some sort of codes flashing if the cycle was interupted by a pressure switch or limit. I would look closer at the LUX thermostat than anything else.

  9. #9
    Join Date
    Nov 2004
    Location
    CA
    Posts
    238
    I kind of knew it was HEIL even before you posted the Model #. Now forget about 1/4" slope per 1 foot rule. Make it steeper. Trust me. I had some call backs after brand new installations due to water in the Ventor motor. Weird. After raising the Exhaust pipe - problem disapeared.
    And make sure pipe rises vertically as much as possible right after the Ventor.

  10. #10
    Join Date
    Jan 2004
    Location
    Northen West By God Virginia
    Posts
    72
    All of HEIL H9 models of that time had poor drain system, go to dealer and get new retofit kit, cost me $1, put one on all furnaces put in before A3 mod#, it will take care of problems.( Till pressure switch sticks closed) while at dealers get new pressure switch # 1014828 save another trip. (under warranty)

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