Had furnace problem - have a few questions...


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Old 02-07-07, 11:42 AM
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Had furnace problem - have a few questions...

Gas furnace: AIREFLO Series AF90MPB\ Model SV9520. It is labeled 90% eff.
Thermostat: Honeywell RTH7400D programmable

The furnace\house is almost 4 yrs old. When we purchased it last year I put in the programmable thermostat. At one time last year winter the furnace never came on in the morning (IE: programmed to 65 at night and then it is supposed to come up to 72 in the morning but it never came on). We had the Gas co. repair it (said the condensor line needed to be cleared\cleaned). It was fine after that.

This year, winter finally kicks in to the low 20's and the furnace again does the same thing (never came on in the morning). When I opened the lower panel I did notice the LED light giving off one or two flashes (sorry did'nt know what it was until I read these forums so I did not give it much thought).

It eventually came on later and in the mean time (past day or so) I have gone to a hold on the temp but until today it still was not performing correctly, set at 72 and it would drop to 68 before coming on and then it would drop to 70 and come on, today it is performing as it should (set at 72 and comes on and stays at 72) but I did have some ?'s just for future reference and I just wanted to know.

1. Is it possible that the condensor line (PVC tube) gets frozen overnight? Is this what the tech did last time this happened? If so what is the solution? I can see the tube and it runs just above the floor (un-finished basement). Does the temp need to be higher then I had it set overnight?

2. When this happened I changed a few settings on the installer setup to the thermostat. I had the "Heating cycle rate" set to "3" before (Gas 90%+ High Efficiency furnace) I changed it to: "5" (Gas furnace less than 90% efficient). What does this setting do? And should I change it back?

3. I also turned OFF what they call "Adaptive INtelligent recovery" it is supposed to be able to adjust to your home\furnace and start the furnace so that the temp you had set is reached by the time you have set.

Since things are going good now I have not changed back either of those two settings.

Sorry for the long post!! Just trying to get educated here !
 
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Old 02-07-07, 01:37 PM
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You will have to report what the LED was telling you on what was wrong for it to lock out.

I don't think the tube has froze over night if you are in the basement with this. (unless your basement is an old farm house that just as cold as outside.) Where is it draining to?

Cycle rate is on an avg how often the furnace will cycle in an hour. I'd suggest to put it back to 3. 5 is going to be too hard on your furnace, and not going to get your full effcency rating.

Reason why you turned off the A.I.R.? What are you doing now instead, setting to to come on sooner say 2 hours??

The AIR has nothing to do with the furnace shutting down.
 
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Old 02-07-07, 02:03 PM
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Yeah I did'nt know what that LED was for until I started searching around on here. If it happens again I will make a note of it. I am almost positive it was a 2.

Not in a barn - just in the basement , it gets cold down there but not like outside. It drains into a opening that is between the concrete slab and the foundation, it runs all around the basement and there is dirt in there (not sure what they call it) and I can see the water drip out when it is running.

Thanks for the info on those settings I will set them back. I turned off the AIR because I thought it had something to do with the thermostat not telling the furnace to turn on at the right time. LOL I thought it might be confusing the furnace??
 
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Old 02-08-07, 04:59 AM
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Did not come on again this morning. THis time I looked at the LED and it is flashing 3 times, which according to manual could be a lot of stuff.

It says "Pressure switch or aux switch still open 30 sec after inducer was energized. Sys is in 5 min. delay mode with inducer off. After 5 min delay new ignition sequence is initiated. Note: Smart valve on\off switch in off position during a call for heat generates this flash code"

There are quite a few things under the check\repair.
 
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Old 02-08-07, 05:23 AM
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Go over the things that the manual suggest to check.

My first thing I'd check is your exhaust pipe outside of the house.

Smart Valve is the gas valve, if it's turned off, it needs to be on to work. Also FYI, I've read on here and others boards that Smart Valve are known to have a lot of problems.
 
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Old 02-08-07, 06:43 PM
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After I left in the morning it started to work. Came home looked at the outside exhaust pipe and there was a HUGE chunk of ice on the ground right under the pipe. Looked like it would fit inside and block the pipe perfectly. I guess it is so cold outside the condensation just freezes and then more and more freezes on top of it? What can be done to stop this?
 
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Old 02-08-07, 08:45 PM
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You will want to make sure the exhuast pipe is tilted back towards the furnace.. You will get some ice. but should be alot that it will block the vent.

How is it the pipe set up outside? take pic if you can.
 
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Old 02-09-07, 03:26 PM
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Thanks for helping, really appreciate it!

Ok if I did this right, (I think you may have to copy\paste) the below pic is the exhaust pipe on furnace:
http://img512.imageshack.us/img512/3152/pic1wg1.jpg

This one is where it leaves the basement:
http://img69.imageshack.us/img69/231/pic2lv7.jpg

And this one is is the outside shot:
http://img512.imageshack.us/img512/3469/pic3lt2.jpg
 
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Old 02-09-07, 06:24 PM
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It looks ok from what I can see..

I do see that they didn't run the intake outside. this a new home?

I don't see any ice build up or anything blocking the vent ouside.
 
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Old 02-10-07, 04:44 AM
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Home is about 3 yrs old.

There is a huge chunk of ice that looked like it was in it at one point sitting on the ground, I thought back to when it happened the first time and we did have an ice storm about then so maybe that was how it got clogged, I will just have to remember to go out there after storm and make sure it is not blocked.

After that it was working fine until I set that Adaptive INtelligent Rcovery setting back to "on" and then it locked out again on me. May be just a coincidence but since I have set it to "off" the past few days it is fine again. Don't know why maybe that circuit in the thermo is bad?
 
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Old 02-10-07, 07:20 AM
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Do you have make up air in the furnace room for it??

the AIR shouldn't have anything to do with that...it just tells the t-stat to come on early. I think it just a coincidence that it happend..
 
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Old 02-10-07, 07:36 AM
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Originally Posted by Jay11J View Post
Do you have make up air in the furnace room for it??
Do you mean if their is enough air for the intake for the furnace? If so I am pretty sure, it is in a full size basement.
 
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Old 02-10-07, 08:00 AM
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You still could have a whole basement, but something should be there to provide make up air for the home..

-Water Heater
-Exahust fan
-Range hood
-Dryer.
-Furnace.


Do you have a pipe coming in to the home from outside that is dropped by the furnace or water heater?
 
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Old 02-10-07, 10:07 AM
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OK, looked a little closer and there is an outside air intake for the water heater (next to furnace) and then the one for the furnace is big,round & silver it goes into the ductwork that runs just above the furnace.

The little white intake right on top of the furnace brings in air as well (felt it as the furnace was running)
 
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Old 02-14-07, 10:35 AM
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I feel your pain, I am having the exact same problem with mine, I put a new stat in vented the fire box a little bit and it worked good for about 4 days, then last night the temperature dipped pretty low again outside and it did the same thing this morning so I have to go and reset it but the LED light was not blinking. I am thinkin it has something to do with the intake pipe or exhaust. Once I reset it it worked fine so I am kind of at a loss as well.
 
 

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