Day and Night Furnace rewire


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Old 01-13-09, 08:30 AM
J
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Day and Night Furnace rewire

I'm trying to straighten out some "fixes" that a previous owner did to my heater. Due to venting problems on the roof and no vents in the garage, he disabled several of the safety switches. I don't have the exact model number of the "Day and Night" furnace, but all I really need to know is what the abbreviations mean on the cover panel schematic so that I can get the appropriate limit switches connected to the right control board terminals. The board is an ICM 281 replacement for a CES110057-1.

I only have 5 of the 6 switches shown:
1) A manual(?) switch on the Big blower motor.
2) A manual switch on a vent tube protruding from the flu after the draft inducer fan. I beleive this one is refered to as the Draft Safeguard Switch.
3 & 4) Are switches on the left and right side of the gas burner nozzles. I can't remember if these were manual or automatic.
5) An automatic switch protruding into the heat exchanger area.

Three switches are shown in the schematic in series between pins 5 and 10 of the control board:
LOT#2 - Limit Overtemperature - Manual Reset
LOT#1 - Limit Overtemperature - Manual Reset
LS - Limit Switch, Overtemperature - Auto Reset

And three are shown in series along with the pressure sensor between pins 6 and 11:
DSS - Draft Safeguard Switch
ALS1# - Auxiliary Limit Switch - Manual Reset
ALS2# - Auxiliary Limit Switch - Automatic Reset

I just need to know which lable aplies to which actual switch so that it is wired properly and safe when I'm done. Once the furnace is safe, I will figure out what he was trying to do.

Thanks in advance for any help you can provide,
Joseph
 
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Old 01-13-09, 07:08 PM
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I don't have time to research your problem right now (will try to later) but I hope you get help! Don't mean to alarm you but defeating the safety circuits on a gas furnace that isn't working properly is pretty much the equivalent Russian roulette.

Perhaps you need to think about seeing an attorney. Selling a house with such a furnace should be against the law. If it should cause damage or personal injury you probably would have a good case for a lawsuit.
 
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Old 01-13-09, 07:40 PM
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Trying more DIY on a furnace already the victim of a hacker is a mistake. Find and honest and competent repairman to do the job for you.

You need someone who knows what they are doing to do that job for you, in my opinion.
 
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Old 01-14-09, 06:06 AM
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More details than you ever wanted to know....

Thanks for the responses. It probably sounds worse than it is and even though I'm not an HVAC guy, I work with electronics for a living and am prety good at figuring out how things work. (Now you should be really scared)

I noticed the bypassed safeties when I changed out the control board. It died a couple of weeks ago. I put them all back in the circuit at that time, but did not necessarilly get them on the correct board terminals. There are two separate logic circuits monitored by the board and they each have a different "lock-out" period and different generated error code for faults. Four of my five limit switches are manual reset, so if one of them should open, the control board will lock-out until I open the heater and reset it myself.

After starring at the drawing on the heater panel for a while and researching the troubleshooting page for the control board, I came to the conclusion that "LOT#1" and "LOT#2" are the switches at each end of the gas burner manifold and should be wired in series with the switch that protrudes into the heat exchanger. LOT#1 & 2 are manual reset, so if flame should get to them, the furnace will shut down until I physically reset the switch, and generate an error 13.

That just leaves the switch in the exhust flu and the one in the blower. The switch in the exhust flu must be the Draft Safeguard Switch and, by process of elimination, the blower must be "ALS1#". If either of these opens, I should get an error 31 and, again, they both need to be reset manually by me.

How'd I do? Does all that make sense?

Now I have to figure out my exhust vent problem. It only happens when we get a strong north wind. I really can't move the roof vent, but I think if I vent the garage in the right place, my draft will consistantly be in the right direction (up as opposed to down).

Again thanks for getting back to me,
Joseph
 
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Old 01-14-09, 12:21 PM
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Heh, heh! This reminds me of a story from the good old days.


I was called out when I was working as a repairman for a gas utility. The customer said their furnace seemed to be overheating.

When I went down to the basement, I found a big old forced air gas furnace that had been converted to natural gas. The sides of the furnace were glowing a dull orange in color from the heat!

The furnace had a fan switch to turn the fan on and off, and a limit switch to turn the burner off if the furnace overheated. But someone had wired those switches improperly so that if the furnace overheated, the fan shut off, not the burner.

And the limit switch wasn't wired to shut off the burner.

So when the furnace overheated for some reason, the burner didn't shut off but the fan did, which meant there was no way for the furnace to get rid of the heat the burner was producing. And nothing to shut the burner off.

I still remember that as a graphic example of the importance of furnace limit switches, and I tended to recommed that people keep their piles of newspaper away from the furnace, too!
 
 

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