Primary/Secondary Limit Switch Open Question

Joeski · Post by **Joeski** » Fri. Feb. 20, 2015 10:39 pm

Hello all you fine coalpail.com people.

Thank you in advance for any help you can give me. I came home this evening at around 8:00 PM to a house that was at any where from 61 to 66*F depending which area I was in. I normally try to keep it at 68*F but with this intense cold it hasn't been keeping up.

So I go down to the gas furnace and look at the LED lights for the error code. The left light is blinking slowly and the right one is on steady. The sticker on the furnace reads this
"Primary/Secondary Limit Switch Open"

What if anything should I do about that?

Turning off the breaker to the furnace reset it and the heat came back on but in a short time the error code came back and also no heat.

I turned the breaker off again and the heat came back but I set the temp on the Thermostat to 64*F in hopes it stays on tonight.

It's a Lennox furnace and I find out it's only a 100,000 BTU one for a 3050 square foot house.
Model # G26Q3/4-100-5 Serial #5899B 55167

Some questions.

1.) Is the unit trying too hard to heat the house and therefore is setting off a safety feature to not "destroy" itself?

2.). Is 100,000BTU a joke for a house this big. It was built in 1999 and is insulated fairly well.

3.). I think it's time to get a real heat source for this house meaning KING COAL!!! I paid $469.00 my last gas & electric bill and am never really warm. At my house in the Pocono's I have a Leisure Line Pocono bottom vent and that is 110,000 BTU and a spare Reading Susquehanna that is too big now for my wife to handle because of health issues. I don't think I can get that into this houses basement due to it's weight.

A Leisure Line Hyfire II seems like it might be the answer or a nice big base burner for the no electricity factor.

Pauliewog · Post by **Pauliewog** » Sat. Feb. 21, 2015 1:06 am

Common cause is a dirty air filter or blower motor fan . I would check those first. Do you have the manual for the code? Is there any letters or numbers after the dash?
Paulie

Joeski · Post by **Joeski** » Sat. Feb. 21, 2015 3:15 pm

Pauliewog wrote:Common cause is a dirty air filter or blower motor fan . I would check those first. Do you have the manual for the code? Is there any letters or numbers after the dash?
Paulie

THANK YOU!!! That worked! I can't believe it was so easy. Everything usually tortures me and for a long time too.

Pauliewog · Post by **Pauliewog** » Sat. Feb. 21, 2015 8:18 pm

Joeski wrote:
Pauliewog wrote:Common cause is a dirty air filter or blower motor fan . I would check those first. Do you have the manual for the code? Is there any letters or numbers after the dash?
Paulie
THANK YOU!!! That worked! I can't believe it was so easy. Everything usually tortures me and for a long time too.

Happy to help out. Every now and then life throws an easy fix our way.

Now .......... Start searching for a base burner and eliminate those furnace problems forever

Paulie

lsayre · Post by **lsayre** » Sat. Feb. 21, 2015 8:40 pm

Birds often go into the (vents through the wall) PVC exhaust pipe to get out of the cold and die there rapidly from CO, leaving you with a clogged vent pipe and a furnace that won't run. It has happened twice already this heating season for the local church that my wife attends. Alternately, if the snow gets high enough it can block your through the wall vent pipe with the same result.