21 Seneca 37TS Furnace Short Cycle

[ebarchak]

Has anyone had a problem where their furnace lights but only for a second and then goes out? Sometimes it will do this 3-4 times and then finally stay lit. Sometimes it does not do it at all. The fan is running the whole time and propane in 50%.

[us71na]

As a first step go outside and turn off your propane tanks. Wait 10 minutes and then slowly open the propane tank valves. Check the stove to see if you get full burner flame, then restart your furnace.

Sometimes, opening the valves quickly will trip the safety device that prevents rapid flow in the event a line breaks.

Second step is to check the sail switch in the furnace to make sure it is moving to tell the burner that it is safe to heat.

[ebarchak]

Originally Posted by us71na

As a first step go outside and turn off your propane tanks. Wait 10 minutes and then slowly open the propane tank valves. Check the stove to see if you get full burner flame, then restart your furnace.

Sometimes, opening the valves quickly will trip the safety device that prevents rapid flow in the event a line breaks.

Second step is to check the sail switch in the furnace to make sure it is moving to tell the burner that it is safe to heat.

I tried both recommendations. The gas turn off seemed the help the most. The sail switch was completely clean and moving. The unit is still short cycling. The weird thing it is actually lights for 5-6 seconds and the shuts off.

[Rustynuts]

Originally Posted by ebarchak

I tried both recommendations. The gas turn off seemed the help the most. The sail switch was completely clean and moving. The unit is still short cycling. The weird thing it is actually lights for 5-6 seconds and the shuts off.

This is usually a sign of the high temp switch being bad. If this switch goes bad, the furnace thinks it’s overheating and shuts it down. It’s a pretty easy part to replace.

[ebarchak]

The dealership got me in yesterday. They said the burner was out of alignment. Worked better, but still short cycles, but much less often. Taking it back next month for punch list items.