Can you Help with my Furnace Problem

[dnrtheil]

Long story short.
Used Furnace NT30 with spark ignition.
After install, the furnace ran through two complete cycles, fan start, heat up, cool down, fan off. On the third try it would not produce a flame. I am 100% sure the sail switch works, the ignitor produces a spark, I can smell gas outside at the exhaust port, I can also hear gas leave the LP tanks while the furnace is trying to start. Is there a chance the spark is not enough or that I am not getting enough gas into the combustion chamber to produce a flame? I see a couple of on-line stores do not let you return a gas valve and at $90.00 I am hesitant to get one and that not be the problem.
Any thoughts?

Thanks - Derek

[garry]

Sounds like the spark is firing to the side and not across the gas I have seen this happen before.

It can be adjusted but you will have to look at it when sparking to see where it is sparking. It will always go to the closest ground.

[dnrtheil]

When the electrode fires or sparks, should it be constant or not? Should you be able to hear the spark click like on a house furnace? I installed a new electrode and it still will not start. I am wondering if the spark is not getting enough power, as it looks weak and does not fire consistently. I am thinking of ordering a new board.

Derek

[Bfrank]

If your valve is sticking that could cause your problem or it could possibly be the board bad grounds usually are the culprit, you might consider pulling the unit and setting it up to run on a bench by supplying gas from a tank for a grille the unit should slide out of it's housing if you can get to
the gas line to disconnect it you will have to remove the screw in the center of the outlett on the coupler mounted on the outside then it will slide off of the intake and exhaust ports. I paid 700 bucks for a new one
and just slid the new unit into the old housing because of the duct work
and I have been very happy with it. Good Luck

[HowieE]

If it fire once the that kind of confirms it works.

The next thing I would do is loosen the gas line at the furnace just enough to smell gas. Tighten it down and try again. If a slug of air got in the gas line the pilot orifice is very small and will not bleed the air off in several cycles thus causing one to think the furnace is bad.

If after you do not get heat knowing there is gas at the furnace then it is time to look elsewhere.

[dnrtheil]

Originally Posted by Bfrank

If your valve is sticking that could cause your problem or it could possibly be the board bad grounds usually are the culprit, you might consider pulling the unit and setting it up to run on a bench by supplying gas from a tank for a grille the unit should slide out of it's housing if you can get to
the gas line to disconnect it you will have to remove the screw in the center of the outlett on the coupler mounted on the outside then it will slide off of the intake and exhaust ports. I paid 700 bucks for a new one
and just slid the new unit into the old housing because of the duct work
and I have been very happy with it. Good Luck

I have thought about checking the grounds and other connections at the board and replacing the wire going from the board to the electrode.

Originally Posted by HowieE

If it fire once the that kind of confirms it works.

The next thing I would do is loosen the gas line at the furnace just enough to smell gas. Tighten it down and try again. If a slug of air got in the gas line the pilot orifice is very small and will not bleed the air off in several cycles thus causing one to think the furnace is bad.

If after you do not get heat knowing there is gas at the furnace then it is time to look elsewhere.

I am certain gas is getting into the combustion chamber, I was able to get the furnace to start Saturday after bending the electrodes around. Next time all I got were two bursts of flame. Another burst of flame tonight after installing a new electrode.

Derek

[vinstream]

Can you hear the sail switch click on after the fan blows? If there is not enough movement of air the sail switch will not let the furnace light! I have found that a low battery will not turn the fan as fast as needed for the switch to work..... If it worked and now does not work again... I think it could be low battery or maybe time for a new fan....

[dnrtheil]

Originally Posted by vinstream

Can you hear the sail switch click on after the fan blows? If there is not enough movement of air the sail switch will not let the furnace light! I have found that a low battery will not turn the fan as fast as needed for the switch to work..... If it worked and now does not work again... I think it could be low battery or maybe time for a new fan....

I can hear the sail switch click just after the fan starts to blow, I also hooked up a continuity checker to the sail switch. I am 100% sure it is working. Also I have the A/S plugged into 120 volt source so the power converter is putting out plenty of power. I have a new board on order, but will check the connections on the existing board tonight.


I noticed there is a small light (clear bulb) on the board, but I never see it light up at all!

Thanks - Derek

[kennethowens]

Can you try one of those long matches. If a match will
light it....then the striker(function / location) would be
next.

[rbr]

Have you pulled out the valve & burner unit? I had a similar problem and found mud dauber nests around the burner, impeding airflow enough to prevent ignition while everything else was working properly. Works great after cleaning.

[dnrtheil]

Originally Posted by kennethowens

Can you try one of those long matches. If a match will
light it....then the striker(function / location) would be
next.

The combustion fan blows too much air to keep a match lit plus I am afraid to even try a long lighter, thinking the flame will shoot out the small hole (where the electrode is installed) like a jet engine. I can smell LP gas, so I am pretty sure it's getting gas.

Originally Posted by rbr

Have you pulled out the valve & burner unit? I had a similar problem and found mud dauber nests around the burner, impeding airflow enough to prevent ignition while everything else was working properly. Works great after cleaning.

I have had the burner out as well as the gas supply line, there is a small nut with a small hole at the end of the supply line where it enters the burner, that was removed also, both were cleaned. When it does light the burner lights evenly. I have not removed the gas supply line from the valve, either before of after the valve.

Thanks - Derek

P.S. does anybody have a video of a good working electrode?

[vinstream]

I ran into this only one time so it's a bit of a long shot.... You could have bad gas or slug build up in your gas line! It is caused in old systems (1964) that have water in the main line, the water that turns into a slug will let some gas by but not enough to long use. The way to check is disconnect the line at the heater and look for the slug... Its a long shot but one more thing to check out!

[dnrtheil]

Originally Posted by vinstream

I ran into this only one time so it's a bit of a long shot.... You could have bad gas or slug build up in your gas line! It is caused in old systems (1964) that have water in the main line, the water that turns into a slug will let some gas by but not enough to long use. The way to check is disconnect the line at the heater and look for the slug... Its a long shot but one more thing to check out!

My gas lines are all new, they were installed last fall. Everything involved with gas delivery is new except for the tanks. I was wondering if it was possible to get bad LP gas, but every other gas appliance works just fine right now.

Take Care - Derek

[HowieE]

Have you cracked the gas line to ensure you have gas at the heater? The fact that all the other gas appliances work is no indication that gas is at the heater. If a slug of air, and now that you say you had all the line open, is in the line to the heater it will take a very long time to bleed that through using the pilot orifice.

[dnrtheil]

Originally Posted by HowieE

Have you cracked the gas line to ensure you have gas at the heater? The fact that all the other gas appliances work is no indication that gas is at the heater. If a slug of air, and now that you say you had all the line open, is in the line to the heater it will take a very long time to bleed that through using the pilot orifice.

I have had the gas line apart just a sit goes into the furnace valve. I can smell gas coming out of the furnace exhaust vent, after the furnace goes through it's three try start up.

Thanks for your input - Derek

[dnrtheil]

After installing a new board from Dinosaur (I went with the Fan 50), a new electrode and a new fan limit switch (this is the one that shuts off the fan after the furnace cools down). The furnace lit twice in a row with out hesitation. I think my old board was not producing enough spark, or a late spark. There is a neon light on both boards, on the new board this neon light lights up when spark is produced, I never saw the neon light on the old board light up. Just a word of note, if you install a new board or upgrade as I did. Read the instructions carefully, if I would have read them closer the installation would have gone much quicker. With the Fan 50 board and an older furnace, the extra orange and red wires that come with must be hooked up according to the instructions the board will not work, even if you get the fan to kick on.

On to the next project...

Thanks for all of you help - Derek