HVAC Questions? Ask an HVAC Expert for Answers ASAP
Hello there! I'm Norman but you can call me Norm. Let's see what I can do to get you some answers today. I'm ready to get started whenever you are.
Can we start by you telling me a little more about your oil furnace, such as the model number, the age, the location, etc.?
It's a mo HTL 100 series 55 about 30yrs in the basement
The vents and the furnace have just been cleaned and vacuumed as well.
Wow she's old! I'm fairly certain I will not be able to find information on that baby.
I'm wondering if it would have a heat limit switch on it?
Without an exploded service view this may be difficult for me to instruct you. Lets start here...Are you familiar with the flame-rod, if so, does this furnace have one, if so, have you cleaned it?
When you reset are you resetting a limit or just the furnace itself?
The flame rod senses the consistency and quality of the flame at the burners or pilot.
There two electrodes beside the nozzle, i',m guessing one is a flame sense and the other is the igniter. I think the reset just restarts the furnace.
And yes it was cleaned.
The flame sensor should look like a steel rod. You can ensure that is clean by using a fine grit sandpaper or steel wool. How did you clean it when you serviced the unit?
the question about the heat limit switch is a good one, however most furnaces have a resettable limit near the burner box. Most of the time they are manual. You can check yours to see if it has a manual reset button in the middle. If it is not tripped that is probably not your problem. You can test for voltage on both sides of the switch to be certain when the furnace goes through start up procedure.
It had been sooted up when I cleaned it. I don't think the furnace had ever been cleaned before. I used a degreaser and a coarse paper towel on it.
use something a little harsher on it like I recommended above. This may be part of your problem.
Have you replaced any oil filters and nozzles?
There is one grey Honeywell box that the Tstat wires go to with a reset button and another box above it with a cream colored Auto/man. dial on it. The oil filter is new, the air filter about 6mos.
The air filter still looked fairly clean.
When it fires up, the flame looks good, How would a new nozzle affect the duration of burn?
I have cleaned the orifice and the little filter inside the nozzle as well.
It is a strong yellow flame, with a good roar to it, a little louder than before the vents were cleaned.
I can't see the start of the flame as there is a ccollar over it leading to the ceramic fire pot.
I'm sorry my computer crashed.
On my phone now so I may be a little slow
Does the flame ever tend to surge?
No, it lights and stays steady,then cuts out.
As for your remark about the flame color the flame of some oil burners may be light yellow in color. More often it should have a blue - white or chrome colored flame. A dark yellow flame is an indication of a lack of air in the mixture. If is the case you may have problems on that end tripping the limit.
Adjustments should be made by a professional with the correct tools.
A proper air to fuel ratio is required for a effective flame on an oil burning unit. It will take a combustion analyzer or a smoke tester to make any air adjustment.
You can also tell if your burner is not receiving enough air by checking the amount of soot. A low air mixture will produce more soot and will also produce higher levels of dangerous carbon monoxide.
I guess I'll have to phone around to find an old furnace tech. Living on an island does have a few drawbacks. Thanks for your time.
You are very welcome. Have I answered all of your questions today?
Yes thanks, XXXXX XXXXX of any more.