[tbv4]

Need Your Help!

I replaced 2, about to be 3, igniters on my furnace's Beckett AF burner in the last 18 months.

A little over a year ago I replaced the original furnace burner igniter with the hot water heater igniter, both are Beckett AFs - and it just failed again. Any reason why the furnace burner igniters would keep failing?

The hot water igniter has been working fine. I know it gets a lot less use. I'm blaming the furnace igniter failures on age, they're 7-8 years old - but can' help but wonder if they're failing for a reason. Should I be checking or replacing something else too.

The furnace burner has been serviced annually but I question how/what they did when they cleaned it and tuned it up. They say they changed the electrodes and I believe they did but wonder if they set things up properly, or if that matters.

Planning on buying and installing the third igniter myself, prev service guy gave me a used igniter that was intermittent but charge me for a new one. I'm not too sure if the new service guy has been cutting corners too. I've successfully swapped the igniters in the past and found new non-Beckett replacement units on eBay and elsewhere for less than $40. Also is there a beefier igniter I should be using to replace the original 51835 ?

Any help certainly appreciated.

[hvac1000]

Low supply voltage (115/120) can cause a extra strain on the ignition transformers. You need to test the feed voltage to the unit at the unit when it is running to see how much voltage drop you have.

[tbv4]

Thanks for the info. On fire-up igniter has 120v, few secs later the fan kicks in and it drops to 115v and after a few more secs it settles in at 118v. Then the cycling begins burner is on for 2 1/2 minutes and off for ~1 1/2 minutes. When the burner is off, fan still runs, and the igniter has 0v. When it starts back up it goes back to 118v.

I monitored this for ~15 minutes and it's fairly constant at +-.5v of 118v.

I'll check it periodically while it's running to make sure it stays this way but it looks pretty solid.

Thanks again, trying to study and observe.

[hvac1000]

115/120 is good. I know it is warmer outside now but the unit seems to be short cycling. Just a thought.

(Then the cycling begins burner is on for 2 1/2 mins and off for ~1 1/2 mins.)

[KISS]

You can't touch it. Wear gloves.

[tbv4]

I thought the cycle was a bit short too. Not sure how to adjust it but will look into it. What are typical #s?

Thanks HVAC1000.



PS: Not sure what KeepItSimpleStupid is talking about.

[mygirlsdad77]

Kiss is just letting you know not to touch the heating element with your fingers. They are very sensative and the oil from your fingers will cause it to burn out prematurely. However, I do believe Hvac is on the right track. Short cycling of furnace will cause overuse of igniter. Think of it as a lightbulb, it will burn out eventually, but the more its use the quicker it will burn out.

[tbv4]

Makes sense but doesn't seem like I can adjust anything. What controls the cycle?

This is a UniCell system from Watertown MA and the label inside says it's mfg for Heat Controller, Inc - Jackson Michigan. Looking at the parts and wiring diagram on the cover the circuitry seems fairly simple, just a few relays, transformer, and IR relay. Appears the IR sensor controls the heat-cool relay and there's no adjustments.

Thanks to everyone for your help and insights!

[vinpadalino]

How do you know there bad? DO you test it with a tester, or a screwdriver?

[hvac1000]

The wall thermostat usually controls the cycle time of the burmer unless the Furnace fan and high limit control is also playing a part. If a furnace is completely set up correctly and the burner has the correct nozzle installed the burner will come on and not turn off until the thermostat is satisfied.

Now if the thermostat is not set up correctly it can also cause the burner/furnace to short cycle. Thermostats have what is called a heat anticipator circuit OR the newer digital thermostats allow you to change the range in the set up program.

Short cycling can cause higher utility bill and discomfort due to the blowing of different temperature air at different parts of the cycle.

[KC13]

FOR SALE: hvac1000's home phone number... JUST KIDDING! HA!

[hvac1000]

Just remember that can go both ways.LOL.

[tbv4]

The original problem was discovered after the reset button on the furnace's control unit keep popping. Then one day it wouldn't reset. Called in a service man and he tested it w/screwdriver and replaced it. Unfortunately, and to my surprise - he charged me for a new unit but put in another intermittent old unit. As luck would have it the replaced igniter had a similar problem so I switched it w/the hw htr igniter (same exact burners and control units). They both worked well in the other’s burners for a little over a yr. Around the middle of this winter I started noticing the furnace was starting very erratic (shaking and rumbling). A couple months later the furnace reset button popped and I couldn't get it going (only hit it twice). Suspecting the igniter, my ol’friend, I switched them and whala the furnace fired right up, w/a little smoke of course.

All,
Knowing the furnace igniter is intermittent and the hw htr’s is missing I bought 2 new Beckett 51771U igniters and put them in. Everything seems to be working fine now. I believe the original France (not Beckett) igniters we’re just old (~8yrs) but as others here have indicated the cycling is also suspect and should be corrected and am working through this now.

As for the cycling I have an old rotary thermostat and have been thinking of replacing it w/a new programmable one, looks like now’s the time. I’m also considering swapping the whole hw burner w/the furnace's burner to reduce future problems and get more life out it, kind of like rotating tires.

Many thanks to everyone for all your help and great info.

[hvac1000]

Good luck with your work.