Fusible Links on Electric Strip Heaters

Eugene Silberstein 3

Nooooooooo...

It's a good thing that you serviced it and got it up and running correctly. Imagine how you would have felt if you saw a picture of the house (or what was left of it) on the 5 o'clock news that night after the house fire killed all of its occupants.

I know I'm being a little dramatic but, then again, not really....

Keep up the good work and continue to do the right thing!

Eugene Silberstein 3

When the Fusible Link Melts

I was mentioning this in class Thursday night and it definitely pays to mention here as well.

If you are servicing a system that is equipped with electric strip heaters and find that the fusible link has melted, please remember to ask yourself why the link melted in the first place. Never replace just the fusible link and think that you are through.

The temperature at which the fusible link melts is higher than the cut-out temperature of the limit switch. If the limit switch is operating properly, the fusible link should never melt. The melting of the link is a last ditch effort to prevent the structure from catching fire. If the link is found to have melted, the limit switch is also defective and in need of replacement. And, if the limit switch is defective, that means that the device has most likely been opening and closing a lot. This means that there is another problem with the system as well.

This additinal problem could be a defective sail switch, air pressure switch, blower motor, blower motor starting component or a number of other items.

So, if you find a melted fusible link, replace the link, but also replace the limit switch as well as repair what caused the limit to open and close in the first place.

Remember... Keep asking yourself WHY... When you can no longer answer that question, you have found the cause of the problem, not simply the effect.

Peace

bill_61

i remember one electric furnace i was working on. it started with a routine checkup(18year old rheem)blower was filthy, cleaned it......coil was filthy, cleaned it.....replaced the filter of course. two fuses were blown but the limit was still ok(ran the unit with no fan for a bit). two weeks later i went back, not enough heat, one of the fuses that i just changed was blown again. enough was enough..changed the limit and replaced the fuse.....a week later the other fuse was blown. after searching through a wiring mess i found a relay that decided to open when it felt like it for the electric heat. the bottom heater was staying energized!! hours of rewiring and replacing all the relays(took no chances) and everything was good to go until the next day there was a call for no heat again.......the old circuit breaker just couldn't handle the load of everything working properly and burned up. 18 years and never been serviced...i should have never touched it!!

Mitch_4

manual reset / fuseable links

My personal philosophy is that if it a manual reset safety, or fusible link. then it MUST be investigated before repair / replaced and I leave the job site. If I can find nothing. Then I test everything, document the result, before I go.

Visions of a home on the evening news after I have been there has happened to me once. (not my fault...HO left deep fat fryer on when they left) and it scared me sh**less.

if you service something like this. don't just cover your behind..armour plate it!

Mitch

Warren Young

How is that possible?

Warren Young

How is that possible?

Dear Bill, How is it possible for the system to have been running for 18 years, and the wiring is inadequate? Was there something added on to the system over the last 18 years? Was the circuit breaker changed? I am not quite a tech, or even close to it. I am just a student; But I am very curios to know how this is possible after so many years. Was the circuit breaker itself frail and crumbling? By the way Mitch that story was very funny.

bill_61

not really professor. that job was (surprise, surprise) a condo complex and i learned after the fact that the half that was getting rebuilt was due to a fire that was caused by one of the electric furnaces......we still have that account and are pushing for replacements at every turn.......got about 5 out of 30 so far.

bill_61

everything was adequate...the circiut breaker was just old and when it finally got the full load amps of the furnace pulling through it(all 3 electric heater strips operating), it wasn't used to it and didn't like it....."poof"

Mitch_4

yeah

looking back I can laugh now... but seeing the house you left that morning on the evening news wasn't funny at the time. an I was a fairly new tech then (only about 2 years after getting journeymans ticket.

No...not at all.

Visions of courts, lawsuits ran through my head for about a week until the firemarshall's report came out. I could see my life in ashes..I was fanatic about jobs until then just "making sure" production and appetite dropped. I was a friggin mess.

But I can laugh now!Pray you never have it happen.