Electric furnace fuse problem

[fermat]

Hello hvac pros

My 30 yr old home electric furnace (Amana) has recently had an electical "fuse board" failure. The board burned completely through (an area about 1.5 inches sq) under fuse holders in 2 places. One 60 Amp fuses did blow. And it's getting cold in my house right now.

Now I want/need to replace the fuse circuit board myself. I don't care or worry about getting electrocuted :-) I shut off the power to it and I already removed the bad one. But, I am having difficulty finding a replacement part for it. I called several local Hvac shops here in Phoenix (A/C dealer and repair heaven) but they won't sell me a part or even tell me where to get one. They even suggest buying a whole new furnace and A/C system! I've search the web and I can't find a part there either, I can't even find the bad-board part number. But the furnace model number is EFL 2070-1A. Can someone help me out? Tell me where I can get a part? Or a substitute for the original part? Thanks guys

[Charles Spitzer]

how do you know if the new board won't have the same problem due to a problem elsewhere in your unit?

that would be an expensive test.

[PrecisionMachinisT]

Assuming there was wire terminations on both the line and load side of the old fuse block, and failing to find a suitable replacement that would physically mount in the old position, its likely I might simply mount a new or used fused disconnect to the outside of the unit.

[fermat]

I don't know for certain, but I have good reasons to believe that the problem was on the board. I have a multimeter and I checked the load circuit. I also ran the sequencer without the 240v supply on. The fuse mounts were fried because they had worked loose and arcing occured with much attendent heat. I have trouble-shot everything from sewing machines to spacecraft systems. Testing is not my problem. It's getting parts from an industry that wants to bilk the DIY end user.

Thanks

[Joseph Meehan]

First consider it is 30 years old. Finding parts may not be easy or possible. Who knows that may be next or how soon.

You can rig some sort of Buba fix, but you run some risk there as well if you want to sell the home or if there is some sort of failure and the insurance company finds it and decides not to cover you.

It might be time to take this as an opportunity to upgrade. I am going to guess that you could save money using a heat pump and that may pay the cost of the new system over time. How old is the A/C If it is very old I am sure you will be able to get a good payback.

[Jeff Wisnia]

My thoughts exactly.

And, to help prevent future "mysterious" fuse burnouts apply a conductivity enhancing/corrosion prevention chemical to all metal to metal "spring" contacts, i.e. the fuse/fuseclip and switch blade/finger ones. I kept losing fuses in my two heat pump systems, maybe one a year out of eight cartridge fuses in all, until I cottoned on to that.

Oxides form with time and increase the contact resistances to the point where enough heat is created to darken the fuse end cap, melt the fuse link and/or char insulators.

There's a Thomas & Betts product called Kopr-Shield and also the one I use which is made by a Canadian guy I went to college with almost 50 years ago:

I haven't had a fuse problem of that kind with our heat pumps since I applied Stabilant to the contacts about five years ago.

HTH,

Jeff

[fermat]

I like your suggestion. The original installation of the air handler with the bad fuse block is (still) in the attic and the CBs are outside in the breaker box about 20 ft distant. A separate 240 vac power line connects them. Could I simply install a substitute fuse block outside (near the CBs)? They would still be in-line fuses only they would farther from the unit.

[PrecisionMachinisT]

Within a suitable enclosure, probably yes.

Though in addition to just a fuse block, I would prefer to use a knife-switch type of fused disconnect, this allows one to work on the equipment without worry of someone throwing the circuit breaker back on when you are least expecting it.

Similar to this :

[twstanley]

[indago]

041209 0219 - fermat posted:

I don't know how thick the board is, but you could probably find some circuit board material at Radio Shack and cut a piece to add onto the board you have and superglue it in place. You could get some fuseholder parts at your local electrical supply store and modify the holder to fit in place on the new piece of circuit board. Put the whole thing back the way it was and you will be back in business. Nothing so hard about that...

[fermat]

Thanks. That is the best fix in my case.

[TURTLE]

This is Turtle.

Go down to any trailor house supply places and just about every trilor house sales places has one and tell them you want a 60 amp fuse block for a trailor house electric furnace. They have the Breaker replacement kits for about $125.00 and the 60 amp fuse block for about $60.00. This is high as a cats back but you can get one there.

Now let me tell you a little secret here. If you have a properly sized breaker suppling the power to it and no other devices tied to it. You don't need the fuse block for protection , for the breaker in the switch box will protect it. The reason I say this is you can get heat to your house and when you get around to finding a fuse block. You can replace it. The fuse block is a secondary protection and the breaker in the switch box it the master or main protection here. A lot of 10 KW electric furnaces now days don't have no breakers or fuses in them at all.

TURTLE

[fermat]

Now that is what I call help. Thanks Turtle. Some guys advise that I should just buy a new 5 ton A/C and air handler because it's 30 yrs old. (This is a split sytem.) That would cost over $7000. Your fix costs nothing now and maybe $60 later. I suspected that using "both" fuse and breaker protection was overkill. I thought about this a lot, and I read all the responses I get. I like yours best. But I don't know the applicable codes for res, electric and I don't want to risk voiding my fire insurance. So I'll play it safe and wait till I can get the right parts. Actually, it has warmed up here in the dessert - it's not too cold now.

Thanks, and have some well deserved happy holidays for helping an old man out. The more you give - the more you get, and this holds for both good and bad.

[fermat]

You and I think alike, that's almost exactly what I did. thanks

[Gary R. Lloyd]

You don't really believe this, do you? If there is anything I have learned about DIYers it is this: No matter how much I help them, no matter how much money I save them, no matter how much additional knowledge they could gain, they are not going to buy my books. It is strictly a one way street.

Gary R. Lloyd CMS HVACR Troubleshooting Books/Software

[fermat]

Gary

Yes, I do believe what I said. The problem you are having is that you expect returns that correspond to what you give and too soon after. But returns may be unrelated in kind or type of given deed, and delayed any amount, even into the next world. Patience is the virtue you need to cultivate. I have trouble with that one myself. Good luck on your book sales.