Intertherm mrac-e2512

[Fuzzdobber]

A friend of mine purchased a trailer part one of the units has the model listed above and my first call was no heat on this electric furnace. It was the top 30 amp fuse blown, so I slipped in a new fuse and walah! Worked fine for about a week...So I got to inspecting and found that someone had been messing with the wiring and had one of the wires that was suppose to be going to a 40 amp fuse ( as this unit has 2 30'S and 2 40's) going to a 30 amp fuse among otherwiring issues as well, sooo I pulled all the wires and rewired everything to factory spec. checked all amp draws and everything was great!Problem fixed right? Wrong! A week and a half later had to come back, guess what same fuse with nothing but top strip running off it was blown yet again....Every thing is drawing what its suppose to for a week or more, nothing else is on the circuit, all wires are tidy and tight, pulled out strips they look great wire sized properly, new sequencer and limit installed, motor was new when unit was purchased. All I could do for now was I switched the upper 30 amp side of my top strip to my lower 30 amp fuse and the lower 30 amp fuse for the top strip to the upper 30 amp fuse... If the top fuse blows again I can only assume its the fuse block (although per my inspection looks great) Any thoughts on the situation? I appreciate it guys .....!

[Robert]

Hi Michael,

That's an old furnace and anything original will have wear and looseness, etc... .


You'll have to physically remove, bypass, etc,, until you find what is gradually heating up with higher amps.



Completely remove the block, check those lugs carefully.


Just one of them things that takes elimination and will probably be something you think is ok.


Check the fuse holder prongs, anything that can be loose or corroded to associate small ammount of heat to build up over a week or so.


Disconnect one element at a time to see if it still blows. If it does it with each one disconnected at a time, that rules out all but wires and the fuse block.



Thanks,
Robert

[Fuzzdobber]

Approximatly how much would a fuse block cost for this unit?

[Robert]

Probably no longer available, so would have to check on price and availability of newer one that may work.

How many fuses and what amps are they.


Thanks,
Robert

[Fuzzdobber]

Well as you know I switched the wire from the top 30a fuse that kept blowing to the lower one and the lower one has now blown for the first time... That means the fuse block is fine I also swapped the wires from each fuse to rule out a bad wire so now Im left with a a limit and a sequencer I just replaced in november and last but not least evidently....the strips 11.6 240. Sounds like the strips to me what do you think? They look great , so it must be a hairline crack Im missing or something. Do you still carry strips for this or a retro fit set? How much?

[Robert]

Amp the coils to see if pulling high amperages.


Are the coils small and do they run ~through~ round insulators ?



Thanks,
Robert

[Fuzzdobber]

They are pulling between 24 and 25 ampieres and yes they are the round insulators with the smaller coils... Can I substitute a newer 11.6 kw set with a contactor set up rather then the sequencer as long as I change the limit back to original 170 degree rather then the newer 190 degree? The reason I ask is due to this being an older unit the original strips are 150.00 vs the newer contactor type sold at baker brothers down here are only 78.00. This retro fit would as well come with all new wiring ( although I have re crimpped and checked all original wire for lose connections that could have caused this problem) I may have missed something, In essence i would be killing 3 birds with one stone if you think I could use the newer model strips and its cheaper.
Thanks for the help.

[Robert]

Hi,

Good ole Baker Brothers. The limits are designed to go hand in hand with the sequencer or contactor timings.


Changing to a new set up may bring different timings and with that, different temps.

This may play havoc on the limit .


It can possibly be done, but alot of temp testing needs to be done or get the timing temps to be sure it all will work and maintain safety.


Also make sure the size dimensions fit.


You just have to be sure that the temps, timings, voltages, kilowatts and amperages ALL match old design.


If not, can be dangerous and void insurance if a fire happened within furnace.


We sell 5KW restring kits for $29 each.


Thanks,
Robert

[Fuzzdobber]

Thanks for the advise!

[Fuzzdobber]

Hey Robert guess what... Everything is new new I've done what I said and a week later fuse has blown again...Can you believe this? Im at a loss for words, whats your oppinion?

[Robert]

Put an Ammeter on the power wire going to fuse and set it to record highest amperage reading.

When it blows, check the recording on ammeter.


IF it is high, locate what is pulling high amps.


Otherwise, better take another look at the fuse block.

Gotta love phantom ghost electrical faults.


Where are you at in SC ?



Thanks,
Robert

[Fuzzdobber]

Dillon, recently moved from the Columbia, Blythewood area...

[Robert]

LOL, you weren't a Gamecock fan was ya ? SC is my home State was why I asked.

To explain previous question, I'm from the Clemson area, Oconee and Pickens Counties.


Thanks,
Robert

[Fuzzdobber]

Unfortunatly a usc fan I am lol....my sister just graduated as a matter of fact on the 17th...summa cum laude in medical with the highest gpa in 50 years..proud of her too bad she didnt take up hvac heh lol. GG this year the best team won! Where abouts in tn are you? I recently had a job offer in lebanon at a Tadds Wholesale.

[Robert]

Well, I won't hold it against ya too much,LOL. I'm in West Tennessee.

Congrats to your sister, that is quite an accomplishment.


My wife is from here and when I was retired from Law Enforcement on disability in SC in '97, we moved up here.

I have been in HVAC for 28+ years, even while in L.E., so I fell back to this only.



Take care and best wishes,
Robert