72 kw chidlow electraire blowing fuses

[Knobhead]

What has this got to do with a storage heater fault?

 

[Engineer54]

After 25 years of service, this unit is rapidly coming to the end of it's life. Your going to be chasing round like a blue arsed fly, trying to keep this unit in service from now on!!

The only way to bring this unit back to full service for any length of time, is by replacing ALL the heating elements. Probably the cost of the elements and your time to replace them, is going to be a very big chunk of a replacement unit!! The time has come for this unit to be replaced for an up to date unit that in all likelihood will have lower running costs. If your clients can't see this, then it's time to walk away... lol!!!

 

[jumpin jax]

Hi, I understand what you are saying and agreed it is reaching the end of its life but where in this heater, with resistive loading, is the extra draw of current coming from to cause this sudden problem?

 

[Top Cat]

Hi jumpin jax, just wondered if you put your location maybe one of us could give a second opinion. Sometime two heads are better than one!

The only other thought i had was could either an element lead or some other feed to the elements be breaking down on that phase so when it gets hot it shorts to earth or neutral

 

[jumpin jax]

Hi TC, i like your chain of thought but i would have thought that on the initial short circuit the element would have failed completely, i will try and post a picture, the 3 contactors on the left control the elements and the contactor with overload supplies the fan.

 

[Engineer54]

Hi, I understand what you are saying and agreed it is reaching the end of its life but where in this heater, with resistive loading, is the extra draw of current coming from to cause this sudden problem?

That's what i'm saying ...who knows?? You have 25+ years of dust and debris to start with. Depending on what's happened to that failed heating element, you could even be picking up one portion of that element!!

On units of this size and of this age, you can be just scratching your head getting nowhere fast!! It sounds as if this unit is going to be uneconomical exercise to repair, which leaves replacement, or finding another source of heating energy to replace this unit. I personally wouldn't be wasting anymore time on it. Even if you find further problems with the elements, your not going to be able to fix them, without taking the unit and bricks apart!! It's a dead duck mate!! lol!!!

 

[Top Cat]

So i take it the fuses shown are not the ones that are blowing as you have 3 per phase? Do any of these fuses blow when the main one blows? If not surely it must be before these fuses?

Also just noticed coming out of fuses the colours, R,Y,B, - R,Y,B, - BR,R,B ? Could that be a pointer to something that went faulty in the past?

Also if the yellow phase is fully loaded (slightly overloaded) a pinched live cable that is slightly melting when the heater gets hot would not take much of a fault to bow the fuse.

Food for thought!

 

[Top Cat]

That's what i'm saying ...who knows?? You have 25+ years of dust and debris to start with. Depending on what's happened to that failed heating element, you could even be picking up one portion of that element!!

On units of this size and of this age, you can be just scratching your head getting nowhere fast!! It sounds as if this unit is going to be uneconomical exercise to repair, which leaves replacement, or finding another source of heating energy to replace this unit. I personally wouldn't be wasting anymore time on it. Even if you find further problems with the elements, your not going to be able to fix them, without taking the unit and bricks apart!! It's a dead duck mate!! lol!!!

Don't agree i have been nursing along electricair units for 30 years. Not very often i have had to give up on one. Usually it is when they have iron blocks and they get "core growth" and you can't get the blocks anymore.

 

[Engineer54]

Don't agree i have been nursing along electricair units for 30 years. Not very often i have had to give up on one. Usually it is when they have iron blocks and they get "core growth" and you can't get the blocks anymore.

So how long does it take, for you to replace the elements on these units, whether they have iron block or heat bricks??

If you have such extensive experience with these units then you must have a wiring diagram that you can pass on to jumpin jax. As far as i'm concerned, it's one thing to replace a contactor or two, than having to strip down this 72kw heaters heating bricks to remove and replace the elements, then build them back up again.... I'll stick by my initial thoughts, that this unit is past economical repair

 

[Top Cat]

So how long does it take, for you to replace the elements on these units, whether they have iron block or heat bricks??

If you have such extensive experience with these units then you must have a wiring diagram that you can pass on to jumpin jax. As far as i'm concerned, it's one thing to replace a contactor or two, than having to strip down this 72kw heaters heating bricks to remove and replace the elements, then build them back up again.... I'll stick by my initial thoughts, that this unit is past economical repair

Point 1:- On an electricair unit it takes about an hour to change the elements because you just take off the front cover and insulation. The elements slide out from the blocks and the new elements slide in.

Point 2:- I did not say i had extensive experience of these heaters. I have a good knowledge of electricair units they usually range from 6 - 18 Kw, mostly single phase. The unit in question i have never seen before but most are a variation on a theme. As you can see by my numerous posts i have been trying to help this person out, why would i not give him the wiring diagram if i had one? I also posted a link to a firm that deals with electricairs to see if they had any ideas.

Point 3:- What would a 72Kw heater cost to replace? If you give the client the choice of ripping it all out and putting a new one in or let me have a go at repairing it and it may cost a few hundred pounds but no guarantees i no what i would do.

Ill stick to my original thoughts as well!

 

[silva.foxx]

Hi TC, i like your chain of thought but i would have thought that on the initial short circuit the element would have failed completely, i will try and post a picture, the 3 contactors on the left control the elements and the contactor with overload supplies the fan.

Them contactors... is the middle contact 21-22 normally-closed NC?

I can't make them out properly from the image... but now assume the markings to be of auxilaries.

:6: Please carry on...

 

[jumpin jax]

Engineer, TC, thanks for replies, It would certainly cost alot to replace these units and as TC says for the sake of replacing all the elements the heaters would not be written off as the only item of the whole machine that could cause trouble is the circuit board which i am sure with a bit of contactor magic could be over-ridden. I did notice the remix of colours on contactor 3. The machine, according to the data plate, weighs in at 4.5 tonne. That is alot of brick work as there is no lifting gear access. I am sure if TC had a wiring diagram he would without doubt pass it on, In these days of economic struggle i am sure this company cannot afford another heater or two just yet.
Silva.fox , all three of the contactors are either all in or out, i cannot remember at the time of the photo wether the boost was on or not, perhaps my original photo is a bit larger.

 

[Engineer54]

Point 1:- On an electric air unit it takes about an hour to change the elements because you just take off the front cover and insulation. The elements slide out from the blocks and the new elements slide in. Well, if these elements are of the solid construction and just slide out without having to dismantle the bricks you have a point!! I was assuming that the elements were the coiled type laid between the bricks!!

Point 2:- I did not say i had extensive experience of these heaters. I have a good knowledge of electrical units they usually range from 6 - 18 Kw, mostly single phase. The unit in question i have never seen before but most are a variation on a theme. As you can see by my numerous posts i have been trying to help this person out, why would i not give him the wiring diagram if i had one? I also posted a link to a firm that deals with electricairs to see if they had any ideas. Well ...you did say you have been running these heaters along for 30 years!!!

Point 3:- What would a 72Kw heater cost to replace? If you give the client the choice of ripping it all out and putting a new one in or let me have a go at repairing it and it may cost a few hundred pounds but no guarantees i no what i would do. As i said, if you needed to dismantle the bricks to replace the elements, then the cost of the elements and labour would have been a very big chunk of any replacement cost...

Ill stick to my original thoughts as well!

Well if what your saying is correct then, as i said you have a point. In which case why not go that route and replace all the duff elements. You'll then be starting from a standard set up, which is going to be far easier to fault find, than trying to compensate for various existing faults on the unit...