The Craftmans Shop > New from Old
Resurrection of a CFEI 100 KVA Induction Furnace
awemawson:
So I put on my brave trousers this morning and wetted up the system - great relief - no leaks phew !
Amusingly I noticed that the water from the bore hole was warmer initially than that circulating in the (not powered up) furnace body and electronics driver (10C compared to about 6C)
So today I've been routing the trace anti frost wire that turned up this morning - it was every bit of the nightmare that I'd expected. No where could I find a minimum bend radius for it - wrapping round the heat exchanger I'd have liked to pull it much tighter but didn't dare.
Lagging the heat exchanger was the obvious thing to do, and I've masses of rock wool slab left over from quietening the generator, but fixing it was a pain. Initially I thought dabs of hot glue gun glue, but fibres just pulled off the slab. Then I thought ty-wraps - which sort of work but if pulled to a sensible tension just squash it, so it's not as neat as I'd wish.
Tomorrow I'll embark on fitting the split lagging to the pipework (Note the pipes with no trace heating are the furnace side of the heat exchanger so are heavily dosed with glycol antifreeze)
awemawson:
This morning I got the pipe lagging fitted.
The pre-applied sticky stuff on the split lagging is pretty effective but is a menace as you try to guide it into tight spots.
I decided to back it up with ty-wraps as I don't quite trust it not to move over time, especially on bends.
awemawson:
Before pushing the chiller unit back against the wall I thought I'd fit a foil jacket around the heat exchanger for two reasons. Firstly the lagging is far from continuous at the top so the marginally warmed air from the trace heating / anti frost tape will rise and go to waste, and secondly the insulation being rock wool is rather friable and tends to shed fibres.
I used standard 'kitchen foil' which is terrible to wrap round things like this with sharp bits - it tears at the slightest catching. I'm sure normal aluminium foil used to be much thicker - this measures as 10 microns - there must be better stuff available surely.
Anyway hopefully that's the frost damage repairs and anti-frost measures finished at long last.
Having dragged the chassis out and pushed it back a few times I thought it sensible to run it for a while to prove it was all still water tight - yes I'm glad to say. Water was coming from the bore hole at 11 degrees C and it took quite a while for the equipment to rise from the 7 - 8 degree level up to marginally below 11. Potential ground source heat pump I suppose !
Anyway maybe I can now get back to casting . . .
ddmckee54:
Andrew:
You've got a nice little box shaped bundle there. Maybe you should check with an HVAC installer and see if you could get some of the foil backed insulation board that they use. You could use it to make yourself a nice little removable insulated box to cover the heat exchanger.
Don
awemawson:
Nice idea Don but the rockwool and kitchen foil were 'in stock' ! The four pipe and the bolting to chassis also wouldn't help, but it's now done and I'll see how it performs when we have the next cold snap.
The heat cable thermostat turns on at about 3 - 4 degrees C and with a bit of hysteresis probably goes off at 6 or so.
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