The Craftmans Shop > New from Old
Resurrection of a CFEI 100 KVA Induction Furnace
awemawson:
Thanks for the encouragement Will, I’m not looking forward to rolling about on the floor in a confined wet space removing that pump this morning.
. . . But it has to be done!
awemawson:
As anticipated, rolling about on the floor getting the pump out was not my most enjoyable experience, but, never mind, THE PUMP IS OUT :thumbup:
Leaving a powerful fan blowing in the area overnight had done a remarkably good job evaporating most of the water. The plastic pump inlet coupler unscrewed with relatively little trouble but this was not so with the one on the outlet. I tried every trick in the book - gentle tapping, gentle warming, and increasing levels of violence, but it was obvious that it wasn't unscrewing without breaking (plastic remember). I suspect that some of the solvent glue used to assemble the pipework had inadvertently got into the thread of this fitting. Angle grinder and hack saw removed it allowing me to get on disconnecting the electrical connections and unbolting the motor base from the chiller chassis. The four bolts were fortunately stainless, not galled solid, and not too tight - lucky as access underneath is challenging.
Having got the pump on the bench and now able to read it's label it turns out to be a Grunfos CH4-60. Options are replace (at least £500 with the VAT ) or get a seal kit (£143) Interestingly the one for Glycol cold water version is cheaper than the standard one :scratch:
I will have to replace a bit of the existing plumbing - working back from a stub of original 40 mm plastic pipe, the branch leads to a 1/2" BSP re-circulation valve (controls pressure) and to the pump that is standard 1" BSP so simple enough.
Time to go and get changed - covered in concrete dust - yuk !
awemawson:
With the spare parts not yet to hand I'm not going to dismantle the pump, however I wanted to make sure that I can when the time comes, so am applying PlusGas to all the various bolts and screws. All now move except the two short pan head screws holding the fan cover, hopefully a bit of soaking will loosen them but if necessary they can be drilled out.
Removing the 1" BSP plastic pipe screwed into the outlet revealed a curious mangled spring which is part of the ceramic seal assembly which explains why the leak was so gross - usually they just weep when they fail.
I turned off the old plastic joiner and threaded the pipe 1" BSP to raise the knuckle joint above the electrical connector box.
awemawson:
Of course the inevitable happened, and one of the fan cover screws sheered off, and the other was so mangled as not to be considered worthy of being used.
Simple matter to mount up in the Bridgeport, drill out and re-tap M4 and replace with stainless button cap screws. It is possible that had I left the PlusGas a bit longer they might have loosened, but I think not, and I wanted access to the fan to be able to rotate the pump and get a better look at that curious displaced spring. It rotates with the pump shaft and I'm fairly certain that it is the one that presses the two halves of the 'mechanical' ceramic seal together to make a leak proof joint.
Hard to work out how it got into this state - I can only think that the pump has ingested something that got caught on it so hopefully when I dismantle the six stages of the pump there won't be more damage to contend with :scratch:
Sea.dog:
It's good to see you're under way with this project Andrew. Looking forward to the inaugural firing up :zap:
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