The Craftmans Shop > New from Old
Resurrection of a CFEI 100 KVA Induction Furnace
awemawson:
--- Quote from: AdeV on April 16, 2020, 04:48:01 AM ---SO.... drill hole in manhole cover - lower pipe, job's a good 'un! :beer:
--- End quote ---
Yes Ade, that's the idea, but I'd still like to be able to remove the man hole cover.
I've been tapping a 3" long strip of 1.2 mm steel 15 mm wide gently into the gap - if you start where the gap is full depth (2") and work against the 'wall' of the next bit you can crumble bits of the rust / clay / mud until eventually you get another full depth bit, but by heck it's as tedious job. If only the Grand Children could come and stay - ideal pocket money earner except for our current virus lock down !
Drilling the cover will be a last resort - most bore hole pumps seem to be 3" diameter - also I have absolutely no idea if the lining pipe is in the centre of the circular lid, or well to one side, and it would be a shame to miss.
Remember that the underside of these covers are webbed like the under side of a surface plate so random holes can end up in unfortunate places un-knowingly :clap:
awemawson:
Matthew (who lives in France) kindly got in touch with CFEI on my behalf to find out about back up batteries and what they retain. Not really unexpectedly they have little information to reveal other than 'change the battery with power on' which is the same for most systems.
The lithium battery in 'half AA' size 3.6 volts is fortunately a standard RS item so one should be delivered tomorrow, plague, tempests and viruses permitting.
Thank you Matthew for that.
David Jupp:
Plate heat exchangers are good - but for welded ones make sure the water is clean and soft, as you can't get them apart to clean.
The fluid velocity is important to get the heat transfer coefficient up. A single coil in tank won't be great, as the velocity around the coil will be modest at best.
awemawson:
Good point about not being able to dismantle for cleaning. Would plumbing arranged for an occasional reverse flush be sensible?
The water circulating in the furnace / furnace driver loop can be closely controlled as it is always the same. This cannot be said of water from the bore hole. Historically bore holes round here ceased to be used for public supply due to high iron content. Not sure how much filtering and settling it is practical to apply.
Assembled gasketed bolted together plate heat exchangers are far less available than brazed / welded ones.
David Jupp:
Not convinced that reverse flush will help much - deposits tend to be uniformly across the plates. On a plant where I worked, we used to swap plate exchangers over weekly, strip and wash down the plates with a 'steam gun'. That was though in a location where we needed particularly good cooling, and part of the system was open to atmosphere so 'bugs' could get in - other exchangers were cleaned far less frequently. Welded plate exchangers are found in most combi boilers and seem to last quite well...
Spiral plate exchangers can have a door on the end for cleaning, but I bet they cost more. Shell & tube likely to be quite good, though larger. I guess a lot will depend on what you can find and price.
A simple pipe in pipe exchanger is good if you don't need lot of cooling - or they tend to get large and unwieldy.
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