I noticed that his thermoswitch well did appear to be soldered or brazed to the element.



Seems like one way to assure that the well quickly gets hot whenever the element overheats, but then it would make it difficult when replacing the element but not the whole base.

OldNuc wrote:The thermal switch should NOT be in contact with the element.

Rich - are you saying that if the well is touching the element you would expect to get nuisance tripping of the thermal switch at operating temp?

Greg: If that well is indeed soldered to the element, I expect you could get a torch and free it, but if you want to play it safe, hacksaw off the element, keeping the saw away from the well. You don't want a hole in that -- better to have a bit of copper remaining attached to the thermal well of the element base.

It is hard to tell if that is intentionally soldered without knowing the switch trip point. If is the usual 250-275F then being attached to a potential 900F+ heat source is not going to work well. Those elements run hot enough to cause voiding in the water with boiler pressure at 13-15psig which gets you into an element outer surface temperature well into the 300F+ range as there must be a differential temperature to transfer the energy out of the element and into the water. Such an arrangement could be done but in the relatively common occurrence of a loss of water event the solder would melt and then the switch might even reset if it was an auto reset type. I would think, without actually having this in my hands, that the blob you are looking at occurred after the failure. There have been multiple attempts to get this machine to heat up and if it was operated on a non GFCO circuit then who knows how long it has been split open. There is material on the element coil above the split loop that looks like a failed solder joint, I don't think it is but you never know.

Bottom line is that element is shot and a bit of historical research shows that all of these thermal switches do a decent job of preventing a fire but are less than successful of saving elements. Look at all the various different switch designs that have been used over the years.

I was involved in another thread some time ago where I pointed out that the true function of that switch/fuse is to reduce the probability of a fire from a loss of water condition and it was near impossible to reliability save the element. Heat conducting strips did not work either. For example if the water level lowers below the element top level the element will begin heating up rapidly in the sections not covered by water and the covered section will continue to operate at a much lower temperature in the normal operating range. This results in a large difficulty in finding a thermal switch sensitive enough to operate on small changes in temperature reliably. These switches usually function as designed if the machine undergoes a complete and rapid loss of all water but fail miserably if it is a slow loss of the water. The large pressurized power reactor world has been looking for a solution to this element overheat when water is lost for a very long time. The solution was less than simple though.

Doug works on a virtually identical element in one of the OE instructional videos. I don't have access to a media blasting cabinet so I'll be relying on hand work to clean this up, but my hope is that this is just some gunk or scale. I might see if I can pass something like fishing line between the thermal fuse well and element. I know the element is toast but want to see if I can reuse the baseplate. Otherwise I have to drop $165 at Cerini and modify the dipper tube to accommodate the different config of element.

I get a stable reading of 13.8 ohms across the two terminals but the reading never stabilizes with one probe on a terminal and the other on the base plate.

Just a thought but it is entirely possible someone in the past attempted to repair that split with a hard solder.

drgary wrote:The solder may be between the thermal fuse well and the element, not attached to the thermal fuse itself, which sits in the well, on the bottom (dry) side.

By looking at OEM elements and their orientation they are not supposed to contact the base plate which contains that well.

Looking at the base plate is it possible that a non OEM design heating element and base plate assembly has been installed at some previous date? Those bolt holes look like they were hogged out with a post hole digger.

The base plate has a 1974 stamp on it and certainly appears to be original. The sealing work around the terminal posts also looks original. Agreed that those two deformed holes are pretty weird. The other four holes are in perfect shape. The bolts were fairly stubborn but certainly not the worst ones I've removed on a rebuild. I suspect it was the first time they were removed but who knows for sure. The element to boiler gasket was essentially a piece of ceramic - definitely the original that had just completely ossified. It came right off cleanly in about six pieces. The inside of the boiler doesn't have any scale whatsoever. My best guess is that this sat unused for quite a while - hopefully not with water in the boiler - and when someone more recently filled it and turned it on, the hardened seals failed and it leaked water onto the element posts.

If I compare the element itself to the one from OE's Cremina instructional video series, it looks identical to that one. It's just the mystery of if the thermal fuse well is truly attached in some manner to the element or not. It very well could be accumulated crud and not a solder.

If it's just soldered to the base plate and you want to re-use the base plate you may be able to heat up the junction with a soldering gun or large soldering iron (or even a torch) and pry the element off with a screwdriver.