A visit to my broker
Our hot-water cylinder (HWC) was made of copper and so had some value as scrap. It has been reported that the price of copper has increased by about a quarter in each of the past two years, reflecting the increased world demand for the metal. For instance, an electric vehicle (EV) contains about four times as much copper as the equivalent internal combustion engined car and, as the proportion of EVs in our car fleet increases, more and more copper will be required. The copper cylinder had to have its pipe junctions and electrical connections removed and to be extracted from the encasing foam insulation and the galvanised sheet steel shell. This is a messy process, generating a large volume of waste, and my broker recommended that I bring the whole cylinder into his yard as he was well set up to do the dismantling. I was curious about the number of scrap cylinders he was buying in an average week.
“Too many to count,” was the reply.
The HWC, stripped of its insulation, is crushed in a special machine and folded into a compact parcel. Pallet-loads of the folded copper cylinders are sold by auction to the highest bidder. Some Christchurch businesses use large amounts of copper and buy scrap from local dealers.
My broker pays in cash — you have to show identification first — and has a set rate for HWCs depending on their size. I had done some research about the prices a few local firms pay for cylinders and, while I can’t say that my broker pays the most — I got $127 — I do know that he pays considerably more than some others. I also don’t know how much better I would have done had I gone to the trouble of stripping the insulation myself.
Getting paid for the ruined cylinder did salve the wound of our HWC failing, but only very slightly.
which limited the amount the insurer was liable to pay. He clambered under the house and took pictures, and said that we would hear from the insurers shortly.
The plumber was certain that the leak was from the copper HWC and said that he had replaced many. He attributed the failure to the chlorine in the water. He also had an unexpected piece of bad news. Our tall and narrow cylinder was no longer manufactured, he said, and the smallest diameter cylinder available would be too wide to fit into the same position. The twostage repair would not be possible unless the cylinder was relocated to the outside of the house. This required some thought.
Exterior HWCs are significantly more expensive and have greater heat losses than interior cylinders. They have increased insulation, but the heat losses are perhaps double those of an interior HWC. They’re also rather unsightly. On the other hand, they free up space inside the house and — this was the most persuasive argument — if they leak there is no damage to the fabric of the house. My daughter and her husband had installed one during the rebuild of their house, so we were familiar with the idea; I had, in fact, made the concrete base for their one.
A decision was made
A tankless, ‘instant’ hot water system, fuelled by LPG, was suggested by the plumber, as it would be significantly cheaper to install and not so liable to failure. However, we had seriously looked at LPG for cooking when we were buying a new stove three or four years earlier and had been put off by several unattractive aspects. The potential ban on new LPG installations and the looming exhaustion of local supplies didn’t make gas any more desirable.
A large exterior HWC was agreed on, the position decided, and the plumber supplied a quote.
Then another problem became apparent. HWCs are required to be restrained by three approved straps attached to the building, to prevent them from tumbling over in an earthquake and potentially crushing nearby persons. A cylinder full of water is very heavy and, because of its height, relatively easy to unbalance, so the attachment has to be reliable. Our house is clad in Western red cedar from the USA, which is a most durable timber but not very strong and the coach screws usually used to fasten the straps would, I imagine, easily pull out of it under load. I told the plumber that I would not only cast a concrete base for the cylinder but also fashion a cradle to hold it and provide anchorages for the restraining straps. I had in mind the sort of structures that safely hold water drums in position in large boats — and I had the perfect material available to use.
Ya never know when you’ll need stuff
Some years before, my neighbour had replaced his early 20th
century front fence with a tall, very nice, recycled brick one. I had had a couple of gate posts made in the same style as the posts in his original fence, so he offered his old posts to me. They are made of the lovely Australian hardwood, jarrah. The above-ground sections were in perfect condition but 100 years in the ground had been extremely hard on the underground parts, of which little was left. One post, which had lost its turned top knob, was ripped on my Auckland-built 1960s Dyco Durasaw table saw into two 100 x 50mm boards about a metre long. These were fastened to the framing of the house wall by long galvanised steel bolts or shorter coach screws. Chocks that fitted the curvature of the cylinder were made from the jarrah offcuts — using the 14-inch bandsaw at the local MenzShed. I determined the curvature of the chocks by making a cardboard circle the same radius as the new HWC and transferring the shape of the circle’s circumference to the wood. There was some scepticism from the guys at the shed as to the bandsaw’s ability to cut the thick hardwood, but it had no difficulty in swiftly and accurately shaping the chucks, which were fastened with bugle-headed woodscrews to the jarrah boards. I can see I will have to find room for a bandsaw in the workshop.
What earthquakes do to bolts
I plan to attach the third restraint to two of the house’s driven piles. The simplest method would be to drill holes in the wooden piles and use bolts to hold a horizontal board to which the cylinder’s restraints would be fastened. Bolts through the poles in pole houses were once universal, but the huge magnitude 6.9 Loma Prieta earthquake in California in 1989 showed that these bolts would split the poles they traversed under violent shaking, causing irreparable damage — the pole would have to be replaced. I saw identical damage to local pole houses after the magnitude 6.3 Christchurch earthquake in 2011, the hefty vertical poles being split in line with the bolt hole and the pole houses then being insurance write-offs.
The preferred method of attachment these days is steel bands that embrace the pole as, in a shake, the bands don’t fatally damage the pole they are fastened to. The bands around our piles will locate a 1600mm-long galvanised hollow rectangular steel beam to which a jarrah pad and two chocks are attached. The thickness of the jarrah pad will be found by measurement between the hot water cylinder and the steel beam.
The 800mm square concrete pad was made to be about 150mm above ground level to keep the cylinder out of less serious floods. I took considerable trouble with the boxing, because the concrete had to be dead level, to ensure that the cylinder was truly vertical, so as to sit snugly against the house wall. I made the concrete in my small electric concrete mixer and the resulting slab was satisfactory without being outstanding.
Plumber time
The following week Dean, a Brisbanite plumber, arrived to install the cylinder,
which took the entire morning.
The old cylinder was disconnected and drained, then straps were wrapped around it so it could be hoicked out of its narrow alcove and tossed disdainfully off the back deck and onto the trailer for a final journey to my broker. The new cylinder was then strapped into place against the