My last AGA saga…….

17 04 2020

You read it right, I have no more AGA sagas left in me…….. I don’t need more, I have everything I need (or want for that matter) right here now. Four and a half years in the making, our beloved AGA is finally going, and we’re loving it. To say it’s transformed our lives is of course an understatement. Not only does it produce great meals, it’s keeping us warm through the cold fronts (like today, 6C outside, almost 21C inside) and makes oodles of hot water, meaning no more trips to the shed for a hot shower.

If you’re new here, this saga started four and a half years ago when I drove uteII to Adelaide to pick up the dismantled behemoth I’d bought from Queensland even before driving to Geeveston to live. Having brought it here, with some of its innards needing replacement, I then fell on my feet again after meeting Geoff online who sold me the parts I needed for a very fair price too……. All I needed to put this whole show together was a house, and a hot water tank.

I’d laid a brick plinth some weeks earlier, and cleaned up the rusty base in preparation to moving all the bits from the shed to the house. Building an AGA is like putting a giant (and heavy!) jigsaw puzzle together. I did have an ancient building manual with B&W pictures. It helped, but not as much as John from England, a retired AGA engineer, whose assistance over facebook proved invaluable.

To bore those holes, I opted to buy a masonry drill with grunt, then found masonry hole saws on eBay. The tools were only going to be used once, but in the end they weren’t that dear. I wasn’t looking forward to this, but it turned out to be less hard than I’d anticipated, though when the drill broke through to the other side, it made a bit of a mess. As my father used to say, you can’t make omelettes without breaking eggs…!

Just soldering the one inch pipes together turned into a saga…… the gas bottle I was using was struggling to put enough heat into those larger fittings. It was fine on 1/2 inch fittings, but this was different. I even got Pete the welder to give me a hand, and he used a different bottle with different gas that made it all look so easy. Lesson learnt.

This may look intricate, but it’s actually dead simple. The two big pipes are connected to the AGA through the wall; the bottom one connects to the bottom of the wetback, the top one joins the top of the wetback to the top of the tank, which is where all the hot water goes, pushing the colder water down, through the non return valve, back to the wetback for more heating. This is known as a thermosyphon, involving no pumps or external energy. There’s no pressure in the tank, as I connected a pipe from the top of the tank, poking through the roof, and shaped like a shepherd’s crook (which is what they are called). Water does slowly evaporate through this vent pipe, and about once a week, the 1/2 inch ball valve (just to the left of the bigger one on the 1″ pipe) has to be opened to top up the tank. It’s with this valve that I filled the tank when it was all done. This alleviates the need for a TPR valve (Temperature Pressure Release). Our last system in Cooran had one of these, and it was constantly releasing water, plus they failed three times, unable to cope with the near boiling water the combined solar/wetback sources were generating……. At $100 a pop, I wasn’t impressed, and furthermore, I can see the day they’ll become unavailable, especially at this time…….

Hot water is extracted by pumping cold water through the 1/2″ pipe downstream of above mentioned valve. This pipe is connected to a stainless steel coil inside the tank. The coil is heated by the water in the tank, they are totally unconnected. The heated water comes out the top 1/2″ pipe, having been flushed through this coil. This is known as a heat exchanger. That water then goes to all our hot water pipes, and it’s working beyond my wildest expectations….. I could not be happier!

My mate Trev talked me into having an electric booster, because it’s possible that during the odd heat wave we get in Tasmania (we recently had a 39 degree day!) the AGA might not be lit. In this case we’d almost certainly have a glut of solar power, and we could run the 2.4kW booster off the batteries for a couple of hours in the middle of the day.

The AGA’s top plate was in poor shape, and cracked to boot. Having it re enameled was out of the question, as it would have involved a return trip to Melbourne and god knows how many hundreds of dollars. So instead I had it sandblasted in Geeveston, and Pete welded up the crack. Another great job, thank you Pete. By now he has a fair bit invested in this project, and he’ll get a dinner invite as soon as all this distancing madness ends.

Underneath the top, was cast the date it was made……. January 17 1955, making it about three years younger than the Cooran AGA…..

The top was painted with high temperature engine paint, which cost a lot less than re enameling. I was worried it might scratch easily, but so far so good, even though it’s not cured at 200 degrees as recommended, it’s bearing up under the strain.

The next big job was refilling the beast with its insulation, another aspect I wasn’t looking forward to having gone through this once before. John Nesbitt poo pooed the whole idea of refilling it with its original diatomaceous earth, but having moved it over 1000km, and me being reluctant to waste anything unnecessarily, that’s exactly what I did, all six rubbish bins worth!

At least this time, unlike in Cooran, this ordeal only lasted a couple of days instead of weeks! I then cut out a new blanket of ceramic insulation to cover the powder, the circular bits were stuffed into the domes to improve efficiency……..

Having fitted the top back on permanently now, the next big job was installing the flue; which turned into its own saga……. these days, there are all sorts of regulations about fitting flues to, surprise surprise, ensure you don’t burn your house down. So I contacted two flue tradies who separately told me it couldn’t be done because the stove was too close to the wall… I had actually done my research, and our AGA is 50mm farther from the wall than normally recommended…. I did this to give me extra room for the plumbing sticking out the back instead of the usual top with a two oven stove……. At this stage, I was starting to tear what’s left of my hair out, because the shit was hitting the fan in China, and I just knew it was coming here. Getting struck out by collapse this close to the light at the end of the tunnel was not an option, so I decided, again, to do this myself. I ordered a flue kit from a specialist firm 40km away, who promised me it’d be ready at the end of the week; as usual, they forgot to tell me which week…. I had already taken possession of my three metres of 5″ stainless tubing from Nubco, removed and replaced two sheets of iron off the roof to cut the batten that of course lined up exactly with the middle of my flue, and cut a round hole in my expensive hoop pine ceiling. It was nail biting stuff, but I got my flue kit, and the heater people promptly closed up shop……. Phew……

But it doesn’t end there. The SS tube didn’t fit, I kid you not. It was maybe 0.5 to 1mm too thick or something, a problem that simply didn’t occur in Cooran, and which I wasn’t ready for. I tried grinding some meat off – and you better believe, SS is bloody hard – to no avail. Glenda, bless her heart, said call Pete……. Pete suggested cutting slots every inch or so in the end to go into the flue box such that as it was forced in by tapping it from above, those slots would close inside the collar it was meant to fit into. It worked…. must be worth another dinner..!

First firing, a bit smoky as usual, you can see the shepherd’s crook too…

Having brought the AGA’s original top hat from Adelaide as more of a bit of nostalgia than anything else, I didn’t order a new one with the flue kit. Lo and behold, it didn’t fit either. How they mated a 6″ top hat to a 5″ flue remains a mystery, a mystery I managed to resolve with an angle grinder and some screws…

Anyhow, it’s all over, thank goodness…….. Bliss is a working AGA on a rainy and windy day like today…….





First 2020 house update

1 02 2020

Another year, another decade…….. will Australia run out of domestic oil this year? Watch this space I guess. I haven’t blogged here in ages, largely sick of repeating myself all the time, and it’s been pretty busy here, trying to get this darn house done so I can get back to some serious food production. Since the bushfires, breaking my ribs, and the erection of the roof starting a building frenzy, the market garden has been thoroughly ignored, and we’re no longer food self sufficient I hate to admit…… In my defense, there’s been real progress all the same. Like running water…!

Setting up the tank pads was more work than anticipated (isn’t it always..?) and after having some great visitors from Queensland, one of whom is a builder, I was thankfully talked out of building another concrete pad and retaining wall, even though I had all the necessary left over blocks to do so. This one only needed to be 600mm high, so didn’t need the high strength of the wall at the other end of the house.The result is a timber one Charles the French wwoofer and I have now built.

A few days later, our new custom made 18,000 litres stainless steel water tanks arrived… they’re custom made because a standard 3 sheet high tank would not fit under the gutters; but because we were buying two, they cut the third sheet in half, putting one of those halves on each tank. The eastern tank even has a firefighting hose attachment in case the fire brigade need our water. We chose SS because we could afford it; it’s fireproof, should outlast us and our kids, and I detest plastic and plastic liners. As it is I’m resigned to using plastic pipes to connect the two tanks together and to the house, there’s no other way…….

The place still looks like a building site…… because it is.

The resulting running water is much appreciated, let me tell you……. Now for running hot water…! Which brings me to the AGA.

AGAs are, I’m reliably informed, loose bits of cast iron flying in tight formation! Having now put one mostly together, I don’t know how I ever managed to shift the last one in one piece without crashing it……. All the parts inside, and trust me, they’re heavy, sit on ‘tripods’ made of threaded rods or trunions that can be turned to adjust the height and level of everything. I discovered, from communicating through a facebook group of AGA aficionados that the top oven adjustment can be reached from the roof of the bottom oven. Better still, this retired AGA engineer told me to remove the original slotted screws and replace them with Allen keyed ones…. it does pay to know someone who knows more than you!

Anyhow, the stove was rebuilt to the stage a wetback could be designed by yours truly. Armed with scrap cardboard, scissors, lots of tape, and four hours (no less!) I carefully made a model of what I wanted Pete the blacksmith to duplicate in stainless steel……. Making a 3D model of a curved and sloping box that had to fit withing constrained positions turned out trickier than I thought. Again! I actually impressed Pete, especially when he brought the beast home and it fitted perfectly.

Pete measuring the mounting tabs before completing all welding……

While in Hobart, I had a win at Tradelink who actually managed to find me 32mm to 25mm adaptors with compression fittings, and even an expensive 25mm Italian made non return flap valve to stop the thermosyphon running backwards when the stove is cold…… Now all I have to do is bore two 50mm holes through the 200mm reinforced concrete block wall behind the AGA to connect it all to the new hot water system, and THAT, my friends I’m not expecting to be a walk in the park…….. but I love a challenge!

The only other major news is that the back wall has been finally waterproofed with bitumen paint so that it can be insulated, and then backfilled. This is the last step in ensuring the house reaches its full thermal performance capability……

Yep……. STILL looks like a building site.