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 Living on the Road :: Wothahellizat Mk2: Construction Diary : #16

Sun 6 Jan 2008

Ok Ok, I'll insulate the A/C ducting :-) I admit I was tempted not to, but I've had a couple of emails urging me to do so. I doubt we'll ever use the thing, but you never know and it does make sense to do it right.

After what seems like ages of wet and cool weather we have 30°C and 94% humidity today, and while that's a little tedious when engaged in manual labour, normally I find those levels quite comfortable. We've lived in temps up to 42° in the previous motorhome and didn't find it to oppressive. We didn't use the A/C then and were quite comfortable with a couple of fans.

The trouble with air conditioners is that, unless you are plugged into the mains, or willing to run a generator, you can't afford the power. As we free camp almost every day of the year and run almost entirely on solar power the running of an A/C is not really an option.

The only reason we have it at all is I think it's possible that one day we may be working somewhere and have power available. I this case I think it will be nice to have a cool home to return to after a hot day.

Meanwhile, returning to the subject of insulation, we've been doing the roof lately and have a stack of odd-shaped off cuts left over. Chris notices that the rear wall/deck floor needs to be insulated, and given that it will be covered by the cladding it doesn't matter what it looks like. So she gets to work using the off cuts.


Chris seems to be enjoying herself.

While Chris is playing jigsaw puzzles I'm working on the electricals. I've got a real dog's breakfast of temporary wiring at present and it's about time to clean up the mess and do it properly.

I start by mounting a DIN rail for the circuit breakers.


The DIN rail ready for the circuit breakers and an RCD (Residual Current Device).

The wires leading to and from the breakers will enter through the slot cut into the steel below. Note the "grommet" around the hole, it's really a length of small pinchweld. Pinchweld comes in all shapes and sizes and consists of a flexible steel backbone encased in a plastic and/or rubber molding.

It's usually designed to clip onto the edge of sheet steel and this particular profile makes a fantastic protecting grommet for odd-shaped holes.

Mon 7 Jan

I've installed the circuit breakers and run some of the three circuits we will have, one for the air conditioner, one for my six office GPOs (General Purpose Outlets or power points), and another for everything else.


The circuit breakers, there's a spare one in case I think of a reason for another circuit.

Here's a schematic to give you the general idea of the basic electrical system.

  • Shore power: A connection to the mains or a generator.
  • Inverter: Charges the batteries when shore power is available, produces 240v AC when it's not.
  • Change over switch: Selects whether power comes from the external source or the inverter. Can also be used to isolate the system.
  • RCD: Residual Current Device, detects differences in the current flow of the active and neutral conductors, more than 30mA difference and it will cut the power. The RCD I'm using is also a double pole (meaning that it switches both the active and neutral) MCB so it can be used as an isolation switch as well.
  • MCB: Miniature Circuit Breaker, opens the circuit if the current being drawn exceeds the MCB's rating, thus averting a fire caused by overheating wires.

These days an RCD is required for any 240v circuit and even if it weren't they are a bloody good idea, I've been electrocuted on a couple of occasions and it's not a great experience. Unlike circuit breakers RCDs don't care about the amount of current flowing, just the difference between the active and neutral lines.

In general all electrons going "out" should pass through the load and return. If any don't they didn't just disappear, they must have leaked to earth (hence the old name for them, Earth Leakage Devices), and this is a bad thing because the leak may have been through a human.

RCDs detect this problem and open the circuit, thus saving the aforementioned human.

Tue 8 Jan

Now it's time for one of the fun jobs, building my control panel.

Having a techo background I like my knobs and dials, and the more the merrier. Chris on the other hand couldn't care less and doesn't want all that stuff on show in her home.

I've got a CAD design showing what I want to build.


What I want, mouse over the drawing to see what Chris has in mind.

What to do? Well I've come up with a good compromise, I'll build the control panel of my dreams, but hide it behind a tinted glass door. That way we can still read a couple of the displays, the ones with LED readouts, but the majority of the dials and stuff will not be visible, or at least only partly visible through the glass.

But before we run out to buy some tinted glass I have to build the panel. In the past I've built panels from one large sheet of steel, but this is a job full of anguish because one mistake can ruin the entire panel.

So this time I'll make several panels and bolt them to a frame, a la the 19" rack systems often used in electronics.

And while I'm at it I'll hinge the frame so it opens, thus making the initial wiring and any subsequent maintenance easier.


The front of the panel in thehalf-open position.

At the bottom can be seen the Trace inverter's recently remotified control panel and a cutout for the circuit breakers. Then there are several panels that hold gauges, switches, the security monitor, solar regulator display etc.

The top panel is currently blank and reserved for expansion, well I have been thinking of tinkering with some electronics and I could put some neat stuff in a space like that.


The control panel from the rear.


Meanwhile Chris spends ages cleaning one of our fans, only to plug it in and find that it doesn't work. I pull it apart and immediately see the problem, but it will take a while to fix and I'm not sure it's worth it.


The broken fan, now I know where the inspiration for the bipedal imperial walkers in Return of the Jedi came from.

Tue 15 Jan

After a successful bout of silver soldering (something I've not been good at before, but this time it worked well) I've hooked up the gas appliances. The oven and cook top seem to work OK but I can't test the hot water service until I get it wired up and full of water.

It does get a little warm however around the cook top so I decide to rig up the extractor fan.

I had already provided mounting points for a straight-through blower unit, but it's very noisy so I decide to use a spare squirrel-cage blower I have.

This requires the making of an adaptor plate.


The adaptor plate and a roofing down pipe connector which just happens to be the right size to accept the ducting.

My first thought is to install a roof vent for the ducting, however I am desperately trying not to add holes in the roof and we already have a vent just over the oven, so I direct the ducting towards this vent and we will have a flap fold down to direct the hot air up into the vent.


Here's the finished setup with the ducting just resting in place on top of the oven.

Wed 16 Jan

Peter is burning off at present, he has several fires on the go and they've been burning all day, but after tea the fires need stoking.


Peter stokes one of the fires with the excavator.

Sat 19 Jan

I've been doing a lot of work on the control panel and associated wiring.

There's still a few switches to install and a lot of behind-the-scenes wiring to go, but on the outside it looks pretty well finished.


The control panel almost looks finished.


The rear of the panel showing the wiring as it stands today. When I've run the final wire I'll tidy things up a bit.

Actually most of the important things are working, the stuff left to do is non-essential, such as the security cameras and monitor.

Sun 20 Jan

Despite having an air conditioner it's fans that make a difference when bush camping. The reason of course is power, an A/C uses 2000 watts or more, a fan only about 20.

When you're living on solar power these numbers matter.

We're reusing some of the fans we had in Wothahellizat 1, we chose them all those years ago because they had the control knob in the fan head and they had steel legs. This means that I can easily modify the mounting method if required.

In Wothahellizat 1 we didn't have to, but now we find it's required so I cut off the base leaving just the two steel legs, then weld a plate to these legs and viola, a new mount; and because the control is in the head there are no wires to modify.


The new fan mounts. No wires were harmed in the making of these mounts.

Wed 23 Jan

I've started working on the TV and stereo compartments. The TV has to store up on the ceiling and lower when being used, so I've built a bracket to do this.


The TV bracket after painting. It has hollow arms and pivot points, this will allow me to run the wires inside which should look neater.


The TV bracket installed at the rear of the lounge room with one of the fans.


Next I work on the rainwater system. In this truck we've decided to capture rainwater from the roof. We didn't do it in Wothahellizat 1 firstly because the roof had several levels so we would have needed about 10 down pipes, and secondly because we were never going to be in places where it rained.

Yeah right, everywhere we go it rains.

So on this version we'll be collecting rainwater from the roof.


The schematic for the rainwater collection, the blue line is a vent.

When the valve is closed the water bypasses the tanks and falls through to the ground. When the valve is open the water will pass through to the tanks, some may still wind up taking the bypass route but in general the tanks will get filled. When this happens the water will back up the pipe and overflow to the ground.

There are other ways to organise this but this is the way I've decided to do it.

As a rule the valve will be closed, when rain starts it should remain closed for some time to allow dirt from the roof to be flushed. After a while the valve is opened and clean water enters the tanks.

Below is a photo of the rainwater feed to to left hand tanks, as usual the reality is not as neat as the design.


The rainwater setup on the left hand tanks, mouse over the photo to highlight the various parts.


The valve and 1/2" vent entering from the rear.


The drain through the floor to the outside world. I've used vanity basin wastes for both the inlets on the roof and the outlets on the floor.

In theory I should have four drains in the roof (one in each corner) to allow for non-level parking. Unfortunately there is just no way I can see to implement the plumbing for four drains, so we just have two, one on each side.

Fri 25 Jan

We've also been doing some work on the kitchen storage.


The storage under the kitchen bench.The hole at the upper right is for the Dreampot on its swing out platform.


A close up of the plate storage shelves.

Sat 26 Jan

We decide to test the water works today. A quick check around reveals a couple of untightened hose clamps which I deal with, then we connect a hose and start filling.

I can see and hear the water running along the hose and up to the input pressure-reduction valve. Then nothing.

These input valves are designed to reduce the town water pressure to about 50psi so you don't blow up half your system when filling up in a town with high pressure. They also incorporate a check valve which stops your water from back flowing out into the world.

Of course if you connect these devices back to front you are going to have a real hard time filling your tanks, which quite by coincidence is exactly the problem we're having.

After a little rework we try again, this time the water passes through the pressure reduction valve, through the control valves, and into the tanks.

So far so good. Now what happens when I pressurise the system?

I turn on the pump and we wait, but not for long as water drips, runs and sprays from just about every joint.

Actually is not "every" joint, just the push fit connections. The system is made up of a combination of vinyl hoses connected with barb fittings and hose clamps (I expected half of these to leak and need tightening but they are all good), and nylon tube connected with those newfangled push-on fittings.

I've used these push-on fittings before and thought they were just great. I've also unplugged and re plugged them on several occasions without any problems and so was comfortable reusing on the old fittings in the the new Wothahellizat. But most of them are leaking.

It's the weekend and a public holiday on Monday so I'll leave this for now and get some new fittings on Tuesday.

Mon 28 Jan

I've had some readers point out the weak spot in my rainwater collection design, namely that there is a couple of inches of pipe that will collect some of the initial gunk that washes down from the roof.


The circled area will probably collect dirt from the initial run of water from the roof.

I did realise this but figured that a) it will usually be filled with water from the last downpour and this will tend to deflect any new water, and b) she'll be right mate.

Let's look at two other ways to do this.

In "A" above we see a typical method as employed with household systems. The valve is normally closed so the initial rush of dirty water collects in the pipe below the T-junction until the water level reaches that junction, at which point it flows into the tank.

Some time after the rain has finished you open the valve and release the dirty water.

This system assumes however that you can install enough pipe to hold the initial dirty water, not possible in a motorhome as the tanks are placed low in the body and there is only about 300mm from the T-junction to the outlet. With a 1" pipe this would store about 1/10th of a litre.

In "B" we have a similar design but in this example the valve would be left open so the initial water is bypassed to the ground. After some time you close the valve and the water is diverted into the tank.

From my point of view the trouble with both these arrangements is in the handling of the overflow when the tanks are full. In the household situation the tank usually has a large overflow outlet, so when the tank fills the water just spews out the overflow onto the garden or whatever.

In a motorhome however the only overflow is probably the vent and this is usually a small outlet designed to allow air to flow in to and out of the tank.

As this vent will not be able to pass the water as fast as it's entering the tank the water will back up the inlet and dam on the roof until you remember to open the valve. A situation I don't want.

With my initial design the water only backs up as far as the T-junction and then exits to the ground.

So there's a couple of reasons for doing things the way I have, but I admit that I have that weak point above the valve. I am prepared to just say "what the heck" and get on with other things, but it's not set in stone yet and does bear some more thought.

I do have a couple of ideas but there isn't much room to play with, and the real world has a habit of knocking a good theory on the head.

Thu 31 Jan

We have to drive down to the big smoke today. As the years go by we find that we can tolerate crowds and cities less and less so we avoid them like the plague, but unfortunately there are a couple of things we need for the truck that are not available locally.

We have a pretty good run actually as the traffic is fairly thin, but we still need to drop into the Boondall Wetlands to detox in some peace and quite for a while.

Fri 1 Feb

Right, let's have a look at this rainwater collection system again.

I've had another suggestion that I use a 3-way valve but I've already looked at that and decided that I couldn't arrange for the overflow. I've revisited the idea however and now realise that it can in fact allow for the overflow, and that very little rework is required to fit the new valves.


Mouse over the drawing to show the final design.

This will allow the flushing of the line with no little bits of pipe to trap any junk, and also allow the water to overflow to the ground when the tanks fill.


The three flow options.

I already have one such valve so I'll buy another, spend half an hour with the appropriate tools, and I should have a pretty good system.

Here endith the rainwater collection chronicles.

Sun 3 Feb

Remember the days when hooking up a car "entertainment system" was a simple affair? A wire for power and another for the aerial. If you were rich and could afford a stereo cassette there was also a couple of wires for the speakers.

Those days are long gone.

We've just purchased a "stereo" for the motorhome and decided that an automotive type is more appropriate than the domestic variety because they are smaller and designed to be bounced around around a bit.

So we got a Boss BA400DVD. According to the box it can handle "DVD, VCD, SVCD, AUDIO, CD, MP3, MP4, CD-R, CD-R/W, DVD-R, DVD-R/W, DVD+R, DVD+R/W". I think it has an AM/FM radio buried inside deep inside there somewhere as well, although that's not immediately obvious from the packaging or the manual.

And speaking of the manual (read "several sheets of photocopied paper") it's bloody useless. There's a small drawing that depicts the wiring, and a few paragraphs in Chinglish that attempt to describe the operation of the unit.

"On the turning on by briefly operating the PWR button you will be please to observe the display become alighted"

I also remember the days when the manual was not only larger than the device but also legible and contained useful information.

Those days are also long gone.

Getting back to the subject of wires, I counted no less than 20 cables spewing from the rear of this gadget, luckily they are well labeled and I'm an electronics whiz because some of them don't even rate a mention in the documentation.


The mess of wires emanating from the rear of the stereo.

Mon 4 Feb

Doh...thwack (sound of Homer Simpson-like exclamation and open palm smacking forehead) I'm an idiot. I know I said that was the end of the rainwater chronicles but while lying in bed this morning listening to the rain on the roof I was thinking about 3-way valves (not sleeping in as Chris would have you believe) when it hit me that they come in two varieties, L and T, so called because of the shape of the internal porting.


Mouse over the drawing to see the two positions appropriate for the rainwater diversion.

Now the valve I have on hand is a type-L and the "final" design shown the other day had an extra piece of pipe to handle the overflow situation.


The valve I've had since building Wothahallizat 1.

However if I can find some cheap type-T valves locally I can rework the system as shown below.


The type-T valves do not require any extra plumbing to handle the overflow.

Thu 7 Feb

I found some 3-way valves in town, installed them and have finally finished the rainwater collection system.

The valves are rated at PN25 (25 atmospheres of pressure, just a slight overkill) as most steel ball valves are and priced accordingly ($112 each in one shop, fortunately I found another selling them for $55), I could search around for ages on the web looking for some cheap plastic ones and then pay $50 for shipping, or buy these ones and finish the job.

The other good thing about steel valves is that it's easy to remote the handle which I've done by welding lengths of 8mm round bar onto them so they can be actuated with levers that are conveniently placed inside the kitchen and the shower. This would have been much harder to do with plastic valves and is a good feature as the valves are located as appropriate for the plumbing not the user and so would have been hard to reach. The addition of these remote actuators will make life a lot easier in future.


>One of the valves installed, note the round bar welded to the modified handle.

As if on cue a storm rolls in as I finish the job, it's almost tempting to back the truck out into the rain and start collecting.

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