Tiny House

Tiny House Chronicles: Off Grid Electrics

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Published on the Doomstead Diner on July 22, 2016

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Tiny House offgrid electrics: further insights and modifications

ELECTRICAL 20uly2016

As I mentioned previously we must alter our plans if the original items we intended to source turn out to be unavailable or unaffordable to us. My further research showed that although lithium batteries have fallen in price, the models available to me still remain significantly more expensive than lead acid batteries, watt hour for watt hour, even taking into account the greater depth of discharge and longevity of lithium. Furthermore due to the specific electronics required for lithium systems (battery management systems, specific chargers) and the still small market for them, the costs of these additional essential electronic components remain high.

I will delay sourcing the batteries and solar PV panels for as long as possible because the prices seem to be constantly falling.

If lithium remains too expensive by crunch time, I wish to keep open the option of staying with good old, tried and true lead acid batteries, however one of the most essential features of a lead acid system must be a low voltage cutoff device located at the battery bank to prevent excessive discharge (>50%) and hence damage to the batteries.

My original plan was to run most of the tiny house appliances directly on 24V DC which should lose less energy over the transmission distance than a 12V system. There are a number of 24V DC appliances available and most DC fridges can run on both 12V and 24V, however the market is vastly bigger for 12V DC appliances. For example I was able to find 12V DC but not 24V DC models for the ceiling fan and kitchen rangehood (and hence would need to obtain 24V DC to 12V DC converters to run those).

LVcutoffThe nail in the coffin against me using a 24V household system was my complete inability to source a low voltage cutoff device for a 24V lead acid battery system. Nominal "24V" lead acid battery systems may actually deliver around 29V when fully charged, but when half depleted may deliver around 23V and should be automatically disconnected then to protect the batteries.1

The market for 12V DC appliances is massively larger than 24V, because 12V is the standard for the automotive industry and for RVs and boats. Hence it is easy to obtain a low voltage cutoff device for a "12V" lead acid system which will cut off around 11V or 11.5V depending on your preference.

Hence for DIY tiny house electricians using lead acid batteries, it may be best to stick with a 12V DC system, not 24V, and to use extra thick copper cables to minimise voltage losses over distance, especially the cable to the fridge. You can use a pure sine wave inverter intermittently for the few items where DC appliances are unavailable eg washing machine.

DIY builders must not do their own high voltage AC internal household wiring unless they are suicidal. Market pressures these days are forcing people to use AC appliances (even for RVs) and it must be admitted that the efficiency of AC appliances has vastly improved over the years, whether they be fridges or computers or TVs (which all seem to be LED with no CRT or even plasma displays being sold nowadays). Furthermore the market for and hence availability of AC appliances is magnitudes larger than that for DC appliances.

My main previous reasons to avoid 100% AC in the household and use DC as much as possible were:

  1. Everything being completely dependent on one single device, namely the DC to AC inverter, represents a potential "choke point" for total system failure. (The same can be said for the MPPT charger, however that particular item cannot be avoided no matter what system you choose).

  2. Excessive complexity – DC current from the batteries being inverted to AC, then going to individual appliances and being rectified to DC again. Much simpler for the DC current from the battery to directly power DC appliances which minimises potential points of failure and hence enhance reliability and durability.

  3. Efficiency losses (as heat) from inverter and rectifiers. In particular an inverter which is constantly on, even when no appliances are in use, represents a parasitic current drain.

  4. An inverter may be rated as highly efficient eg >90%, however that depends on the load. At optimal load eg a 3kW rated inverter running a 2kW load, it may well be >90% efficient, however at a low load eg running only a 30W laptop computer, it may only be 50% efficient, depending on the efficiency curve.

The new arguments to adopt 100% household AC wiring are:

  1. I understand that AC to DC rectifiers in just about all modern household appliances are extremely reliable. For example, many LED light manufacturers guarantee their AC bulbs (which incorporate rectifiers) for 10 years.

  2. I was informed that modern inverters do not need to be fully "on" constantly. They can automatically go into sleep mode when no appliances are on, with miniscule current consumption, and can be woken instantly when there is a load sensed.

  3. Modern inverters incorporate programmable low voltage cutoff devices. The commonest offgrid lead acid battery arrays are nominally rated "24V" DC and I understand that it is best to build up the battery system using numerous 2V cells rather than just a few 12V high capacity (eg 260Ah) batteries, because the former confer lower internal resistance. If, despite string protection, one of big 12V batteries fails, that entire costly battery will have to be replaced and until then, the whole system will run at much reduced capacity. If however a string of 2V cells fail, they can be removed and the whole system will run at only slightly lower capacity with the inverter reprogrammed to accept the lower 22V DC battery output and also to a lower cutoff voltage eg 21V (rather than cutoff at 23V for a 24V system).

  4. Even if you run only one 24V DC appliance directly from the 24V DC battery system, if it is inadvertently left constantly on (eg shower exhaust fan), that could overdischarge and damage the lead acid batteries due to the lack of an intermediary low voltage cutoff device. This will not happen if 100% of appliances receive their power from an inverter which incorporates the low voltage cutoff protection.

Hence overall, if you are engaging a certified offgrid electrician to do your household wiring it may be better to go with 100% AC wiring in your tiny house. The system my electrician has suggested to me allows flexibility to accept either lithium or lead acid batteries in the future and it may be simpler to keep a spare inverter on the shelf which can be rapidly swapped if the active inverter fails. He advised me that inverters can usually be repaired, hence the faulty one need not be discarded. If you are building several tiny houses to establish a tiny house community, designing standardised setups allows the possibility of creating a microgrid.

CONCLUSION:

If your system is being wired by a professional offgrid electrician keen to offer you the latest and greatest, and you are too weak to resist the seduction of standard AC appliances (like the author), then you may choose a 100% AC house system which is completely dependent on the inverter and can keep a spare inverter handy.

If you are stronger than the author and better able to adhere to the KISS principle and/or are a DIY electrician who is not intent on suicide, you may prefer a 12V DC system which uses as many household 12V appliances as possible with only one or two items being dependent on an AC inverter. You will use extra thick household copper wires and incorporate a low voltage cutoff device at your 12V battery bank.

If you choose to go with lithium batteries in the first instance, it will be useful to ensure your system can also accept lead acid batteries in the future. This is because if/when industrial society crumbles, replacement high capacity lithium batteries, being uncommon, may be difficult or impossible to obtain. However lead acid batteries, being ubiquitous, should still be easily obtainable for a long time to come.

G. Chia, July 2016.

Many thanks to Lachlan O'Shea of Lockstar energy, specialist offgrid electrician

Any errors in this article are the sole responsibility of the author

 

Footnotes:

1. More precise lead acid battery management is more complex because the voltages mentioned refer to an open circuit without load after the system has "rested" for more than 24 hours. A fully charged "24V" system with an open circuit voltage of, say, 29V, when exposed to high load demand can drop its voltage to 23V, which is not necessarily a trigger for cutting off the system. However those details are beyond the scope of this article.

Tiny House Chronicles: More Adventures in Plumbing

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Published on the Doomstead Diner on June 27, 2016

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My preferred system for solar thermal water heating with passive gravity/thermosiphoning circulation was explained in these old diagrams: (for explanatory text see previous tiny house article on plumbing).

diagram1  diagram2

That arrangment offered these advantages:

  1. Hot water cylinder (HWC) is located indoors, hence retains heat better

  2. HWC positioned vertically, hence more effective thermolayering (smaller interface between cold water layer at the base and hot water layer above, hot water being extracted from the top)

  3. The "heat pipe core" type evacuated tube is preferable to the hollow type, because if one tube breaks, the entire system can continue to function well

Unfortunately I was completely unable to obtain my preferred type of indirect small hot water cylinder with large bore internal copper coil capable of thermosiphoning. This forced me to change tack.

diagram3My other alternative is the "hollow core" type evacuated tube system with HWC mounted on top of the tube array, the entire system which sits outdoors. This is often promoted as a stand alone system: cold water is poured into the inlet near the top of the cylinder and after a few hours, hot water is drained from the base diagram 3. The tubes fill with water from the cylinder and this water is heated directly by the sun (in contrast to the heat pipe core type where fluid picks up heat within a manifold which houses the tops of heat pipes which contain acetone).

diagram4Convection currents in the hollow evacuated tubes are set up as shown in diagram 4. Obviously the convection currents cease at night.

The stand alone system does not allow for continuous filling of the cylinder, unless a header tank with ball-valve is attached to the vent at the top of the HWC.

That arrangement was not suitable for my purposes, hence using some lateral thinking I am pursuing the following arrangement where cold water fills from the base of the HWC, hot water is extracted from the top and at night there is reliance on thermolayering to deliver further hot water. The vent connects to a vertical pipe of around 3 metres height, which ensures a constant pressure within the HWC of 3 metres water, above which pressure is expelled out of that vent (option to return it to the top of the header tank within the tiny house is shown in diagram 5).

Diagram5Disadvantages of the hollow core system are the converse of the heat pipe system:

  1. Hot water cylinder (HWC) is located outdoors, hence cools down faster (unless extra insulation is added around it).

  2. HWC sits horizontally, hence less effective for thermolayering

  3. If one tube breaks, water will immediately drain out of the entire system (including the header tank)

One other option would be to mount the array on the roof and use a solar activated electric pump to pump the water from header tank up to the HWC, however that adds electronic complexity, hence I am going with the ground based system at this time.

Having visited a friend at his offgrid homestead who currently uses the "hollow core" type evacuated tubes, I was advised this system can cope with overnight temperatures down to minus 20 degrees C.

In the case of the heat pipe core type, if water is passed directly through the manifold, at night this small volume of stagnant water can easily freeze and break the manifold. Hence in the heat pipe core type, in cold climates, it is necessary to use food grade antifreeze (eg propylene gylcol) as the heat exchanging fluid through the manifold, which then circulates through a copper coil in the HWC. My friend previously had electrolysis problems with the heat pipe / manifold type system, presumably because, in his case, water rather than glycol was directly passed through the manifold. Some systems use magnesium anodes to overcome this problem but another way to minimise that risk could be to use pure (undiluted) propylene glycol as the heat exchange liquid in the manifold, which has an electrical conductivity a thousand times less than that of pure water. He has not however had electrolysis problems with the hollow core type system.

Having received the stamp of approval for my latest arrangement after discussions with my plumber, we will try it out once the plumbing has been fitted in the tiny house.

Current design of the header tank is shown in diagram 6 and the plan is to elevate it above the loft floor on a heavy duty support base as in diagram 7.

Diagram6  Diagram7

The plan to thermosiphon water heated by the wood stove through the header tank remains, however I discovered that the "Hobbit" stove I ordered could not incorporate both external air intake system and the backboiler tank together. Hence because the former option was far more important, I gave up the latter. This has actually worked out favourably because I now plan to harvest heat from a copper coil wrapped around the base of the hot flue and because this will be less efficient than the backboiler tank (which sits inside the combustion chamber) there will be little to no risk of the water in the header tank overheating (the main purpose will be to raise the temperature of the water in the header tank from finger numbing coldness, perhaps 10 degrees C to a tepid temperature, perhaps 20 degrees C. The header tank will then serve as a modest thermal mass heat radiator through the night).

 

G. Chia, June 2016

Tiny House: Maximizing Solar Collection

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Published on the Doomstead Diner on April 1, 2016

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The ongoing Tiny House Design Chronicles: Maximising solar energy collection

 

Further thoughts about using the Header Tank as a source of thermal mass:

Here is a brief commentary expanding on the previously mentioned idea of using the water in the indoor header tank as thermal mass and how it can be optimally configured to collect solar heat. Further considerations:

  1. As the header tank is located high within the house, any air that this tank heats up will stay high and will not heat the lower level, unless active mixing of the indoor air is enforced. This is simply done by turning on the ceiling fan.

  2. Proper flow of air passing through the house is best achieved not by the fan, but by opening a low window (eg in the kitchen), to let cool air in; and by opening a high window (eg in the loft above the head of the bed), to let hot air out. On a hot summer day these windows (and others) will be kept wide open, but on a cold winter night all windows are likely to remain closed and the hot air in the loft can be allowed to accumulate for comfortable sleep. It is essential that the wood stove extracts oxygen from outside air and not from the air within the house.

  3. For an optimal pressure head, the header tank should be positioned as high up as possible. The highest internal location for the tank will be up flush against the ceiling. In this configuration, the obvious location for the (double glazed) window to receive the sun's rays will be on the roof directly over the header tank*. Whereas at first glance this may seem like a good idea, it is actually not (see Figure 1). A roof window/skylight will optimally receive heat from an (almost) overhead sun, which will occur in summer. However the skylight will be inefficient at receiving the oblique rays from a winter sun. Accordingly this configuration may tend to overheat the house in summer and be poor at gathering solar heat in the winter. Hence my suggestion for optimal collection of solar heat for the header tank is shown in Figure 2 where an optimally angled reflective sill reflects light into the side window (North** facing) against which the tank is positioned.

Figures1&2Materials for the reflective sill: the most efficient reflective surface is of course a mirror, however glass can shatter with hail impact and mirrors are heavy, with sharp edges. A better and cheaper option may be mylar film glued onto (waterproofed) marine plywood.

 

*The considerations described in Figure 1 relate to a roof with a flat north-south axis or a skillion roof sloping down towards the sun-facing aspect and do not apply to a skillion roof sloping away from the sun. In the latter case the configuration in Figure 2 is the only sensible arrangement.

**South facing if you are in the Northern hemisphere

 

Maximising other solar energy collection systems:

Figures3,3a&4The logical extrapolation of the idea of a reflective sill described above, can be extended to a reflective surface placed in front of your solar PV panels or solar evacuated tube array. This is relevant for steeply angled arrays optimised for the winter sun in high latitude locations (see Figures 3, 3a, 4 and 5) but does not apply to flush roof mounted arrays.

It is possible to estimate the extra solar energy collected by calculation, however the best method is to simply try these out using various different angles and measure the extra power output (either displayed on your battery charging monitor or measured with an ammeter).

 

Figure5Super duper ultimate solar energy collection:

Those with OCD may adopt the "frilled lizard" approach, emulating the reflective panels surrounding the front of solar ovens, to try to harvest even the weakest oblique rays of the rising and setting sun. For my part I think the configurations in Figures 2, 3 and 4 may be worth adopting but those in Figures 3a or 5 are impractical.

 

Conclusion:

Simply placing a (more or less) horizontal reflective surface in front of your header tank, solar PV panels or solar evacuated tube array can significantly augment your solar energy collection. This may not be relevant for warm, high insolation locations such as Queensland, Australia or Southern California or Arizona in the USA. However for those living at high latitudes, it can be important for harvesting the oblique rays of the sun during short winter days. Such a strategy may accrue (wild guess) perhaps 20% extra energy, using the dirt cheap accessory of mylar film on plywood. It will certainly be much simpler and cheaper than purchasing a 20% larger solar PV or solar evacuated tube array.

As mentioned in previous articles, "stick on" mylar film and plywood can be used to construct solar ovens, sea-water distillation boxes and "greenhouse" composting chambers (to accelerate the composting of toilet waste). Hence off-grid wannabes should think about putting aside a store of mylar film and marine ply for future use.

 

 

 

 

 

 

 

 

 

Tiny House Electrics

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Published on the Doomstead Diner on February 20, 2016

ELECTRICAL LAYOUT FOR TINY HOUSE_html_m5d1ba832

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Electrical layout for a tiny house design

Geoffrey Chia February 2016

It no longer makes economic sense for a new house owner (who does not need airconditioning) to purchase their electricity from the ever more costly (and expensive to maintain) fixed grid. Not only have the prices of solar panels fallen dramatically, the costs of lithium battery arrays (large enough for household purposes) are also plunging as a result of several factors. Economists who cite this as a triumph of "free market forces" are, as usual, deceitfully distorting the truth to claim undeserved credit for their bogus field of pseudoscience. The huge price drop of solar PV panels over the past couple of decades was in fact due to the decision by the central communist party of China to massively ramp up PV manufacture in response to their problems of domestic pollution and their political intent to achieve worldwide industrial dominance in this field. Their increased output of high capacity lithium batteries (mainly for electric cars) was based on similar motivations. The much hyped but as yet unavailable "Tesla wall" battery has played no part in any of this so far.

In order to preserve the electrical grid and delay the demise of their (soon to be) stranded assets, the threatened "big electricity" vendors, in collusion with governments, are pursuing the following agenda, at least in Australia:

Firstly if you live in a metropolitan or urban zone, they have made it illegal for home owners not to connect to the electrical grid. They do not care whether you actually consume their electricity – their only interest is that you keep paying for grid upkeep and upgrades, whether this benefits the consumer or not. This is how the electricity vendors and local councils will ensure their ongoing income, in the new commercial environment where it will be cheaper and more sensible for the householder to go completely off grid. So much for the economists' so-called "free market", which is employing heavy handed edict to obstruct the consumers' option to go off grid.

Secondly TPTB are now introducing schemes by which they will lease high capacity lithium batteries to individual households which have solar PV. These households will then be able to export electricity back to the grid instantaneously on demand, even at night. Previously, the only electricity sources which could quickly respond to sudden additional grid demand were hydro and gas turbine generators. "Boiler" based coal fired generators are slow moving dinosaurs, only good for baseload.

Household lithium batteries are indeed a game changer and could lead to the creation of a proper "smart grid". With sufficient widely distributed lithium electrical storage, the fluctuating nature of renewable sources such as solar and wind will no longer be an issue. Renewables can then be ramped up rapidly and coal fired electricity can be well and truly killed off. If vested fossil fuel interests had not actively sabotaged such initiatives over the past few decades and if the system of smart grid + 100% renewable electricity had been implemented years ago, this could have made a real difference to staving off catastrophic climate change. Unfortunately it is now too late and climate change has spiralled out of control.

 

Notwithstanding the noble, albeit belated, goal of 100% renewable electricity, there are several factors which are likely to foil the realisation of this technically feasible smart grid. First is the problem of scaling up: we do not know if there are sufficient lithium salts worldwide which can be easily harvested for the production of lithium batteries on the scale intended. Second is the problem of funding: the fraudulent Ponzi stockmarket and overleveraged banks are now on the brink of collapse. When economic collapse does occur, there will be no capital or credit to fund anything (unless the BRICS countries can establish their own financial/banking system in time and drive this project themselves, completely sidelining the Industrial West). Third is the problem of energy constraints: we need fossil fuels and petroleum in particular to manufacture and distribute solar panels, wind turbines and lithium batteries. The ultimate hope would be that renewable energy can itself eventually be used to manufacture more renewable energy generators in the future – which is yet to be proven and highly doubtful. The current low price of oil hides the fact that we are fast falling down the precipice of high net energy conventional oil availability. Below the EROEI of 10:1, complex industrial activities can no longer take place and the establishment of centralised, gridbased 100% renewable energy will not occur. This dream would have been entirely feasible if it had been commenced, say, 10 years ago, but now seems almost impossible. The worst thing about the "big electricity" advocates is that they fail to adequately emphasize the importance of energy efficiency – they want consumers to continue being addicted to high consumption lifestyles which is the cornerstone of their business model and is in my view criminal.

I personally do not see any point opposing plans of "big electricity" because even though, in view of the constraints above, the prospect of centrally provided 100% renewable energy is now almost impossible, it is not absolutely impossible. I rate the chance of their future success around 0.1%. There is however a better, proven strategy with a 100% guaranteed likelihood of success which can be done right now. It is also suitable (in more modest iteration) for people in poorer countries who can technologically "leap frog"over being tied to the grid and proceed directly to electricity independence, just as they have leap frogged over the need for fixed telephone lines and proceeded directly to mobile smart phones.

For those who are willing and able, the only sensible plan at this time is to ruthlessly pursue energy efficiency and to establish your own completely off-grid domestic electrical system, which is in fact super easy to do. For some, this may involve the construction of a tiny house on wheels in the metropolitan area where you live, which in the first instance can be connected to the grid while the industrial system still functions. This house can be rapidly moved to a remote location when TSHTF and then happily switch to off grid mode. The low prices of electrical components and (semi) intact industrial economy at present mean that there is no better window of opportunity to grasp than right now.

The fact that items such as solar PV panels and LED lights can easily last more than 20 years means that you will continue to enjoy a high quality of life well after the rest of the world has descended into the stone age. Even conventional lead acid batteries can easily last 15 years if depth of discharge is kept minimal each cycle. Even if your batteries and inverter ultimately fail, with a DC system you can run your fridge directly off the solar PV panels during the day. "Eutectic" mixtures (eg concentrated brine – which has a freezing point well below zero degrees C, which is frozen during the day when the compressor is running), kept in containers in the freezer, can keep the night time unpowered fridge icy cold. Repositioning your fridge to a cool shaded location outdoors will increase its efficiency. A little bit of creativity can go a long way to maintaining a high level of comfort and convenience over a long duration.

As mentioned before the first three principles of electricity management are efficiency, efficiency, efficiency. Only after that should you consider the questions of solar PV panel and battery capacities.

 

ELECTRICAL LAYOUT for a tiny house design (please refer to the diagrams)

This is configured for a particular design: http://www.resilience.org/resource-detail/2544932-building-a-tiny-house

I initially planned to have two lead acid battery arrays indoors, which I then changed to a single lithium array located in an outdoor shed (wired to an "electrical shelf" under the stairs). However in my final iteration I am opting for a single lithium array located under the front deck, wired to an "electrical shelf" in a nearby cupboard.

Whereas these days the risk of spontaneous combustion of lithium iron phosphate batteries is extremely low, it is still more prudent to store the batteries outdoors (furthermore the batteries also function more efficiently in a cooler, shaded, well ventilated outdoor environment).

 

Basic design:

ELECTRICAL LAYOUT FOR TINY HOUSE_html_m73e64f88

Ground based solar panels feed wires to MPPT regulator (located under front deck) which feed the battery array (24V Lithium Iron Phosphate) which then send thick 24V DC cables into tiny house (location of electronic shelf has been changed from under stairs to top shelf of cupboard in updated diagram).

In tiny house, 24V DC bus (with fuses) feeds 24V wiring to DC appliances (fridge/freezer, ceiling fan, kitchen exhaust fan, shower exhaust fan, water pump), as well as various DC sockets which sit beside AC sockets

24V DC bus also feeds pure sine wave inverter which then goes to 240V AC panel with circuit breakers. This panel then feeds the washing machine and the AC sockets.

Safety cut off device is also incorporated.

The 240V AC panel can also be supplied directly by a mains electricity plug-in supply (switch toggles to either mains supply or battery supply from inverter)

*MPPT regulator and battery sit on heavy duty cargo trolley (with fireproof, waterproof covering) which can easily be wheeled in and out, from under the timber dec
 

APPLIANCES

WM = Washing machine

FF = Fridge/Freezer

SEF = Shower exhaust fan

TEF = Composting toilet exhaust fan (12V DC fan)

REF = Rangehood exhaust fan

WP = Water pump

Ceiling fan as labeled

 

LED strip lights:

These are all "warm white" and of the latest type where the light output is diffuse along the strip (not able to see focal bright points, unlike the old type)

1 = On ceiling, illuminates both staircase and head of loft bedroom

2 = On ceiling, illuminates both foot of loft bedroom and West end of lounge

3 = Above windows, under shelf

4 = Above windows, under shelf

5 = Weatherproof outdoor LED striplight above panoramic door / window

6 = Above kitchen counter at junction of wall and ceiling

7 = three small strip lights on underside of cross beams

8 = At top edge of mirror cabinet

 

LOCATION OF SWITCHES (red letters A, B & C):

  • Switchpanel A is located on the wall above the kitchen counter here and has switches which control lights 1 and 7, and another switch for the water pump

  • Lights 6 and 8 have their switches immediately adjacent to them

  • Switchpanel B is located on the side of this storage cupboard around chest height and has five switches which control lights 2, 3, 4 and 5 + ceiling fan

  • Switchpanel C is located at loft entrance, on the side of the headboard cupboard, situated low down near the loft floor and has two switches which control lights 1 and 2

  • Switches for exhaust fans (in showerstall or rangehood) are next to / on those appliances.

  • Exhaust fan for composting toilet has no switch, it is merely unplugged

Please note: light 1 can be turned on and off from BOTH switchpanel A or C

light 2 can be turned on and off from BOTH switchpanel B or C

 

LOCATION OF SOCKETS:

  • Loft bedroom sockets are located on the wall as indicated, just above height of headboard

  • Kitchen sockets are above level of kitchen counter (just under cabinet)

  • Indoor lounge sockets are located in wall about 10cm above floor

  • Outdoor sockets are low and towards eastern edge, out of swing radius of opening lounge door

There is great pressure from the commercial sector these days to force you to wire your offgrid dwelling with an AC system only (whether 240V 50Hz as in Oz or 110V 60Hz as in the US). This is certainly the easiest option – it is what conventional electricians are familiar with and are comfortable with. However it means your entire electrical system will be completely dependent on the flawless performance of one single device which must be constantly kept running 24/7: the DC to AC inverter. Even though inverters are cheaper and more reliable these days and it is not difficult to purchase a spare, for many other reasons my preference is to have dual wiring (240V AC and 24V DC) and to run the frequently used appliances (LED lights, fridge, fans) on 24V DC. As such, the inverter will only need to run intermittently for devices such as the washing machine, thus vastly prolonging the inverter's lifespan. Furthermore if you lose the function of the washing machine it is not the end of the world – a toilet plunger and bucket can work just as well (the main hassle being wringing out the clothes).

Supplemental charging after many overcast days can be devised according to your particular circumstances, whether by wind microturbine, pumped water storage with microhydro, or even by diesel generator while fossil fuels are still available.

The keys to the longevity of any system are reliability, durability, simple design (minimising the number of potential points of failure) and redundancy. These principles have been illustrated in both my plumbing and electrical layouts. If the tiny houses in your community are designed to utilise standardised components (whether they be evacuated solar hot water tubes or MPPT chargers or 24V DC devices etc), if you purchase numerous spare parts a priori and if you have the expertise within your group to perform regular maintenance and repairs (ideally the folks who built those tiny houses should live within your community), you will create a robust and resilient situation which will enable your comfortable lifestyles to be maintained for two or more decades after the collapse of centralised services. Furthermore in the post collapse situation, the salvage economy will become vitally important. The restoration or repurposing or cannibalisation for spare parts from old devices (whiteware, electronic goods etc) will enable those with a practical inventive streak to breathe new life into what we nowadays regard as discarded junk. For example, the electric motor of an old washing machine can be repurposed to become an electricity generator powered by stationary bicycle, enabling supplemental charging of your batteries while simultaneously providing you with healthy exercise.

 

GC Feb 2016

 

ADDENDUM: UPDATE ON HOT WATER PLUMBING

 

For thermosiphoning to work properly, it is important to purchase an indirect hot water cylinder with a large calibre internal heat exchange coil which has been purpose designed for this function. One example is the AGA cylinder from www.gasapplianceguide.co.uk Copper cylinders are not prone to electrolytic corrosion, hence there will be no need for a magnesium anode. Obviously if you are not prone to frost then the way to go is with a direct cylinder which makes things simpler and cheaper.

The simplest way to deal with excessive heating of the hot water, causing overflow, is according to this diagram:

4 ConventionalSystemUsingMicroprocessor&SensorsThe signal that overheating is occurring will be water spilling out of the external overflow pipe from the header tank, which will be visible from both within the house (through the end window) as well as from the outside if you are working in the field. The response to this will be to simply cover the evacuated solar tube array. Regular overheating of the water in the hot water tank will in fact be desirable, to kill off any prospect of harbouring Legionella.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Forget Wall Street. Worry about fintech. Dangerous neighborhood? It has been 10 years since the last financial crisis, and some have already started to pred...

In an overwhelming 89-to-8 vote, the Senate has approved a defense budget of $692 billion. The National Defense Authorization Act, which passed the House on different ter...

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Turkey Under Fire For Signing Arms Deal With Russia, Bucking NATO

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Senate Approves $700 Billion In New Military Spending

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Anti-Brutality Protests Hit St. Louis Streets For Fourth Night

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Retweeted The Rude Pundit (@rudepundit): Seriously, Trump’s hair looks someone pissed into a cotton candy machine.

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Knarf’s Knewz

Three people go about their daily lives inside a 2 [...]

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Forget Wall Street. Worry about fintech. Dangerous [...]

In an overwhelming 89-to-8 vote, the Senate has ap [...]

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Doomstead Diner Daily 9/18[html]... [...]

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Quote from: Surly1 on September 16, 2017, 04:20:56 [...]

2017-09-09 - The three percent of scientific paper [...]

Quote from: RE on August 27, 2017, 12:42:58 PMI am [...]

I am still awaiting your apology AG.RE [...]

Agelbert NOTE: Foss IGNORED this October 4, 2013le [...]

Three people go about their daily lives inside a 2 [...]

Criminal networks smuggling rhino horn out of Afri [...]

Forget Wall Street. Worry about fintech. Dangerous [...]

In an overwhelming 89-to-8 vote, the Senate has ap [...]

Quote from: RE on September 16, 2017, 02:29:59 AMh [...]

https://journal-neo.org/2017/09/13/gold-oil-dollar [...]

The fat lady is on the stage  [...]

China is the largest customer for US oil. Maybe th [...]

http://www.silverdoctors.com/headlines/world-news/ [...]

You gotta be high on SOMETHING to run into a bug b [...]

Quote from: luciddreams on August 05, 2017, 06:29: [...]

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I have taken a lot of abuse on my opinion of what [...]

Alternate Perspectives

  • Two Ice Floes
  • Jumping Jack Flash
  • From Filmers to Farmers

Of Harvests and Hurricanes By Cognitive Dissonance   Aside from the planting and harvesting of vario [...]

The American Way: Mindless Pursuit By Cognitive Dissonance   It’s actually embarrassing if I’m to be [...]

I apologize for being missing in action for nearly two weeks. July and August are very busy for Mrs. [...]

This and That - Vol. 1 Lines in the Sand By Cognitive Dissonance   When I was younger I would get in [...]

We Are All Going To Die! By Cognitive Dissonance   This one is short and sweet folks. The subject al [...]

Event Update For 2017-09-16http://jumpingjackflashhypothesis.blogspot.com/2012/02/jumping-jack-flash-hypothesis-its-gas.html Th [...]

Event Update For 2017-09-15http://jumpingjackflashhypothesis.blogspot.com/2012/02/jumping-jack-flash-hypothesis-its-gas.html Th [...]

Event Update For 2017-09-14http://jumpingjackflashhypothesis.blogspot.com/2012/02/jumping-jack-flash-hypothesis-its-gas.html Th [...]

Event Update For 2017-09-13http://jumpingjackflashhypothesis.blogspot.com/2012/02/jumping-jack-flash-hypothesis-its-gas.html Th [...]

Event Update For 2017-09-12http://jumpingjackflashhypothesis.blogspot.com/2012/02/jumping-jack-flash-hypothesis-its-gas.html Th [...]

With a bit of ice on the floor depositers could almost ride the seeds right on in (photo by Global C [...]

Well, at least it was made sure that the Svalbard Global Seed Vault looks real pretty (photo courtes [...]

Now it's data that makes the world go round? It's comfortably accepted by many that what w [...]

I left off last week's post – "Money Doesn't Grow on Trees, Industrial-Scale Renewabl [...]

When you wish upon a star the Blue Fairy sends Tinker Bell, who plants a magic seed, which grows int [...]

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Sustainability

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Is Apple Acing Chemistry but Flunking Biology?"It used to be that half of all heart patients first report their condition to their physician [...]

Irmageddon"Denial and existential climate threat are a stable pair."Image courtesy Tatyana Tomsickov [...]

The Beauty of Biomass"You probably wouldn’t want to invest in beachfront property at the rate sea level rise and sup [...]

Creative Loafing with Joe the Baker"I just want to make a really good loaf every time."Malthouse Couching by Andrea GentlWhil [...]

Planting A Personal Forest"If you appreciate the effort it takes for a single individual to become carbon-neutral, you ca [...]

The folks at Windward have been doing great work at living sustainably for many years now.  Part of [...]

 The Daily SUN☼ Building a Better Tomorrow by Sustaining Universal Needs April 3, 2017 Powering Down [...]

Off the keyboard of Bob Montgomery Follow us on Twitter @doomstead666 Friend us on Facebook Publishe [...]

Visit SUN on Facebook Here [...]

Americans are good on the "thoughts and prayers" thing. Also not so bad about digging in f [...]

In the echo-sphere of political punditry consensus forms rapidly, gels, and then, in short order…cal [...]

Discussions with figures from Noam Chomsky and Peter Senge to Thich Nhat Hanh and the Dalai Lama off [...]

Lefty Greenies have some laudable ideas. Why is it then that they don't bother to really build [...]

Democracy and politics would be messy business even if all participants were saints. But America doe [...]

Top Commentariats

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"The great project to rescue the American economy by the Fed has hit an obvious wall. The debt [...]

The Federal Reserve is setting America up for economic disaster - The Hill http://thehill.com/opinio [...]

The U.S. Will Act on North Korea Missiles That Pose a Threat, Mattis Says https://www.bloomberg.com/ [...]

Wages Rising Just A$3 a Year Has Aussies Snared In Debt Trap https://www.bloomberg.com/news/articles [...]

They could just issue their own crypto currency, Quakercoin. [...]

The Bakken statistics are still kept: https://www.dmr.nd.gov/oilgas/stats/historicalbakkenoilstats.p [...]

Steve, if you have time to indulge me, what do you think the effect of the depreciating dollar (103 [...]

Some truth comes out of MSM: "Electrical power is needed, too, to keep water and sanitation sys [...]

Hey Steve! I'm sure your bat/laptop has plenty more hits left in it the problem is that it migh [...]

Welcome back to blogging, Steve, I missed your view of things and your way with words. "Economi [...]

RE Economics

Going Cashless

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Simplifying the Final Countdown

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Bond Market Collapse and the Banning of Cash

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Do Central Bankers Recognize there is NO GROWTH?

Discuss this article @ the ECONOMICS TABLE inside the...

Singularity of the Dollar

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Kurrency Kollapse: To Print or Not To Print?

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SWISSIE CAPITULATION!

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Of Heat Sinks & Debt Sinks: A Thermodynamic View of Money

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Merry Doomy Christmas

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Peak Customers: The Final Liquidation Sale

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Collapse Fiction

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Technical Journals

Climate change is prevalent across the world and can have large influence on plant regeneration, rec [...]

This study aims to estimate the influence of atmospheric circulation modes on future Baltic Sea leve [...]

Given the growing evidence and scientific consensus on global climate change, carbon emission tradin [...]

U.S. forests and agriculture present unique opportunities to mitigate greenhouse gas (GHG) emissions [...]