Fireplace water heating system (Part 1)

Fireplace water heating system (Part 1)

 

A couple of years ago, we installed a log fireplace at home, a 13KW box from Rotin fires of Zabbar. I'll try to find and post the brand and specification details of the firebox. We light it up only for 3-4 months a year, starting in November/December till March.

These are obviously the worst months for heating water from the sun simply because the days are the shortest and temperatures are the lowest. In fact, during this period we have a deficit of hot water from our water solar heater and we need to boost it up with the electric heating element.

This is why I decided to explore the possibility of heating my solar water tank using escaped heat from the fireplace.

 

The pictures below show what I did to capture heat from the fireplace.

 

The above pictures are a 0.5 metre section of the chimney with a 15 metre half inch copper pipe wound around it. The idea is to capture heat escaping from the chimney pipe and getting it absorbed in the liquid circulating in the copper pipe which will eventually heat up the hot water tank. 

 

 

 

Getting the copper pipe around the chimney pipe proved to be a tough job; in fact I needed help from my two little boys :)

Once the copper pipe was properly wound and secured to the chimney pipe, I used a blanket to insulate the copper pipe from the outside air, thus decreasing heat losses.

The below pictures show the final result. The blanket has been further covered with fibre-glass to further insulate and protect against the elements.

 

I'll be posting another article with all the details of the plumbing and circulating pump once I have everything installed and working.

Off-Grid System (Update)

 

Off-Grid System Upgrade.

 

Thanks to an EU competition, the European Citizens Climate cup , which came to end last May (2012), me and my family placed 2nd with just a 0.5% less reduction in electricity consumption than the winner. I still was awarded €1000 cash to be spent on Renewable Energy stuff. My natural choice was more solar panels :)

I had been planing to upgrade my off-grid system consisting of only 320W of panels for quite some time now and this reward was more than welcome. With the money, I purchased 4 solar panels - IBC Monosol 190MS from Crosscraft. This upgrade of 760W was to increase my off-grid system power production to an STC of 1080W.

The picture below is displaying the mouting of the new panels. These have been mounted horizontally and fitted exactly across the roof. 

 

 

Another picture of the new panels as taken from above. The new panels are fixed just in-front of the other grid-tie system panels.

With a new off-grid power generation of 1 KW, I wanted to make sure that no power is wasted once the batteries are full. This can easily happen in Spring and Summer when the days are longer and the load is lower. (Please refer to my separate article titled Off-Grid System for a list of loads being supplied from this setup).
To cater for this access energy, I installed a new 500W grid-tie inverter. This inverter is capable of accepting directly the power from the panels mentioned above and export the power to the grid. In fact the input voltage for this inverter is low (28v - 52v).


 

My off-grid panels are wired in parallel in 4 groups. The left most DC amp meters records the power coming in from the seperate groups.

 

Group Details:

• 2 Sharp panels x 80W each = 160W
• 2 Sharp panels x 80W each = 160W
• 2 IBC panels x 190W each = 380W
• 2 IBC panels x 190W each = 380W

To control when and how much to export to the grid, I needed a way of determining the batteries state of charge. I did this by simply monitoring the battery voltage and switching on the panels when the battery voltage is low while diverting the panels to the grid once the battery voltage reaches a pre-determined high voltage. The circuit below does just that! It monitors the battery voltage in these steps;

• at 27v. Diverts the first 160W to the grid-tie inverter
• at 28v. Diverts the second set of 160W to the grid-tie inverter
• at 29v. Diverts the first 380W to the grid-tie inverter.
• at 30v. Diverts the second 380W to the grid-tie inverter. This actually switches off all charging from the solar panels.

Once the battery voltage goes down again, the circuit will disconnect the panels from the grid inverter and direct the current back to the batteries in reversing order.

As can be easily noted, the export inverter is rated at 500W (Max) while I have double in solar power. Although all panels can be automatically diverted to the inverter, the inverter is only capable of exporting 500W. I know about this limitation and in fact I have left space for a second identical inverter to be installed right below the first.
Being in Winter, I don't have much access energy to export, and in fact the max exported I noticed was 320W and occasionally the first set of IBC panels.

The pictures below is the switching circuit used to control the batteries charging and load diversion. Notice the 4 relays, used to switch the 4 seperate groups of solar panels.

 

 

I'll be posting a seperate article to describe how the above circuit works.

Cordless telephone chargers (Solar)

 

Three years ago (Feb 2009) I bought the following Panasonic cordless telephone system from Amazon consisting of 4 cordless telephones; a base unit and another three separate chargers. It works great and can't complain about it.  

Targeting to transform my house into a Zero-energy building, it was time to look at this small energy consumer and upgrade it to charge the telephones (not the base telephone since this needs power 24/7) using small solar panels.

I happened to have previously bought some submersible fountain pond water pumps from eBay for another project. I did use the small pumps but never had found any use for the 7.2v 1.12W panels, well until today! These panels match exactly the chargers for the separate cordless telephones. I plugged in a panel instead of the charger and it has worked OK for the past 45 days, i.e. the small solar panel was enough to keep the telephone batteries fully charged. Obviously, one panel per telephone is needed and the panel placement (in full sunshine) is of great importance to get maximum output from these small panels.



 

Below is a panel, 7.2v 1.12W

 

 

 

I have posted here details for building a simple battery based power supply for the base station.

Solar Water Heater

Building of a Solar Water Heater.

This article is a description of a closed-loop Solar Water Heater (SWH) I have built and installed at my residence. Although today, the prices of SWHs have gone down in price, (also thanks to the government rebate), I must admit and others who bought a ready-made SWH will agree with me, that the quality of some brands has also gone down! Besides cheap workmanship with some Chinese brand SWHs, one thing I cannot stand is that most of the imported brands can't withstand Malta hot Summer or better have to be manually protected during the Summer months to reduce stress on the system. It's understandable that in Summer (or the warm months), the demand for hot water decreases and therefore only a small percentage of the daily heated water is used, thus hot water accumulating daily in the tank with an increasing temperature. This will pose more stress on the SWH storage tank and other components, resulting in a reduced lifetime! To overcome this problem, most of the installed SWH collector plates are covered in Summer to reduce heat absorption, heating less water and therefore reducing stresses. The SWH described here does not need to be covered, and all components are protected from this problem!

A good reference for starting to learn the basics on SWH can be found on the Home Power magazine web site. Please do visit the site since it will give you a good description of all the components I have used in this system.

System Description:
The system I opted for is a closed-loop, meaning that the sun will heat a liquid which in turn will heat the water though a heat exchanger. Although a closed-loop system is not a requirement for the country I live in since we don't have freezing temperatures and there is no need to empty the system at night, I still opted for this slightly more complicated system for the below reasons;
1) I wanted my home-made solar collecting panels and storage tank to last longer. This can be achieved by NOT passing water through the collector/storage tanks circuit but instead passing glycol. Glycol will not rust and prevents limescale from forming which has the side-effect of decreasing the system efficiency.
2) I did not want my SWH storage tank exposed to the elements, simple because I want it also to last longer. Using a closed-loop system, the storage tank can be easily placed away from the solar collectors
3) Decrease heat lose especially in Winter. In fact I placed the storage tank inside.
4) The SWH I've designed will have two three energy sources;
 - The sun, which will heat up the collector and the storage tank.
 - Log fire. I'll be utilising unused/escaping heat from the fireplace to heat up the SWH storage tank.
 - An electrical element which will be used when the above two sources are not enough

The pictures below detail the construction/function of the SWH.

------------------------------------------------------------------------------------------------------------
The picture below is displaying one of the solar collectors without the tempered glass. The horizontal top (outlet) and bottom (inlet) pipes are 1/2 inch while there are ten 3/8 inch vertical laid copper pipes fixed to a matt black painted galvanised sheet. The total area of each collector is 2 m^3.

The image below is showing the two solar collectors mounted facing South with a total collecting area of 4 m³. (The collectors in this picture are not yet connected). The supporting frame used is 3mm
galvanised steel.

The below image is displaying the underneath of the SWH tank. Connections:
1) Two connections inlet/outlet are used for the closed loop solar collector (heat exchanger circuit 1).
2) Two connections inlet/outlet are used for the closed loop fireplace source (heat exchanger circuit 2).
3) The middle large hole will house the electric 2KW element.
4) The other large hole will house the zinc anode.

The image below is showing the interior of the SWH storage tank. Notice the two circuits (left & right interlaced). The vertical copper pipes are about two-thirds the length of the storage tank.

The image below shows my neighbour Mario doing the copper brazing work on the tank circuits. He's a professional machinist by trade and therefore all this was a  piece if cake for him!

Sketch of all the SWH components connected...

The below image is the 'brain' of the system. Its all controlled by the Steca TR0301 controller. I won't be detailing here all the specifications of this controller however at a glance;
1) Can monitor 3 separate temperatures; Solar collector, SWH tank top and bottom water temperatures.
2) Pre-set with a starting differential temperature of 8°C
3) Cut-off differential temperature of 4°C
4) Cut-off maximum tank temperature of 60°C
5) Holiday function.

The below image is displaying the SWH components.
 - Top left is the 18 litre expansion tank. When the pressure inside the system increases due to high temperatures, the glycol moves temporarily into this tank to relief the pressure.
 - Below the expansion tank is an MCB box. An MCB is used to manually switch the electric heating element while the second MCB is used to power the differential controller.
 - Next to the MCB box is the Differential Controller.
 - Next to the Differential Controller is the internal circulation pump. This pump is switched on/off automatically by the controller and is used to circulate the glycol around the collector panels and heat exchangers inside the storage tank.
 - On top of the circulation pump is a small pressure gauge, measuring the pressure inside the closed-loop circuit.
- Below the pump are three values used to prime the closed loop circuit.

The below image is displaying the SWH storage tank pipe connections.
- The two top connections are the inlet/outlet to/from the solar collectors closed loop circuit.
- The next two connections are the inlet and outlet for the hot water system.
- The bottom connection is the 'hot' feed to the washing machine.

The below image is displaying the SWH storage tank with all the external components (on the left) and the inlet/outlet piping on the right.

Conclusion.

The system has been in operation since 2008 without any problems. The sun does provide all of my family hot water requirements for a full eight months, while the remaining four winter months are assisted by the electric heating element.

Hopefully I will get all my hot water without using electricity including the winter months, since I'm currently working on the second circuit / heat exchanger to heat also the water using heat from the log fireplace. I'll be posting an article once this is ready and in operation.

Product Review - Touch Dimmer Switches

Touch Dimmers Review

This review is for a couple of dimmers I bought directly from TLC.

The Dimmers I'll be referring to are these;
 - 2 Gang 2 Way 400W IQMaster Remote Touch Dimmer Switch (VLIQ1402). Bought two of these.
 - 2 Gang 2 Way Slave Dimmer (VLIQS002). Bought two of these also.

Environment.
Mains System Voltage: 240v
Mains Frequency: 50Hz
Load for the four individual dimmers;

• 100W (incandescent bulb)
• 100W (incandescent bulb)
• 400W (rope light - incandescent bulbs)
• 100W (5 x MR16 - 20W Halogen)

My intended configuration was to connect the master dimmers and the slave units to enable me to have a 2 way circuits, with the benefit of remote control!

For the benefit of the readers, I have copied below the technical data sheets as listed on the TLC website

iQ - Intelligent Remote/Touch Dimmer Switches

Employ the latest, state of the art, microcontroller based electronic circuitry and use current sensing to compute the load conditions. These products show progressive reaction to overload conditions, depending on the extent of overload as shown in the table below. iQ Intelligent Dimmer Switches are NOT suitable for use with Fluorescent Loads, including Energy Saving Lamps.
iQIntelligent Remote/Touch Dimmer Switches incorporate the following advanced features
Suitable for dimming Low Voltage Halogen lamps via good quality, fully dimmable electronic transformers.

Soft Start, which gradually increases the light output from the load over 1 to 3 seconds after switch on. The Soft

Start feature is also particularly beneficial when used to dim Mains Voltage Tungsten Halogen lamps which have inherent very high inrush current at switch on.

Overload reaction

Case Approximate load Power output to load when dimmer control is on the dimmer as set to maximum a percentage of its maximum rating

1 Up to 125 Load will receive maximum power continuously.
2 >125 to 150 Output to load will be reduced to 50% of the maximum after a delay of approximately 20 seconds after switch on.
3 >150 to 200 Output to load will be reduced to the minimum setting of the dimmer after a delay of approximately 20 seconds after switch on.
4 >200 Output will be disabled (load will be switched off) almost instantaneously after switch on.

iQ Dimmers:

Fused GLS Tungsten Filament lamps to BS161, rated at 230/240V. Dimmable wire wound or electronic Low Voltage Transformers of good quality.
Note: Transformer must be suitable for dimming using phase delay (leading edge) and NOT only phase cut (trailing edge) type of dimmers.

Warning: These dimmer switches are not suitable for use with Fluorescent Lamps or Energy Saving Lamps.

Well, looking at the above specs it's difficult not to be tempted to go for these dimmers! They are practically indestructible thanks to their overload functions, besides their soft start feature which will prolong bulb life.

I did install them however I'm very disappointed and I'm afraid I'll be looking to purchase something else, something better which works well, obviously!

Here is why I'm disappointed:
1) Dimmers get very warm when in use. This may be normal BUT all electronic components will have their working life greatly reduced when working close to their maximum temperature.
2) Dimmers are also warm when not in use. This should not be the case, since the load seems to be fully switched off. This can indicate that either a small amount of power is still being fed to the load or else the dimmer itself is consuming power when not used (the later is normal however it depends how much is the idle power!), both undesirable when my aim is to reduce power consumption.
3) Dimmers are almost all the time reacting to overload when in use. I'm suspecting this, simply because the lamps do not light more then 50%! This should not be the case! There is simply NO overload as can be seen from the loads which I described above which are all within the product specifications. On replacing the dimmer switches with normal switches, the lamps light up without problems. I even tested the circuit with a clamp meter to check for any wiring faults / short circuits and could find none! Once I reset the dimmers, they may work OK for some time and then we're back to an overload situation with just 50% of the available light.
4) Need to switch off the mains supply for the dimmers to reset. Although the specifications read that the switches will reset themselves automatically, they simply DO NOT. I have to turn off the main supply and restore back the power for the reset to work.

Something I did notice last Summer was that when I switched on the AC in the room where I have the dimmers installed, the overload situation disappeared, Yes problem solved! The room temperature was less than 20°C and it seems that this helps the dimmers in keeping them cool and therefore fully functional! To be honest, this is not acceptable because I can't keep the room cool for the dimmers to work!

Hope this review will help others in determining whether this product is a good for them or not!

Greywater System

Greywater System

This article will describe a multi-stage filtration system I built, to collect, clean and re-use water dumped from the washing machine. This water is eventually used as flushing water for a toilet.

The below flowchart lists the main steps I adopted to achieve my goal.

1. The washing machine performs a spin cycle during which water is dumped off.

2. Water from the washing machine is first collected into a buffer tank. The size of the selected tank is 100 litres. This capacity is more than enough to temporarily store a full washing cycle. This tanks serves two purposes;

• Act as a buffer for the filtration/cleaning system. Since the adopted sand filters take time to filter the water and the machine dumps a large amount of water in a very short time  (during the spin cycle) water needs to be temporarily stored to be slowly processed afterwards.
• The buffer tank is also trapping 'large' particles and stopping them from moving on to the next stage. This has been achieved by permanently fixing a piece of cloth just on the tank outlet.

3. From the buffer tank, water is passed through sand filters. The sand filters will clean and clear the water. I opted for three parallel filters to speed up the filtration process since the sand filters although doing a great job perform it very slowly!.

4. Water from the sand filters is passed through a 'fine grain' filter during which a small dose of bleach is added.

5. The water is dumped to a 500 litres storage tank. A toilet flushing is connected/fed from this tank.

One key feature of this system is that water flows between stages thanks to gravity! I have arranged the system in such a way as to eliminate the need for pumps which would have added cost to the system besides complexity and electricity consumption.

-------------------------------------------------------------------------------------------------------------------

Since a picture is worth a thousand words, I have taken some pictures of my installation to better illustrate the system.

The below image is a photo of one of the sand filters laid on the floor. It's length is approximately 1 meter and is fully packed by fine grain sand. I've used 110mm drain pipes to construct the body of the filter, blocked at each end by screwable taps.

The photo below is showing an end connector of the sand filter. I drilled the 110 tap and installed a further 15mm adaptor which will be used to connect the filter to the rest of the system.

And this photo is showing the underneath of the TOP tap.

This is the photo of one of the BOTTOM taps. I have covered the outlet with a thick cloth (similar to what I did inside the buffer tank) to restrict sand getting out from the bottom of the filter. It turned yellow because of the glue which I used when it settled.

The 100 litre buffer tank, mounted on steel brakets using nine 8mm stainless raw bolts.

The buffer tank feeding the three parallel sand filters.

Displaying the three sand filters paralleled fed from the buffer tank and in turn feeding the 'fine' filter.

This below photo is the 'fine' filter which further cleans the water. I have placed bleach tablets inside this filter before feding the 500 litres storage tank.

The 500 litres storage tank.

The toilet flushing modification. Switching between greywater and the normal main water is just a matter of closing an angle valve and opening another, as shown below.

 

Note. Some parts of this system have been replaced as detailed here.

Off-Grid System Setup

Off-Grid System
My off-grid systems have been online for the last 5 years, installed in 2006 and basically consists of a primary 24v setup and a secondary 12v setup. My scope for this setup is twofold,

1. Have a backup system in case of a system outage. Although it will not power and provide all my electricity needs, at least it will handle the basic. 
2. Reduce my electricity consumption.

Specifications - Primary System (24v):
System DC voltage: 24v
Solar Panels: 4 x 80W Sharp panels, totalling 320W.
Wind turbine: Modified 400W Air-X Marine wind turbine. Details of the modifications can be found in this post.
Batteries: 2 set of 24v fork-lift batteries. Total of 12 batteries per set @ 2v per cell. (about 8 years old when I took them and unfortunately had been heavily abused - sat discharged and lacking electrolyte for a long time and therefore the plates have been exposed to the air and most probably are heavily sulphated). No idea about their current capacity; although I'll measure it and post my findings in a separate post, however they are very, very heavy and each cell physical size is:
  Set 1: 20cm width x 15.5cm depth x 40cm tall
  Set 2: 20cm width x 12cm depth x 46cm tall

Note: These batteries have been changed to a new set. Details can be found here.

Inverter: Modified BEST FORTRESS UPS 600VA. This is basically a computer UPS, with these modifications;

1. Removed the two internal 7AHr batteries and instead redirected the UPS to get it's power from an external source, i.e. the fork-lift batteries.
2. Removed the internal beeper which acted as an alarm when the UPS was operating on batteries. Obviously in this case I didn't want the beeper to sound for 24 Hrs a day!
3. Installed two CPU fans to help in cooling. This UPS relied exclusively on convection for cooling. Since this UPS was going to be used 24Hrs a day and in inverter-mode, it was getting quite warm especially in Summer due to the higher ambient temperatures. I therefore built a circuit to automatically switch on the fans when the UPS internal temperature reached a certain threshold, set to approximately 40°C. The circuit can be found here.

Desulfator: Infinitum 24v battery life optimizer.

Specifications - Secondary System (12v):
System DC voltage: 12v
Solar Panels: Two small panels totalling about 40W
Batteries: 1 set of 200 amp hr ex telecoms batteries.

--> Update! Batteries & Panels have been upgraded/replaced!


Usage:
My house loads are the majority 240v 50Hz AC, however I do have some loads which work directly from the DC batteries.

I've listed below the pros and cons of a DC system versus an AC system.
Advantages:

1. Running DC loads will eliminate the inverter inefficiencies.
2. Transformers and/or chargers inefficiencies are also eliminated (or reduced).
3. The inverter can be lower rated since it won't need to handle all the house power.

Disadvantages:

1. DC appliances may be more expensive to purchase.
2. DC appliance may be more difficult to source especially from local suppliers.
3. A separate DC wiring infrastructure is needed.
4. Since DC wiring is low voltage, compensation for voltage looses will have to be made up using extra thick wiring.

DC loads
Having said all this I still opt for DC loads when possible. Although my DC load is limited, it currently consists of;

1. Several 12v DC LED lamps (installed in the kitchen).
2. Several 12v DC halogen lamps (installed in the kitchen cupboard).
3. 15'' Digital picture frame.
4. Cable modem (TV, Telephone and Internet).
5. WIFI router 
6. Reverse Osmosis pump
7. Well-pump automatic relay circuit.
8. House alarm DC supply.
9. Weather station - step-down to 6v.
10. Walk-in wardrobe lighting.
11. Chimney space heating.
12. Electric Shoe Dryer.
13. Wardrobes Internal LED lighting. These are enabled automatically on opening the wardrobe doors.
14. Panasonic Cordless Base Station

 AC Loads
Currently the inverter powers;

1. All the house lighting.
2. TV, DVD, decoder, Hi-Fi.
3. Solar water heater circulating pump.
4. Multiple 13amp socket outlets distributed across the house.

 -----------------------------------------------------------------------------------------------------------------------

Below I have attached  pictures of my system.

24v battery sets. Both sets are enclosed in wooden boxes to disable access to my two small children to the battery terminals! Batteries are located in the garage so no problems with regards to heavy gassing.

The 4 Sharp solar panels configured in series/parallel. Each set is installed on it's own pole and feeds its own on/off switch,fuse & amp meter (as shown further down on the DC monitor box). I'm running a common negative 20mm wire for the panels while using a 4mm wire for each set of panels.

General view of my garage wall. Several components are being displayed, listed below;

1) The yellow box is the SMA grid-tie inverter.

2) Below the SMA inverter is the main change-over switch which is used to switch over the house lighting circuit from either the inverter or the local utility provider. The three meters on the same box are a frequency meter, an AC voltmeter and an AC amp meter.

3) The box left of the SMA inverter is a DC junction box with 300 amp switches. 1 red switch is used for the inverter, while the other red switch is a two position switch connected to both 24v battery sets.

4) The 600VA inverter is located on a small shelf (top right hand corner)

5) Below the 600VA inverter are the wind turbine electronics.

6) Next to the wind turbine electronics box is located a 24v DC meter box (details just below).
7) The small box located at the very bottom is the 12v DC meter box (details further down below).

Below is photo of the several DC meters which I use to monitor the system.

1. On the left are four DC amp meters, feed from the solar panels.
2. The right-most meter is an amp meter fsd 10amps used to monitor charging from the wind turbine.
3. The middle top meter is a 30v fsd meter
4. The middle centre meter is a 30 amp meter. It measures the total charging current (Solar + Wind + Charger)
5. The middle bottom meter is another 30 amp meter measuring current consumed (Inverter + 12v Chargers + DC appliances)

The picture below is displaying the 12v DC meters.

The box above serves three purposes.

1. Monitor 12v system. The left meter is a 5 amp meter measuring the 12v DC load. The right meter is another 5 amp meter measuring the 12v DC charging current. (Solar Panels + Wind Turbine + automatic charger)
2. Controls the 12v system.The bottom left switch and fuse control the Power out. The bottom right switch and fuse control the Power in.
3. 12v automatic charger. The internal charger monitors the 12v batteries and if the voltage falls below a certain threshold (currently set to 12.4v), the charger automatically kicks in down-converting power from the 24v system. The charger remain on for 5 mins (irrespective if the voltage went up), after which it switches off. If the battery voltage is still low, the charger will switch on again, repeating until the battery voltage is above the threshold. The centre LED indicates when the charger is ON. The charger is based on the popular 7812 (1 amp) fixed voltage regulator, having it's current output increased to 8A thanks to two 2N3055 transistors, mounted on top to help dissipate heat. The heat sinks are clearly visible...

The below two boxes are;

The left box is an LED voltmeter for the 24v system used to indicate the State of charge (SOC).

The right box is a 12v battery charger, taking it's power from the 24v system. The charger is based on the popular 7812 (1 amp) fixed voltage regulator, having it's current output increased to 8A thanks to two 2N3055 transistors mounted inside the box. This charger is mainly used to charge any 12v batteries such as our cars starting batteries.

The below photo is showing a 24v charger. Nothing fancy about it. Just a transformer, two 35amp bridge rectifiers in parallel mounted on a heat sink and a large electrolytic capacitor to smooth out the output. This charger is only used in emergencies, i.e. when the batteries SOC goes down below 50% and no charge from the solar panels is available.

Air-X new controller

I have removed the internal Air-X circuit board from the turbine nacelle as described here and instead built three simple circuits to convert and connect my 24v Air-X marine turbine to the batteries.

I've called the circuits;

1. Rectifier Circuit
2. Brake Circuit
3. Controller Circuit.

1. Rectifier Circuit

Below is the main three-phase rectifier circuit. B1, B2 and B3 are 35 amps 200v rated bridge rectifiers. I've used three separate bridge rectifiers instead of one three-phase rectifier simply because it was easier to source and it turned out to be cheaper too. The three phases from the turbine is fed into the three rectifiers producing a wild varying DC voltage. This output is connected to either the 12 or 24 battery sets through a relay as described below in the Controller Circuit.

2. Brake Circuit

The braking system I opted for my wind turbine is a manual system.

The original Air-X used it's internal controller to electronically brake the turbine. This used to happen by applying a brute short circuit across the phases without first slowing the turbine down. This sudden braking used to violently shake the turbine, transmitting the vibrations down the turbine tower, adding unnecessary  stresses on the turbine blades and thus increasing the possibility of blade fractures!

I decided to improve the braking system by stopping the turbine in two stages. First a load is applied across the three phase, slowing down the turbine and approximately 10 seconds afterwards, the three phases are shorted out.

With reference to the below circuit, switch S1 is the braking switch. When it's closed, i.e. the brake applied, two things will happen;

1) Relay RL1 is immediately energised and the three phases are shorted out through resistors R3, R4 and R5. These resistors are 1Ω 100W resistors mounted a heat sink. This will slow down the turbine.  

2) The 'delay circuit' kicks in. Capacitor C1 starts charging through diode D1 and resistor R1. When it reaches a certain voltage (thus the delay), transistor TR1 is switched on and this in turn will energise relay RL2. Relay RL2 will short out the turbine three phases, thus applying the maximum load which will stall the turbine. Diode D3 will protect TR1 from RL2 back emf. The delay can be increased by increasing R1 and/or C1.

 

3. Controller Circuit
The below circuit is the new controller I've built for my Air-X. It's much simpler than the original internal regulator, however I now have the added benefit of charging 12v batteries in low wind conditions.

The three phase from the turbine is rectified by two bridge rectifiers B1 and B2. These are 1 amp rated rectifiers and their output is used to;
1) Power the circuit itself, including the controlling relay. No external supply is needed to power the controller. I will just use 0 watts in no wind conditions.
2) Used as a reference voltage to control the controller (relay) output.
Capacitors C1 and C2 provide smoothing to the rectifiers output, while LED D2 acts as a quick reference to indicate the current turbine power strength. The higher the turbine spins, the brighter the LED.
The varying DC voltage is fed to a 12v voltage regulator IC1 and it's output is further smoothed by these large capacitors; C3, C4, C5 and C6. These capacitors act as reservoirs to power the circuit. They are needed to reduce any voltage fluctuations due to fast changing wind conditions. 
IC2 is the popular quad opamp LM324. In this case, I'm using only one of the opamps in a comparator mode.
Pin 2 is held fixed at 6v (half the regulated supply voltage) by the voltage divider resistors R5 and R6. Capacitor C8 helps in keeping this reference voltage constant.
On the other hand, Pin 3 is fed from the turbine unregulated output through potentiometer P1, R7 and D5. This varying voltage is smoothed by capacitor C9 which also act as a reservoir to eliminate any fast-changing wind conditions.
When pin 3 is lower than pin 2, i.e. in low wind conditions, the output from the opamp is off, TR1 is off and relay RL1 is De-energised and therefore the output from the turbine connected to the 12v batteries.
When pin 3 goes higher than pin 2, i.e. in high wind conditions, the output from the opamp is on, TR1 is on and relay RL1 is energised and therefore the output from the turbine connected to the 24v batteries.
Potentiometer P1 is used to adjust the threshold voltage at which the turbine is connected to either the 12v or 24v batteries.
LEDs D3 and D4 indicate whether the turbine is charging the 12v or 24v battery sets. D3 is on when the opamp is on i.e. in the 24v mode while the green LED is on when charging the 12v batteries.

Completed circuits
The three above circuits have all been housed into a plastic box as shown below.

• Attached to the top heat sink are the three bridge 35 amp rectifiers.
• Attached to the right heat sink are the three 1Ω 100W resistors used for the first stage of the brake system.
• The three relays in the middle
• The left relay controls the output from the controller, i.e. charging either 12v or 24v.
• The middle relay is the dead-short across the turbine output. Full break.
• The right relay is the brake first stage relay which shorts the turbine output across the power resistors, slowing it down.
• The controller circuit is sitting at the bottom of the box.

Home Energy Audit

It all started from an article which was published on the TimesOfMalta website of the 12th June 2011. The article made reference to an energy competition, the European Citizens Climate cup. I joined, and being one of the first 50 participants to register, I was awarded a free energy audit from Projects in Motion Ltd.

On the 4th of October 2011, Ing Kevin Alamango visited my house and performed the energy audit of my property. Me and my family (well we all have to pull the same rope) are satisfied with the results, obviously there is still more work to do. I would really like to thank Kevin for his time and professionalism. The audit results can be found here