Category: Selection

Electric Underfloor Heating

Watching ‘The Block‘ it seems Electric Underfloor Heating is very trendy these days . . . . so here are some of my thoughts:

Advantages

  • Provide a stable heat.
  • Safe, with no very hot temperatures.
  • Each room can be run separately.
  • Quickly evaporates damp areas.
  • Less air movement than other systems

 Disadvantages

  • Slow to heat up, and slow to cool down when heating no longer needed.
  • Expensive to install and run.
  • Less suitable for intermittent heating
  • Less effective if under materials that have insulating properties such as carpet, or timber.
  • Can damage timber floors.

Types

In Slab

The heating cables are fixed to the top layer of slab reinforcement, before the slab concrete is placed. The system heat up the whole slab, which then heats up the room above.

This system has a long warm up time making it suitable for ‘Off Peak’ tariff electricity, with the concrete slab heating up during the night and releasing the heat steadily during the day.

In Screed

With this system the heating cable is fixed on top of the slab using a light steel mesh, or fixing strips. The cables are covered with 15-25mm of screed.

In screed system which tend to heat less of the slab have faster warm up times than ‘In Slab’ systems and can be considered as ‘direct’ acting system with some storage characteristics.

Under Tile

Under Tile heating consists of a thin heating cable pre-laid on a self adhesive fibreglass mesh which is then covered with the tile adhesive.

This system has the fastest heating up time but the least amount of heat storage.

Finally

I can’t say I am keen on underfloor heating as I used to work in an office that had it many years ago. . .  It caused my feet to sweat excessively with predictable effects when I went home and took my shoes off!

If I was going to use it at all I would probably favour just a ‘Under Tile’ system for bathrooms.

 

See Heating for more posts

 

 

 

Electricity Meter Box Location

Have you thought about where your meter box will go?

As you can see from this photo it is often one of the earliest things to be installed . . . . . Don’t like it in the location and its going to cost big dollars to change!

Because the Meter Box is normally at a height of around 1m above ground and fairly large its much more obvious than the water and gas meters.

The first Australian House I built and I completely forgot about the meter box until I saw it in place, in the middle of a blank wall facing the front of the property.

It ‘Stuck out like a Ruckman at a Jockey Convention’.

Some Thoughts On Location

Have a look where the box is on the Display House.

If you want it at the side of the house think about where your fences are going to be, you don’t want it behind a fence.

The box needs to be convenient to find if a Circuit Breaker trips at night.

If you are planning Solar Power the closer it is to the panels the better.

Although I am not a big worrier about Electromagnetic Radiation there are some people who recommend that you don’t have a meter box on the same wall as a bedhead.

Probably the best site is next to the front door if you can find a space.

 

For more posts see Electrical

 

 

 

Electrical Circuits – How Many Should You Have?

Have too few circuits and you will get the circuit breakers in the Power Box tripping out all the time!

Minimum

The minimum number of electrical circuits  for a new home would be 4/5, as follows;

  • Lights
  • General Power outlets (GPOs)
  • Hob and Oven
  • Air Conditioning
  • Hot Water Service (Only if Electric)

In my opinion this is only suitable for a Granny Flat, although I have heard of it suggested for larger properties.

Suggested Circuits

A good procedure is to have separate circuits for rooms that have heavy loads as well as separate circuits for major items.

This gives the following circuits for a 3/4bedroom house

  • GPOs Kitchen
  • GPOs Laundry
  • GPOs Living*
  • GPOs Bedrooms*
  • Lighting Living*
  • Lighting Bedrooms*
  • Hot Water Service**
  • Oven
  • HotPlates**
  • Centralised Air Conditioning

* Upstairs and downstairs for a 2 storey home

**Not required if Gas Appliances

3 Phase Power

If you want Reverse Cycle Air Conditioning for a large house or want Instantaneous Hot Water you will need 3 Phase Power. In this case it may be worth spreading the GPO and lighting circuits over the different phases.

 

For More posts see Electrical

 

Heating – Which Is Cheapest?

Thinking about how you are going to heat your new Home and get Hot Water?

Heating costs do vary depending on state and depending on whether you live in the bush or city.

Historically the cost of heating a home has been, from cheapest to most expensive:

    • Solar. (check out Passive Solar)
    • Wood , Collected. (Will take around 10 days to gather enough for winter)
    • Heat Pumps.
    • Natural Gas. (The way gas prices are going up, $300-$400/year announced today! this may no longer be the case soon!)
    • Off-Peak Electricity. 
    • Peak Rate Electricity. (peak rate electricity is relatively cheap in Tasmania)
    • Wood, Purchased. (Better to buy at least 1 cubic m rather than buying at the servo)
    • Liquified Petroleum Gas. (It’s not just the cost of the gas you also have to pay for cylinder rental)

Whichever method you choose its going to be cheaper if you get the House Size and the Insulation right!

 

See Comparing Gas and Electricity for more information

See Heating for more posts

 

 

 

Safety Switches & Circuit Breakers

Did you know there are two safety devices in your electricity cabinet to keep you safe?

Safety Switches

Safety switches were originally known as Earth Leakage Circuit Breakers (ELCB) but are now more commonly Residual Current Devices (RCD)

These super fast switches (less than 1/20th of a second) cuts the power off the instant a fault has been detected to protect you from serious electrocution.

RCDs generally control several individual circuits.

The RCD checks the incoming and outgoing current at your switch board. If the current isn’t balanced a person may be getting an electrical shock. The RCD’s are designed to disconnect quickly enough to minimise the risk of death’ or serious injury .

A RCD will always have  test button’ like the units below, which should be regularly (monthly) pressed to check that it is working.

There are extra RCD’s in this installation as we have 3 Phase Power for our Instantaneous Electrical Water Heater rather than the single phase power in a typical house.

Circuit Breakers

Circuit breakers are provided for each individual circuit in your house.

A circuit may be a single appliance, several power outlets in a part of the house, or a number of light fittings.

Their purpose is to stop you adding too much load to the circuit, which can cause the cables to heat up, leading to a fire risk.

 

For more posts see Electrical

 

Light Bulb Comparison

In a previous post on Lighting Levels I talked about using lumens to plan lighting. . . . . but which type of bulb should you use?

There are now 3 types of bulbs in common use

  • Halogen (A more efficient version of the old incandescent light bulbs)
  • Compact Fluorescent Lamp (CFL)
  • Light Emitting Diode (LED)

Light Output

Typical values of light output are:

  • Halogen – 15 Lumens/watt of power
  • CFL – 54 Lumens/watt of power
  • LED – 90 lumens/watt of power

Actual values will vary from manufacturer and also depending on the  colour temperature of the light.

From the above figure it can be seen that a LED provides a significant power saving, even compared with a CFL.

Initial Cost

For an output of around 450 lumens enough for something like a desk lamp you can expect to pay:

  • Halogen – $3
  • CFL – $6
  • LED – $20

Bulb Life

  • Halogen – 2,500 hours
  • CFL – 10,000 hours
  • LED – 50,000 hours

The long life of LEDs meant that though the initial cost of $20 seems expensive over the life of the bulb you would have needed 5 CFL bulbs ($30) or 20 Halogen bulbs ($60)

Other Issues

CFL lamps do contain a small amount of the toxic element mercury, and do take several seconds to Warm up to full brightness.

Both halogen and CFL lamps tend to have limited durability if subject to vibration or rough handling.

A dimmable LED is around 40% more expensive than a basic LED.

 

For more posts see Electrical or Light Fittings

 

Instantaneous Electric Water Heater

No Gas Supply? . . . . .No room to put a heat pump

Well an Instantaneous Electric Water Heater may be an option.

This is a unit in apartment we used to rent

As you can see its very compact and is tucked away in a wardrobe.

The unit provided all our hot water for washing and showers.

It only heating the water when we need it, and we never ran out of hot water.

The unit is quite cool to the touch even when someone is running a hot shower.

Probably the only downside is that due to the high power consumption when the hot tap is running it needs  3 Phase Power.

If you are looking for reviews of home improvement products like this why not visit www.needforhome.com?

 

For more posts see Plumbing

Polished Concrete

So you like the idea of Polished Concrete. . . . but with costs ranging from $55/m2 to $120/m2 there are quite a few things to think about.

Slab Design and Construction

Quality of finish starts with the design and specification of the slab. That includes:

Colour

Although a standard concrete can look good when polished there is also the opportunity to make the following changes:

Aggregate Talk with your specialist subcontractor who should be able to provide a range of different aggregates. (NB some porous aggregates such as sandstone and limestone are unlikely to polish up well)

Cement Paste In addition to the standard light grey a range of concrete colours can be provided with the addition of various oxide based pigments.

Typically if you want either, or both, of these options the slab will be laid with a layer of concrete with your selected finish as a final delivery of the pour, over a standard concrete.

Grind and Seal Finish

Suitable for indoor and outdoor concrete.

In this process the floor is generally ground twice . The floor can then be grouted (see below) followed by 2 coats of sealer to give the concrete a shiny appearance (The sealer will eventually wear and need to be sanded back and re-applied.).

There are typically between around 5 steps in the process.

An advantage of this process is that you are able to make it anti-slip by puting  grit into the sealer. Great for around pools.

Mechanically Polished Concrete (MPC)

This high end process is really only suitable for inside concrete

This concrete polishing process the floor is generally ground twice depending, as above.

It’s then grouted (see below).

A densifier is then applied to harden the floors surface.

Next is up to 7 passes with diamond impregnated resin pads to get the desired shine (the concrete itself shines rather than a sealer which could scratch off).

Finally a penetrating sealer is applied to leave a stain resistant floor that that looks and feeling like glass.

The process has between 10 – 14 steps.

Aggregate Exposure

There are 3 levels of grinding exposing various levels of the aggregate commonly known as:

  • Nil Exposure –(less than 1mm) – Very little/no stone shows on the surface of the concrete (Difficult to achieve unless the concrete has been poured perfectly)
  • Minor/Random Exposure or Salt and Pepper Look (1-2mm) – Small amounts of aggregate visible on the surface – some areas may have minimal exposure while other areas some may have heavy exposure.   – approx 1-2mm from surface.
  • Full exposure (5mm) – this is where you can see all the stones on the surface.

Grouting

Any insitu concrete will have some defects such as small ‘air’ voids or small cracks.

To get the best finish they need to be filled with grout.

With a  natural cement concrete grouting may be carried out with a cement paste in the case of a grind and seal.

If you have a coloured concrete a better grout result is achieved by mixing a latex based product with the concrete dust from the grinding procedure to get a better colour match. This procedure should always be done for mechanically polished concrete.

Summary

There are a lots of options when thinking about ‘Polished Concrete’ so make sure that you understand the options and specify exactly what you want.

 

For more information see Concrete

 

 

 

Comparing Gas and Electricity

Traditionally gas has been cheaper than electricity but with the price of gas rising this has changed.

Actually comparing value for money is quite complicated so I though I would explain how to do the various calculations.

Cubic Metres to Megajoules

Gas is measured at the meter in cubic metres but you pay by the megajoule (MJ) To convert cubic metres of gas to megajoules you have to multiply by

  • The Heating value (*Typically around 38.7)

and

  • A Pressure Factor (*Typically around 1.01)

*check a recent gas bill for the actual values

The value you have calculated is the Megajoules input into your heating system. The actual output can be quite a lot less.

Gas Efficiency

To find the heat output from your heating unit you need to find the actual efficiency of the unit, which can very considerably.

No gas heater has 100% efficiency as some heat is always lost up the flue.

A basic gas heater (3 Star) may have an efficiency of around 60% while some of the 6 star units have an efficiency closer to 95%.

Once you know the efficiency you can just multiply the Megajoule input by the efficiency to get the Megajoule output/Cubic Metre

Megajoules to Kilowatt Hours

1 MJ = 0.278 kilowatt-hours (kw-hr)

Electrical Efficiency

There are two different ways of using electricity to heat your new home.

Direct, or conventional, heating or using the power to run a Heat Pump, or Reverse cycle air conditioner.

The method you choose can make a dramatic difference to the heating efficiency.

Conventional Electrical Heating

With conventional Electric heating, such as panel heaters or fan heaters things are much more straightforward.

Every kw into your house means one kw output (100% efficiency)

That doesn’t mean that overall electricity is 100% efficient, just the inefficiencies occur before the power goes through the meter.

Heat Pumps and Reverse Cycle Air Conditioning

An advantage of Heat Pumps/Reverse Cycle Air conditioning is they have a positive efficiency, they can put out more kw of Heat than the electricity that goes in.

They do this by extracting the heat out of the outside air.

Pick a good unit and you might find them 200% or even 300% efficient for heating!

 

 

 

Solar is Winning

Electricity demand has dropped so much that Australia currently has at least 3 major coal fired power stations more than it needs! (This year the surplus capacity at peak demand is estimated to be around 8,000 megawatts)

In early July this year there was actually zero demand for power station generation in Queensland, mainly due to an estimated power output of 600 megawatts from rooftop solar.

A report by the Australian Energy Market Operator have warned that the electricity generation market is close to breaking point.

Electricity demand, which has been dropping since 2009, will continue to drop for at least the next three years. The closure of major industries such as aluminium smelting and car manufacture is only likely to further decrease demand.

Why Aren’t Power Prices Dropping?

In most ‘Free’ markets when demand drops so do prices.

While demand has been over the past few years electricity prices have doubled . . . . and don’t think that’s mainly the Carbon Tax!

Over 51% of your bill is for Network costs (Federal Treasury Estimates)

When the Goverments’ privatised electricity they allowed the Power Companies to recoup their investment in network upgrades by increasing their charges.

The networks have spent over $45,000,000,000 in the last five years to meet an ‘Increasing Demand’ which we are all now paying for in our bills.

The ‘Joke’ in all this is by increasing their prices the electricity companies have made their ‘Main Competion’, Roof Top Solar, more attractive!

What Now

So after 5 years of getting everything wrong are the power companies interested in doing the right thing? . . . . Like investing in generating power from renewable resources that work when the sun isn’t shining?

No they are lobbying the government to wind back the renewable energy target!

It’s no wonder that some people with solar panels are talking about disconnecting from the grid!

For more informaton click on this link from the ABC: The Price of Power

 

 

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