ARTICLE courtesy of Methven, PHOTOGRAPHY courtesy of Methven

If your house was built around the time Neil Armstrong was striding across the moon there's a great possibility that there’s not much in the way of insulation in the walls, your water pipes are probably made of copper, and most likely without any lagging or insulation. You may even have a little bit of galvanised pipe in your cold water supply pipes. Your hot water cylinder is an electric low pressure copper cylinder with insulation below the current industry standards and it is quite possible your shower is a shower rose located over the bath and controlled by two taps. If this sounds like your home and you are interested in finding out how a home renovation project could bring your home into the 21st century, this article was written for you...

1. Check the flow from your shower

Showers use about 30% of the total energy and water in your house.  See how long it takes to fill a 10 litre bucket - less than a minute and your shower is using more than you really need. 

Talk to your local plumber or plumbing merchant about more efficient showers and what’s applicable to your installation.  A word warning - be careful in what you choose.  Some showers are very water efficient, but won’t work in low pressure installations.  Showers like Satinjet can use less water when installed correctly in high flow situations, but still give the feeling of using more water than is actually delivered.  Satinjet showers are also generally good in pressure challenged installations.  It pays to ask someone that knows about these things.

Consider changing to a slide shower.  There are slide showers that can be retrofitted to a shower rose outlet and provide the flexibility in use that a hand piece on a hose offers…change the height for different users (lower for the kids or so women don’t struggle to prevent their hair getting wet), take the handpiece off the rail for rinsing babies or giving yourself a facial massage or when cleaning the shower.  If you want to go a little further, consider getting a professional to reline your shower enclosure (maybe with or without the bath).  This will allow you to change the pipes behind the wall, install a single lever or thermostatic mixer a relocate the outlet to an elbow for a slide shower.

If you’ve already got a slide shower and want to upgrade the handpiece, remember you don’t need a plumber to change it.  Just unscrew the handpiece from the hose and screw the new one on.

2. Wrap your hot water cylinder

Just like a sleeping bag keeps you warm by trapping heat inside, a hot water cylinder wrap will improve the insulation properties of an old hot water cylinder.  With less heat escaping, less energy is required to maintain the temperature of the water inside the cylinder.  However, this is probably still not as good as a new cylinder.  Designed with more efficient methods of heating and insulation, and fitted with extra safety features, a new cylinder will always be more efficient than an old one.

3. Check the temperature of your hot water

Thermostats control the temperature of the water stored in your hot water cylinder.  Old thermostats can be a little inaccurate and the temperature in your cylinder may be too hot.  Water needs to be stored above 60°C to ensure legionella bacteria doesn’t grow, but keeping it hotter than this is a waste of energy.  It is also potentially very unsafe.  Water at 70°C will cause 3rd degree scalding to an adult in about 1 second, less for the young skin of a child.  The Building Code of New Zealand requires water “used primarily for personal hygiene” be delivered at a safe temperature – below 55°C.   Unless your hot water cylinder is located next door, there isn’t going to be sufficient heat loss from the pipe to get the water to the required safe temperature – not really practical.  This is where a tempering valve comes in.  Installed about 1m from the outlet of your hot water cylinder, this valve mixes hot water with cold water to provide safe temperature hot water.  It will also shut down if either supply to the valve fails.

4. Install a Cold Water Expansion Valve

When you get your plumber to install a tempering valve, talk to him about installing a Cold Water Expansion valve (CWE). Here’s the physics of it… anything heated expands, but the volume of a hot water cylinder doesn’t change.  Therefore, the pressure inside the cylinder increases during heating.  Because of this and to protect you pipes and fittings, cylinders have relief valves which do the same job as that pipe up through your roof.   Just like hot air rises, so does hot water.  This means the hottest water is right where the pressure relief occurs…not so smart.  Depending on how much hot water you use, you could expect 2-4 litres per day of expansion water (either visible as drips from a drain pipe or a wet streak on the roof).  Remember, to prevent your cylinder bursting, this must happen.  It is not so much a waste of water (Captain, you canna change the laws of physics) but it is a waste of energy.  A CWE is located on the inlet pipe to the cylinder and relieves any excess pressure from thermal expansion with cold or cooler water – in other words, water that has had less energy pumped in to it.  NB: This solution may not be possible for very low pressure installations.

5. Upgrade your individual basin taps to a single or twin lever mixer or a 3 hole faucet

The object here is to get a single outlet where you can mix water.  Think about the last time you washed your hands under an individual hot tap.   It’s human nature to use that one because it isn’t as cold as the cold water tap.  This is because what was once hot water in the pipe between the cylinder and the tap that has been allowed to cool…all that money you have paid to some electricity conglomerate to heat the water just so the heat can evaporate…then as soon the hot water comes through to the tap, it is too hot to use.  So you switch to the cold tap to soothe the burns and meanwhile, the heat in that slug of hot water between cylinder and tap you just changed now evaporates.   Having said all this, the only way around this problem is having a water heater at the outlet which has its own inefficiencies and down-sides.   The best solution is limiting the volume of hot water used.  I would say put the plug in, but some ‘designer’ basins don’t have plugs… Either only use the cold tap (which is really the most economical solution but is against human nature) or mix less hot water with cold to get the right temperature.

6. If buying new tapware, showers, appliances or toilet suites, check for the WELS rating

WELS or Water Efficiency Labelling Scheme rates how water efficient a product is.  Similar to the ECCA Energy Rating labels on electrical appliances, stars are given to represent a products water efficiency level – more stars means more water efficient.  As testing is done to a standard, you can compare products to see which is more water efficient.

7. Lag your pipes

If you can access the pipes, particularly the hot ones, wrap them with a suitable lagging material.  This has the same effect as the cylinder wrap and limits the evaporation of heat from the pipes between cylinder and outlet.  Replace any galvanised pipes replace them.  Due to corrosion and mineral deposits, the effective bore of these diminishes over time restricting the amount of water (and dynamic pressure) you get.  If you need to replace any pipes, there are many different solutions available, each with its pro’s and con’s, so talk it over with your plumber which solution best suits you.  Remember, all pipes should be secured appropriately to prevent water hammer.

8. Primary energy source for your water heater

Not everyone has gas to their door, but gas is considered more efficient in heating water than electricity.  If you do have gas, other options open up e.g. storage water heater versus instantaneous water heaters.  Talk to your plumber about available options and what is best for you.  Also consider any possibilities for supplementary heat sources…

9. Add supplementary heat sources to heat your hot water system

Systems are available that can draw energy from external sources to heat your water ‘for free’. 

Wetbacks are often used in rural areas or where fires are extensively used for space heating or cooking.  A pipe coil is combined with the fire and water circulates from the cylinder to the fire and back again through thermal currents (hot water rising, cooler water falling).  As the amount of heat applied to the water cannot be controlled, these can only be installed on open vented systems (a pipe up through the roof).   This theory is applied to combination systems that use heat transfer to heat the hot water supply, giving a ‘mains pressure’ hot water supply.

Solar panels utilise the energy from the sun to heat water.  Again, this can act directly on the hot water supply or via a heat exchanger.  Manufacturers claim fairly sizable energy savings which can be related to your location.

Heat exchanger panels are the exact opposite to a refrigerator.  Rather than using refrigerant gases to cool food, the same processes of compression and expansion of gases are utilised to literally pull energy out of thin air and then use this to heat the water.  A small amount of energy is required to pump the refrigerant around but manufacturers claim fairly sizeable energy savings.

All of these require resource consent, some capital expenditure and you may be eligible for government subsidies.  They can also be incorporated to include space heating (e.g. under-floor or radiator heating) or pool heating so do your research in to which system is best for you.

10. Cylinder relocation 

If you are going to the expense of installing a new cylinder with supplementary heating systems, consider the location of your hot water cylinder.  Sometimes cylinders are located for convenience rather than were is most economically sensible.  Talk to your plumber, builder or architect for advice on this.

11. Rain Harvesting

As towns and cities grow, water resources are being stretched.  Urban water supplies require dams or river water filter stations which don’t come cheaply.  If your connected to a municipal water supply you will be paying for the privilege, either on a user pays rate via a water meter, or indirectly through your rates.  Not only are you paying for the clean water you use, there will also be a charge for the water you are putting down the drain.  This is generally based on a percentage of water in.  So, for environment and economic reasons, it pays to reduce the amount of treated water you use.  A simple way to do this is to harvest the rain water that falls on your roof and store it for later use.  

There a number of ways to collect and store the water and largely depend on what you intend to use it for – watering the garden or washing the car right up to providing all water for your household.  If you are planning to be somewhere in the middle, you could consider using the harvested water for you toilets (about ¼ of your water usage is flushed down the toilet) and maybe your washing machine.  Remember, if you are connected to a town water supply, these cannot be directly connected. 

Talk to your plumber about the best ways to meet your requirements for reducing water consumption costs.

You might be interested in reading: Water saving tips.

 

Methven LogoLife-enhancing shower experiences. That’s what Methven is all about, and they’ve been providing them for a very long time. Their story began in New Zealand in 1886, as a producer of brass and iron hardware. Today, Methven is New Zealand’s largest supplier and a leading designer of distinctive showerware, tapware and hot-water valves to home renovators, plumbers and the construction industry.
 

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