THE RIGHT STUFF
➲ Cover feature
CENTRAL HEATING UNITS
Discharge of spillage from central heating units located outside the building, in the roof, or under floor, may in many cases go unnoticed. What may be found is CO being drawn into the building where the heat exchanger has cracked or seals within the combustion chamber have been damaged.
a) If the appliance is an open-flued appliance, and installed indoors, then follow the testing procedures for open-flued gas appliances first.
b) For all central heater appliances, note the background CO level. Operate the heater, and place the detection equipment sampling probe in the airstream of a duct outlet( floor register or ceiling register). Monitor for CO for a further 10 minutes.
If the CO level exceeds the background level, then the appliance is leaking or spilling COS and must be isolated.
If any cracks or openings within the heat exchanger of the central heater are evident, combustion products that contain CO may be dispersed throughout the building.
Note: As the heat exchanger heats up, and cracks and openings expand, more combustion products may enter the supply air stream and flow into the building.
Source: Energy Safe Victoria – www. esv. vic. gov. au
Master Plumbers, in partnership with the Victorian Building Authority( VBA) and Energy Safe Victoria( ESV), conduct regular and free carbon monoxide courses for Victorian plumbers.
These courses aim to provide you with the skills and knowledge to use carbon monoxide testing equipment, and test appliances for carbon monoxide leaks.
De Vincentis says there are significant differences between how smoke and carbon monoxide act. The reliance on such alarms is therefore imperative.
“ You can smell, see, and taste smoke, and it has an immediate physical effect on you,” he says.“ So if the smoke alarm fails, there may still be opportunity for you to stay safe, as smoke has an immediate effect on you.
“ But carbon monoxide is odourless, invisible to the eye, tasteless, and its effect on the body is less obvious. So carbon monoxide detectors should be just one part of the solution – the others being regular appliance servicing and testing.”
THE RIGHT STUFF
With campaigns around Australia calling on homeowners to have their gas heating appliances serviced every two years, service technicians need to be sure they are using the correct equipment to carry out effective servicing and testing for carbon monoxide.
This includes a carbon monoxide detector or analyser, calibrated correctly and within the required timeframe, to detect the presence of carbon monoxide.
It was not until the heater stopped working that De Vincentis called a plumber to investigate.
“ Luckily for us, the law in the UK requires that any work carried out to gas appliances requires testing for carbon monoxide,” he says.“ We were shocked when the plumber told us that dangerous levels were present that would have killed us in our sleep if left unabated for a few more days.”
Returning to Australia, and reading about the tragedy that struck the Robinson family in Mooroopna in 2010, De Vincentis was alarmed to find that mandatory carbon monoxide testing was not required in Australia.
Soon after, he established Carbon Monoxide Testing Australia, which provides professional testing to homes in Melbourne.
TRUE FLUE
Correctly operating flues are critical in avoiding the incidence of carbon monoxide poisoning.
The risk of carbon monoxide poisoning is reduced if the products of combustion from a gas appliance installed inside a building are dispersed to the outside atmosphere. They should be via a suitable and sound flue.
However, the danger exists where large quantities of carbon monoxide are being produced during combustion and the flue is not dispersing it to the outside atmosphere. This may occur where:
• The flue does not terminate outside the building
• The appliance heat exchanger is split or cracked
• The flue terminal of an open-flued appliance is blocked
• The flue is broken or blocked.
Alarmingly, testing by his company this winter has revealed a number of faulty gas heaters leaking carbon monoxide in Melbourne homes – some of which have been new or near-new appliances.
“ We identified two ducted gas heaters in new homes in Doreen that had cracked heat exchangers and were emitting dangerous levels of carbon monoxide into the roof space,” says De Vincentis.
“ Had these continued to operate undetected, we could have seen a tragedy occur to two families. It just goes to show that your old-fashioned wall-space heater isn’ t the only risk – both old and new appliances can be faulty and emit dangerous levels of carbon monoxide.”
As well as having appliances serviced every two years, De Vincentis recommends homeowners install a carbon monoxide detector, of which there are a number available in the marketplace. He says that just as smoke alarms have become mandatory in homes, so too should carbon monoxide detectors to keep families safe.
In fact former Federal MP for Murray, Dr Sharman Stone, introduced a bill to parliament in 2011 that called for carbon monoxide detectors to become compulsory in all homes.
However, issues around their reliability have resulted in such laws not yet coming to pass.
Flexible flue.
“ Carbon monoxide detectors indicate the presence of CO in parts per million( ppm),” according to the ESV’ s Carbon Monoxide Measuring Equipment information sheet.“ They are smaller than gas analysers and their only function is to measure CO.”
It says the carbon monoxide detector operates with only one electrochemical cell, which has a shelf life of around two years.
“ The plumber or gasfitter who installs or services gas appliances will find this device cheaper to buy than a gas analyser, but should appreciate it is limited to the measurement of CO.”
Carbon monoxide detectors should feature the ability to measure low levels of carbon monoxide in increments of 1ppm or smaller; to measure carbon monoxide with a precision of ± 5 % of the reading; and a low battery indicator.
Manual zeroing functions and an audible and visual alarm are also helpful features.
ESV says carbon monoxide detectors should be calibrated on a minimum yearly basis using test gases that are NATA traceable or equivalent. Gas analysers whether using infrared or electrochemical cell, may also be used to measure carbon monoxide.
For more information on the correct equipment to be used to accurately test for carbon monoxide, visit the ESV website at www. esv. vic. gov. au n
12 | HVAC & R Nation | www. hvacrnation. com. au | March 2016