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Ground Mounted Hot Water Units

Are you or your home at risk from unsafe hot water storage units?

Here we talk about hot water storage units that are externally mounted on the ground and are heated by gas, solar or electrical supplies and how a little time spent on regular checks and maintenance can help your system remain safe and in working order.

Hot Water Unit Base Support Slabs.
Recent inspections have revealed potential safety issues to some installed ground based hot water storage units. On existing homes within a period of 15 days our pre-purchase property inspections revealed 10% of homes to have the hot water unit sinking into the ground, putting undue stress on the supply pipes, where  left unattended these pipes are liable to fracturing allowing water or gas to escape with potential disastrous consequences.

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During new homes [just completed– PCI Handover] inspections we noted some base support slabs to be inadequately constructed and installed, this can again can lead to future issues with the units sinking and leaving [you] the home owner with costly repairs.
Note: Ground mounted units need to be installed in compliance with Standards AS/NZS 3500.4, AS/NZS 3000 and all local codes and regulatory authority requirements.

Hot water units should be installed with the base slab at about floor slab level and 75mm above surrounding surface levels to facilitate good airflow for burning and to ensure the cabinet is not in contact with the soil to prevent rusting. The base slab should be of concrete with minimum dimension of 600mm x 600mm x 50mm, if a pre-cast slab is used then it should be fully supported on solid compact ground. Supporting the slab “on a couple of bricks” is not stable or acceptable as the bricks can settle and easily move causing both the unit and the base slab to move and become unstable.

Hot Water PRV’s (Temperature Pressure Relief Valves)
PRV’s are one of the hot water storage unit’s safety mechanisms, should the system overheat this valve [Hot PRV] is designed to open when any overheating of the system occurs. Overheating causes expansion and an increase in system pressure, if the valve does not operate then failure in other parts of the system can occur with potentially disastrous consequences; the storage unit can burst, external or internal [roof spaces] pipes can split/burst leaving the home owner with expensive repair costs, interruption to home occupancy and possible personal injury. Check and,  Have this valve replaced if it does not operate.

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Maintenance/Servicing.

Minor Maintenance Every Three Months.
It is recommended minor maintenance be performed every three [3] months. Minor maintenance can be performed by the dwelling occupant.
This minor maintenance includes:
1. Checking the unit and its base support slab [some units have been seen without support slabs!] for signs settlement and movement, [the units casing set may below the ground level], wall retaining brackets pulling away from wall or set at an angle between unit and wall, unusually bent and out-of-line service pipes, pipes showing stressing at wall fixings. If you are unsure about the safety of the units installation contact us at Housecalls reports@housecalls.net.au M. 0418 902 240, or contact your local licensed [gas] plumber.
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2. Operate the easing lever on the temperature pressure relief valve [Hot PRV, mounted on top or high level to the unit side]. It is very important you raise and lower the lever gently. Warning: Exercise care to avoid any splashing of water, as water discharged from the drain line will be hot. Identify and stand clear of the drain line’s point of discharge when operating the valve’s lever.

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Where the [PRV] drain line pipework is incomplete or damaged [as shown in the image above] have the pipe repaired or extended so as the drain point end safely discharges near the ground or into purpose fitted ground drain. Remember to test the valve, gently operate the easing lever on the temperature pressure relief valve. It is very important you raise and lower the lever gently [some units are fitted with turn type valves, operate these gently]. Remember use only licensed personal to carry out plumbing renewal and repair works.

3. Check the drain line from the safe tray [if one is installed] is not blocked.

EXPANSION CONTROL VALVE. In many areas, including Western Australia and scaling water areas, it is mandatory an expansion control valve is fitted to the cold water line feeding to the water heater.

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The expansion control valve may discharge a small quantity of water from its drain line during the heating period instead of the temperature pressure relief valve on the water heater. Operate the easing lever on the expansion control valve once every six months.
It is very important the levers are raised and lowered gently [some units are fitted with turn type valves, operate these gently]If water does not flow freely from the drain line when the lever is lifted/turned, then contact your Local Qualified [gas] Plumber and have it replaced. The expansion control valve should be checked for performance or replaced at intervals not exceeding five [5] years, or more frequently in areas where there is a high incidence of water [calcium] deposits.

Service Every Twelve Months
For safe and efficient operation, it is recommended a service be conducted on the water heater every twelve (12) months and must be carried out by qualified personnel.
Warning: Servicing of a gas water heater must only be carried out by qualified personnel. Phone the Manufacturer’s Service Department, their nearest Accredited Service Agent or contact your Local Qualified [gas] Plumber. Only genuine replacement parts should be used to water heaters.
The annual service needs to include the following actions:
• Inspect and flush the temperature pressure relief valve.
• Inspect and flush the expansion control valve (if fitted).
• Check and if necessary adjust the inlet gas pressure.
• Check the piezo igniter, gas control and thermocouple.
• Check the operation of and clean the pilot light and main burner.
• Visually check the unit for any potential problems.
• Inspect all connections.
• Check the drain line from the safe tray (if one is installed) is not blocked.
Note: The water heater may need to be drained during this service. After the completion of the service, the water heater will take some time to reheat the water. Hot water may not be available for a while.

Major Service Every Five Years
It is recommended a major service be conducted on the water heater every five (5) years and must be carried out by qualified personnel.
Warning: Servicing of a gas water heater must only be carried out by qualified personnel. Phone the Manufacturer’s Service Department, their nearest Accredited Service Agent or contact your Local Qualified [gas] Plumber. Only genuine replacement parts should be used to water heaters.
The major service should include the following actions:
• Replace the temperature pressure relief valve [PRV].
• Inspect and flush the expansion control valve [if fitted]. If required, replace the valve.
• Inspect and if required, replace the anode[s]. If the anode[s] is not replaced, it should be replaced within three years of this service.
• Check and if necessary adjust the inlet gas pressure [gas unit only].
• Check the piezo igniter, gas control and thermocouple [gas units only].
• Check the operation of and clean the pilot light and main burner [gas units only].
• Visually check the unit for any potential problems.
• Inspect all connections.
• Check the drain line from the safe tray [if one is installed] is not blocked.
Note: The water heater may need to be drained during servicing. After the completion of the service, the water heater will take some time to reheat the water. Hot water may not be available for a while.

Remember – always use reputable licensed trade personnel to carry out plumbing and electrical works

Information kindly produced for you, by the Housecalls Property Inspection Team. ©Housecalls Property Inspections Pty Ltd. 2016

About The Company
Housecalls is independently owned and operated by a licensed builder. We are based in Perth where all our inspectors have 40 plus years’ practical experience in the residential construction industry, coupled with our local knowledge we are able to specialise, and pride ourselves, in giving our clients the best in property reporting services for the Perth Metro area.
Contact Info
9/45 Tidewater Way,
Ascot WA 6104

08 9457 6066

reports@housecalls.net.au