Hot Water Cylinders
Low Pressure Hot Water Cylinders
Hot water pressure problems are comon in New Zealand households. The majority of New Zealand homes have low pressure hot water systems. You will be able to tell if your hot water system is low pressure by running the hot water tap in your kitchen sink and comparing it to the cold water. If there is a noticeable difference in water pressure, your system is low pressure.
The pressure in the system is between 36 – 72kPa. The hot water cylinder is made of copper and is open-vented. The system comprises a thermostat, an element, a pressure reducing valve and possibly a vacuum valve. A vent pipe will either poke out of your roof, or over an outside gully-trap. A small amount of water dripping occasionally from this pipe is normal as the system vents pressure, but a constant drip or dribbling indicates a problem.
There are a few common problems with Low Pressure systems.
- An old cylinder will eventually leak and need to be replaced. Auckland’s water is not as hard as other cities around the world so you can reasonably expect to get 20-30 years from your cylinder. Keep a close eye on the floor around your cylinder as they can sometimes leak for months before being noticed, which causes considerable damage to the floor and results in high power bills.
- The valves will require occasional replacement of washers or diaphragms. If you see water coming out of the vent as described above, call us, as this indicates a problem with the valve. The water that is being discharged has been heated and paid for by you. Seeing to the problem quickly will save you money.
- If the valve itself is quite old, we will normally replace the entire valve, rather than a washer or diaphragm. This is because we can’t guarantee the old valve and it is very likely to require attention again in the near future. It is therefore more cost-effective for you to replace the whole valve for around $200 - $250, than for us to come out several times at your expense.
- The element may corrode inside the cylinder, resulting in a sudden loss of hot water. Call us for assistance.
Mains Pressure Hot Water Cylinders
A mains pressure hot water cylinder is made of steel and runs at 500-800 kPa. The water cylinder is closed-vented, so you won’t find a vent pipe anywhere. The advantage of a mains pressure hot water cylinder is that water is delivered to the entire house at the same pressure, so it is less affected by multiple demands on water usage, such as simultaneous showers, running taps, washing machines etc.
A mains pressure hot water system comprises a thermostat, an element, a cold feed expansion valve, a limiting valve and possibly a tempering valve. The cold feed expansion valve will drip over a waste somewhere near the cylinder, in a similar way to the outlet pipe of a low pressure system (see above.
The most common problems with a mains pressure hot water cylinder are valve-related.
- Pressure limiting valves can fail and allow too much pressure into the system, resulting in water continuously dribbling out of the expansion valve.
- Failure of the expansion or tempering valve will require replacements as there are no washers or diaphragms in these systems.
Phone: (09) 525 2686
Fax: (09) 525 2683
Mobile: 027 230 6758
Seen Enough?
Click here to check out the range of plumbing services we at Turner Tap provide.
