Water Heaters are a luxury we take for granted
In Singapore, hot water is a luxury that many people take for granted. We enjoy rejuvenating hot showers every single day. For many, our shower time is the only uncompromised me-time we get! That precious fifteen minutes of bliss helps us to reduce stress and even improve sleep.
The great news is that the modern day water heater is very safe to use.
Why safe?
There are three crucial safety features in our heaters. They are always working in the background, giving us no trouble. That is why we usually don’t even notice they exist.
Let’s give you a quick introduction and show you where they are.
1. Where are these safety features?
1.1 Thermal Cut Out
At the side of the heater, there is an opening for service access.
Here's us conducting a tech-level detailed training of the insides of a heater. Here, the cover is open and you can see several colourful wires and components nestled in it.
That is where we find out first safety device, the thermal cut out. It is safely tucked away in the service panel.
1.2 Thermostat
1.3 Why so special? In two places?
Older heaters of the past have very basic functions. You only got a heater switch to power the heater on and off. A typical heater rocker switch looks like this, with a red light.
In these older heaters, you have no temperature control and no access to the thermostat.
Modern digital heaters come with a control panel.
The panel offers you more controls that make everyday use convenient and easy. One of the good things that a panel offers is the ability to adjust the heater temperature to suit your needs.
If you have a digital panel, your thermostat is inside it.
1.4 Pressure Relief Valve
The third safety device is outside the heater. It is a pressure relief valve, fixed on the incoming cold water pipe of the water heater.
Since the valve is in a very visible location, you may even be able to see it in your own home. Take a walk into your bathroom to check it out!
1.5 Fun fact: Not all heaters have 3 safety devices
Instant and gas heaters don’t have relief valves. Does that make them any less safe?
Of course not! In Singapore, anything that is on the shelves are 100% tested and trustworthy.
Different heaters, different requirements
Gas and instant heaters fall in the category of ‘instant’ heaters. This means they heat up water on the go. Water flows into the heater, gets hot, and passes out immediately. Instant water heaters are built differently than storage heaters. Instant systems contain no pressurised tanks and do no need a relief valve to function well.
Let cover what each safety feature can do, so you can appreciate how all the three devices work in harmony.
2. Thermal Cut Out
To understand how a thermal cut out works, you must first know the heating range of a water heater.
If you have a digital heater, you can adjust the temperature, ranging from 35 to 75 degrees Celsius.
2.1 Why is the thermal cut out important?
Notice the highest possible user-adjusted temperature is 75ºC? 75ºC is a safe temperature. You never ever want the water heater to go up to 100ºC, because at that level.. water converts into steam!!
At steam level, the pressure and internal expansion in your heater will become so great that it may explode. You’ll have a bomb on your hands!
This is where the thermal cut out is so important.
2.2 How is the thermal cut activated?
At around 90ºC, the thermal cut-out shuts off electricity immediately. If you are using an instant heater, the cut off temperature is lower, around 80ºC.
The cut off is sharp, and the heater will stop working right away. As a homeowner, you will experience this cut off as an electric trip.
For a your own safety, engage a water heater specialist to perform a reset. The expert must go through a checklist, testing each of the heater’s components to find out what caused the trip. They are only allowed to reset the thermal cut out after determining the cause and fixing it.
2.3 I can do this on my own.. Right? NO!!!
A thermal cut out is easy to reset, you only have to push the red button in the middle. But it can only be reset after all the necessary safety checks are complete.
It is important to detect the root of the problem and solve it fast. The consequences of ignoring the warning signs can be disastrous!
2.4 This happened when all 3 devices failed
It occured at a condo in Marine Parade. Always be alert to devices that aren't working properly. It could save a life. Purchase from a well known brand and read the reviews carefully.
Choose to work with reputable and experienced installer. It is not worth risking your life for some small savings. Your family is worth more than that.
2.5 What to do if my heater has tripped?
Resist the temptation to do anything on your own. Set the main switch to ‘off’ and call in an expert to help. Tell them your heater has tripped.
Remember, there could be a few things that have stopped working in the heater. Let a professional do a complete check for you.
3. Thermostat
The thermostat is like the air con remote control of your water heater. Recall the 35 to 75 degrees Celsius range? This range breaks down into 3 categories:
35 to 49: seldom used
50 to 65: often used
66 to 75: disinfect
If you are using a Gen 1 water heater, you cannot set your tank temperature. The default temperature is 60 to 65. This is pre-programmed by the factory.
3.1 Why is it helpful to control the temperature?
Being able to control the temperature allows you to set the heater to work according to your needs. This could save you energy.
For example, we don’t always set our air conditioner to 18ºC. We may lower it to 21ºC on cool days to save energy.
The concept is the same for storage water heaters. The default tank temperature is 60ºC. But if your country a tropical climate, you can set it lower at 50ºC to save energy.
Living in a hot country has its benefits. Some of our tougher family members prefer cooler showers! A control panel allows you to lower your heater thermostat, giving you freedom of choice.
While lower temperatures will help save the earth, do not set your storage heater lower than 50ºC in Singapore. Why?
3.2 Instant and gas heaters
An instant heater has a power selector, similar to a thermostat. Turning this knob will set the heater from 1kW (low power and heat), to 2kW (medium power and heat) to 3kW (max power and heat).
Gas heaters have a built in thermostat. They are usually set between 35 to 45ºC.
3.3 How do I know if my thermostat is faulty?
If your thermostat has stopped working, it will be obvious. Your water will either:
- not heat up
- or it will overheat, activating the thermal cut out and cause a power trip
Overheating past the 75ºC working range means the heater’s thermal cut out will activate, causing a power trip.
3.4 How to fix a broken thermostat?
You need a new circuit board for the panel or a new thermostat for the replacement.
It is important to get a water heater specialist to replace your thermostat. There was a terrible installation where the thermostat was not connected. Instead of checking the manual, the installer skipped connecting the safety devices completely!
ARRRGGGH!! How can anyone be so irresponsible??
Needless to say, the heater was a gone case within the week. It overheated to the point of no repair.
Incorrect installations are not covered under the heater warranty. Not even if the heater is under a full warranty. What is a full warranty?
In the end, the poor owner had to buy and install a new one. He paid all the costs because the bad installer disappeared into thin air. A terrible start to living in his new house!
If you get a reputable installer, this would not happen in the first place. Choose well.
4. Pressure Relief Valve (PRV)
The pressure relief valve is often forgotten by installers as it is an external fitting. Do not allow them to forget it! This small but important device can make or break your warranty! Make sure you see it fixed on the cold pipe.
Uncertain about your heater's installation? This easy 4 Point Checklist will turn you into an expert right away.
4.1 How does a relief valve work?
When water gets hot in the heater tank, the water goes through thermal expansion. This expansion creates a build up of pressure in the walls of the tank. If this pressure is not released, the tank will soon crack and burst.
To stop this damage to the tank, you need to release the pressure somewhere. This is where the pressure relief valve comes in handy. The pressure shifts from the tank to the valve, and is escapes at the valve in the form of dripping water.
Each valve releases pressure according to its rating. The most common rating is 0.8MPa. As long as the valve experiences pressure at 0.8MPa (8 bars), it will start releasing water droplets.
4.2 Relief valves release pressure from both ways!
What does that mean? We’ve showed you how pressure from the heater tank gets released at the relief valve. But did you know that PRVs can also release pressure from the incoming water pressure at the cold pipe?
If incoming water pressure from the cold pipe is high, it will also cause the PRV to leak!
Sometimes I get calls from very puzzled homeowners.
Why is relief valve leaking? The heater has been off the whole day!
PRV never leaked for years! Why suddenly started dripping water?
Now you know why. It is because of the pressure from the incoming cold pipe, which you cannot control.
An example: If a neighbour on your floor shifts out, the same amount of water gets split to a fewer number of people. That could cause your incoming water pressure to increase, and your PRV to leak more.
4.3 How to care for my relief valve?
- Downward flow: If your PRV joins to a rubber tube, always make sure the tube is in a continuous downward position (see 1).
The drainage tube should never run upwards, because water cannot flow upwards (see 2). A tube turned upwards will cause a blockage and prevent pressure from escaping.
- No blocks: You can also make sure that the tube which connects to the drainage never gets blocked by dirt (see 3). This will help the water droplets drain off well.
The drainage tube should never run upwards, because water cannot flow upwards (see 2). A tube turned upwards will cause a blockage and prevent pressure from escaping.
4.4 How to know when relief valve is not working well?
Continuous leak
A pressure relief valve should to drip water. When this drip becomes a flow like from a tap.. something is amiss. This can happen when there is too much pressure in the pipes, or when the relief valve is faulty.
Loud sounds
The relief valve can make strange intermittent sounds, like humming and squeaking. Listen to these samples to identify a PRV noise. This can be due to water pressure that is too high
Humming sound
Relief valve squeak
4.5 What is normal water pressure?
Low water pressure around 1 bar causes problems with water heaters.
High water pressure above 5 bars put your faucets, heater and PRV under stress.
Ideal pressure is between 2 to 3 bars - a perfect level for households.
4.6 What to do if relief valve is leaking or noisy?
Check your water pressure. Is it too low or high? You can call the Town Council, MCST or a plumber to help you check your water pressure. Perform checks at the riser, and at the bathroom right before the heater.
If the water pressure is normal, and the leak or sound is coming from the relief valve, the relief valve may be faulty. Take a video and send it over to a heater expert. They should be able to identify the sounds, isolate the issue and provide a solution.
Above average high pressure reading - 3.8 bar
Conclusion
Understanding the safety features in your water heater helps you use it with confidence.
Keep every safety device in tip-top condition! A great way to do this by maintaining your water heater often. This helps to prevent danger due to wear and tear. Three years is a recommended time frame by Enterprise Singapore.
Hope you enjoyed this read and learnt something new!
Safety Device FAQ
Is it safe to use a 3-pin plug to install a heater?
Do not use a normal 13A 3-pin plug to connect a heater. 13A sockets are insufficient to support this high wattage appliance.
Instead use a dedicated 20A power source.
Can I get my own installer to fix the heater?
Yes. As long as the heater is installed according to the instructions provided in the manual, warranty will remain intact. Most IDs will do the installation as it is already included in their package. We can pass them an additional installation guide.
Why does my heater switch spark?
Heater switches draw a larger current so it is normal to see a spark sometimes at the back of your switch due to a buildup of charge.
To avoid seeing the spark, use a larger rocker switch design instead of a small switch.
