Friday, October 12, 2012

Renovation: Water Heaters

Getting heated water to your bathrooms nowadays is easy and affordable, depending on your needs and which method you choose. Most common method is by simply installing a POU (point of use) instant heater and you'll be showering in heated water in no time. However, a POU instant heater can only supply heated water to a specific area (for example the shower area) and you'll need one for each bathroom. If you need heated water from your sink, you'll need a centralised heater as a POU heater cannot perform this function (which will be explained later). You will also need the appropriate piping which can be costly, depending on the type of house you have and of course mixer taps (with hot/cold water inlets) Newer HDB flats where the wiring and piping are concealed already has the necessary piping taken care of. Same goes with most condominiums and landed properties. For older HDB flats however, there are no other options but to lay additional piping for heated water coming from the heater. Unless you are a plumber or have the necessary tools, you'll almost certainly need to call one to do the job. Once the necessary piping is available, all you need to do is to install a centralised heater and you'll have heated water in shower area and from the sink. Contrary to popular belief, there is actually more than one type of central heaters you can opt for. Most commonly used are the storage heaters where it is basically a heater with a tank to hold the heated water. The other type is a tankless instant heater that heats the water up as you use it. If you are wondering if the tankless instant heater is similar to the POU instant heater, you are not far off. The working concept is similar - which is to heat the water as water flows through it. However, you cannot use a POU instant heater as a central one because the POU heater is activated when water flows into the heater while the centralised one is activated when water flows out. That means you will need an on/off tap to supply cold water to the heater while it gets heated up and out from a hose etc. You cannot re route the heated water to another tap as then you will have to turn on two taps which will make it ridiculous So which is a better solution? To tank or not to tank? A storage heater is normally bulky, therefore can be unsightly and is also inefficient as it 1. heats the water up even when not in used to maintain the water temperature. This means you have to turn it on all the time or have it turned on for some time beforehand to allow it to heat the water up. Obviously the latter is not convenient. 2. heats up the whole tank regardless of the amount you actually plan to use. 3. can run out of heated water if the supply in the tank runs low as you are using it. Think of the electric thermos and you’ll get the idea. A tankless heater on the other hand is way smaller, therefore not that unsightly, and more efficient as it is turned on only when being used. This means, you can turn the main switch off when you are not using it and back on when you need to. If you think that it is inconvenient, then you just leave it on and it will only consume energy for the LED indicators which is negligible. There are two types of tankless instant heaters - one is electric and the other is powered by gas. You can install the electric tankless heaters almost anywhere you want but for one powered by gas, it can only be installed in an open area like the service yard. This effectively makes the gas heater not an option if it needs to be installed in the bathroom. Even if it can, having to lay gas piping into the bathroom can be costly and unsightly and even be impossible, due to the location of the gas pipe and the bathroom.

If your service yard adjoins to your bathroom (where the central piping inlet is located), then you can install a gas central heater in the service yard and extend the hot water pipe to bathroom. You have to drill a hole though so be careful that you do not damage any concealed piping as the cost to repair it will be astronomical. You have to also lay gas piping to the service yard. Check out City Gas for their range of gas heaters.

If your service yard is not adjoined to your bathroom, then an electric tankless heaters is your best bet. One such example is the Bennington C600. It is small and considered affordable at approximately $280. 

Take note that a tankless central heater is not a perfect solution and here's why. For one, it is not absolutely instant. Depending on the location of the heater and the length of piping it has to go through before it reaches the outlet, there will be a delay. However, this applies to any centralised heaters as well. So if you have never used a centralised heater before, this is expected. You will also see a drop in the water pressure. For most cases, this should not be an issue as no one uses boiling water in huge flow unless they want to scald themselves. So most likely, after mixing with cold water, the pressure should be just right, at a temperature most people use to shower or wash up. However, if it is an issue for you, it can be easily remedied by changing the shower heads or installing water saving devices onto the tap which will increase the pressure accordingly. Though it may be an inconvenience and even additional investments, the savings (both electricity and water) later on should make up for it. Whichever type of heaters you decide on, you may want to have heated waters in the kitchen or even the service yard since you already have a centralised heater. However, as far as I know, HDB flats with concealed piping do not extend to the kitchen and service yard. In this case you have, again, three ways to go about it. 1. You can extend and lay additional piping from your central water heater to the kitchen. This option saves you the cost of another heater but make sure that
- the piping works does not cost more than the heater 
- piping works are not unsightly. 2. Another way is to install another heater near the outlet to minimise any exposed piping. If you only need heated water for the kitchen sink, you can actually install it under the sink as show below

A storage heater is too big in this case therefore only tankless heater is possible. Since gas tankless heater cannot be installed in confined spaces like the cabinet under the sink, an electric tankless heater is the only option. In this case, the Bennington C600 will again be suitable. Though it will cost you another initial investment, this can be justified if: 1. Additional piping will cost just as much 2. Additional piping cannot be concealed and will look unsightly. However, do take note that you may need to lay a new wiring to support a higher ampere rating depending on the heater you choose. The Bennington C600 on a 13A socket can only run at mid power (3kW). It runs at a max of 4.5kW and requires a 20A socket. All the above options depends on the cost and aesthetic results. So below is a summary of all the available type of heaters

Heater typeHeatingComments
Point of use (normally called 'instant heater')ElectricalPros: Simple to fix without the need for expensive piping
Cons: Needs one for every outlet
Centralised Storage (normally called 'storage heaters)ElectricalPros: No drop in water pressure
Cons: Bulky, inefficient power usage and not on-demand.
Centralised Tankless (or called multipoint heaters')ElectricalPros: Small, efficient, available on-demand
Cons: Drop in water pressure
Centralised Tankless (normally called 'gas heaters')GasPros: Similar to its electrical cousin.
Cons: Similar to its electrical cousin. May need to connect to an electrical point for ignition. Can only be installed in a non confined space. Additional gas piping required.


SNH Tradecentre said...

Storage heaters, or heat banks, are highly useful devices, as you've outlined, but it is important you know what you are looking for, as there's a large variety of heaters on the market.
A very insightful and useful blog. A great reference point for anyone looking to enquire into storage heaters.

Great Stuff.

Allan Mullaly said...

Thanks for discussing on water heaters. I feel lucky myself to be in that era where great innovation made for tankless water heater and other home comfort appliances. I have Rinnai tankless water heater and in winter cold days it performs so well.

Jack Reed said...

A very brief descriptive info you have shared here regarding water heaters, I personally like Nortiz tankless water heaters because of their fast water heating efficiency, thanks a lot for sharing this info.

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Anonymous said...

Hey There,
Thanks for your very useful post. Looking to get a heater for our new BTO, your blog was excellent, I am off to the Bennigton shop this weekend.
Again Good stuff mate

Muhd Nurhidayat said...

Good article and personal experiences. I have been waiting for quite sometime to decide on which water heater to use. Staying in low level floors and taking advantage of the laid concealed pipes in HDB BTO, the centralized electric heater is the way to go. Thanks man!

Azhar Khamis said...

I Muhd Nurhidayat,

All HDB BTO owners should install a centralised heater. It makes no sense not to. The only question is which type to install.

Glad you found this article useful.

Anonymous said...

Hi, you mentioned newer BTOs already have concealed piping and wiring. May I know how to tell from which year I should look at when purchasing a resale flat?

Azhar Khamis said...

Anything after 2003 is a pretty safe bet.

Anonymous said...

Hi,my flat was installed with centralised heater since 18yrs ago...i will like to change it to u have any idea will that required addition pipes and what kind of complication i might encounter...?

Azhar Khamis said...

Hi. You will need to change your mixers if you plan to remove the central heater. Else just turn the central heater off permanently and install POU heaters just like you are installing a new shower head. One thing for sure is you will need to have a power supply nearby for the POU to tap on.

Anonymous said...


Jenny - Renovation Expert said...

Look HDB isnt ever gonna put in a water heater for you, we personally use panasonic water heaters and they r not too shabby. Just that water doesnt get hot enough sometimes!

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