How to: Choose a water heater - gas vs electric, storage vs instantaneous
Hot water in the shower is something we take for granted, but it's essential all the same. When moving in to a new home, or completely renovating an old one, there're many things to consider and decide upon. It seems that choosing options for even heating water can cause one to fall into a chasm, especially since there's so little easily accessible information about what to look out for.
To help in that process, we'll explain the main things to look out for, as well as the choice we made in the end.
What to look out for when choosing a water heater
These are the main things to look out for when choosing a water heater:
- Heat and water output
- Water pressure
- Energy usage/efficiency (long term cost)
- Size and aesthetics
- Availability of gas/electricity
- Ease of use
Heat and water output
“a nominal maximum power output of 8.5kw and a maximum water pressure of 8 bar is more than enough to supply hot water to 2 showers at any one point of time.”
Not all heaters are made equally - some are able to heat more water at any one point of time. This is important for obvious reasons. If your water heater isn't able to heat your water fast enough, you're either going to have to shower in lukewarm (or even cold!) water or the water pressure from your shower head is going to be very low and miserable. This gets worse if the heater is connected to more than 1 shower, if 2 or more people use the heater simultaneously.
We've found that our heater, which has a nominal power output of 8.5kw and a maximum water pressure of 8 bar is good enough to supply hot water to 2 showers at any one point of time. We use an instantaneous gas heater, which is generally more efficient and powerful than an instantaneous electric heater. Instantaneous electric heaters generally have a lower heat and, correspondingly, water output, so they can only supply 1 shower at a time. This means you'll need on electric heater per shower.
If your heater can supply more than one output at a time, you can also connect it to your bathroom sinks, kitchen sinks etc. You won't be able to do that with instantaneous electric heaters that are directly connected to a shower head.
Water pressure
Speaking of water output, "no one gives what he doesn't have". The water pressure that goes out from your heater won't exceed the water pressure you get from your water supply, unless you're using a storage heater (we explain more below). This means that if the water pressure supplied to your house is low, no matter which instantaneous heater you use, you're going to get a low output of water and pressure. The only way out of this would be to get a storage heater (see below).
“if the water pressure supplied to your house is low, no matter which instantaneous heater you use, you’re going to get a low output of water and pressure.”
There is no definitive way to find out the water pressure of water supplied to your house without actually turning the tap on and seeing for yourself. This might be hard if you're moving in to a new house. (You could try asking neighbours on the same floor). But here are some general pointers to estimate water pressure supplied to your house (for apartment blocks, like HDB flats):
- For HDB flats, the water tanks are usually stored on the roof. It's a basic principle of physics that the lower you are from the water source, the higher the water pressure. So if your HDB block has 20 floors, and you're living on the 10th floor, your water pressure is likely to be high. Of course, some flats have multiple water tanks of different floors, so take note accordingly.
- The fewer neighbours you have, the lower the strain on the water source, so it's more likely your water pressure is higher.
- Newer HDB flats generally have better water pressure (probably because the designers started taking this into account).
- Water pressure can vary throughout the day - at evening time, when most people go home and take a shower, it's more likely to be lower.
For storage heaters and gas instantaneous heaters, water pressure is also affected by the number of showers you supply water to from your heater. If too many people use hot water at the same time, you'll have lower water pressure, unless your heater has a high pressure output. Also, cheap instantaneous electric water heaters might have a low output and give low pressure, be sure to check the specifications.
Energy usage and efficiency
“As of October 2017, gas in Singapore is 18.92 cents/kWh, while electricity is 20.72 cents/kWh ... that adds up to $207.17 in a year for a gas heater and $226.88 in a year for an electrical heater.”
Other than the price of the water heater itself, you should also consider the long term costs. A water heater that uses more power can cost you a lot more in the long run. As of October 2017, gas in Singapore is 18.92 cents/kWh, while electricity is 20.72 cents/kWh. If your heater uses 3 kW for heating, and it's used on average for an hour everyday, that adds up to $207.17 in a year for a gas heater and $226.88 in a year for an electrical heater.
Take note that gas heaters are generally more efficient than electric heaters; so for the same usage, it'll usually use less power (we explain more below). Also, although water heaters might state their "power usage" specifications, note that this will be the maximum power that the heater uses. If you warm your water to a lower temperature, then obviously you would use less power.
Size and aesthetics
This is visibly evident - you'll want a water heater that looks good. The range of electric heaters is much wider in Singapore than gas heaters, so you're going to find nicer designs with electric heaters.
Take note, however, that instantaneous electric water heaters are usually connected directly to your shower head, which might spoil the aesthetic of your bathroom and shower area. On the other hand, storage heaters can be hidden anywhere in your house. Similarly for instantaneous gas heaters, you can hide them in your service balcony (instantaneous gas heaters must be placed in an open area for safety reasons), or maybe your industrial-styled kitchen?
Availability of gas or electricity
This is a straightforward point - be sure that wherever you want to place your heater, an appropriate power supply point is available. This is particularly important for gas heaters, because you'll need gas piping to the area. Also, not all houses have a direct supply of gas from CityGas.
Ease of use
“Storage heaters ... usually need to be turned on a while before you use them and turned off after you’re done - if you forget to turn it off, you’ll be wasting a lot of power heating water you don’t need. ... this can be solved with some smart home automation.”
What's the point of a powerful heater if the water still comes out cold when you open the faucet? Most instantaneous water heaters are automatic these days - they activate and heat up the water only when hot water is used (when you turn the tap on). Storage heaters, on the other hand, usually need to be turned on a while before you use them and turned off after you're done - if you forget to turn it off, you'll be wasting a lot of power heating water you don't need. (Of course, this can be solved with some smart home automation - but that's a post for another time).
There are other things to look out for, too: if you're particular, you would want a heater that has adjustable temperature control (ours can be adjusted in 1°C increments all the way to 60°C). Also, if you use a bathtub, you might want a heater that has a remote control. Yes, you read that right, there are heaters that can be controlled remotely - then you can adjust your water temperature to the perfect degree while in the comfort of your bathtub.
Comparison: Storage vs instantaneous water heaters
Now that you know what to look out for, how do you choose a water heater? We break it simply for you:
Storage water heaters
- Storage water heaters give you the best in class for water output; provided you're willing to wait. It takes a while for the water to get hot (you'll need to wait between 5 to 10 minutes after turning them on).
- The water pressure from storage heaters is always good, because it's from your own tank.
- Storage heaters are usually less efficient and use more power because they have to heat up a whole tank of water. Also, don't forget to turn them off or you'll be wasting a lot of power.
- Storage heaters are much bigger than instantaneous heaters, you might want to find a place to hide it behind dry wall/a false ceiling.
- Storage heaters are less easy to use - you'll have to remember to turn them on and off, wait a while for the water to be hot, and you can't adjust the water temperature. (This all can be solved with some smart home automation - we'll show you how in future).
Instantaneous water heaters
- The water output for instantaneous water heaters varies widely - you'll have to check the specifications for the model. But the water gets heated up immediately, and you'll feel the water within 30 seconds to a minute.
- The water pressure for instantaneous heaters depends on your water supply, and the specifications of the model.
- Instantaneous heaters are generally more efficient and use less power because they only heat what you need. Also, they don't have to be turned off to save power.
- Instantaneous heaters are smaller than storage heaters. But if you don't like the look of it, it's harder to conceal/hide.
- Instantaneous heaters are easier to use - just set the temperature once, and you're set. No need to wait for the water to be hot and no need to remember to turn it off.
Comparison: Gas vs electric water heaters
What about the power source? Here's how to decide:
Electric water heaters
- Electric water heaters are less power efficient, so you'll usually have a lower heat and water output. If you have an electric heater for each shower, this is less important.
- If you choose a cheap electric heater, you might have water pressure too low for comfort - be sure to check the specifications.
- Electric heaters tend to be cheaper upfront, but they'll cost you more in the long term because of poorer efficiency (and the slightly higher cost of electricity).
- Electric heaters are smaller, but you'll need to place one in each shower (for instantaneous electric heaters), and that might affect the aesthetics of your bathroom.
- Electric heaters don't usually give off any sound. If they do, you might want to call an electrician over.
Gas water heaters
- Gas water heaters are more power efficient, so they're more likely to have a higher heat and water output - you can supply more than one shower.
- You're less likely to face problems with water pressure because of the better heat and water output.
- Gas heaters cost more upfront, but they'll save you money in the long term because of their power efficiency (and the slightly lower cost of gas).
- Gas heaters are usually bigger than electric heaters, but they can supply multiple showers and you can place them in your service balcony or kitchen.
- Gas heaters are louder than electric heaters - you'll hear the gas burning when in use (it's not very loud though).
What we chose
We chose the Macro MA-10FE instantaneous gas heater for ourselves because it suited our needs. We needed to supply hot water to 2 toilets, with a total of 2 bathroom sinks and 2 showers. We took a gamble with water pressure (and subsequently discovered we had a good enough pressure from the water source).
These made an instantaneous gas heater appropriate - it was quick in providing hot water, efficient and didn't need to be installed in our bathrooms (which would have made our already small shower space even smaller).
The Macro MA-10FE was one of the options and we bought it. Read our review of the Macro MA-10FE instantaneous gas heater here.