A gas instant water heater is going to the best geyser in most cases as the water is only heated when it is needed and means you have an unlimited supply of hot water as long as you have an energy source for your instant water heater. This means you do not heat up water when it is not needed. However, solar water heating will be the best option if you combined a gas instant water heater with a solar water heater. You use solar to heat up your most of your water and have the gas geyser kick in when you run out of hot water, thus having the best of both worlds.
We recommend getting a gas geyser first for the convenience of unlimited hot water and then adding solar at a later stage.
Types of instant water heaters
Electric Instant Water Heaters
These units may have relatively good efficiency but they require enormous amounts of power to operate and often don’t supply water at a very fast rate. For an electric instant water to heat up water at a 25℃ increase in water temperature per minute (the equivalent of a 20L gas geyser), it would require wiring that can handle 159 amps 😮 (35kw), that’s insane. Let’s say you had a wiring system that could handle that, what happens when Eskom turns off the power? Electric Instant Water Heaters do not make sense for home use in South Africa.
Additionally, the electricity to use an electric instant water heater is produced mainly by coal which has significant environmental impact compared to the alternatives: LPG and solar.
Gas Instant Water Heaters
The efficiency of gas instant water heaters close to or better than electric instant water heaters. Gas geysers do not need the huge electrical infrastructure that electric instant water heaters need but only require 60 watts to run the fan or no electricity at all. The electric fan force driven gas geysers can be used in conjunction with a solar water heating system (60℃ max) to heat up water if the solar geyser runs out of hot water, in those cases the gas geyser will only use a small amount of gas to get the existing lukewarm water to the desired temperature, giving you the best of both worlds.
Types of tanked hot water storage
Electric Tank Geysers
These are the normal geysers found in most homes. They generally consume more electricity than the cost of running a gas geyser even with a timer. The problem with timers is that you only have hot water at the times you have your timer set, meaning at other times in the day you may not have hot enough water. Electric tank geysers make sense if you have very specific times you need hot water and your timer can accommodate you and if the saving of having a gas geyser does not make sense. For example, if you are a single person and you have plans of moving out of your house in a short time span then the saving of having a gas geyser will not outweigh the cost of the unit and installation.
However if there is a power outage then you are not going to have any hot water. So you would need to weigh up the convenience of hot water on demand vs the cost.
Solar Water Geysers
If you are building your house from scratch or replacing a burst geyser it may make sense to fork up a few extra rands to retrofit a solar collector. Solar is the future, but it has some obvious drawbacks. Namely, not having hot enough water in the morning without having gas or electric assistance and running out of hot water. These problems are remedied by using electricity or gas as a back up so the ideal situation is to have both gas and solar if it makes sense to make that sort of investment. If you plan to stay in the same house for a long time then it may make sense to install both if you want to get away from Eskom and still have hot water whenever you open the tap.
Considering the current state of Eskom it might be necessary to at least have a gas geyser to start with for the convenience of hot water on demand, especially if you have a family with more than 2 people in your household, and then add on solar later to save extra later.