How to Choose the Correct Solar Water Heaters in Kenya – High Pressure vs. Low Pressure

Solar water heaters in Kenya are manufactured as pressure and non-pressure models. Pressure model (also called high pressure solar heaters) means, water in the tank are under high pressure, it’s equal to the pressure of tap water. Non pressure model (also called low pressure solar heaters) means, water in the tank is under low pressure, and is equal to the gravity of the water. There are some fundamental differences which you should be aware of before deciding which one works best for you and which one you should install as a Solar Water Heating System in Kenya

LOW PRESSURE SOLAR WATER HEATERS

A non pressurized solar water heater in Kenya is one that doesn’t use pumps to circulate the water or heat transfer liquid in the system. This type of solar water heater therefore depends on convention and gravity to circulate the water throughout the system.

The non pressurized solar water heaters do not depend on a heat transfer liquid but instead heat up the water directly in the collector tubes. As the water flows through the collector tubes, it gains the heat energy from the sun and gets hot. Since hot water rises, the water that is getting heated up moves up the tubes and eventually ends up in the storage tank located above the collectors.

The storage tanks are highly insulated to ensure that the water that enters the tanks remains hot for a long period. Also, the tanks need to be installed at a high ground to make it easier for the water to flow down the system for use when needed. The non pressurized solar water heaters in Kenya are also called passive solar water heaters

Typically characterized by vacuum glass tubes connected directly into a tank with a small holding tank on top of it. The low-pressure gravity system consists of a vacuum glass tube collector, an insulated storage tank and optional stand parts (make up tank). The evacuated glass tubes are filled with water and exposed to sun, thus heating up the water in the glass tubes.

Advantages

This type of solar heater is simple, with no moving parts.
Due to its simplicity, it is usually a cheaper option (roughly 50 – 60% of high-pressure systems)
Due to lower pressure and stress on the tank and collectors, it has a longer life than mains pressure solar geyser systems.
This type of solar heating system is lightweight.
Can provide hot water without external power.
This type of solar geyser system is highly effective in converting sunlight into heat

Disadvantages

It has limited uses with modern plumbing systems, as it can only be used where there is small head of pressure.
Unless it is installed at a high level above the water outlets the water pressure will be very low.
It can cause serious scalding if not installed or used correctly.
The entire solar heater system needs to be shut down even if one glass tube breaks.
All the weight of the heater is carried by the roof which may need additional support
The tank does not look very attractive when installed on top of a roof
It breaks easily

HIGH PRESSURE SOLAR WATER HEATERS

The pressurized solar water heater in Kenya is one that uses a pump to circulate the water in the system or the heat transfer liquid. This kind of system is also called an active solar water heater.

Typically characterized by an enclosed heating unit containing copper tubes connected indirectly to a tank. The tank may be located next to heating unit or separately such as under the roof. The high-pressure Direct Pressure Solar Water Heating System in Kenya features evacuated tubes and heat pipes. The evacuated tube absorbs solar energy and converts it into heat energy, this energy is then used in the process of heating water. There is no direct connection between the heating fluids in the copper tubes and the water being heated.

Since the system is under pressure and uses a pump, the water is delivered to you quickly without losing heat along the way. Another important advantage of this system is that water is delivered at a high pressure. You will have enough pressure to shower and use the water for other purposes at the same time.

That is not all, with a pressurized solar water heater you can retrofit the system to have the water stored in another tank of your choosing. This is important especially where you want to have hot water stored and accessed in different locations for those demanding uses. These systems are more robust but require regular maintenance to ensure they always perform to the very best.

Advantages

The main advantage is that the water pressure can be very high.
Works well with water pumps that have been installed
There does not have to be an ‘unsightly’ solar heater water tank on the roof.
They can sometimes be retrofitted to use existing storage tanks.
The tank or collectors can be located in more accessible or appropriate locations.
More robust than low pressure systems

Disadvantages

They are more expensive than low pressure solar heater systems
Some models require power to run the pump and temperature differential controller – this can be overcome by installing a photovoltaic module.

After having worked with both types of heaters we highly recommend spending the additional amount and installing high pressure solar water heaters.

CONCLUSION:

After having worked with both types of heaters we highly recommend spending the additional amount and installing high pressure solar water heaters. There is nothing as annoying as trying to take a shower and the hot water only keeps dripping instead of having a strong steady flow. The difference in price may sway some people to choose the cheaper low pressure option, however, if you can afford it then always go with a high pressure system.

If you want a solar water system that is reliable and provides hot water at consistent temperatures, then you should consider investing in the pressurized solar water heater. We are suppliers of quality pressurized solar water heaters and can help you choose the right one for your needs and budget.