An instant geyser, often interchangeably called an instant water heater or tankless water heater, is a marvel of modern plumbing that delivers hot water on demand, without the need for a bulky storage tank. Unlike traditional geysers that constantly heat and store water, instant geysers only activate when you turn on the hot water tap, heating the water as it flows through the unit. This on-demand heating translates to significant energy savings, reduced waiting times, and a compact design ideal for small spaces.
Perfect for bathrooms with single showers, kitchen sinks, or any point-of-use where quick hot water is needed, instant geysers offer convenience and efficiency. This buying guide will help you understand the types, capacities, safety features, and considerations for choosing the best instant geyser for your home.
1. Fuel Type: Electric vs. Gas
Instant geysers primarily come in two fuel types, each with its own set of advantages and considerations.
Electric Instant Geysers:
How they work: Use an electric heating element to rapidly heat water as it passes through the unit.
Pros: Generally easier and cheaper to install as they only require an electrical connection and water lines. No harmful fumes are released, making them safer for indoor installation without special ventilation (though proper earthing is crucial). Very compact and can be mounted directly above a sink or shower. Provide consistent hot water as long as power is available.
Cons: Require a high current draw (typically 3kW to 6kW or more), which means they need a dedicated electrical circuit and proper wiring. Higher running costs compared to gas for very heavy or continuous usage, especially if electricity tariffs are high. May struggle to provide very hot water in extremely cold climates if the inlet water temperature is very low and the flow rate is high. May not be suitable for multiple simultaneous outlets (e.g., two showers running at once) without experiencing a drop in temperature or flow.
Best for: Kitchen sinks, single bathrooms, small households, or as a secondary hot water source.
Gas Instant Geysers:
How they work: Use LPG (Liquefied Petroleum Gas) or PNG (Piped Natural Gas) to heat water with a burner as it flows through.
Pros: Generally offer higher flow rates and a larger volume of hot water compared to electric models, making them more suitable for slightly higher demand or multiple outlets. Lower running costs than electric models, especially for prolonged use, as gas is often cheaper per unit of energy than electricity for heating.
Cons: Require a gas line connection (LPG cylinder or PNG pipeline). Crucially, they require proper ventilation to safely exhaust combustion by-products like carbon monoxide. Typically larger than electric models. Installation can be more complex and require professional certification for gas lines. Safety risks if not maintained or ventilated properly (carbon monoxide poisoning, gas leaks).
Best for: Homes with reliable gas connections, larger families with higher hot water demand, or where running costs are a primary concern.
2. Capacity and Flow Rate: Matching Your Needs
Unlike storage geysers measured in liters of stored water, instant geysers are primarily rated by their power (kW for electric, L/min for gas) which determines the hot water flow rate. They usually have small internal tanks (1-6 liters) which are more about instantaneous volume than storage.
For a single kitchen sink (washing dishes):
- Electric: 3 kW (good for light use) to 4.5 kW.
- Gas: 3-5 Liters/Minute (LPM)
For a single bathroom shower (bucket bath or quick shower):
- Electric: 3 kW (for moderate heating) to 4.5 kW or 6 kW (for colder climates or faster heating).
- Gas: 6-8 Liters/Minute (LPM)
For more demanding showers or very cold climates (Electric):
- Look for models with 4.5 kW or 6 kW power ratings. These provide a higher temperature rise at a given flow rate.
Factors to Consider:
Inlet Water Temperature: In colder regions, the incoming water is colder, requiring more power (higher kW for electric, higher LPM for gas) to achieve a comfortable hot water temperature at the same flow rate.
Desired Temperature Rise: How hot you want your water to be.
Number of Simultaneous Outlets: Instant geysers are best for point-of-use. If you need hot water for a shower and a sink simultaneously, consider a higher-capacity gas model or two separate instant geysers (one for each point of use).
3. Safety Features: Non-Negotiable Protection
Safety is paramount for any water heater. Modern instant geysers come with multiple layers of protection.
For ALL Instant Geysers (Electric & Gas):
- Thermal Cut-off: Automatically switches off the heater if the water temperature exceeds a safe limit (e.g., 50°C to 60°C), preventing scalding and damage.
- Pressure Release Valve (PRV) / High Pressure Withstanding Capacity: Releases excess pressure if it builds up inside the unit, preventing bursts (especially important for high-rise buildings with high water pressure, look for 8 Bar pressure rating).
- Auto Shut-off: Turns off the heater if water flow stops or is insufficient (dry heat protection).
Specific to Electric Instant Geysers:
- Shock-Proof Body: Made from high-grade ABS plastic to prevent electric shocks.
- Earth Leakage Circuit Breaker (ELCB) / RCCB (Residual Current Circuit Breaker): Integrated or recommended as an external device, it detects small leakages of electric current and instantly cuts off power, preventing severe shocks.
- Fire Retardant Cables: Internal wiring designed to resist fire.
Specific to Gas Instant Geysers:
- Oxygen Depletion Sensor (ODS): Shuts off the gas supply if oxygen levels in the room drop below a safe threshold, indicating poor ventilation and a risk of carbon monoxide buildup.
- Flame Failure Device (FFD): Automatically cuts off the gas supply if the flame extinguishes unexpectedly.
- Overheat Protection: Similar to electric, prevents excessively hot water.
- Carbon Monoxide (CO) Detector: Crucial. While usually not built into the geyser itself, it is highly recommended to install a separate CO detector in the room where a gas geyser is placed. CO is an odorless, colorless, and deadly gas.
- Venting System: Ensure it has a proper exhaust vent for combustion gases.
4. Power Consumption and Energy Efficiency
Instant geysers are highly energy-efficient for intermittent use, but power ratings vary.
Electric Instant Geysers:
Power Rating (kW) - Typically range from 3 kW to 6 kW. This is the power consumed when heating. The higher the kW, the faster and hotter it can heat water at a given flow.
Energy Consumption - They only consume electricity when the hot water tap is on, minimizing "standby losses" common in storage geysers. Your total electricity bill depends on duration of use and local unit rates.
Gas Instant Geysers:
Efficiency - Generally very energy-efficient as they only burn gas when hot water is requested.
Recommendation - While instant geysers inherently save energy by not storing hot water, choose the right capacity to avoid over-sizing (which can lead to higher upfront cost) or under-sizing (which might not provide enough hot water).
5. Inner Tank Material (for the small internal tank)
Even instant geysers have a small internal heating chamber/tank.
- Stainless Steel: Durable and resistant to corrosion.
- Copper: Excellent heat conductor, but can be more prone to corrosion in certain water conditions.
- Coating (Glass-lined/Vitreous Enamel): In some models, the small tank might have an anti-corrosion coating to enhance durability, similar to storage geysers.
- Recommendation: Look for high-quality materials with anti-corrosion properties, especially if your area has hard water.
6. Installation and Design
Location - Install close to the point of use (e.g., in the bathroom, above the kitchen sink) to minimize heat loss in pipes and get hot water faster. Ensure it's in a well-ventilated area, especially for gas geysers.
Professional Installation - Always opt for professional installation by a certified technician. This ensures correct wiring/gas line connections, proper earthing (for electric), and adherence to safety standards. Incorrect installation is a major safety risk.
Design - Modern instant geysers are compact and come in sleek designs (vertical or horizontal) and various colors to blend with bathroom or kitchen aesthetics.
High-Rise Building Compatibility - If you live in a high-rise building, ensure the geyser is rated to withstand high water pressure (look for "8 Bar pressure" or more).
Conclusion
An instant geyser is an excellent investment for quick, energy-efficient hot water delivery at the point of use. By carefully assessing your specific needs for capacity and flow rate (e.g., for a sink vs. a shower), deciding between electric (convenient, safer indoors) and gas (higher capacity, lower running cost but requires ventilation), and, most importantly, prioritizing multiple safety features, you can choose a reliable and convenient appliance. Always ensure professional installation to guarantee safe and optimal performance.