Preparing domestic hot water is not only a matter of comfort, but above all of running costs, energy efficiency, and the ability to integrate with renewable energy sources. For investors this means choosing a solution matched to their lifestyle; for installers and designers it means proposing a system that will operate stably and economically for years. What should you pay particular attention to if you want to heat water efficiently and economically?
Key takeaways
- There is no single best domestic hot water (DHW) system, because the choice depends on the number of draw-off points, available space, access to gas, and the comfort expected.
- Instantaneous gas solutions are a good choice where compactness and quick access to hot water without storage matter.
- A DHW heat pump with an integrated cylinder works well where water demand is higher and there are several bathrooms.
- Hybrid PVT panels can realistically cut gas use for DHW preparation by more than 25%.
- In modern installations, the heat source’s cooperation with renewables and matching the system to the building’s real needs are becoming increasingly important.
How to match a DHW system to the building and the household’s needs?
The first rule is simple: the hot-water source should cover users’ actual demand. In an apartment or a small unit, compact dimensions and simple installation usually matter most. In a single-family house, output and the ability to use several draw-off points at once while keeping a stable water temperature become more important. Remember that oversizing the appliance means unnecessarily higher purchase and running costs.
When will a gas boiler or instantaneous water heater work best?
A gas instantaneous water heater or a combi boiler will work well where hot water should be available as soon as the tap is opened and there is no room for a cylinder. Such appliances are best installed close to the draw-off points. Their advantages are compact size and — in modern models — economical operation and a stable water temperature.
If, however, the house has a higher DHW demand, a better choice will be a system boiler with a cylinder. This solution lets you store a larger volume of hot water and raise user comfort, especially when the household uses the kitchen and bathroom at the same time. An extra advantage of a gas boiler is the option of summer mode — DHW only — which reduces gas use outside the heating season.
A DHW heat pump – who is it best for?
A heat pump is an option for people who want to cut running costs and increase the share of renewable energy, or who do not have access to gas. Typically the appliance heats the rooms (central heating) and provides domestic hot water (DHW), and in the case of inverter heat pumps such as Termet Heat Titanium Pro, it can also cool rooms on hot days.
The market also offers lower-output heat pumps designed specifically for heating domestic hot water. An integrated cylinder of 80 to 300 liters makes it possible to provide hot water even with several bathrooms. Such appliances are energy-efficient, almost maintenance-free, and work well with a PV installation, which lets you power the pump with free electricity.
It should be remembered, however, that a heat pump needs installation space and a properly prepared system (a cylinder is required). In practice this is a particularly attractive solution in new homes or when comprehensively modernizing the system. An advantage is the option of a subsidy, for example from the Clean Air (Czyste Powietrze) program.
PVT panels and hybrid systems, or how to lower DHW costs
Hybrid installations are an increasingly popular direction, for example a gas boiler working with PVT panels. Photovoltaic-thermal panels produce electricity and heat at the same time, and the heat can be used to warm water. On sunny days PVT can fully cover water-heating needs, and in less favorable conditions the boiler takes over that role in part or in full.
Packages such as the Termet GOLD PLUS II boiler with two PVT panels can cut the gas needed to prepare DHW by more than 25% and lower the system’s emissions by around 24%. This shows that you do not always have to choose between gas and renewables, because the best result often comes from a well-considered combination of the two.
What to choose in practice?
For apartments, small units, and points with modest water draw-off, instantaneous solutions are usually enough. In single-family houses with higher hot-water demand, systems with a cylinder — gas or heat-pump based — work better. Investors focused on cutting costs and greater energy independence should consider integrating the heat source with PV or PVT.
When choosing how to prepare DHW, the most important thing is not betting on the “trendiest” solution, but matching the system to the specific conditions: the building, the number of users, and the comfort expected. In practice the solutions that work best are flexible ones, i.e. a modern gas boiler, a heat pump with a cylinder, or a hybrid system with PVT, designed as a coherent, efficient system.
You can learn more about how a gas boiler works with photovoltaic panels from Akademia Ciepła — Termet S.A. on YouTube: