When you return to your Athens home after months you may be alarmed to find that the water from the hot tap is cold. Alternatively, on first opening up the home after a long period of closure, you may be met with an unpleasant smell of eggs. There may even be a damp patch on the outside of the terrace. These can be signs of a problem with the solar water heater (iliakos thermosifonas), but the source needs to be investigated.

As reported by the industry, many Greek homes have solar collectors and a storage tank installed on the roof or terrace. Industry figures put their combined energy savings at more than 4 billion kWh a year. They last for a very long time, so are usually forgotten until they fail. Energymag

Quick answer: How to maintain a solar water heater in Greece?

  • Follow your model’s maintenance schedule. EBIL’s manual recommends visual checks twice a year and professional servicing every two years. Pyramis Premium instructions include an annual anode check, so a two-year interval is not suitable for every unit.
  • Keep the maintenance invoices and service records. Periodic maintenance and its documentation can be conditions of the manufacturer’s warranty.
  • Investigate a constantly dripping safety valve. High water pressure is one possible cause, but the valve and system need checking.
  • Check the solar water heater before leaving for extended periods. Turning on the electric heating element with an empty tank could result in serious damage. ebil.gr

It is essential to follow the instructions of the manufacturer of your unit. For the wider context, read what happens when a home in Athens is left empty.

How do Greek solar water heaters work?

Most solar water heaters in Greece are closed-circuit thermosiphon systems. As described in the manuals of two Greek manufacturers, EBIL and Pyramis, the “closed-circuit” system consists of:

  • A collector that heats an antifreeze fluid in a sealed circuit.
  • A heat exchanger in the tank that passes this heat to your domestic water.
  • An electric element, switched on and off by a thermostat, to complement solar collection on dull days.

As mentioned above, the solar unit is composed of two separate water systems: the antifreeze fluid one and the potable water one. Thus, failure of one system does not necessarily mean failure of the other.

What does regular maintenance involve?

This is manufacturer guidance. Details vary by model.

  • Visual inspection: Collector glass, connections, pipe insulation and the storage tank should be checked for damage, leaks and cleanliness. EBIL recommends this twice a year.
  • Professional servicing: EBIL specifies servicing every two years, covering components including the flange, safety valve, electric heating element, anode and closed-circuit fluid.
  • Tank cleaning: EBIL recommends cleaning scale and sludge from the tank every two years.
  • Anode checks: Pyramis Premium instructions require the magnesium anode to be checked annually and replaced when sufficiently worn or covered in deposits. ebil.gr

Improper use, unauthorised repairs and excessive pressure can affect warranty coverage. Check the terms for your particular unit.

Better still, be able to show the date of last servicing. An invoice, with a date, for the servicing of your solar water heater is a very useful document. You will find a detailed Greek home insurance guide for overseas owners elsewhere on this website.

What do the anode and scale do?

Inside the tank there is a magnesium rod (anodio magnisiou), which corrodes to help protect the steel tank. It will need to be replaced, a job for a technician, when it has been used up. If it is neglected, the tank can become vulnerable to corrosion and leaks.

Water hardness affects the build-up of scale in the solar water heater and storage tank. However, the permitted water specifications and maintenance intervals vary by model. A general hardness figure for Athens should not be used to decide whether your particular heater needs annual or two-yearly descaling.

Ask your technician to assess the deposits and local water conditions, and follow your unit’s manual. The Pyramis Premium manual, for example, includes specific water-quality limits and an annual anode inspection requirement. pyramis.gr

Why is my solar water heater leaking?

Common causes include:

  1. Loosened or worn connections. Tightness and possible replacement of seals should be checked as described in the manual.
  2. Constant dripping from the safety valve. Occasional discharge during heating can be normal. Persistent dripping may involve excessive pressure, thermal expansion or a valve fault and needs professional diagnosis.
  3. A worn tank, flange gasket or anode seat. These are for the technician’s attention and possibly a repair or replacement.
  4. A leak in the external piping of the system. It must be found and repaired.

Never block or bypass the safety valve to stop a drip.

The water collects on the roof and could drip through to the apartment below or stain the ceiling. In the case of shared roofs it could even drip down onto a neighbor’s balcony.

If a solar water heater has been installed on a roof shared with other owners, it is best to clarify who bears the cost of roof repairs. If water leaks through the ceiling and floods the apartments below, our guide to water leaking from an apartment above explains the practical next steps.

Can water pressure damage a solar water heater?

Yes, high mains pressure can cause unexpected problems such as leaks and unusual dripping of the relief valve. The two manufacturers give different requirements for their systems.

  • EBIL: The consulted manual requires pressure reduction and an expansion tank when mains pressure exceeds 6 atmospheres.
  • Pyramis Premium: The manual specifies a pressure reducer when supply pressure exceeds 8 bar. ebil.gr

These are examples from particular manuals, not interchangeable settings for every solar heater. Your technician should check the instructions for your exact model and specify the correct valve, pressure control and expansion arrangements.

A constantly dripping valve does not automatically need replacement. The cause should be diagnosed first; a faulty valve must be replaced with the correct component.

How do you protect a solar water heater in winter?

The Athens area has relatively mild winters but the northern suburbs such as Kifisia and Ekali have colder winter periods than the coast.

The antifreeze solution in the closed-loop system is designed to protect the system in winter. The consulted EBIL manual’s dilution table gives protection to approximately −6°C for a 20% concentration of its specified fluid. This is not a universal dilution rule: different fluids and manufacturers have different requirements. The technician should check the fluid, concentration and condition of the circuit at each service. ebil.gr

In winter:

  • The less sunny weather means that the backup electric heating may be needed more to supply hot water.
  • Check exposed pipe insulation and look for valve leaks after a cold snap.
  • Drainage: Check accessible roof and terrace drains for debris and blockages after bad weather. Look for standing water and signs of damaged waterproofing. See storms and empty homes in Greece.

What should you check after a long vacancy?

  • Summer cover: Before a long summer absence, ask your technician whether the manufacturer requires an opaque collector cover and arrange safe fitting. Collectors can reach extremely high temperatures, and overheating can trigger a safety cut-out. A technician should investigate before resetting it.
  • An empty tank: This is one of the most serious problems. The electric element must never be switched on with an empty tank.
  • Odour: A persistent unpleasant smell from the hot water needs investigation. Ask a technician whether the tank or pipework needs cleaning rather than attempting to drain a hot system yourself.
  • Standing water: Legionella bacteria can grow in stagnant water, particularly at temperatures of 25–42°C. Infection can occur through inhaling contaminated droplets, including those produced by showers. EODY identifies temperature control, maintenance and reducing stagnation as preventive measures. ΕΟΔΥ
  • Visible condition: Is there any sign of leakage from the tank or pipework? Is the safety valve discharging persistently? Is there unexplained standing water on the roof?

After months of vacancy, ask a qualified technician about appropriate flushing and bringing the water system back into use before showering. Flushing should minimise exposure to spray, and a smell-free system is not proof that the water is safe.

The home watch service that I carry out for my members includes a check of the cold water system as part of the overall check. This does not replace specialist water-hygiene assessment or solar heater servicing.

Solar heater leaks can develop slowly, and by the time service is booked, a big stain may have formed on someone’s ceiling. Homeowners that want to avoid these kinds of problems have a dated record of the last service of their solar heater and a local contact that can check the roof top and the hot water system while they are abroad.

Yanis, Founder of Home Watch Athens

How Home Watch Athens can help

Home Watch Athens is a founder-led, members-only property oversight service for owners who live abroad. We do not service solar heaters or manage short-term rentals. However, we watch for visible signs of failure and organize appropriate maintenance and repair for you:

Services outside the regular visit, including technician attendance and repair coordination, are quoted separately and require your approval.

Please visit our home page to read more about us or our property management in Athens page for more information about our property services in Athens.