Electric water heater (boiler): 50 or 80 litres, choice and prices

The key question when choosing an electric storage water heater (boiler) is capacity: 50 litres usually suits a 1–2 person home and 80 litres a family of 3–4, because heated water is mixed with cold water and yields roughly 1.6–1.8 times as much warm water. As of 22 September 2026, the Prayk catalogue has 278 water heater listings with a median price of 120 AZN. Interestingly, on the second-hand market an 80-litre boiler is barely more expensive than a 50-litre one: both groups have a median of 120 AZN.

Short answer: 50 litres for 1–2 people, 80 litres for 3–4, and 100 litres or two separate units for 5 or more. Prayk (22.09.2026) has 278 water heater listings: median price 120 AZN, with half of them between 75 and 200 AZN. The 85 Ariston listings have a median of 100 AZN (half between 75 and 120 AZN). Listings with “50” and “80” in the title share the same median — 120 AZN.

50 or 80 litres: how to choose by household size?

The tank capacity tells you how much hot water is available in one go. The thermostat is usually kept around 60 °C, while a shower uses water at about 38–40 °C. Hot water is diluted with cold water at the mixer, so a 50-litre tank delivers roughly 80–90 litres of warm water. In winter the mains water is colder, the ratio drops and the same boiler “runs out” sooner.

Assumptions: 60 °C in the tank, 15 °C cold water, a shower flow of 8 litres per minute and a 5-minute shower. Besides the number of people, consider habits: if everyone showers in the morning at the same time, you need a lot of water in one go; if you take turns in the evening, the unit has time to reheat. A separate small boiler (10–15 litres) in the kitchen also takes load off the main tank.

Heating time and electricity use: 50 vs 80 litres

Heating 1 litre of water by 1 °C takes about 1.16 Wh of energy. So heating 50 litres from 15 °C to 60 °C needs about 2.6 kWh, and 80 litres about 4.2 kWh. A more powerful heating element (the electric heater inside the tank) delivers this energy faster, but total consumption stays the same.

To estimate the monthly cost, add up in kWh how many full or partial heat-ups happen per day and multiply by the current tariff; the household electricity tariff is published by the Tariff (Price) Council. For a household using the same amount of hot water, the difference between 50 and 80 litres comes mostly from heat loss — the tank cooling down during the day. That is why a well-insulated model with a high energy class and a thermostat that is not set needlessly high save more than the capacity difference.

Boiler prices on Prayk: how much is normal to pay?

These numbers have two layers: the lower part of the range is used boilers sold by owners, the upper part is new models from shops. Most Ariston listings are used units sold by owners, which is why their median is below the overall median of the section. Ariston makes up about a third of the section (85 of 278).

76% of listings are in Baku (211 of 278), followed by Digah (19), Masazir (11), Khirdalan (8) and Sumgayit (7). A boiler is heavy and bulky, so choosing a listing nearby cuts transport costs — the Nearby page shows the closest listings on a map. All offers are in the Water heaters section, and related appliances are in Climate technology. The section also includes gas instantaneous heaters; this guide is about electric storage boilers.

How to compare Ariston models?

Ariston is an Italian heating brand and the most common make in the listings, so it is a handy example for comparison. When reading a model name and data sheet, look at:

• Capacity: the number in the model name usually means litres (for example, “80”).
• Mounting type: the letter V often stands for vertical and H for horizontal mounting; a horizontal unit suits a low ceiling or the space above a door.
• Body shape: cylindrical models are the classic option, flat (slim) ones fit narrow bathrooms better.
• Inner tank: enamel, titanium-enhanced enamel or stainless steel; the coating and the anode (a magnesium rod that protects the tank from corrosion) directly affect service life.
• Heating element: a “dry” element does not touch the water, collects less limescale and is usually easier to replace.
• Controls: a mechanical thermostat is simple, an electronic panel offers precise temperature and an eco mode.

Check the power rating, warranty terms and data sheet of a specific model on the manufacturer's official website. For a used unit, confirm from the seller's receipt whether the warranty is still valid.

What to check when buying a used boiler?

1. Age: look at the serial number and production date on the label and ask how many years the unit has been in use.
2. Signs of leaks: rust or limescale stains on the pipe connections at the bottom, around the flange and under the casing may mean the tank leaks — do not buy such a unit.
3. Heating element and anode: ask when they were last replaced; if never, offer to deduct that cost from the price.
4. Operation: if possible, see the unit working — the indicator should light up and after a while the outlet pipe should start to warm.
5. Kit: the safety valve, wall bracket and power cable should be included.
6. Transport: agree in advance who removes and carries the unit; a tank that has not been drained is very heavy.

Installation: what to ask the installer?

A boiler is a heavy appliance connected to both water and electricity, so installation is best left to an experienced professional following the manufacturer's manual. A general checklist:

• Electrics: ask about a dedicated circuit and breaker, earthing and a residual current device (RCD); the cable cross-section must match the unit's power.
• Wall: in an 80-litre boiler the water alone weighs 80 kg, plus the unit itself. A thin partition cannot carry that load — choose a brick or concrete wall.
• Safety valve: it is fitted on the cold-water inlet; dripping during heating is normal. Never block or remove the valve — route the drip to the drain.
• Pressure: if the building has high water pressure, discuss a pressure-reducing valve with the installer.
• Service space: leave free space under the unit for replacing the anode and heating element.

In the Masters section of Prayk, the boiler, heater and water heater installation and repair subsection has 70 listings. When choosing a professional, look at their profile and photos of previous work, and agree on price and warranty in writing in advance.

Selling your boiler: what to put in the listing?

Buyers first look for the brand, capacity (litres), type (electric or gas), age and condition. State when the heating element and anode were last replaced, that there are no leaks, what is included and who will dismantle the unit. To price it in line with the market, Prayk shows the market price of similar listings; tips on text and photos are in our article 8 rules of a listing that sells fast. If the right boiler is not listed yet, save your search and Prayk will notify you when a new listing appears.

Frequently asked questions

How many people does a 50-litre boiler serve?

Usually 1–2 people. 50 litres of water heated to 60 °C, mixed with cold water, give about 80–90 litres of warm (40 °C) water — that is two short showers. A family of 3–4 is more comfortable with an 80-litre boiler.

How long does an 80-litre boiler take to heat up?

Heating 80 litres of water from 15 °C to 60 °C takes about 4.2 kWh. With a 1.5 kW element that is roughly 2 hours 50 minutes, ignoring losses, and with a 2 kW element about 2 hours 5 minutes. At the same power, a 50-litre boiler heats up about 1.6 times faster.

How much does a used Ariston boiler cost?

As of 22 September 2026, Prayk has 85 Ariston water heater listings; the median price is 100 AZN and half of the listings are between 75 and 120 AZN. The exact price depends on capacity, age and the condition of the heating element and anode.

How much more expensive is an 80-litre boiler than a 50-litre one?

In the Prayk catalogue the gap is small: the 31 listings with “50” in the title and the 47 listings with “80” have the same median — 120 AZN (22 September 2026). On the used market, condition and brand matter more than capacity.

Can a boiler be plugged into an ordinary socket?

That depends on the unit's power and the state of your home wiring. Manufacturers usually recommend a dedicated circuit, earthing and an RCD. The exact requirements are in the installation manual; make the decision together with an electrician.

When should the magnesium anode be replaced?

While protecting the tank from corrosion, the anode gradually dissolves, so it needs periodic checks. The interval depends on water hardness and usage — follow the period given in the manufacturer's manual. If you are buying a used boiler, always ask when the anode was last replaced.

Sources and methodology

Listing counts and prices come from Prayk's public catalogue on 22 September 2026: all 278 listings in the “Water heaters” section, plus title searches within that section for “ariston”, “50” and “80”. Median and range (the middle half of listings, p25–p75) are calculated from AZN prices only. A title search finds the number anywhere in the title, so the “50” sample may include a few listings of a different capacity. Heat-up time and energy are calculated from the specific heat of water (4.186 kJ/(kg·°C)) without heat losses. Electricity tariffs: Tariff (Price) Council of the Republic of Azerbaijan. Model data: Ariston official website.