Frequently Asked Questions


I am suffering from a short-circuit. Can the water heater be at fault?

It can. First disconnect the coffee machine, the tea cooker, the hair dryer, fryer. And switch off the microwave, dishwasher or washing machine if that was running. And then try switching back on the circuit breaker and see what happens. If it blows again then most likely cause is that the heating element has cracked exposing electricity inside the heating element to water causing this short-circuit. A heating element can crack due to excessive calcification on the heating element or an air pocket has built up inside the tank exposing the heating element to air and not water. An air pocket causes excessive heating up of the heating element resulting in the cracking of the heating element.

Causes excessive calcification:  

  • Wrong pressure relief valve: If you use an 8 bar pressure relief valve on a 6 bar working pressure water heater the valve will be unable to release excess pressure. This causes excessive calcification.

Important: Avoid problems! Always install the right presure relief valve!

Lemet water heaters have a 6 bar working pressure and should ALWAYS be fitted with either the supplied WRAS approved 6 bar pressure relief valve. Wesen water heaters have a 8 bar working pressure and should ALWAYS be fitted with either the supplied 8 bar WRAS approved pressure relief valve

  • Pressure fluctuations; the pressure is too low or the pressure is too high. These pressure issues will also lead to excessive calcification.

Causes air pocket inside tank:

  • The principal cause is usually that the tank hasn’t been filled up entirely with water when it was installed. An air bubble has formed that will move through the tank. It can take a day, a week or even a couple months before the heating elements is exposed to air, overheats and cracks leading to a short-circuit.

How to avoid an air pocket in the tank when you install the water heater?

  1. Don’t plug the power cord to the socket. Leave it unplugged!

  2. Keep the water inlet closed of the mains water supply line

  3. Attach the right pressure relief valve (6 bar for Lemet. 8 bar for Wesen) to the water heater on the blue side and the other side of the valve to the water pipes (either copper pipes or flexible hose, depending what plumbing you have in the house). Never install the pressure relief valve further away than 2 metres from the blue side. Make sure the rubber washer is on the inside of the valve and do NOT overtighten the pressure relief valve

  4. Connect the water pipes to the red side to get your hot water to your shower and sinks.

  5. Now open the water inlet of the mains water supply line. Make sure it is fully opened

  6. Open a warm water tap and wait for the tank to fill

  7. The tank is filled one the water flows from the tap uninterrupted in a forceful jet

  8. Close the warm water tap

  9. Plug the power cord in the socket, switch the water heater on and set the temperature. 65 degrees celsius for Wesen and Lemet Ecoway is the ideal set temperature. For the Lemet greenline model just the knob to just below the max (in the red)

Air in the pipes can also cause an air bubble inside the tank. This can happen when the water company has repaired the water mains in your street and you have had to switch off the main water inlet in your house.

How can solve this?

  1. Please unplug the power cord from the socket

  2. Open a warm water tap and wait for the the water the flow from that tap in a forceful jet.

  3. Now plug the power cord back into the socket and switcht the water heater back on.
Who are we? is a trading division of ShopA, a Dutch company with over 5 years experience in selling water heaters in The Netherlands, Belgium, Luxemburg and Germany. Having established these markets it was a logical next step to expand on to the UK market. Wanting to offer our range of high quality and competitively priced water heaters, to both consumers and companies.

We stock the following European brands: Lemet, Wesen, Wijas and Ariston.

Lemet is a well-respected Polish manufacturer with almost 40 years of experience in manufacturing water heaters and boilers.

Wesen is a high-quality and innovative manufacturer, based in Spain, with more than 25 years experience in manufacturing water heaters.

Wijas is another Polish brand from whom we source our instant water heaters. In 1998 Wijas started manufacturing Perfect instant water heaters.

Ariston is a renowned Italian brand.

We work closely with our manufacturers to improve existing products and to develop new ones.

How can you reach us?

You may send an email to:

Or you can phone us, during business hours (Monday-Friday: 08.00-17.00)  020 33 18 17 36

And if you would prefer us to call you back: please submit a request, on our website, by using the ‘call me back button’ and we will call you as soon as possible.

Why are your electric water heaters so cheap compared to other brands and shops?

This is the most frequently asked question.

We are a highly efficient and cost-effective company:  we have a fully automated warehouse in Haarlem, The Netherlands. We work with a small and highly efficient team and we buy our water heaters in very large quantities, directly from the manufacturers, enabling us to keep our prices low.

Do you supply consumers?

Yes we do.

Do you supply companies?

Yes, we also supply companies. Often we get demands for larger projects. Send us an email to for a tailor-made quotation.

How do I order?
Find the product you want to purchase and press the button ‘Add to cart’.

In the top righthand corner of the screen you will see a black icon stating the number of items you have ordered.

Click on that black icon and either view your cart or click on the checkout icon to submit your order.

A new screen will open: this is the checkout page.  

Select ‘New customer’ if you have not ordered or registered with us before. There are two options: you can register an account for quicker ordering in the future or you can proceed as a guest. Fill in all your details to complete your order.

If you are a returning customer and have registered with us please select ‘Returning customer’ and fill out your email and password. All your details will appear, you can now proceed to finalize your order.

Can I place an order by telephone?
No we can only process orders that have been finalized and paid for in our webshop.
Do you have a showroom I can visit?
No we do not have a showroom as we are a webshop. Our water heaters are dispatched straight from our fully automated warehouse. This allows us to save costs and offer you high quality water heaters at very competitive prices.
What is the guarantee on an Ariston, Lemet, Wesen and Wijas product?

The Ariston has a 3 year guarantee on the tank and a 2 year guarantee on all other components.

Lemet has a 2 year guarantee on all components.

Wesen has a 5 year anti-corrosion guarantee on the tank and a 2 year guarantee on all other components.

Wijas has a 2 year guarantee.

In the description with each article you can check the guarantee period for your product.

If you have a malfunction it is important for us to first establish the cause. Once this has been determined we will send you the replacement part(s). Please contact us by email when you encounter a malfunction and supply us with photos so we can quickly ascertain the cause of the malfunction and whether this falls under the guarantee. Often you can solve the problem yourself, with a bit of help from us.

If you prefer you can also send the water heater back to us,so we can solve the problem for you in our workshop. We do not repair on-site as we do not have installers on the road. We do not install water heaters and cannot be held liable for installation or the dismantling of your water heater. But we shall do our utmost to assist you in solving your problem.

Please note that your guarantee will be void if you have not maintained the heater as indicated by the manufacturer or if you haven’t used the supplied safety relief valve. You can opt to use a KIWA or NSF approved safety relief valve. Always use a 6 bar for Lemet and an 8 bar for Wesen.  Never put an 8 bar safety relief valve on a 6 bar water heater or 6 bar safety relief valve on an 8 bar water heater!

Defects as a result of fluctuating water pressure are also not covered by the guarantee. Sometimes it is advisable to install a pressure reduction valve, on the water mains by the main valve, to protect your water heater from these fluctuations. Especially older buildings, farms and apartment buildings can suffer from fluctuating water pressure.

The guarantee applies exclusively on products supplied by us.

How is an energy label determined?

An energy label classification ranges from A to G with A being the most energy-efficient. The energy label will show the energy consumption of your product. All our products are ErP (Energy related Products) compliant and are subject to energy efficiency requirements.  

Tests are carried out using a standard formation in order to make a fair comparison between the various models of a particular product. If you want to know more on how a formation is built-up and how a test is carried out, please click on the link below.

The indicated energy consumption might differ from your actual consumption as water temperature, ambient temperature, usage time, eg. all play an important role in the actual energy consumption. Please bear in mind that to heat your water the heating element will always use full capacity. A 1500 watt heating element will obviously heat up 50 liters of cold water slower than a 2000 watt heating element. But in the end to heat up that 50 liters of water both the 1500 watt unit and the 2000 watt unit will use the same amount of energy.

Who are your manufacturers?


Lemet PPUH was founded by Leon Pleśniak, in 1978, to supply the local Polish market with products in heating technology. It was only later that the factory started specializing in water heating products. Lemet has evolved extensively and still is, boasting almost 40 years of experience.  With its production facility is in Branice, Opole, Lemet is still a family-owned business that currently employs 40 people. Lemet still maintains the motto: hiqh quality products at affordable prices.  

Lemet electric water heaters are currently sold in Poland, the Czech Republic, the Ukraine, Russia, Germany, Denmark and Sweden. Shop A, our parent company, sells Lemet in The Netherlands, Belgium, Luxemburg, Germany and the UK.


  • Nearly 40 years of manufacturing experience

  • High quality products

  • Competitively priced

  • Well insulated, energy efficient product

  • Can be connected as either a hot-fill or a cold-fill

  • Ecoway range with self-learning digital display with a daily programming function (3 time ranges)

  • Manufactured in the EU

  • 2 year guarantee


Wesen is a brand of Nielsen Clima Spain, with over 25 years experience in manufacturing hot water solutions. It was founded by Lasse Nielsen who, in 1981 had to design a central heating system, as part of his final year project. A few years later Lasse Nielsen was commissioned to design a heating and domestic hot water system for an old building in Berne, Switzerland, that was to be converted into apartments. His solution for hot water: electric water heaters. He started  designing a sleeker and modern looking model: a flat electric heater with two cylindrical tanks, thus seeing the start of a new venture, under the name of WESEN.

Wesen initially started producing appliances that were individually designed for the needs of each apartment building. But it was quickly launched into mass production, of various series, of the most attractive and functional water heaters on the market. Today Wesen is manufactured in both China and Spain.

Wesen electric water heaters are typified by their sleek modern design and being user-friendly. These high quality water heaters are very durable and energy efficient, using the latest technology in electric water heaters.


  • Sleek and modern design, one of the slimmest water heaters on the market

  • High quality and competitively priced

  • Manufactured with the latest technology

  • High energy efficiency thanks to the PUR foam insulation of the tank and an ingenious digital display controller

  • Different models within the range, that are either suited for both horizontal and vertical fitting (Inox Flat series) or only vertical fitting (Silver Flat series)

  • Two lightweight stainless steel (Inox) tanks making it practically corrosion free. Unique feature in the industry!

  • Two tanks instead of one, reducing the heating time considerably and solving pressure-related issues (having to withstand less pressure per square centimeter)

  • Because of very little corrosion there is no need to replace the anode any more

  • Lightweight unit thanks to the stainless steel tanks so easy to transport and to mount on a wall

  • Inox Flat Series: First tank has a double heating element. Second tank holds a single heating element

  • Silver Flat Series: First tank has a single heating element. Second tank holds a single heating element

  • Both Series: Power button to speed up heating time by running all 3 heating elements simultaneously. Unique feature in the industry!

  • User-friendly digital display

  • Complete kit with mounting bracket, safety relief valve, screws and plugs

  • 5 year anti-corrosion guarantee on the tank and 2 year guarantee on all other components.


WIJAS S.J. was established in 1971 in Poland as a family-run business. Initially it provided only tooling services but in 1980 the production of household appliances commenced. In 1998 WIJAS S.J. started to produce PERFECT water heaters.

With continuous improvements to their products the water heaters manufactured are characterised by reliability, high-quality workmanship and its compact dimensions. The company is constantly evolving: upgrading its machinery, introducing new technologies in the production process and expanding its sales network. Only high quality components of renowned manufacturers are used.

Each water heater is subject to a strict quality control before it leaves the final assembly department. Products are highly esteemed by customers: Wijas received the Golden Consumer Laurel in 2005 and the Bronze Consumer Laurel in 2006.


Ariston was founded in the 1930s in Italy and started producing electric water heaters in the Sixties. Ariston Thermo is the parent company that markets Ariston water heaters. Ariston is a leading European brand with an extensive range of products for all possible hot water solutions. Their products stand for comfort and are very energy efficient. Ariston manufactures in compliance with all European guidelines with the highest possible production standards. Ariston today has 5 production plants and over 600 employees.

The electric boilers manufactured by Ariston are high quality and innovative products. The most popular range is the Ariston Velis range is typified by the flat (10.63") and modern design. Ariston velis water heaters can be installed both vertically and horizontally. The ECO function monitors your hot water usage for a week and sets up a program according to your usage. The Ariston Velis has two inner tanks and two separate heating elements (1 of 1000 watts and 1 of 1500 watts). These do not heat up at the same time like with its competitive model Wesen. So the maximum power consumption is 1500 watt.

What is the function of the magnesium/ titanium anode?

The magnesium anode, also called electrical anode, limits the stress corrosion within the enamel tank, guaranteeing a longer life cycle of the electric water heater. The anode is also called a sacrificial anode and will corrode instead of the heating element. In other words it sacrifices itself to protect the heating element. An anode needs to be replaced every 2 to 2.5 years.

Some electric water heaters have a titanium anode instead of a magnesium anode. This is called a ACI system and works with a forced direct current voltage that is counter to the galvanized tension. This anode also needs to be replaced frequently.

What is the function of the pressure relief valve?

A water heater is a pressurized tank. When the heater operates the water inside the tank will expand. Once over the maximum tank operating pressure the pressure relief valve releases pressure from the tank by dripping water through a discharge pipe. This discharge pipe should always be installed directly underneath the pressure relief valve facing downwards to drain off the drops of expansion water into a drain.

Is the pressure relief valve you supply WRAS approved?

Yes it is. We supply a 6 bar WRAS approved pressure relief valve as standard with all LEMET water heaters. And an 8 bar WRAS approved pressure relief valve as standard with all WESEN water heaters. WRAS approved means the pressure relief valve complies with Water Supply (Water Fittings) Regulations for the UK and Scottish Byelaws.

Please make sure a discharge pipe (with or without a drain valve) is fitted directly underneath the pressure relief valve with0 a Tee fitting in between. The discharge pipe will drain off drops of expansion water coming from the pressure relief valve when the unit is operating. The discharge pipe should always be facing downwards to drain off uninterrupted in a drain. The pressure relief valve is there to reduce pressure and to prevent water from going back into the mains water supply line from the tank.

Please check this link for full details of a WRAS approval:

What is a WRAS approval?

Can you explain the function of the pressure relief valve and how water pressure works?

The water heater comes standard with a WRAS approved pressure relief valve with a maximum work pressure of 6 bar for Lemet and an 8 bar for Wesen water heaters. If you decide to use a different pressure relief valve valve and make sure it is the right bar and that it is WRAS approved. Using an incorrect pressure relief valve will result in damaging your water heater and will also void your warrantee. Never put an 8 bar pressure relief valve on a 6 bar water heater or 6 bar pressure relief valve on an 8 bar water heater!

Water pressure ensures there is sufficient water for all houses or apartments connected to the water network. Minimum water pressure required for a washing machine or central heating system is 1,5 bar. Ideal water pressure for a washing machine, dish washers and an electric water heater is around 3 bar. Anything over 5 bar will damage said household appliances.

If you live in an apartment, farm house, flat, old house or an elevated area you will most likely suffer from fluctuating water pressure and/or a too high water pressure. We highly recommend you to install a pressure reducing valve. Please install that valve where the mains water supply comes in the building and set it at 3 bar.

How does water pressure work in an apartment building?

With each meter gained in height, you will lose 0.1 bar in water pressure. To give an example in an apartment building:

  • first floor:   2,1 bar

  • second floor: 1,8 bar

  • third floor:    1,5 bar

  • fourth floor:    1,2 bar

A low water pressure will cause a reduced flow of water from your tap. First of all check if the tap is not the culprit. If the water pressure is too low please check main valve, of the water supply, to ensure that it is fully opened.

How much water does a shower use?

It depends on the shower head, the set temperature and the number of persons using the shower. Please use our water heater calculator: to find out what size water heater would probably suit your needs. It is just to help you on your way. In the end you decide what size you require. We always recommend, after using the calculator, to go for a slight overcapacity.

This calculator is based on a water temperature inside the tank of around 65 degrees celsius. You can enter the amount of people who want to shower, which shower head you use and how long each person normally showers.

To help you along here is a convenient chart of water consumption for various shower heads:

Water consumption per minute of your shower head

water-saving shower head

7 litres water per minute

Normal shower head

10-15 litres water per minute

Rain shower head

20- 25 litres water per minute

As you can see it is definitely worthwhile to consider a water-saving shower head as it saves at least 30% on water consumption. The patented shower head we offer has a very powerful jet of highly oxygenated water. See this link for full details: 

What is the maximum output of water (liters per minute)?

The maximum output of water, from your water heater, is dependant on several factors. The maximum water pressure depends on the pressure from the water network, as it is a closed system. The water pipe pressure is also influenced by the pipelines you are using. The water output also decreases as a result of narrow water pipes and by using lengthy pipeline (the longer the distance the water has to travel the less the output will be). The amount of water is thus also influenced by the width of the water inlet and outlet of the water heater. The standard water pipe diameter in the UK is ½” (15mm).

Guideline* for the maximum output of litres per minute is:

  • Diameter main water line 15mm (½”) - approximately 25 ltrs/min

  • Diameter main water line 22mm (3/4") - approximately 50 ltrs/min

  • Diameter main water line 28mm (  1 ") - approximately 75 ltrs/min

*This guideline is indicative.

What is the difference between a Wesen and an Ariston Velis?

  • The Wesen Inox Flat electric water heater looks very similar to the Ariston with its sleek and  modern design. But it is actually slightly slimmer than the Ariston Velis. The Wesen Inox Flat has a depth of 10.3”, The Wesen Silver has 9.48” and the Ariston Velis is 10.6”

  • The Ariston Velis shows the temperature per 10 degrees centigrade using LED’s. Wesen water heaters have a digital display allowing you to read the exact temperature.

  • The Ariston Velis EU boiler has a glass coated ceramic tank with an anode that needs to be replaced every 2 to 2.5  years. The Wesen has an Inox (stainless steel) tank making it corrosion free so you no longer need to replace the anode.

  • The maximum working pressure of the Wesen boiler tank is 8 bar. The 8 bar safety relief valve is always included.The Ariston Velis EU is tested up to 8 bar but is limited to a maximum working pressure of 7 bar. It also comes with a standard issued WRAS approved pressure relief (6 bar) valve.

  • The Ariston Velis EU has two separate heating elements (1000 watt and 1500 watt), which do not operate simultaneously. The Wesen Inox  has 2 heating elements. The Wesen Inox Flat has 1 double heating element in the first tank and one single in the second tank. The Wesen Silver Flat has 2 single heating elements. Activating the power button both elements will operate simultaneously, accelerating the heating process.

Inox Flat:

30 tot 50 litres, First tank: 2 x 700Watt / Second tank: 700Watt.

80 tot 100 litres, First tank: 2 x 800Watt / Second tank: 800Watt.

150 tot 200 litres, First tank: 2 x 1000Watt   / Second tank: 1000Watt

Silver Flat:

30 to 80 litres: First tank: 700 watt/ Second tank: 1300 watt.

  • Thanks to the Inox (Stainless steel) tank the Wesen water heater is much lighter than a Ariston Velis, making it easier to transport and to mount.

  • The Wesen water heater comes with the safety relief valve and the mounting screws are also included. With the Ariston Velis the safety relief valve is included but you will need to order a mounting set separately (do not forget to put this in your shopping cart during your ordering process).

Instant water heater: which instant water heater should I choose?

Please consult the following link:


What is the power consumption of an electric water heater?

The power consumption of an electric water heater is dependent on several factors. According to a Dutch government website power consumption is between £150 to £500 annually.

Here are the deciding factors to determine your consumption:

  • The size of your water heater in liters

  • Do you use a water-saving shower head or a rain shower? (see statistics below)

  • How often do you use warm water?

  • At what temperature do you use hot water?

  • How long do you use hot water for? (how long do you shower?)

  • What is the ambient temperature?

  • At what temperature is the water heater set?

  • What power does your electrical heater have?

Approximate water consumption per minute of your shower head

water-saving shower head

7 liters of water per minute

Normal shower head

10-15 liters of water per minute

Rain shower

20-25 liters  of water per minute

Can I put an electric water heater on an existing circuit?

Water heaters up to 150 liter can be fitted with a standard earthed plug and can be connected to an existing circuit on your circuit board. A standard fuse in the UK is 16A, which translates into 3600 watt.

Most water heaters have a heating element of between 1500 watt to 2000 watt, which translates to 6.5 to 8.7A. The 80 litre Wesen Inox Flat has the largest output of 2400 watt translating into 10.9A.

For water heaters of 200 liter or more we have two options:

  • The standard option of a single phase (230 vac) heating element

  • Or the power current option of 380Vac.
Can I install an electric water heater as replacement for a central heating boiler?

We wouldn’t recommend this as it will take a very long time to heat your living space. You would need to buy a very large electric heater that is capable of heating a substantial amount of water, which simply would not be economical compared to an ordinary gas-fired central heating boiler.

Moreover, the life expectancy of the anode and heating element would be much shorter as there is a lot of metals and other dirt in a closed central heating system that would corrode these parts very quickly.

You could use the electric water heater as a buffer tank and integrate it with an existing system, such as a wood fired boiler. These buffer tanks will not need a heating element or anode and instead of a glass coated enamel inner lining it will have to have a metal lining.

Can I connect an electric water heater to a gas-fired central heating boiler?

If you intend to fill the electric water heater with hot water from the central heating boiler, the answer is yes. This is called a hot fill and is possible with every single water heater we sell in our webshop. But we wouldn’t recommend it as it is a closed system with lots of dirt and other residu in the water. This will soon damage the water heater.

If you want to use hot water from the electric water heater to fill the central heating boiler please ask the supplier of your central heating boiler. Please mention to your supplier that it has to be suitable for hot fill.  

What is water pressure , bar and why would I need a pressure reducing valve?

Water supply network

The average water pressure is around 3 bar. The minimal water pressure your water company has to offer is 0.7. If that is the case you should have hydrofoor (a water pump)  installed to increase water pressure so the flow of water from your tap and shower is sufficient. A hydrofoor normally produces too much water pressure. So installing a pressure reducing valve set at 3 bar (optimal water pressure for all household appliances) is vitally important. Anything over 5 bar will damage your electrical appliances such as; the diswasher, electric water heater and your washing machine.

If you live in a house the water pressure downstairs will be higher than on the first floor. Besides that the water pressure can fluctuate per floor. For instance when you are using a lot of water in your kitchen the water pressure will fluctuate as a result of it. Logically you will have less water pressure in the bathroom on the first floor.

Electric water heater

Every water heater will have a maximum tank working pressure indicated in bar or mPa. This is the pressure building up inside the tank as a result of heating the water. So not the water pressure coming from your water mains.

Every single electric boiler (electric water heater) sold in the UK should comply with EU standards and is able to cope with a high water pressure for a short period of time. A boiler operating above the maximum working pressure for a longer period of time will get damaged. Therefore it is vitally important to use the right pressure relief valve. NEVER USE AN INCORRECT PRESSURE RELIEF VALVE. So please consult the manual of your electric water heater to find out what the maximum working pressure is for your product and use the supplied (or right) bar safety relief valve. The non-return valve inside the safety relief valve will prevent the water returning to the water mains from the electric water. So if you use an incorrect safety relief valve it will cause leakage and excessive calcification. An example: if you use an 8 bar pressure relief valve on a 6 bar maximum working pressure electric water heater the tank inside will build up excessive pressure (over the 6 bar maximum working pressure) leading to leakage from the tank (with a good chance of a short circuit) and excessive calcification inside the tank. So always use the right pressure relief valve.

Pressure relief valves for Lemet and Wesen electric water heaters

The pressure relief valve will kick into action releasing pressure by dripping water from that safety relief valve. For the Wesen the operating pressure is 8 bar, so if the pressure inside the tank builds up over 8 bar i twill release pressure through the pressure reliief valve. The Lemet electric water heaters have a 6 bar operating pressure, so anytime the pressure surpasses 6 bar the pressure relief valve will release the excess pressure.

Pressure reducing valve.

this is not a pressure relief valve but a valve that regulates pressure. The pressure reducing valve allows you to set the water pressure at 3 bar (the ideal water pressure) and it helps avoid water fluctuations. We recommend to always use a pressure reducing valve when you live in flat, apartment building, farm or live in an elevated area. Or if your company works from an industrial estate or old warehouse. A pressure reducing valve set at 3 bar will help avoid damage to your faucets, electric water heater, dishwasher and washing machine.

Apartment buidlng and flats

Often an apartment building or a flat will have a pump (a hydrofoor) to get the water up to the top floor. This can result in a water pressure of over 7 bar on the lower floors whilst the topfloor just has two bar water pressure. Another problem is fluctuation in water pressure when several people in your buliding use water. You can imagine that if the ground floor apartments use water at the same time there will be little water pressure on the top floor.

This can be damaging to your electric water heater and the other, before mentioned household appliances. Fluctuations will cause air bubbles to form inside the tank of the water heater eventually exposing the heating element to air causing it to overheat and short circuit.

The solution to avoid these issues is to install a pressure reducing valve. For an apartment building preferably on every floor where the water comes in. Or for a warehouse or normal house where the water mains enter your premises. A pressure reducing valve is the easy solution! (PAGE 8).


For more details regarding water pressure please consult the following links:


When choosing an electric central heating boiler, why do you specify square meters and not cubic meters?

The manufacturer has chosen to express the surface a unit can heat in square metres instead of cubic metres. That surface is based on a room height of no more than 7’9”(2.4 metres). Example: the 4kW model will heat a space of 50m2 with a height of 2.4 metres.

I use 1200m3 of gas per year. What would my energy costs roughly be if I would switch to an electric central heating boiler?

If you know what your gas consumption is per year you will have a rough indication, using the calculator below (we emphasize that this is a mere indication). Once you have switched to an electric unit you will not need gas any more. Also an electric unit is lower in maintenance compared to a gas-fired central heating boiler. In the calculator we have used 0,17 pence per kWh as the price for electricity. An average household uses roughly 1500m3 of gas annually.

Do I need a three-phase power supply for an electric central heating boiler?

Our electric central heating boilers can also be supplied as a 230 Vac version up to 9kW. You would of course require a separate circuit for the water heater on your circuit board. Please check the description of the product on our website for the necessary power supply and corresponding fuse.

Can I replace a gas-fired model for an electric central heating boiler?

Yes you can, but please make sure you use the supplied safety relief valve to retain the guarantee.

Please note that an electric central heating boiler is for heating your living space only, and not to produce hot water for shower and sink. For hot water you will need a separate electric water heater to supply hot water or instant water heater.

What capacity electric central heating boiler do I need to replace my gas-fired model?

A gas-fired central heating boiler normally has a higher capacity than an electrical model, as it also produces hot water for your shower and/or bath. In theory, the output you need to heat up your house with a gas-fired boiler is the same as it is with an electrical model. So if you require 9kW output with a gas-fired central heating boiler to heat up your house you would require roughly the same for an electric central heating boiler.  

Can the electric central heating boiler heat water?

No, it cannot. It can only heat your radiators and/or floor heating system.

What do I need to fit an electric central heating boiler?

Assuming you want to replace your gas-fired central heating boiler with an electrical model the first step is, obviously, to get rid of the gas-fired model and install the electrical model. Make sure you replace the existing valve with the supplied safety relief valve meant for the electric central heating boiler (ensuring optimal effectivity of your new boiler as well as to retain the guarantee).

If you are placing an electric central heating boiler in a new situation, where it does not replace an existing gas-fired model, bear in mind that you will need to order the radiators and/or floor heating system elsewhere as we do not supply any of these accessories.
Which electric central heating boiler should I choose?

Please note, that when you choose an electric central heating boiler you must bear in mind that it is strictly for heating the radiators or for your underfloor heating and NOT for providing hot water for a shower, a kitchen tap or a bath. Check for the entire range.  

Not every household will have sufficient power supply to install an electric central heating boiler. Always consult a certified electrician first to asses what is possible for your house. And to see what alterations in your circuit board need to be carried before purchasing an electric CV boiler.

You might find the following chart helpful in deciding what kWatt output you require to be able to heat your living space sufficiently. The manufacturers have chosen for square meters, based on a room height of no more than 7’9”(2.4 meters).  





4 kW ->

50 m2

12 kW ->

150 m2

6 kW ->

70 m2

18 kW ->

220 m2

9 kW ->

110 m2

24 kW ->

300 m2

What are the annual electricity costs of an electric central heating boiler?

It’s impossible to calculate. It depends on too many factors: the ambient temperature, set temperature, the temperature of the water etc.

In practice an electric central heating boiler will not differ much from a gas-fired heating boiler.
What is the power consumption of an electric central heating boiler and an instant water heater?

Assuming you have an electric central heating boiler or instant water heater of 9kW it goes without saying that it will consume 9kW. How often it has to heat up all depends on the set temperature, ambient temperature, temperature of the water etc. And that will determine your total consumption.

What is a heat pump boiler?
A heat pump boiler takes air in through a ventilation system and extracts ambient heat from that air to heat the water. The air drawn in is channelled through a heat exchanger that is filled with a coolant that produces a gas. The created gas is sucked in by a compressor creating a higher temperature. That heated gas is then sent through a second heat exchanger creating more heat. The heat with the addition of electrical energy leads to a desired temperature that helps produce hot water. This process repeats itself to adhere to your hot water request.  

Compared to a conventional electric water heater a heat pump boiler uses up to 3 times less energy. A heat pump boiler will only be economically interesting when you use more than 100 litres of warm water a day. It goes without saying that the more warm water you consume per day, the more interesting the option of installing a heat pump boiler, becomes.
How can I pay?

In our webshop you can either pay with paypal, by creditcard or by bank transfer. Please take note that with a bank transfer it will take longer to process the payment and this will prolong the shipping time.  This is because of the time the bank needs to process the transfer. Other payments are processed instantly.

As soon as a payment is processed we will ship your order.  

Important: For Paypal payments the address you used to register with Paypal has to correspond with the delivery address. If these addresses do not correspond we cannot ship your order.

Can I pay my order by bank transfer?
Usually all our payments go through our payment provider, If you would prefer to pay by bank transfer  this is also possible. However please bear in mind that this way of payment will result in a delay in receiving your delivery. The reason: a transfer process takes approximately 5 days, depending on your country. Only once we have received a full payment your order can be processed and shipped.

In theory you should have received an email from with all the details. The details are the same as below:

Bank account no.: NL40INGB0654880735

Made out to: Stichting derdengelden sisow


Important: Clearly state your invoice number for reference when paying by bank transfer. A wrong invoice number or no invoice number will result in a further delay in processing your order.

Can I get a discount?

Normally, we do not give discounts as the prices we offer are already highly competitive. However, for larger orders we can offer you a discount. If you are considering purchasing a large quantity please contact us by email ( so we can make you an offer.

Why have I not received an invoice yet?

When you finalize your order and have paid for it you will receive a purchase confirmation email from us. In the attachment of that email there is a PDF file with your invoice. Please be advised that it is important to retain this invoice, not only for your own administration but because the invoice is also your guarantee certificate.

You will need a PDF reader such as: Adobe Reader.

If you do not have a pdf reader please click on the link  below to download a pdf reader.

Adobe Reader

Do you ship abroad?

Yes, we do. Please do not hesitate to contact us, by email (, to enquire about shipping abroad. We will gladly supply you with a personal quote to suit your specific shipping needs.

How much are the shipping costs?

For the UK we have one flat rate shipping fee of £15.00 for all water heaters up to 100 litres. For the larger Lemet units of 200, 300,400, 500 and 800 litres we will charge an additional £50.00. These units will be shipped directly from the factory and usually will take 1 or 2 weeks to be delivered.   

Can I pick up my order at your distribution centre?
Because of our fully automated warehouse in The Netherlands, this is unfortunately not possible.
When can I expect my delivery?

Your order should be with you within 3 working days, after we have received a complete payment. Please bear in mind that a bank transfer will result in a delay in receiving your delivery. The reason: a transfer process can take up to approximately 5 days, depending on your country. Only once we have received a full payment can your order be processed and shipped.

Orders of larger water heaters shipped directly from the factory usually take around 7-9 working days to arrive.

The box I have received has already been opened. Is that right?

Yes it is possible that the box has been opened. Every electric water heater is double checked for any visible damage and whether the pressure relief valve has been included in the box. We want to make sure that we send you a complete set.

There is some water in the electric water heater is that normal?
In the factory random checks are carried out. An electric water heater will be filled with water and is switched on to check for leaks and other faults. For this purpose the factory uses specially disinfected water to avoid bacteria build-up and eliminate the possibility of the formation of legionella. 99.9% of that water is afterwards removed from the electric water heater, but it can happen that a few drops or a small pocket of water remains in the tank. 
We emphasize that we only sell new electric water heaters, so rest assured you will never receive a second hand water heater. We assure you that boiler you have been sent is absolutely new.
Why is the button of my 5 or 10 litre water heater loose?

Unfortunately it can occur, that during transport, the button comes undone. This can occur due to the fact that the bracket, securing the thermostat, moved.

Press the button firmly onto a screw or a silver/copper-coloured pin. Use a screwdriver to slide the button into place over the hole so the button will function. See the instruction video.


How do I report damage?

It can occur that your order has been damaged during transport, even though the utmost care has been taken. All our products are shipped with an insurance (special delivery guaranteed), so in case of loss or damage we will be able to claim compensation. It is imperative that you check your parcel immediately upon receipt, for any damage or missing parts. Please inform us immediately if there's damage or a part missing.

If you are missing parts or your parcel is visibly damaged please report this immediately to us by email, so we can solve the matter. In case the delivery person has already left, please contact the shipping company as well to report the loss or damage. This is very important for a successful compensation claim. If you wait a day the shipper will claim it happened after delivery and no compensation will be rewarded!

When a box is visibly damaged please take pictures as proof and email these pictures to us. Make sure to:

  • Take a clear picture of the damage

  • Photograph the entire water heater with the damage clearly visible

  • Photograph the packaging of the damaged boiler
Can I return goods to you?

We respect your statutory right. You may return your order within 14 days after receiving it.

Please note that non franked shipments will be rejected!

What we DO take back:

  • Products that are returned to us within 14 days of receiving your order

  • Unused products

  • Returned products must be intact and in their original packaging

  • Parcels with sufficient postage paid

What we DO NOT take back:

  • Products that have been connected to the water inlet

  • Returned products with parts missing

  • Returned products no longer in their original packaging

  • Products that are returned to us, after 14 days of receiving your order

  • Parcels that do not have sufficient postage paid

Because electric water heaters are used for drinking water and kitchen purposes we are bound by a number of hygienic regulations. Therefore we can ONLY accept the return of electric water heaters, instant water heaters, central heating combi boilers and solar heating systems that are unused, unopened and are still in their original packaging.

Return address:

Bower Green

℅ waterheaterstore

Norwood Green

Station Road




Because electric water heaters are used for drinking water and kitchen purposes we are bound by a number of hygienic regulations. Therefore we can ONLY accept the return of electric water heaters, instant water heaters, cv combi boilers and solar heating systems that are unused, unopened and are still in the original packaging.
What should be inside the box?

All electric water heaters come with a free of charge safety relief valve. You need to use the supplied safety relief valve to retain the guarantee. You will also receive a flexible hose to attach to the safety relief valve. This hose releases the  excess pressure, by releasing droplets of water from the valve.

The box does NOT contain copper pipes and compression fittings or a flexible hose to connect the water heater to your water inlet. Please visit your local DIY store for these parts.

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