Boilers in Tenerife work hard. Hot water on demand through a system that constantly cycles water at high temperature — while that water is carrying 500–600mg/L of dissolved calcium and magnesium. Every time that water is heated, some of those minerals solidify and stick. Over time, the heat exchanger, pipes, and components accumulate scale that reduces efficiency, increases the load on the system, and eventually causes premature failure. It's slow, invisible, and expensive when it finally happens.

What Limescale Does to a Boiler

A boiler's heat exchanger is designed to transfer heat from the burner to the water passing through it. When scale forms on the internal surfaces of the heat exchanger, it acts as a thermal barrier — heat transfers less efficiently, so the burner has to work harder and longer to achieve the same water temperature.

A 1mm layer of limescale on a heat exchanger surface can reduce its efficiency by around 10%. At 5mm — achievable in a few years at Tenerife water hardness — efficiency loss can reach 25% or more. You're burning more gas or electricity to heat the same water.

Beyond efficiency, scale affects:

  • The heat exchanger itself — thermal stress from uneven heating causes micro-fractures over time
  • Valves and seals — calcium deposits harden moving parts and cause leaks
  • The expansion vessel — scale can affect pressure regulation
  • The pump — scale in the water circuit increases wear on the circulating pump

The Cost of Letting It Happen

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Without a water filter
Annual boiler service finds increasing scale. Efficiency drops gradually. Eventually a component fails — or the heat exchanger cracks. Engineers visit more frequently. Replacement comes 5–8 years early.
€1,500–€3,500
Boiler replacement cost
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With a whole house filter
Scale-inhibited water reaches the boiler from day one. No mineral deposits forming on the heat exchanger. Efficiency maintained. Service remains routine. Boiler reaches its full design lifespan.
€699
Whole house filter — installed

Warning Signs Your Boiler Is Already Affected

Watch
Boiler making unusual noises
Popping, banging, or kettling sounds (a boiling/rumbling noise) are caused by scale on the heat exchanger creating localised hot spots where water boils. This is an early warning.
Watch
Hot water taking longer to reach temperature
Scale on the heat exchanger slows heat transfer. If your hot water is noticeably slower to reach full temperature than it used to be, scale is the likely cause.
Concern
Higher gas/electricity bills without changed usage
If your energy bills have crept up and your usage hasn't changed, a scaled heat exchanger working harder than it should is a likely contributing factor.
Act now
Frequent pressure drops or engineer callouts
Recurring pressure problems and the need for regular engineer visits beyond the annual service often indicate scale-related wear on valves, seals, or the expansion vessel.
Boiler inhibitor vs water filter

Boiler inhibitor (a liquid additive in the central heating circuit) protects the closed central heating loop from internal corrosion. It does not affect the hot water supply circuit where limescale forms. A water filter addresses the supply water — the only effective way to prevent scale formation in the heat exchanger and hot water system.

The Fix

A whole house water filter installed at the mains inlet treats all water entering the property — including the hot water supply to the boiler. Scale-inhibiting filtration media alter the structure of calcium carbonate so it remains suspended in the water rather than crystallising onto surfaces.

The result: water continues to flow through the boiler, but doesn't deposit scale. The heat exchanger stays clean, efficiency is maintained, and the boiler reaches its designed lifespan rather than failing early.

A €699 filter protecting a €2,000+ boiler

That's the calculation. Our whole house filter doesn't just protect the boiler — it simultaneously protects the washing machine, dishwasher, shower, and every other appliance and surface in the home. The filter pays for itself many times over compared to early appliance and boiler replacement.

Frequently Asked Questions

Will a filter remove existing scale from my boiler?
No — a filter prevents new scale forming but doesn't dissolve existing deposits. If your boiler is already significantly scaled, a powerflush by a qualified engineer is the way to remove existing deposits. Installing a filter after a powerflush gives you the best starting point — clean system, protected going forward.
My boiler is fairly new. Should I still get a filter?
Yes — and actually this is the best time to install one. Protecting a new boiler from its first day means it starts and stays clean. The scale builds gradually; a boiler that's been running on hard water for 3 years has already started accumulating deposits that will affect its long-term performance. Starting fresh is ideal.
Does the filter need to be close to the boiler?
No — the whole house filter installs at the mains water inlet to the property, usually in a utility room, kitchen, or the point where water enters from the street. From there, all water throughout the property is filtered — including the hot water supply to the boiler, wherever it is located in the building.
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Ultra Pure Water Tenerife British-owned water filtration specialists. Based in Tenerife South, serving Costa Adeje, Los Cristianos, Arona, Playa de las Américas and surrounding areas.

Stop Hard Water Destroying Your Boiler

One whole house filter protects your boiler, washing machine, dishwasher and every other appliance — simultaneously. €699 installed. Get a quote and we can typically be with you within the week.

WhatsApp Us Now See Pricing →

Based in Tenerife South. We typically reply within the hour.

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