Immersion heater, thermostat or cylinder replacement - how much?

Immersion heaters, their associated thermostats and cylinders come in many forms. The most common cylinders in the UK are:

• Direct, with one or two immersion elements (if two the lower will usually be for use on cheaper rate electricity)
• Indirect, where the immersion element is usually used as back up
• Combination (also know as Fortic) often found in older flats
• Self Priming / Primatic - now little used
• Harco packs, which could often be found in public housing
• Pressurised systems, a relatively modern and increasingly popular type.
  

The 50plus technical support section has a pictorial overview of cylinder types; read the document here.

Replacing an immersion heater thermostat is a simple task in the majority of cases as the thermostat is typically replaceable without removing the element and/or draining the tank. Allow 30mins plus the time to locate the correct replacement

Replacing an immersion heater element can a reasonably straight forward job as long as:

(i) the system can be drained down, a requirement in nearly all cases but sometimes not with a pressurised system and

(ii) the existing element can be removed. It is not unusual for the old element to be 'stuck' in place. This is usually caused by corrosion or in hard water areas by a build up of scale and if this is the case a new cylinder may be be required.

If all is well the job should take around an hour or two. If the drain down and refill are problematic then significant additional time can be needed. Immersion elements with thermostats are inexpensive, often from around £20.

Cylinder replacement is a different scenario. The main dependencies with regard to how long the job will take are:

• The cylinder type. For 'standard' cylinders expect to pay around £200 for the cylinder, less usual models can be in excess of £900
• Access. If the situation is akin to the airing cupboard having been built around the cylinder then expect the work to be considerably extended. Also watch out for the old type cylinders in a tight space with little or no insulation. Modern cylinders have around 2" (50mm) of insulation built onto the surface so a same size replacement takes up more space. A new or recent cylinder has factory fitted foam insulation which is blue. Older cylinders are green, orange or have no insulation around bare copper.
• System drain down and refill. Always something that should straightforward but often isn't. Non operational valves and airlocks can cause delay.

• Typical recommend time - 1 day (6 to 8 hours)
• Click here to find out the cost of labour.
  
  

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For more on heating systems see our technical support section.

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