Service requirements

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The service requirements for each of our products include a number of standard procedures together with some product specific actions as listed below.

General Requirements - Annual Checks

Water Quality - Inhibitor levels must be topped up and all filters / strainers must be checked and cleaned.

All heating systems require some sort of chemical additives (inhibitors) together with mechanical components to help prevent corrosion and maintain system cleanliness. Working together the chemicals help clean and protect the various metals used throughout the system and items such as air and dirt separators, magnetic filters & Strainers can enable the removal of air from the system and actively filter the water to remove any particles of dirt which would otherwise accumulate and eventually cause a restriction in the flow.

There are many different types of central heating inhibitor on the market, but it is important that the right product is selected to suit your specific installation and the various materials that are in contact with the heating water. Your installer / service engineer will advise on the best inhibitor for your system.

The same goes for air and dirt separation, however it is recommended that any system which includes ferrous metals (such as radiators) should always be fitted with some sort of magnetic filtration.

Component functions - All components should be checked for correct operation, noise, leakage and corrosion.

All systems are fitted with some sort of moving components such as pumps, motorised valves, air vents and safety relief valves. If any one of these components fails to operate correctly, the system may not operate correctly and could become unsafe. All systems also include various different materials which can corrode if left unprotected, and could result in damage to the fabric of the building it they fail.

There are a number of tell-tale signs which everyone should be aware of, and may require an interim service if they become a problem. These include noise coming from a valve or pump as it operates, signs of water leaks from any valve, fitting, pipe or air vent, noise coming from the pipework or banging of the pipework when taps or valves are closed and general signs of corrosion on pipes and fittings.

Controls - All controls should be checked for correct operation and electrical safety.

All heating systems are fitted with some sort of controls. These can range from a basic thermostat, to fully interlocked systems controlling several zones throughout the property with programmable time and temperature controls.

A full functional control system is essential to achieve an efficient system and if you are finding that you have unusually high gas and electric bills or the heating / hot water is too hot or cold or slow to heat up, then it may be down to poorly installed or set-up controls.

Record keeping

It is important to maintain a record of all service work and related actions, so that your service engineer can be reminded of the work that has taken place previously. A maintenance record may also be requested if / when a warranty claim is raised, because regular servicing is the key to efficient operation of all our products.

Records should include the following as a minimum:-

  • Service engineer details, name, address, phone number
  • Details of checks and actions taken
  • Details of the type and quantity of inhibitor in the system
  • List of relevant settings / readings
  • List of recommendations
  • The next recommended service date

Cylinders and Thermal Stores

We have a huge range of cylinders and thermal stores designed to connect to every different kind of heat source and heating / hot water system, therefore it is important to identify the type of system you have, and the ancillary products connected to it.

Your cylinder or thermal store should be serviced at the same time as the heating appliance(s) to ensure they both function correctly together.

Please visit our wiki page Standard Storage Data Sheets or contact a member of our team to ascertain which system you have installed.

Amazon Unvented / Open Vented Cylinders and Xcel Thermal Stores (DS-1 to DS-18, DS-22 & DS-23)

In addition to the general requirements above, it is VERY IMPORTANT to have your cylinder serviced annually to avoid a potentially life threatening failure. Your service engineer should service the cylinder inline with the current building regulations which include verifying the operation of any safety relief valves connected to the cylinder, checking the condition, function and pressure of the expansion vessel, and ensuring that all the controls are operating correctly.



If you have one of our HEATBANK® PANDORA cylinders, in addition to the general requirements above it is important to check the water level in the cylinder. Although the water is sealed within the cylinder it may evaporate over time and eventually it can affect hot water operation, so checking the level annually will avoid any issues from occurring.

It is also important to add inhibitor approximately every 4 years. The recommended amount is 1% of cylinder volume, and you will find the volume written on a label on the side of the cylinder. For instance is the cylinder has a volume of 210 ltrs, then 2.1 ltrs of inhibitor should be added.

It is not necessary to drain the cylinder down to add the inhibitor, instead we suggest draining off about 5 ltrs via the drain valve at the base of the cylinder, add the required amount of inhibitor via the filling elbow at the top of the cylinder and then top up with water. Finally ensure the filling cap and drain valve are tightly sealed, clip the filling hose back onto the cylinder for future use and clean the cylinder casing before reheating.

Hydraulic Interface Units (HIU's & CIU's)

There is very little to service on our heating or cooling interface units, no matter what their size or output, however it is important to remember that HIU's are often connected to three different hydraulic circuits, a primary circuit supplied from the district heating / cooling system, a secondary central heating / cooling circuit and a hot water circuit. The service and maintenance of the primary circuit will almost certainly be the responsibility of a district network management company and it is therefore recommended that any servicing of the HIU is carried out in collaboration with them.


In addition to the general requirements above, annual checks should include checking the operation of the unit to ensure it is supplying heating / hot water at the set temperatures and flow rates. The output temperature and flow rate is a function of the input temperature and flow rate provided by the district network, so it is important to check the input as well as the output because the issue may be with the district network as opposed to the HIU itself.

Water Quality

It is also important to ensure that any filters / strainers on both the primary and secondary circuits are clean and clear of debris.

A label on the unit should display the temperature setpoints for both heating and hot water, which can be checked using temperature sensors connected to the pipework or held under the tap. If the temperatures are not as expected then further investigation is necessary. The condition of the filters / strainers will give an indication as to whether the issue is related to water quality on the primary or secondary circuit and if the cause is still unclear we recommend checking the performance of the plate heat exchanger against published performance charts for that model of HIU. It is worth remembering that if a heat meter is fitted, the primary flow and return temperatures can be checked along with the primary flow rate and energy exchange, this can give a valuable insight into many issues with the performance of the HIU.

Energy Metering

Possibly the most important part of a HIU service is to check that the energy meter is correctly fitted and recording the energy usage of the HIU. If the meter is incorrectly fitted, damaged or faulty then it may not record the energy usage correctly resulting in incorrect billing.

Unfortunately it is not possible to fully check the performance of the energy meter, however as a minimum we recommend using temperature probes connected to the primary flow and return pipework to confirm the temperatures being read on the energy meter.

Contact Thermal Integration for further assistance with any of the above issues.