FAQ's
Please find a list of our frequently asked questions below!
If you’re struggling to find an answer to your query, please Contact Us or click the 'Chat' button at the bottom of this page and our team will be happy to help.
What is a heat interface unit (HIU)?
A Heat Interface Unit (Or HIU) controls the heating and hot water available to your property and ensures the water is heated to the required temperature. A HIU acts like a combi boiler but runs on hot water instead of gas and is a bridge between your home and the Heat Network.
How often should a HIU be serviced?
Your heat interface unit (HIU) should be serviced yearly to check your system is running safely and efficiently. View our HIU Service packages designed to give you peace of mind that you’re covered if things go wrong, helping to avoid any costly repairs.
Do I legally need to have my HIU serviced every year?
If you’re responsible for the maintenance of a HIU in your property or a property you manage, you may be legally required to service your HIU regularly.
HIU Service can provide a range of service packages starting from only £95! View our HIU Service packages here.
Who will provide my HIU Service?
Our nationwide team of HIU Service engineers will carry out your inspection on your chosen appointment date. Our engineers will arrive at your appointment with:
- HIU Service identification badge
- HIU Service branded van
- HIU Service branded uniform
So, you can be sure that your HIU is being maintained by the experts.
What areas do you cover for a HIU Service?
HIU Service has a team of northern and southern based engineers ready to service your HIU right across the country! Not limited to only HIU Servicing in London!
What happens during my HIU Service appointment?
During your service appointment one of our specialist HIU engineers will inspect, clean and check your HIU and associated controls, whilst testing the performance of the heating and hot water system.
How do I pay for my HIU Service?
You can pay for your HIU Service or repair through our online booking form by PayPal or Credit/Debit card.
We are unfortunately unable to take payment over the phone or through any other alternative option.
How do I know what make/model HIU I have?
Your heat interface unit may be identifiable through a few elements, such as manufacturer sticker, colour, heat meter installed at your property and manufacturer manual.
Don’t worry if you’re struggling to identify your HIU, contact our team today for help.
What is a heat network?
Heat networks are systems where heat is distributed through a series of pipes within a single building, multiple buildings or even across an entire city! If your home is serviced by a heat network, you do not need an individual boiler or electric heater.
Heat in a heat network is centrally generated. The central heat source is often referred to as the Energy Centre. Energy Centres can be powered in many ways and might come from a number of different energy sources, including renewable technologies and then distributed to your property by distribution pipework. You will normally have a Heat Interface Unit (HIU) or other system to turn the heating on and off - it’s normally around the same size as a gas boiler.
This means you will pay for what you use, as measured by a heat meter, also known as a thermal energy meter. You won't have your own individual boiler and your utility supplier for heat and/or hot water will be the Heat Network Operator, which is the organisation that operates and/or owns the heat network.
There are a number of sustainability benefits of heat networks as well as providing a reliable and cost-effective method of supply to consumers. A heat network isn't a new idea and they have been extremely popular across Europe for decades and are increasingly common in the UK, especially when linked to renewable technologies.
How do I book a HIU Service?
You can book your HIU Service or repair today through our online booking form.
For group HIU Service bookings please contact our team with your request.
What will I receive after my HIU Service or repair is complete?
After your HIU Service or repair is complete, you will receive a confirmation document from our customer support team which will include details of the work our HIU technician has completed during their visit to your property.
Can I make a group HIU Service booking?
Yes! We can arrange group HIU Service bookings for your building or a building you manage. To view our discounted rates and enquire for a Group HIU Service Booking please complete our online form.
How can I make a complaint or provide feedback?
We welcome any feedback on the services we provide, and we want to proactively resolve any issue that may occur, please contact us if you wish to register a complaint.
I’ve made an appointment for my HIU Service, how do I change it?
Please contact us and we can rearrange your appointment for you.
What is the difference between a HIU Service or Repair?
A HIU Service helps stop issues before they happen, it is preventative, whereas a repair helps resolve an issue you might be experiencing. When our HIU Service team attend your HIU if you have not told us about a repair, we will complete the HIU Service but cannot complete a Repair.
How can I find my tado smart thermostat user guide?
The tado user guide is available on the tado website, through their help and support pages, you can also contact tado for any help and support in using your tado Mobile App.
Can you provide HIU Replacements?
We are happy to supply and install HIUs! This might be to upgrade your existing HIU, or the installation of a new HIU. Please contact us directly to discuss your requirements.
What are the benefits of servicing my HIU?
Improved Energy Efficiency
A well-maintained HIU operates more efficiently, helping reduce your energy consumption. This can lead to noticeable savings on your heating and hot water bills.
Enhanced Performance
Servicing ensures your HIU delivers consistent heating and hot water. It helps prevent temperature fluctuations, low pressure, and flow rate issues.
Prolonged Unit Lifespan
Regular maintenance reduces wear and tear, which can extend the life of your HIU and delay the need for costly replacements.
Early Detection of Problems
During a service, engineers can identify and resolve minor issues before they escalate into major faults or complete breakdowns, saving you time and money in the long run.
Compliance with Manufacturer Requirements
Many HIU manufacturers require annual servicing to maintain warranties. Missing these checks could void your warranty coverage.
Improved Safety
A professional service includes safety checks to ensure your HIU is operating safely, giving you peace of mind—especially in communal or residential buildings.
Reduced Risk of Emergency Callouts
Preventative maintenance lowers the chance of sudden breakdowns, helping you avoid inconvenient and costly emergency repairs.
Landlord and Compliance Benefits
For landlords and property managers, regular HIU servicing helps meet building and safety regulations while keeping tenants satisfied.
What are the signs that my HIU needs servicing?
Inconsistent Heating or Hot Water
If your radiators aren’t getting hot, or your hot water takes too long to heat—or runs hot and cold intermittently—your HIU may not be operating efficiently.
Low Water Pressure
Reduced or fluctuating water pressure in your taps or showers can be a sign of blockages, limescale build-up, or a faulty pressure valve in the HIU.
Strange Noises
Unusual sounds such as banging, gurgling, or whistling could indicate air in the system, pump failure, or worn internal components.
Leaks or Visible Damage
Any sign of water leakage, rust, or corrosion around the HIU should be investigated immediately to prevent further damage.
Constant Need to Reset the Unit
If you're regularly resetting your HIU to restore heating or hot water, it's a strong indication something isn’t working as it should.
Higher Energy Bills
An unexpected spike in your heating or hot water charges could mean your HIU is running inefficiently and using more energy than necessary.
Long Heat-Up Times
If it takes longer than usual for your home to warm up or for hot water to reach your taps, your HIU may be underperforming.
Error Codes or Warning Lights
Modern HIUs may display error codes or warning indicators when there’s a fault. These should never be ignored and require a professional check.
Cold Radiators Despite the System Being On
If your heating is on but radiators remain cold (especially in specific areas), this could point to a control or flow issue inside the HIU.
It Hasn’t Been Serviced in Over a Year
Even if your HIU seems to be working fine, manufacturers typically recommend annual servicing to maintain performance and warranty coverage.