Add Detail Ltd – Expert HIU Repair & Service London

Q: What are the most common HIU heating and hot water call-out repairs?

Typical call outs include diagnosing and fixing temperamental, inconsistent or complete loss of hot water in kitchens and bathrooms, and restoring heating to radiators or underfloor heating throughout the home.

Cost-Effective HIU Heating and Hot Water Solutions

HIU REPAIR

HIU SERVICING

ALL SERVICES

Dedicated Team of HIU Engineers and Customer Service Professionals

NO HIDDEN FEES

✅	Fair, Transparent Pricing
✅	Fixed/Hourly Repair Rates
✅	Fixed Price Quotes
✅	Discounted Group Rates
✅	Spring/Summer Discounts
✅	No Charge for Parking, CC or ULEZ
✅	Card Payment Availability

HIU SPECIALISTS

✅	Established in 2014
✅	5 Star Rated Services in London
✅	Certified HIU Experts
✅	Danfoss and Caleffi HIU Specialists
✅	Most Common Parts in Stock
✅	Quick Turnaround for Non-Stock Parts

GUARANTEED SERVICE

✅	Fully Insured Services
✅	12-Month Parts Replacement Warranty
✅	One-Hour Response to Online Inquiries
✅	Expert HIU Engineers in London
✅	Endorsed by Which? Trusted Traders

Read our Yell reviews

    
 
 
       Posted on Google  
    Barry Ho 
 
 
 
  Good customer service and professional repair
  
 
      Posted on Google  
    Steve Webb 
 
 
 
  My tenant reported that the heat exchange unit in my flat was not working. The managing agent's maintainance company quoted a figure that was much higher than I knew other residents had paid. I contacted Add Detail who provides two options both of which came with 5 year warranties at half the price I had been quoted. The work was done very professionally and neatly and communication with them was very good.
  
 
      Posted on Google  
    Jenny 
 
 
 
  I used HIU Service & Repair - Add Detail to fix a leak on my HIU and replace a value that had been corroded after another contractor let me down. Really pleased with the prompt communication, upfront quote and the engineer even turned up 5 minutes early! Left workspace tidy when he'd finished too. Would recommend!
  
 
      Posted on Google  
    Olivia Wood 
 
 
 
  Really great service and lovely people, explained everything thoroughly, fixed all issues. Really easy to book and organise, definitely recommend and will be using again.
  
 
      Posted on Google  
    Mr K 
 
 
 
  Replaced our 4-port value, quick quote and repair which has been solid so far, good communication and lowest price we found recommended!
  
 
      Posted on Google  
    Lisa Edwards 
 
 
 
  Excellent HIU service from Justin at Add Detail. He was prompt, efficient and very thorough, even providing reports after the visit. 100% would book again.
  
 
      Posted on Google  
    Josh Ambler 
 
 
 
  I recently used AddDetail to install a new hot water controller valve in my HIU after dealing with inconsistent water temperatures in my flat. I submitted a quote request online and received a quick response with a very reasonable price compared to other companies in the London area. The online payment process was simple, and I was promptly given a timeslot and assigned an engineer. Justin, my engineer, arrived exactly on time. He was friendly, professional, and completed the job within the allocated timeframe. I was initially concerned about not having parking at my property, but Justin took public transport, which was a huge relief. My hot water is now working perfectly again thanks to the part replacement. Overall, I’m very happy with the service—would happily use AddDetail again and recommend them to anyone needing HIU repairs.
  
 
      Posted on Google  
    SM 
 
 
 
  Sigis was on time, friendly and helpful. I wouldn’t use anyone else but ADD Detail to service my HIU, highly recommend
  
 
      Posted on Google  
    katerina georgi 
 
 
 
  The service was excellent. Sigi arrived punctually, and was friendly and considerate. The job was completed quickly, for the price quoted, and there was no mess. Very happy with the service.
  
 
      Posted on Google  
    Freddy 
 
 
 
  I cannot fault the service and the professionalism of the engineer who fixed faults and leaks on my HIU unit. They also came in with the best quote for the work which is a bonus. I have recommended you to other apartment owners in my bulding, thank you AddDetail.

ABOUT US

HIU Services in London

Founded in London in 2014, Add Detail Ltd is a trusted name in HIU services across the capital. Our skilled HIU engineers are here to help with all your needs. From installation and repairs to servicing and maintenance. We make sure your home stays warm, comfortable and running smoothly.

We specialise in heat interface units and work with all major types and brands. Our engineers have strong technical knowledge and can quickly find and fix any issues. This helps reduce energy use and extend the life of your HIU.

We also provide digital service reports and keep a full service history for every system. This helps maintain peak performance and supports long-term reliability.

When you choose Add Detail, you get reliable support for your property’s heating and hot water systems. You can rely on us for safe, efficient, and long-lasting HIU care.

Fast Responses To Your HIU Enquiries Are Guaranteed!

Connect with us for professional HIU service and repair solutions in London. Reach out via our contact form or call 02088224451. Our services are fully insured, ensuring quality workmanship and peace of mind with every project. Learn more about HIU – Click here.

12 Tips To Keep HIU In Tip-Top Condition

Book an annual HIU service to keep the system working well. Read more
Choose an HIU specialist that uses original parts for all repairs and servicing. Read more
Fit an inline scale reducer to help protect the HIU from limescale. Read more
Check the heating water quality and top up the inhibitor when needed. Read more
Connect the HIU to a smart thermostat for better control of your heating. Read more
Add a magnetic filter to the heating system to collect dirt and debris. Read more
Ask an HIU specialist to explain how the heating and hot water controls work. Read more
Repair dripping taps and poor plumbing, as they can affect HIU performance. Read more
Keep radiator valves working, bleed radiators and balance the heating system. Read more
Check underfloor heating parts, including the manifold, actuators, flow meters and thermostats. Read more
Keep a full record of all HIU repairs and services. Using the same company can also offer useful long-term benefits. Read more
Arrange an inspection as soon as you notice a heating or hot water problem. Read more

ACCREDITATIONS

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GET A QUOTE ONLINE

Looking for a fixed price quote for HIU repair? We will get back to you within 24 hours.

GET A QUOTE ONLINE

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CONTACT US

To find out more about our services or to discuss your requirements, get in touch.

HIU FAQs

What is a HIU and are they easy to maintain?

A Heat Interface Unit (HIU) controls heating and hot water in properties connected to a central plant or communal boiler system.
They’re easy to maintain, and with regular servicing you can help prevent breakdowns, ensure energy efficiency, and keep your system running safely.

How often should I service my HIU?

We recommend servicing your HIU every 12 months to maintain efficiency. This reduces the risk of costly repairs and extends the unit’s lifespan. Annual servicing is often required to maintain warranty conditions.

What areas do you cover?

We’re based in London and cover a wide area across the city. Contact us to check availability in your postcode or click here to see the areas we cover.

Do you offer emergency HIU repairs?

Yes, we provide emergency HIU call outs across London. If your heating or hot water has stopped working, contact us and we’ll try and get there as quickly as possible.

Do you offer landlord or block maintenance contracts?

Yes, we work with property managers, landlords and residential blocks. We offer routine HIU maintenance contracts, group bookings and detailed service history tracking.

What happens during a HIU service?

Our engineers will inspect and service your HIU. The service includes the following:

Inspection for leaks, corrosion, or damage.
Cleaning of strainers and filters.
Pressure and temperature checks.
Verification of flow rates.
Inspection of thermostatic controls and sensors.
Expansion vessel pressure check.
A service report detailing the condition and performance of the HIU.
Recommendations for corrosion/leak repairs, part replacements or upgrades if needed.
As part of the service, we also carry out small repairs. For example if there is a stuck pin on the valve or seized pump that can be fixed without breaking any seals or removing parts.

What are the most common HIU heating and hot water call-out repairs?

Identifying and resolving temperamental, inconsistent or complete loss of hot water issues in kitchens and bathrooms. Restoring heating to radiators or underfloor heating throughout the home.

Do you fit new HIUs and replace old ones?

Yes, we offer full HIU replacement and installation services in London. Our competitive fixed prices include a 5-year guarantee on both parts and labour.