Add Detail HIU

04/03/2026

This one is a leaking Hero HIU. The customer decided to rebuild it instead of replacing it.

New parts to go in: AVPL, RAVK, two VMTs, DHW head + body + PHE, UFH actuator and a wiring centre investigation.

Planning in progress 😊

19/02/2026

HIU repair completed on a Caleffi SATK30 unit.

The faulty modulating valves and DPCV were replaced, restoring heating and hot water to the apartment.

▶ Full repair video available on our YouTube channel (link in comments).

Add Detail Ltd – HIU servicing and repairs across London.

22/01/2026

RHICO HIU three-way valve replacement, including the thermostatic control head and valve body. The valve was leaking through the pin, causing the unit to overheat as it failed to stop the primary flow. As a result, both the hot water and heating systems were not operating correctly.

24/12/2025

✨ Wishing you a joyful Christmas and a New Year filled with success, growth, and new opportunities. Thank you for being part of our journey. 🎄🎉

24/09/2025

The most popular and cost-effective Danfoss HIU repair we see.
➡️ IHPT valve + heat meter washer replacements.
Why? You only need to drain the unit once and most of the joints are right next to each other saving time and money. 💡

15/07/2025

HIU performance can be affected by dripping taps and poor plumbing in the apartment.

HIU performance is affected by dripping taps and poor plumbing in the apartment can indirectly affect a HIU in several ways.

25/06/2025

Although the weather is not conducive to thinking about heating, replacing your HIU now means you’ll be ready for winter when it does come 🙂
Danfoss FlatStation HIU has mainly brass and stainless steel components compared to some other brands. Reliable and silent HIU.

07/06/2025

With fewer emergency heating repairs, the warm season ☀️ is the perfect time for HIU replacement.

Recent swap to a ModuTherm MTA Eco Twin HIU with a pre-fixed isolation valve bracket – it's a compact unit.

Everyone is happy!

30/05/2025

💡 Why does HIU servicing matter?
For those less familiar with the system, here’s a simple guide on why regular HIU servicing is important - helping keep heating and hot water running reliably, while avoiding costly issues later.

📄 Read more: https://adddetail.com/hiu-annual-service/

HIU's annual service is an important and obvious way to keep HIU in good condition and to make sure it doesn’t waste unnecessary energy.

24/05/2025

We like working with Caleffi SATK30 HIUs — their layout often makes repairs easier to carry out.
A common issue is the DPCV getting stuck, which can cause no hot water and usually means the part may need replacing soon.

20/05/2025

https://adddetail.com/hiu-annual-service/

HIU's annual service is an important and obvious way to keep HIU in good condition and to make sure it doesn’t waste unnecessary energy.