About Us
London's HIU & MVHR Specialists
Collide Group is a specialist Heat Interface Unit and ventilation company serving Greater London. We do one thing, and we do it properly.
Quick answer
Collide Group Ltd is a London-based Heat Interface Unit (HIU) and MVHR specialist founded by Ilyas Safi, based in Northolt, UB5. The company is WRAS certified, carries £5,000,000 public liability insurance, holds a 5.0-star rating from 25 Google reviews, and covers 26 London boroughs. Registered in England & Wales, company number 17129473.
Why We Only Do HIUs
Most London flats built in the last twenty years do not have a boiler. They have a Heat Interface Unit — a compact heat exchanger connected to a communal or district heating network. It is a genuinely different piece of equipment to a domestic boiler, with different components, different failure modes and different diagnostics.
The problem is that most heating engineers were trained on boilers. When a resident loses hot water in a modern block, they often end up with an engineer who has never worked on an HIU before — leading to misdiagnosis, unnecessary part replacement, or the advice that the whole unit needs replacing when it does not.
Collide Group exists to close that gap. We deliberately specialise rather than generalise: HIUs, communal heating and MVHR ventilation, across Greater London. That focus is why we are frequently called in after another company has already tried and failed.
Meet the Founder
Ilyas Safi
Founder & Director
Ilyas founded Collide Group after several years working hands-on with heating systems across London, where he saw the same pattern repeatedly: communal heating faults being handled by engineers without HIU-specific knowledge, and residents paying the price for it.
He now leads every aspect of the business — from attending call-outs personally, to coordinating block-wide servicing programmes for property managers and housing associations. Customers regularly name him directly in reviews, which for a specialist trade business is the clearest signal that the work is being done properly.
“I had a complicated issue with my HIU. Several different companies tried to resolve it and failed. They suggested I get a new HIU which would have been expensive. I got in touch with Collide Group to get another opinion. They were able to fix my HIU and saved me a lot of money.”— Anmar Mehdi, Google review
Credentials & Cover
WRAS Certified
We work to WRAS guidance and use WRAS-approved fittings, protecting the integrity of the water supply in every property we attend.
£5m Public Liability
Full £5,000,000 public liability insurance, with certificates available to clients and managing agents on request.
5.0 Stars, 25 Reviews
A perfect 5.0-star average on Google from London residents, leaseholders and property managers.
Documented H&S
A written Health & Safety Policy and task-specific RAMS, provided to property managers and principal contractors on request.
Legionella Aware
We work to the principles of HSE Approved Code of Practice L8 and guidance HSG274 on water hygiene and Legionella control.
All Major Brands
Danfoss, SAV, Switch2, Caleffi, Alfa Laval, Heatweb, Thermal Integration and Redan — plus Vent-Axia, Nuaire, Titon and Zehnder for MVHR.
How We Work
- Transparent pricing — a £120 call-out covers attendance and full fault diagnosis, with any repair fee agreed before we start.
- We diagnose before we replace. If your unit can be repaired, we repair it rather than selling you a new one.
- Most faults are resolved on the first visit, because we carry common parts for every major brand.
- Written reports and photos on servicing, so property managers have real compliance evidence.
- 12-month warranty on the parts we supply and the labour we carry out.
- We turn up when we say we will, and we leave the property clean.
Company Details
Work With a Specialist
Whether it is a single flat or a block of 200, speak to an engineer who works on HIUs every day.