Grant UK Reviews 2.585

The vortex external boiler is SO complicated to programme. I have read and reread the instructions over 100 times and I am still unable to programme it to my satisfaction. The CP4 booklet should be rewritten in SIMPLE sep by step instructions.

The boiler was an exact replacement for our original unit that had failed (after 13 years faithful service). The installation was, therefore, straightforward and timely.

I haven’t had the boiler very long so can’t evaluate reliability etc.
However, I am very pleased with the performance so far. It appears very efficient and quickly brings up the water temperature. Oil usage appears significantly better than my previous boiler.

Grant boiler working very well, we should have replaced old one years ago. Grant recommended installer was excellent. Home Heating did the install very efficiently.

The boiler is working well.

I had a new Grant Vortex condensing combi boiler installed by a Grant G1 registered engineer. After just 14 months, the base of the boiler filled with water.

The installer immediately pushed it to Grant as a warranty issue. Grant sent an engineer, who blamed the UK weather and suggested the condensate soakaway was saturated, despite the fact we live on sandy, free‑draining soil and have never had this issue with previous oil boilers.

I was then billed £150 for the visit.

I chose Grant and paid extra for a G1 installer specifically for the 10‑year warranty and peace of mind. Being told that normal UK weather caused the fault feels like a design flaw, not a customer responsibility. Very disappointing experience.

I asked for a boiler and heatpump service in November'25 and was told that I could not be given a date but to expect an engineer visit within about 3 months. The wait was explained that Grant Engineers were giving priority to repairs. I called today (19/3/26) to ask when to expect an engineer and was told that the earliest date they could give me was 10/6/26. Grant UK had my November inquiry but now as then they say their priority is still on repair work. In November, I did ask to change my inquiry to a repair to be told that this would make no difference! A service is different and would need a separate engineer visit.

We had a Grant heat pump system installed by a third party supplier November/December 2024. We have since October been trying to get a service plan in place to ensure our system remains within their warrranty. Despite several emails, each answered by telling us there is a 10-12 week lead time for servicing. We are still waiting. Not convinced our install is all it should be and the service by the manufacturers would be invaluble as it could clear up any problems we may have with the original install or our understanding of best practice. However, Grant UK are woeful at response or communication. We are now seriously regretting getting a Grant heat pump and boiler system.

A superb service from the customer care to the high quality product and on time delivery. Making the whole process of purchasing a new eco friendly boiler very pleasurable.

My Mother's had one fitted nearly 12 months ago with a Government grant but sorry to say the back up service is terrible by smart energy who fitted it,the running costs are very high compared to the old gas boiler.

We have had our grant combi boiler for just over 5 years and it is leaking from either the heat storage tank or the heat exchanger and as a result we now have to replace the boiler. I am very disappointed with this product especially as I was told these are supposed to be the Rolls Royce of boilers. Dreadful. Person at Grant boilers didn’t seem to think this was poor so presumably he doesn’t rate the product either.

One of their heat pumps had been installed in my new build home in 2024 but had never really heated the house properly. After a recent cold spell when the heat pump iced over and was hardly giving any heating or hot water, Grant's replaced both the heat pump and hot water cylinder. The difference in both the way the house is now properly warm and the hot water is "hot" is amazing. Not only that but the engineers who replaced the faulty equipment were excellent.

Excellent customer service from Allen Cowe and Mandy. Boiler had been down for an extended period and the technical support and problem resolution from Grants demonstrated excellent, caring and professional customer service. Mandy contacted Allen who visited at his earliest opportunity, located fault and restored service. Cannot thank both for their efforts at a difficult personal time. Steve Mackintosh

High quality product, fitted by professional and courteous installers.

So far - for about two months - very good.

Very pleasant & highly efficient engineers.completed the removal of old boiler & installed new one well within the time expected. Would highly recommend recommend the company.

Old boiler was well past its best, spoke to Craig, our local heating engineer whovrecommendedva Geant boiler as a replacement. Left it to him to supply and fit one, heating is greatly improved.

New property with Grant underfloor heating and water system. Experiencing problems with hot water and having to reset the fan multiple times. Engaged plumbers and electrician who installed the system and after both inspected they advised that it was a potential fault. With no other option than to call Grant out as an in warranty issue (over 1 month to attend), the engineer found no fault and advised that there would be no charge. 5 days later received a bill for £150 for the 20min visit. Unacceptable