Grant Combi MK2 no hot water


I’ve got a Grant combi boiler outdoor model 90 MK2. Recently it started to give colder and colder hot water, but today the water was simply cold, not even luke. I also realized that last days the “hot” water pressure started to drop down. I should add that the heating system is working fine. Can someone help, can I repair it myself?


Hi Jamie,
There are several things that may be faulty, it can be microswitch or heat exchanger or even diverter, also bledding the system may help. If you don’t have much experience with oil boilers repair I would call a boiler specialist. He will come and diagnose your boiler very fast, most probably repairing it the same day.

Grant Vortex Combi no central heating

Hi All

I have a Grant Vortex Combi condensing boiler, I bought it 3 years ago and today I realized that it is no central heating and no hot water. Not a good surprise indeed. I tried to check what may be wrong, but I gave up: pressure is fine, power is on, oil is fine. The only thing which is a bit strange is that it fires up when i take the cover off and switch it on/off there, usually with making whooshing noise, but the switches off. Anyone an idea how to fix it fast?


Hi Joe,

Does it sound to you like burner would try to fire up multiple times? If yes, then solution is pretty simple, but should be corrected/replaced by specialized boiler engineer. I think that either oil pump is broken or in better case photocell is dirty and needs simple cleaning. It shouldn’t take more 2 hours for a specialist.


Grant Minor lock out

Hi Guys,

I have a Grant Minor oile boiler model one S. I use it for central heating and it is pretty old- purchased in late ’90s. Last week it showed a red light on the control box, no central heating provided since then. After restarting burner goes for very short time (4-6 sec) and then boiler locks out. Red lamp pops up again. I am afraid of restarting it many times so I would be grateful if someone would tell me what may be wrong?



Hi Harry

Is your boiler equipped with Riello burner?  If yes then then it may be pre-setting issue and you will need to use a manual for correct burner setting. However if your burner is so old I would rather vote for dirty filer, it is located in the supply pipe and has a glass on it- that should be removed for cleaning. If you see that the whole burner is pretty dirty you may need to take the whole burner out and clean it. I think it will help.

Grant 90 V3 doesn’t heat the water properly

Hi Guys,

I have a Grant Combi boiler model 90 v3. It is 9 years old, it is kept in the basement and has annual services done every year since I bought it. So far is was doing really fine. Recently I realized that boiler heats up the water, but then is not able to keep this temperature up, so every minute of washing up the dishes water is becoming colder and colder. I am sure it is not a normal operation. Can someone help giving an idea what can be the issue?
Best Regards


Hi Dan

There are two things that can be faulty in your case. I would most probably check/replace both, but you decide what you do in your case. After resetting check if your burner motor runs constantly, but it can’t fire up- if yes, then the burner need to be exchanged. If it fires up then there is an issue with an electrical flex and you will need to replace a microswitch.

Grant Vortex 26 Combi doesn’t hold the pressure?


I have a Grant Vortex Combi oil boiler model 26. I am a bit worried because I need to  re-pressurize the system every 2 weeks to 1 bar. The strange thing is that after approximately 10 days system pressure drops down again. It become a habit in last 3 months. I will have a long weekend now and I was thinking it is high time to do sth about it. Anyone an idea what needs to fixed/replaced?


Hi Jack,

You can start with bleeding the system at the boiler and bleeding the radiators. If it doesn’t help you can do further and check for leaks. If nothing helps then you will need to replace a relief valve to fix the issue. 

Grant Vortex Combi 36 leaking fault

Hi Folks,

I have a  Grant Vortex, which is an oil combi boiler model 36 (external). We were quite satisfied with it, but ;ast week we realized that it is leaking, there is a pretty big puddle of water in the basement under the boiler. Any idea what may be an issue and can I return my boiler as it is 4 years old, and warranty is 5 years on this model?

Best Regards


Hi Thomas,

From your description is looks like it is a pinhole leak within the water jacket. For 4 year old model it would be associated with a system fault- not a boiler fault. If that is the case your boiler would fall under warranty claim. In your position I would simply replace water jacket, clean the boiler using some experienced boiler specialist rather than claim a warranty. It will take an hour and doesn’t cost that much