leaholme Registered User
#1

Hi,
can anyone help.
I have a Grant Minor one S central heating burner (20-29Kw.) 1991
The problem is: when I try to start the burner it purges for a short time and then locks out. The red light on the control box comes on. If I reset it by pressing in the button it starts OK and will run until the boiler reaches the set temperature and then it shuts down normally, however when it tries to restart it 'locks out' again and I have to press the button again.
I spend my time running into the boiler house pressing in the button!!!
Any ideas gratefully received.

ART6 Subscriber
#2

Since it's a Grant boiler I assume it has a Riello burner. If the burner doesn't light within a pre-set time it will lock out, and the only way its controller knows it's lit is by the light of the flame detected by a photocell. Often the failure to light up properly is a clogged oil filter or a partially blocked nozzle limiting oil flow or distorting the atomised oil spray pattern, or simply a dirty photocell.

The filter will be in the supply pipe and will normally have a glass bowl that can be removed for cleaning. If it's a partially blocked nozzle or a dirty photocell then you will need to withdraw the complete burner. That's not difficult but it is not really a simple DIY job. Not something to undertake unless you are really sure of what you're doing.

Little Dog Registered User
#3

Hi folks, Just seen this thread I also have a problem with a grant riello burner. The burner is running but not firing thers is fuel and I hear it clicking. Any ideas? The control box was replaced 12 months ago. It picked a good weekend to stop working! Any advise would be much appreciated.Thanls Little dog

items Registered User
#4

Could be a million and one reasons why a burner lock's out but its pretty much the only tell tale sign, boiler requires a service.

If your car had trouble turning over, you'd probably have it serviced, same goes for burners.

leaholme Registered User
#5

Hi and thanks for your replies.
I have a Grant burner, model "Minor one S" (and a Grant slimline boiler)
I have just been working on it and made some amazing (to me anyhow) discoveries:
1. IF the burner fires it runs with the plug going on to the solenoid on the pump disconnected!!! I presume this means the solenoid is stuck open?
2. In this situation (burner running but solenoid disconnected) one of the 3 terminals in the plug is continuously "live"
If the boiler fails to light the terminal never becomes "live" Does this mean there is an intermittent fault with the controller? The controller is a Danfoss BHO 12.1. The pump and solenoid are Suntec.

items Registered User
#6

leaholme said:
Hi and thanks for your replies.
I have a Grant burner, model "Minor one S" (and a Grant slimline boiler)
I have just been working on it and made some amazing (to me anyhow) discoveries:
1. IF the burner fires it runs with the plug going on to the solenoid on the pump disconnected!!! I presume this means the solenoid is stuck open?
2. In this situation (burner running but solenoid disconnected) one of the 3 terminals in the plug is continuously "live"
If the boiler fails to light the terminal never becomes "live" Does this mean there is an intermittent fault with the controller? The controller is a Danfoss BHO 12.1. The pump and solenoid are Suntec.


You might well have a problem with control box but its hard to know for sure, Danfoss are a reputable company their gear tends to be up to scratch so you could be confusing things, again hard to tell for sure.

Burners have different lives, some switched, some permanent, after a powered burner goes through ignition sequence and detects flame, its possible to disconnect a some leads / cables / wires while having burner still running.

One some jobs we used to manipulate a burner to come on while completely disconnecting burner from boiler, just to heat the room for a short burst as we worked, only giving this example to show how its possible for burners to run a number of different ways while burner firing.

It might not be your control box at all, then again it might, best have someone with experience have a look at it.

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