Grant Oil Boiler Not Firing Up? Causes & Fixes For Vortex Models

Press the reset button on a Grant Vortex and hear nothing but a click and a brief whirr, and you will know the feeling: the house is getting colder and the boiler has given up. The good news is that a Grant oil boiler not firing up is usually protecting itself, and the reason is often easier to track down than you would expect.

Our oil engineers at Hinckley Plumbing & Heating work on Grant Vortex, Vortex Eco and Vortex Pro boilers every week across Hinckley, Nuneaton and Tamworth, and out towards Leicester and Coventry. Below is every cause we come across, with the most common first, followed by the rarer ones, so whatever your Grant is doing you should find it here.

How Does A Grant Vortex Tell You Something Is Wrong?

Mostly with a lamp, not a number. The burner has a reset button with a lockout lamp built in, and when the lamp is lit the burner has stopped trying. Some Vortex Pro and combi models add a status light, but what the pattern means depends on the control board, so keep your model’s manual to hand.

Quick Checks Before You Do Anything Else

• Is the boiler isolator switched on, and has the fuse in the spur blown?
• Are the programmer and room thermostat actually asking for heat?
• What does the tank gauge say? A very low tank is a common culprit.
• Is the lockout lamp lit? If so, one press of the reset button is allowed.

The Most Common Reasons A Grant Oil Boiler Is Not Firing Up

1. Low or empty oil tank. Always the first thing to rule out. If the gauge is low, order oil, and expect some air in the line afterwards that an engineer may need to bleed out.
2. No power or no call for heat. A switched-off isolator, a blown fuse, flat batteries in a wireless thermostat or a programmer upset by a power cut will all keep the burner silent.
3. Burner in lockout. The lamp in the reset button is lit because the burner failed to light or lost its flame. Reset once, and treat a second lockout as a fault that needs finding.
4. Air in the oil line. Air gets in when the tank runs low, after a delivery or through a loose joint, and the pump cannot prime. The line needs bleeding and the source of the air tracking down.
5. Blocked oil filter. It exists to catch dirt, and in time it clogs. Replacing it is a routine service item.
6. Blocked or worn nozzle. The nozzle is a tiny jet. Once it is partly blocked or worn, the flame turns weak or sooty, or will not light at all.
7. Dirty or faulty photocell. The photocell is the burner’s eye. If it cannot see the flame, because of dirt or a failed cell, the burner shuts down within seconds of lighting.
8. Worn, sooty or badly gapped electrodes. They make the spark. A weak spark leads to failed starts, or to oil pooling before it lights and a bang on ignition.
9. Contaminated oil. Water and sludge from the tank get drawn into the filter and nozzle and cause repeated lockouts. The cure is a tank clean and a flush of the oil lines.
10. A closed valve or blocked tank vent. An oil supply valve left shut after work, or a tank vent blocked by debris or insects, can stop oil flowing even when the tank is full.

Less Common Reasons A Grant Oil Boiler Is Not Firing Up

11. Motor hums but will not turn. A seized coupling or a tired run capacitor is the usual reason, and both are quick for an engineer to put right.
12. Failed oil pump. A worn pump, or one with a clogged internal strainer, cannot deliver oil at the right pressure.
13. Faulty solenoid valve. This valve opens to let oil reach the nozzle. If it sticks, the burner runs but nothing is sprayed.
14. Failed ignition transformer. No transformer, no spark. The burner will fan and then lock out with no flame.
15. Control box failure. The burner’s brain can fail with age, or after a power surge. It is usually diagnosed once the simpler faults have been ruled out.
16. Overheat thermostat tripped. Grant’s dual thermostat cuts out at around 110°C and has a separate manual reset under a plastic cap. The reset is the easy part. Finding what caused the overheating, such as a pump fault, sludge or a closed valve, is the job.
17. Fire valve closed. It shuts off the oil at around 95°C, so the burner can be starved even with a full tank. It should not be reset until someone has checked why it closed.
18. A leaking or damaged oil line. A split or perished flexible hose lets in air and may leak oil. It needs prompt attention, both for the boiler and for the environment.
19. Low system pressure. On sealed-system models such as the Vortex Eco and combis, pressure that has dropped below the normal range can stop the boiler running. If it keeps dropping, there is a leak to find.
20. Frozen condensate pipe. On Vortex Pro condensing models, a frozen condensate pipe in cold weather can stop the boiler. Thawing it and lagging the pipe usually fixes it.
21. Blocked flue or air supply. If the flue terminal or combustion air supply is blocked, the burner cannot burn properly and may lock out.
22. Severe cold. On outdoor boilers with exposed pipework or an above-ground tank, very cold weather can thicken the oil and restrict flow.
23. Hot water faults on combi models. On a Vortex combi, a stuck diverter valve or scaled plate heat exchanger can mean heating works but hot water doesn’t.

Is It Safe To Reset A Grant Oil Boiler?

Once is fine. Twice is a warning. Each failed start can leave a little unburned oil in the combustion chamber, and a third or fourth attempt can light all of it at once with a loud bang. If the lamp comes back on after your first reset, leave the boiler off.

Why The Overheat Thermostat And Fire Valve Need An Engineer

Both devices are there to stop something dangerous happening. If either has operated, the boiler has told you it got too hot, and pressing the button without looking for the reason defeats the point of having them.

Grant Oil Boiler Repairs Around Hinckley, Nuneaton And Tamworth

Our boiler repair service covers Hinckley, Nuneaton, Tamworth, Leicester, Coventry, Rugby and Loughborough. We will find the cause, tell you what we found in plain English and agree the work before we start.

A well-serviced Grant can run for many years, which is why we recommend yearly oil boiler servicing. If yours is locking out every few weeks despite repairs, it may be time to look at oil boiler installation, and if you are off grid and curious about the alternatives, our comparison of heat pumps versus oil boilers is worth a read.

Arrange A Visit For Your Grant

Send us a message through the contact form and we will arrange an engineer to look at your Grant at a time that suits you.

Grant Oil Boiler Not Firing Up FAQs

How long does a Grant oil boiler repair take?

Many common faults, such as a filter, nozzle or electrode, can be dealt with in one visit. A motor or pump may need ordering in.

Why does my Grant start fine in summer but not in winter?

Cold weather brings out problems like a frozen condensate pipe on condensing models, and a tank that is low in winter is more likely to draw up sediment.

Should I bleed the oil line myself?

No. Bleeding the line is part of the repair, and it is best done once the cause of the air has been found.

Is a Grant boiler over 15 years old worth repairing?

Often it is, provided parts are available and the repairs are not stacking up. We will tell you if replacement looks like the better value.