Grant External combi oil 21e not firing

[WBRacing]

Hi all, I have search about and tried a few of the suggested things that I found but none of the threads I've seen quite sum up my boilers current symptoms.

I purchased my house about 9months ago and thinking it sensible, I got the boiler serviced straight away. It is a few years old (4-5?) and I have receipts somewhere showing it being serviced each year except last year. When the engineer came round he was very thorough and was the original installer of the unit.

He pointed out that there must be a small leak on the system somewhere as it was dropping pressure slowly, but after a quick look around he couldn't spot anything so told me to keep an eye on it and top up the pressure when needed.

This I did but since May I forgot and whilst away on holiday just under two weeks ago I could see that the boiler stopped working (as I have a temp data logger in the house). For 10 days the heating was off until I got home last night.

Before even unpacking the car I went straight to the boiler and sure enough, the pressure was next to nothing. I upped it to just over 1 bar and hoped all would be fine, but sadly not. I should mention that when opening the case to do this I noticed that the DHW pump was warm, however all pipes were cold.

After a lot of tinkering, the current position is this:
When switching the power on, the lights illuminate as per the photo below, the burner reset switch is also illuminated. The DHW pump starts immediately even though there is not (and wasn't whilst we were away) any hot water demanded from it.

I bled the radiators (all were fine), both the CH and DHW pumps (both were fine) and checked the oil pump valve was bled as well, which was fine. There is loads of fresh oil in the tank and everything would seem to me to be good to go.

On pressing the burning reset switch the fan fires up for 8-10seconds, it clicks and then immediately shuts off 2-3 seconds later. I have tried various combinations of bleeding/switching (using the installer switch as well as the indoor thermostat) and running all hot taps individually and at the same time in the house.

Please can anyone advise me as to what I can do to try and resolve this? The engineer who installed it has now retired so I am stuck in a cold house with only cold water to wash with! If there is any more info needed, please do say.

Many, many thanks in advance.

 

[oilhead]

If you need to press the burner reset then the problem is with the burner, probably fuel. Have you checked oil?

 

[WBRacing]

Hi, I have checked as much as an amateur can! Tank is 3/4 full, I carefully undid slightly the bleed valves on the inline filter and on the side of the pump, both immediately bled out oil, no air, bubbles, gunk or water. Are there any more checks I can do to be sure?

 

[Andy4444]

The symptoms you describe indicate, as Oilhead says, a fuel supply problem.

Make sure oil is getting to the oil pump, check filters, fire valve trip, blocked fuel line or water in oil.

Is the motor rotating? If not check capacitor/motor or fuel pump for rotation

I would check the above first and then check photocell for failure.

 

[oilhead]

When you press the reset button and the motor starts, can you hear the flame ignite before it locks out again? If you can't, then there is little you can do without a little experience. One simple check is to remove the red cover from the burner (two screws, one on top and the other in the front.) Undo the screw on the control box and lift up the lid.Disconnect the plug at the front of the terminal block, nearest the boiler. Thisis the photocell. Being aware of the other contacts, press the reset button again and see if the burner fires up. If it does, then goes to lock out after 4-5secs, you have a faulty photocell.

 

[WBRacing]

Thank you both for your helpful replies.

I have taken the fuel checks as far as I can, checking the pump it feels (vibration) like it is working and smell wise there is a strong oil smell now, much more there now than it was this morning which suggests to me that it is getting through.

I followed your advice about the photocell and there is no change. Oilhead - in answer to your question, no the flame doesn't seem to ignite. I can't hear it and there is no noticeable exhaust fumes/smoke/smell. This is true both pre & post photocell disconnection.

I took a phone video of it trying to start in case it would help but it did not come out well!

Sounds distinctly like I'll have to wait until Monday to arrange for a professional visit.

Thanks again for taking the time to try and help me.

P.s. Just wanted to add, would this explain why when I power on the boiler it immediately turns on the DHW pump and thinks there is demand?

 

[oilhead]

The DHW pump will start as soon as the boiler is switched on because the unit is designed to heat up the heatstore for hot water. This is normal.

 

[WBRacing]

The DHW pump will start as soon as the boiler is switched on because the unit is designed to heat up the heatstore for hot water. This is normal.

Thanks oilhead. As a result of your and awowens help I was able to ask the boiler engineer sensible questions. Thanks also to the awesome engineer who spent a lot of time educating me, I now understand the boiler and the way it operates so much better than before.

The issue turned out to be water in the oil tank, well in excess of 30 gallons of water!!! Exactly as you had indicated. Seems I didn't know what I was looking at when I bled it....

It had created mayo in the three filters in the system and not left the oil pump in a healthy way. New filters and a cleaned pump later (post water drain) and the burner was firing perfectly, even better after a tune up.

The boiler then went into overheat, after time investigating the impeller on the DHW pump was found to be trashed, all worn away round the spindle.

Hopefully my sharing this info may help others. Thanks again oilhead and awowens, you were spot on!

 

[discodan84]

Hi all new on here but similar problem. my oil combi boiler did work but ran dry. I have had tank refilled. I have opened the oil line at the isolation tap within boiler housing to bleed air out. all seems to be running up fine... pumps working away..... it is showing all led lights as correct but no heat?... I have depressed the button on the blower..... it runs for approx. 7-10 seconds then stops. button them illuminates red. but still no heat? any tips before a call in a pro?

 

[45yearsagasman]

Pity I had to read through and old thread before your post appears. Better to start your own thread.

 

[oilhead]

Although you have bled oil through to the tap, how much did you run through to prove the supply. Depending on the length of the run, you may havea length of pipe where the oil from the tank may have displaced a small quantity held in undulating pipework. Run 3 or 4 litres through.
If you have been trying to start the burner a lot with a dry pump, you may have kn***ered it. Try bleeding more through first.

 

[oilboffin]

Yes I think oilheads right you could have goosed the oil pump.on the lefthand side of the oil pump
there is a bleed/pressure port undo that and see if oil and air come out if so let it run into a
receptacle and when the air stops do it up and try again if no joy call engineer best of luck.