Grant Vortex - Nearly Locking Out on Firing Up

[martinwinlow]

Hi All,

Everything was fine - then I had to move my 1800l oil tank and extend the supply pipe by about 6m (from about 15m). In order to do so I ran the tank as low as I could. After moving and reconnecting the pipe and firing up the boiler, I saw that the Tiger Loop bowl emptied - I could see air bubbles in it initially, then as the air in the line got pump through, the bowl emptied as I watched. Eventually the boiler would fire but only after 2 or 3 tries. It only actually locked out when I first tried it. Ever since (a week now) it has never locked out but always has to try at least twice to fire up.

Yesterday I checked the tank filter - missing (! - replaced with a spare) and then the boiler oil pump filter. This was badly mucky and there was about 30 grains of sand/whatever inside the pump cover (but on the up-stream side of the filter).

The Tiger Loop level is still very low (was always full before). I see that the basket around the (balanced) flue has a sooty deposit on it. I don't know if that is new but might this indicate other issues?

Thoughts, please. MW

 

[SimonG]

Whats the oil pressure and co2 like?

 

[martinwinlow]

I good question and one I was hoping to avoid having to ask. I'll have to dig out the tester & gauge to see - could it be a dirty photocell? MW

 

[kimbo]

Yes it could be a sooty photocell. Check that first.

 

[WHPES]

Naa, if what you describe on the tigerloop with the air and the level low, my bet is you have a leak somewhere on the suction line and its drawing air in on the suction side. Once your boiler has stopped firing for a while the air seeps in and the fuel level slowly drops back towards the tank causing your boiler to struggle to prime itself each time it fires, and again once it stops firing, air gets in and it starts to lose its prime again.

Soft copper pipe joints are notorious for leaking if they have been disturbed Check your joints and do a pressure test on the complete line from the tank and you will see where the fuel leaks out.

A pump pressure gauge needle will usually wobble when this is happening, a sure indication of air bubbles getting into the pump.

 

[martinwinlow]

OK - thks to you both - I had 'hoovered out the bit of the tank bottom nearest the outlet with a drill-type pump attached to some flexible hose and then a long piece of copper pipe. Fortunately the tank design I have has 4 'pocket's about 2" deep forming the base of the tank. So all the muck and water gets stuck in them. It was obviously moving the tank about that has disturbed the residue.

WHPES' suggestion is also a distinct possibility - tho none of the joints are leaking and I would have thought that if they are poor enough to leak air in when the pump is sucking they would leak oil out when it wasn't sucking and the oil is moving back down the pipe under gravity - there is 3 feet or so of 'head' between the pipe on the ground (under the deck) and where it enters the Tiger Loop ...? Anyway, a pressure test will tell. MW

 

[kimbo]

I agree with whpes but I would still check the photocell it only takes a minute

 

[martinwinlow]

Will do - MW

 

[WHPES]

Your reasoning doesn't quite figure as oil is more viscous than air so you may not see a weep when the boiler isn't firing, and this would only be visible if the leak is near to the base of the tank. If the leak is on the system above the oil level then it will draw air in when the burner isn't running thus allowing the oil to run back to the tank level. Do a standard pressure test and leaks will soon be evident. Don't forget to check the flexi lines, the pump (inlcuding seals and shaft seal), and also the tigerloop and its fittings, plus the remote valve.

Is there a wheel head fire valve in the line? These are notorious for allowing air in under suction.

 

[WHPES]

Just an afterthought - A problem I had like this years ago turned out to be a leaking o-ring on the fuel pump. I had opened the pump to clean the filter and when it was all back together it was no longer fully sealed. Took ages to find it. A new o-ring fixed the problem.

 

[martinwinlow]

WHPES- It had it's problem before I tinkered with the pump and I have checked the photocell - clean as a whistle - I assume it has a sight glass into the combustion chamber which is kept clean by the combustion? Any chance this has gotten permanently obscured by burning mucky fuel? MW

 

[WHPES]

No. Nothing to do with it. It sees the rear of the flame as it is positioned behind the blast tube away from the heat. If the end of the photocell is clean, then soot is not the problem. If it is struggling to fire, then does fire and run, my money's on an air leak.

 

[martinwinlow]

Thanks to all for replying. Problem now resolved.... tho not entirely sure why (isn't that always the way!?) When I put the new in-line paper filter in (just upstream of the tigerlop) I'm pretty sure the supply pipe to the TL was a bit loose - and not leaking. Anyway, when I tightened everything back up, no more hesitant firing. I have not check since to see if the TL bowl is full but I bet it is. Thanks again. MW out.

 

[WHPES]

In that case it is as we said. It was leaking air into the pipe as the pipe is under suction all the time.

 

[peteheat]

In that case it is as we said. It was leaking air into the pipe as the pipe is under suction all the time.

Great call Whipes, you certainly know your Tiger Loops !