oil burner has beaten me for the first time and am annoyed

[ar22]

As usual its a friends boiler so he thinks Im a bluffer

Its an old boiler that is not identifiable but it is fitted with a monoflame minor burner

went to see it as it went straight to lock out, identified a seized motor bearing, replaced and she runs like a dream

so we decided to service it while there

chamber was prety clean and had a very slight hint of running rich (very slight)

it was fitted with an 80H 0.6 jet air set at 3

on the presumption that as the boiler was unidentifiable and that it ran well and pretty clean I would refit like for like and set it up better

here the problem started

new jet and it ran very rich (black) air was at 3 and even fully open (8) was still about 6 on the smoke so no good to me, but why is this ? to me the new jet should have leaned it off a bit

pump pressure was 9 bar

I was clutching at straws so reduced pump pressure to 7 bar, this got it down to about 4 on the smoke so still no good to me

took jet out and put in a .55, ran like a dog, could hear it spluttering and misfiring

refitted the 0.6 tried all pump pressures from 7 to 9 bar

boiler sounds sweet but air is still open max and getting about 4 on the smoke so still very unhappy

what my problem, when I started air was set at 3, now I cant get enough

whats the problem ?????????

is it drawing air in the oil side somewhere ?

(jet it a bit stiff on the last few threads but tightens)


any ideas would be greatly appreciated

 

[Best]

Remember there is often a hinged air flap inside the air intake side on minor burners! One screw you remove & the other 2 you just slacken, as it is slotted. Remove plastic cover & there might be an alloy door covering the opening to fan. Either oil it's hinge or remove flap. You are supposed to check this each service. They jam closed often, especially if damp air can get to them & they are not essential & not an air adjuster.

 

[ar22]

had the air intake off when identifying the seized bearing

this is the Minor with the "collar" type of air adjiuster with red and blue scale 0-8

dont think there is an adjustable flap inside this although there is a small fixed flap that sits at 45degrees in towards the fan but it doesnt move

thanks for the swift reply

 

[Best]

Air setting is normally between 1.5 & 3 on a minor one with .6 nozzle. If oil pressure correct then unlikely new nozzle is the cause in this case ( although they can be seriously faulty). So it should be air flap.

 

[kimbo]

I would say best has got it spot on

 

[ar22]

what oil pressure do you recomend

I was so browned off I refitted the original jet and I still have my problem

 

[Best]

had the air intake off when identifying the seized bearing

this is the Minor with the "collar" type of air adjiuster with red and blue scale 0-8

dont think there is an adjustable flap inside this although there is a small fixed flap that sits at 45degrees in towards the fan but it doesnt move

thanks for the swift reply

Yes, some have that & no door. So burner should be clean burning with pump pressure at 8 or 9 bar & air at 3 to start with. I can only assume nozzle is not sealing right. This would mean oil everywhere, inside boiler. They can be very tight on those burners on threads, as you said. Is it the newer minor burner with the separate diffuser in nose cone? ie not the one piece nose cone? If it is, I hope you put it to proper position. Hope your oil pressure gauge is reading right, although never had one go faulty myself - except one I dropped!

 

[ar22]

Yes, some have that & no door. So burner should be clean burning with pump pressure at 8 or 9 bar & air at 3 to start with. I can only assume nozzle is not sealing right. This would mean oil everywhere, inside boiler. They can be very tight on those burners on threads, as you said. Is it the newer minor burner with the separate diffuser in nose cone? ie not the one piece nose cone? If it is I hope you put it to proper position.

thanks for your replies
its an old burner (1991) with a single peice blast tube

since I had the blast tube off about 5 times and did notice a very slight dribble of oil around the centralising collar over the jet although nothing excessive

will I ptfe the jet in ?

 

[Best]

Might be worth trying a little ptfe, just after threads of nozzle. Done it before myself. There is something strange about those minor burner threads & I notice Danfoss nozzles seem to be tighter on them. Good enough burners though. Hope that sorts it, it sounds likely.

 

[Best]

A 1991 burner is fairly old for a minor burner, especially if it is mostly original. Some had 50 watt motors which are weak. I would think people would be better getting a Sterling burner as cheapest long term, providing actual boiler seems good enough. Sum of major parts cost a new burner.

 

[ar22]

it got a new oil pump last year and a bearing tonight,but runs well (usually)

its an Ulster fry in Lisburn at 10 in the morning then round 2 with the boiler in Moira afterwards

convinced its drawing air so will ptfe new jet and oil pump outlet union and hope for the best


I will get back with my findings


many thanks for your help, I thought I was going mad when at it tonight, but the very tight nozzles did strike me as strange so I hope a sliver of ptfe will cure it

 

[Best]

Didn't realise u r an Ulsterman! Best wee place in the world! Nice wee village, Moira too! Good luck 2moro. Hope u get sorted, as minors can be all work. Better that they are changed to a Sterling, but guess people don't have the money always.

 

[ar22]

All sorted

ptfe on the new jet and normal service resumed

air at 2.5 and 89% efficency so pretty happy

had an issue getting the oil feed line from the pump to seal at the olive but a lot of messing with ptfe sorted it but very frustrating, would you recomend any liqued product for sealing the joints to take over from ptfe ?

many thanks for your replies, they were spot on and saved my day

 

[Best]

That wee olive on the end of the pump side of the inlet pipe is a pain to seal. It would be so easy to accidentally block the end of it when using sealant. I have used a little red jointing stuff ( can't remember it's name), similar to stag. Heldite, is good & nice to work with. Other guys may have different choice of sealant. I have used ptfe before. I think you should seal the side of the olive that's not against the fitting in this case.

 

[SimonG]

Heldite is the stuff for me.

 

[ar22]

That wee olive on the end of the pump side of the inlet pipe is a pain to seal. It would be so easy to accidentally block the end of it when using sealant. I have used a little red jointing stuff ( can't remember it's name), similar to stag. Heldite, is good & nice to work with. Other guys may have different choice of sealant. I have used ptfe before. I think you should seal the side of the olive that's not against the fitting in this case.

I have used Rocol in the past (red stuff)

I think i will look into getting some Heldite as recomended

Ptfe on the olive is a nightmare and as you say you can only use it on the pipe side or else I could block the pipe

a tiny amount of liqued stuff on the the taper and left to almost cure should sort some cheeky ones out although I would avoid it if possible

many thanks

 

[Best]

" Rocol" is the name, as you said. I think it's a bit better than Stag, but they are both too messy & hard to work with. As SimonG says, Heldite is good, so that's what I currently use.