Oily smell from Worcester Bosch Greenstar Heatslave 2 25/32

[Neilyo90]

Hey all,

I know there's been several posts about this before, mainly on the 18/25 boilers from what i've read. But I've got an issue with my boiler producing an oily smell..

When I purchased the house in July 2024, there was a huge issue with an oily smell from the boiler room. It was tracking up into the bedroom above the utility too. We've since had an engineer out who identified a leak on the fuel line that comes up from the ground into the boiler. It was leaking from the joint and tracking back down around the pipe and sitting there. That's been fixed, and there has been an absolutely massive difference. No longer any smells in the bedroom above etc.

HOWEVER I am still noticing when the boiler has been runnning sometimes I get a few whiffs of unburnt oil. Unfortunately where the boiler is, it's not blocked off from the house in any way, it's down a long utility hallway and then around a wall, without a door. So this smell carries through the house sometimes.

I've had the engineer out again, I watched him take the whole thing apart, took the pump off, checked all the joints to the pump, no weeping anywhere.. So I'm at a loss as to what it could be. He's also checked the flue (balanced) and combustion, everythings firing right and the quality of air in/out is spot on.

At this point, it's a very low smell and I could be being abit pedantic but I notice it sometimes and also when we have visitors I ask them if they can smell the oil when they walk in the house, to which the answer is always "abit yeah".

Side note: If I stick my head in the top of the boiler, the front (pump side) has absolutely no smell at all. However the back i'm picking up a slight unburned fumey smell (not exhaust smell).

I'm wondering if I should just block the area off with a door to make it isolated, but I feel liek that's just masking it rather than fixing it.

Any idea's would be welcome!

 

[oilhead]

If the oil line enters from the rear, which I'm thinking is normal, then that is the place to check. Isolation valves are not an uncommon feature to leak around the shaft or connections, but also the swaged ends of flexible hoses are a common source of leaks. If yours have not been changed recently it may be time anyway; they are date stamped and there is a recommended usage. Generally, if you remove the hose and you can rotate the tails in the crimps, then they need changing.

 

[Neilyo90]

Hiya mate, thanks for the reply! So the oil comes into this one on what is the right hand side, that was previously leaking and we’ve changed that fuel line. No more leaks coming from there, and we also changed the oil line from that point to the pump itself.

So we’ve eliminated that bit, the smell seems to come from the wall side of the boiler which is the back, fuel line enters into the back right but connects on the right nearish the front. I’ve also checked the isolation there and it’s not weeping.

So I’m stumped!