Hello,
My Potterton Promax 24HE is going through combustion box door seals like they're going out of fashion! I've just had to replace them again having replaced them just after Christmas.
I'm very careful to make sure that the bolts are torqued down properly - this was after I had to replace the seals for the first time and found that the bolts were barely finger tight! (Thanks BG)
It always starts in the same area - bottom LH corner as you look at it - so there's clearly an issue there, but it eventually spreads 3/4 of the way along the bottom and about 1/2 way up the side. The seal material just turns to powder. Once the seal is degraded, then the boiler starts cutting out as it trips the fan protection stat.
The combustion box is in multiple parts and the lip (that provides the primary seal) on the burner tray part visibly doesn't align properly with the main part of the box in that corner. It's not much - maybe .1 or .2mm. If you put a straight edge across the two parts it can be rocked ever so slightly.
The face of the seal lip isn't finished so initially I didn't think it was critical that this gap existed, but I now think this may well be the problem (as it's allowing hot gases to play on the foam rubber seal).
I don't see an easy way of closing the gap up without either unbolting the bottom part of the box and trying to realign it, or filing the lip flush and then somehow reducing the clearance of the door by flattening/filing the recess that the bolt sits in.
The box door seems to be straight so I don't think a new door will help.
Has anyone else experienced this? Any help appreciated!
My Potterton Promax 24HE is going through combustion box door seals like they're going out of fashion! I've just had to replace them again having replaced them just after Christmas.
I'm very careful to make sure that the bolts are torqued down properly - this was after I had to replace the seals for the first time and found that the bolts were barely finger tight! (Thanks BG)
It always starts in the same area - bottom LH corner as you look at it - so there's clearly an issue there, but it eventually spreads 3/4 of the way along the bottom and about 1/2 way up the side. The seal material just turns to powder. Once the seal is degraded, then the boiler starts cutting out as it trips the fan protection stat.
The combustion box is in multiple parts and the lip (that provides the primary seal) on the burner tray part visibly doesn't align properly with the main part of the box in that corner. It's not much - maybe .1 or .2mm. If you put a straight edge across the two parts it can be rocked ever so slightly.
The face of the seal lip isn't finished so initially I didn't think it was critical that this gap existed, but I now think this may well be the problem (as it's allowing hot gases to play on the foam rubber seal).
I don't see an easy way of closing the gap up without either unbolting the bottom part of the box and trying to realign it, or filing the lip flush and then somehow reducing the clearance of the door by flattening/filing the recess that the bolt sits in.
The box door seems to be straight so I don't think a new door will help.
Has anyone else experienced this? Any help appreciated!
