Glowworm 18HXI water trap leak and black grit

[YorkshireMidge]

My condensing boiler has developed a slight leak from the blue screw on plastic cap on the water trap under the boiler. The "seal" was a disintegrating soggy foam thing, so I've done a temp fix with an O ring whilst I get the proper replacement cap/seal. But I couldn't help noticing the water was dark and load of small black gritty particles had collected - a good teaspoonful I reckon. What are they and are they normal?

Thanks!

 

[heatservice]

Quite normal as condense is slightly acidic, seems to be worst with aluminium heat exchangers.

 

[Combicert]

When the heat exchanger is first made it’s done so using a process involving sand... this grit can be sand particles left over from the manufacturing process ... or just build up of flecks of byproducts from years of use - as above; condensate is slightly acidic too.

Either way, Perfectly normal to find it in the bottom of the trap. The trap will be emptied during your routine boiler service and then filled back up with water - as recommended in the manufacturer instructions.

 

[YorkshireMidge]

Great - thanks for the clarification.