Where's my black grit coming from?

[jshailes]

I have a condenser bolier and have heard that black grit can accumulate in the condense outlet pipe. The reason I've been looking into this is that the copper pipe into the waste pipe is blocked with grit and I'm guessing it must have been either a reaction with the copper or a product of the boiler. Has anyone experienced this before?

 

[emerald]

I have a condenser bolier and have heard that black grit can accumulate in the condense outlet pipe. The reason I've been looking into this is that the copper pipe into the waste pipe is blocked with grit and I'm guessing it must have been either a reaction with the copper or a product of the boiler. Has anyone experienced this before?

it is fairly common to get small amounts of grit (or corrosion of the heat exchanger) in the condensate trap, but its unusual for it to block the discharge pipework, which by the way should be plastic,

i would replace in plastic, then get a gas safe guy to come and service the boiler, and give the heat ex a good rinse

 

[oldplumber]

condensate from a condensing boiler is fairly acidic and having it run off via cu tube is not the norm, you would normally run condensate away in plastic overflow pipe. I would think that the condensate has corroded the copper tube and caused it to block. which i that is the case is easily solved by replacing it with plastic overflow pipe or standard 11/4" waste pipe

see u beat me to it on this answer emerald, still at least we agree on the answer

 

[Blackcatgas]

I have a condenser bolier and have heard that black grit can accumulate in the condense outlet pipe. The reason I've been looking into this is that the copper pipe into the waste pipe is blocked with grit and I'm guessing it must have been either a reaction with the copper or a product of the boiler. Has anyone experienced this before?

The condense pipe should never be copper, the condense is acidic and will disolve the copper pipe in about 6mnths, plastic should be used.
what boiler have you got? is it an old baxi, 133he etc? the black/ grey silt in the condensate trap is the aluminuim heat exchanger being eaten. Or it could be bits of the copper condensate pipe being eaten.

edit, beat to it by the above posters.

 

[Puddle]

silt in the condensate trap is the aluminuim heat exchanger being eaten. Or it could be bits of the copper condensate pipe being eaten.

or could be both

imho

 

[oldplumber]

hat trick of answers that all say the same thing, must be a first for the forum

 

[jshailes]

Thanks for your replies guys. I have been aware about the copper but have just never got around to taking the floor up. The condensate was running out through a "CondenSafe" filter which I was hoping to remove the acidity, however I decided to remove this about 2 years ago because the condensate didn't drain freely through the unit which caused problems with the boiler. The only copper part of the system is shared with the bath/shower so plenty of fresh water flows through here.

So albeit the pipe needs replacing, my main concern is where this grit is coming from. It seemed to block so quickly - no problems until I had a bath last night at which point the water didn't drain and had to resort to syphon it.

I believe the exact model of the boiler is a Worcester Bosch 24Si

 

[oldplumber]

condense filters need annual replacement as the limestone inside will no longer work, and could your blockage be more to do with bath gunge than condensate?

 

[jshailes]

Definately it could be bath gunge. The bath did overflow through the overflow holes which is probably the first time ever but I couldn't really understand how there would be enough gunge to block the pipe, but to be fair I'm struggling to see how anything could block it in such a short period.

I think my plan will be to do as everyone has suggested, replace the copper pipes. Is there any way to check if corrosion has occurred to heat ex? Also is the limestone filter really essential, like I mentioned it's been removed for last 2 years with no problems.

 

[Blackcatgas]

pics of black grit?, have a look at the clear condensate trap in the boiler, if this has no "grit" in it then the source is unlikely to be the heat ex

 

[jshailes]

Image attached of a small amount of the grit removed from the blocked pipe

 

[emerald]

looks like heat exchanger to me

 

[jshailes]

Ok. Blackcatgas mentioned to validate this check the condensate trap for grit. I'm not too sure where this is but I'll check the boiler manual tomorrow. If it is the heat ex, what could've caused this or is it general wear and tear? Also are they expensive/difficult to replace? Would I need a registered gas expert?

 

[emerald]

Ok. Blackcatgas mentioned to validate this check the condensate trap for grit. I'm not too sure where this is but I'll check the boiler manual tomorrow. If it is the heat ex, what could've caused this or is it general wear and tear? Also are they expensive/difficult to replace? Would I need a registered gas expert?

to be honest, you shouldnt really take the cover off, just get a guy round to service it, he should check and clear any build up of corrosion

 

[Blackcatgas]

Ok. Blackcatgas mentioned to validate this check the condensate trap for grit. I'm not too sure where this is but I'll check the boiler manual tomorrow. If it is the heat ex, what could've caused this or is it general wear and tear? Also are they expensive/difficult to replace? Would I need a registered gas expert?

General wear and tear, aluminuim heat exs are normaly very suceptable to this, I always thought that the WBs 24si were made of some sort of special brew metal, something silicate??..... that was resistant to the acidic condense.