Combi boiler questions: what are these plastic pipes for?

[SiD the Turtle]

Hi boys and girls.

Had a minor drip coming out of my Worchester boiler so called out the plumbers. They 'fixed' it but it was still leaking today so had a quick nose myself. I could see that a plastic pipe that is simply slid on to a metal pipe had slipped off, so I've pushed it back on and the leak has stopped. Here's a picture:



This plastic pipe runs down and is joined by another with an odd looking clear plastic valve, then runs under the floor.



So two questions, should there be water in that pipe, and what's that clear valve thing for?

Trying to get the plumber back out without charge, as obviously I'm not a gas safe engineer!

 

[Abyss]

Looks like the condensate and vapour trap. Wikipedia describes it well

The condensate expelled from a condensing boiler is acidic, with a pH between 3 and 4. Condensing boilers require a drainpipe for the condensate produced during operation. This consists of a short length of polymer pipe with a vapour trap to prevent exhaust gases from being expelled into the building. The acidic nature of the condensate may be corrosive to cast iron plumbing, waste pipes and concrete floors but poses no health risk to occupants. A neutralizer, typically consisting of a plastic container filled with marble or limestone aggregate or "chips" (alkaline) can be installed to raise the pH to acceptable levels. If a gravity drain is not available, then a small condensate pump must also be installed to lift it to a proper drain.

 

[robj20]

That's some poor soldering.

 

[a1ex2001]

Condensate and pressure release at a guess, the pressure release has to have a clear section if it doesn't vent visibly outside so you can see if it is releasing pressure. Condensate pipe is in plastic as the liquid corrodes copper although the final size inches of mine is in copper and has been fine for ten years

 

[NickK]

Hehe the bottom of that looks similar to my WB 32CDi.

Left plastic is the condensate pipe - mine is gravity drained into the soil pipe.

The right one is the pressure relief - mine is vented out the gable wall (same as exhaust) behind the boiler.

 

[SiD the Turtle]

Thanks everyone, much appreciated.

Agreed on the soldering, the curse of the relatively new build.

 

[Millwall.FC]

You could put a jubilee clip on it to stop it slipping off over time.

 

[koolpc]

I have read that some plumbers over solder in areas where things are not on show, is that right?

 

[joeyjojo]

As above if you hear dripping in that pipe it's a good thing as it means the boiler is extracting some heat from the exhaust gases which improves efficiency slightly (only works when the incoming water is sufficiently cool).

 

[divuk83]

I'm not a plumber but....

Left hand pipe is condensate, there will be lots of water that comes out of this one. Can you check where it drains off too? Is there a pump or does it drain directly outside? Only reason I mention it is I had a combi in our last house (fitted on an internal wall) that was just dumping all the condensate under the floorboards as the person who fitted it was too lazy to do it properly. I had to fit in a pump in the end to sort it, though this instantly cured the unexplained damp problems on the internal walls! If the boiler is on an external wall you can usually drain it off outside using gravity alone. If it drains externally make sure it's not really narrow pipes (22mm+) and is protected against frost as if it freezes up the boiler will stop working.

I think the other one is the PRV (pressure relief valve) and I was under the understanding that they were supposed to be copper pipes not plastic? I would have also thought it would be better to have this separate to the condensate as it's handy to be able to identify when the PRV is leaking and needs repairing/replacing. This should be vented with a slight drop directly to outside (not a through a pump).

Dave

 

[Deleted member 651465]

Who's the plumber that soldered those pipes? Stevie Wonder Ltd

 

[Hedge]

As long as they don't leak the messy solder isn't really an issue. Probably just an apprentice job or something.

The green on the pipes is flux that the plumber hasnt wiped off. You could clean that if it really bothered you

 

[a1ex2001]

I think the other one is the PRV (pressure relief valve) and I was under the understanding that they were supposed to be copper pipes not plastic? I would have also thought it would be better to have this separate to the condensate as it's handy to be able to identify when the PRV is leaking and needs repairing/replacing. This should be vented with a slight drop directly to outside (not a through a pump).

The PRV pipe can go anywhere as long as it is visible when water is being expelled hence the clear chamber it doesn't have to go outside it can go straight into a waste pipe under the sink or via a pumped sump etc.

The usual is just to run it straight out through the wall and then point it as the ground (It should never be left pointing horizontally as it could blast a passer buy with a load of very hot water!)