We received a phone call last week from Ms. Reynolds who lives in Glasgow, Scotland. She was looking for some advice. Her recently installed boiler froze up in the cold snap a few weeks back. She has called the installer who showed up, removed a section of the condensate waste pipe that was frozen and then left it like that. As you will see from the photos below the open end of the waste pipe coming from the boiler is now leaking acidic water onto her garage roof where it is freezing! That’s not all!

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After getting no response from the installers she called Worcester for some advice and they told her (based on what she told them) that the condensate pipe was not hooked up correctly. She then called the installers again to try and get satisfaction and to date has received nothing.

So she contacted us for some advice. Without seeing the job for ourselves it is difficult to take in the surroundings, locations of suitable waste outlets for the condensate and the like. We can however give some guidance as highlighted in the building regulations and the Worcester boiler installation manual. We also noted that the current condensation waste runs into a cast iron rainwater down spout.

In order to get a higher efficiency boiler compared to older cast iron boilers designers extract as much of the heat energy as reasonably possible from the exhaust before it leaves the boiler via the flue to the outside. The downside of this heat extraction has been the creation of a large amount of condensation which is in fact just waste water. Acidic waste water. This condensation waste water drains back through the flue and internal pipe work inside the boiler and in most cases is collected in a bottle trap. The trap ensures that flue gases don’t escape into the house as well as allowing the water to collect until there is enough to eject.

The waste water is released out through the condensate trap an into the waste pipe work supplied and installed by your installer. Most boilers will connect directly to a 22.5mm overflow pipe work directly and this is one of the main reasons we believe installers use the narrow pipe and don’t increase the size. It’s too easy not to. Another issue we find and have to repair on a regular basis is that some installers make up their own ways to connect up the pipe work instead of following the prescribed methods. We’ve even seen overflow pipes shoved between roof slates!

The building regulations are sometimes difficult to comply with but there is always a way to do it correctly. This article [ CLICK HERE ] shows five diagrams showing the methods that are prescribed by most manufacturers and the building regulations. Another method not mentioned in the article is the use of a condensate pump. The pump is used in areas were there are no nearby waste pipes to connect to or where the waste pipe work is located higher than the boiler such as a basement or cellar. Here are a couple of examples of where we have used pumps. Boiler located in cellar Boiler located in middle of house with no waste pipe work nearby

As for how to run condensate pipe work our first choice would be keeping the pipe work inside the property to eliminate the possibility of freezing. The pipe work should have a continual fall from the boiler to the waste using gravity or you could use a condensation pump. The second choice would be to run the pipe work outside and into an existing foul water waste pipe or gully. The third choice would be a connection to a soakaway. The soakaway however should only be used if no other choice can be found.

So what is the answer to this particular situation? We see a couple of issues right away. The waste pipe exits the building underneath the boiler and runs towards the cast iron rainwater down spout. We can see two connectors on the down spout so can only assume that the first connector wasn’t low enough thereby causing the water to backup and sit in the horizontal pipe where it would surely freeze. I find it interesting that the the second connection is only a bit lower and that an elbow was used to plug into it. Also note that the original connector is still attached! As the pipe work also exits into a cast iron pipe the acid from the condensation water will corrode the metal away. To finish off, the choice to connect to a grey water (rain water) down spout is not a good choice. That down spout may not drain into the foul water waste and so the acidic water could eventually get into the water table. We don’t fancy drinking that! It may be in the case of this house that a better solution would have been run the condensate pipe into the bathroom waste with regular pipe work or with the use of a condensate pipe.

Clearly there are issues to be sorted at the moment as the condensate pipe work is not hooked to anything and appears to be hanging free and dripping onto the roof.

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