How to avoid a frozen condense pipe
If your boiler has stopped working and its freezing outside there is a good chance that your condense is frozen.
The thing that makes condensing boilers so efficient and saving you money is also their achilles heel.
Over the winter cold snap last year
09/10 a very high percentage of emergency boiler call outs were attributed to a frozen condense.
One British Gas engineer estimated it to be 75% at one point.
When the first condensing boilers were fitted in the uk over 20 years ago it was commonplace to use 21mm plastic overflow pipe for the condense.
It is quite likely that older installations and some new 'unregistered' installations have insufficient protection against freezing.
In recent years we have been seeing ever decreasing temperatures during the winter months and this has been causing problems with freezing pipes.
Why do I need a condense pipe?
During normal operation of the boiler condensate will be formed in the heat exchanger and flue. The amount of condensate formed depends on many factors, although over 4 litres a day is not untypical. This condensate is slightly acidic, with a ph of between 3 and 6, similar to tomato juice and must be disposed of correctly There are particular regulations and guidance regarding condense pipes that must be followed.
Steps you can take to cure a frozen condense pipe.
There are a couple of things you can do to get the boiler working temporarily.
1 - Defrost the pipe using warm air or warm water.
Pour hot water on to it until it melts.
Health and safety advice.
DONT use boiling water as this could split the pipe and is more likely to burn you.
If you try this step and you get burned by the water,
then you are a danger to yourself and would be well advised to stay well away from the next steps.
infact you would be best off going inside and calling a professional.
if you are up a ladder and pour the water straight at the wall so it splashes back on you,
you should go inside and get a post it note and write the word
FOOL on it in thick black pen( no actually you would be better using crayon).
Stick the post it note on your forehead and stand in the corner doing star jumps, that should keep you warm until a plumber arrives.
Use a hair dryer or heat gun,
be careful if the pipe gets too hot it will melt.
Health and safety advice
Electric shocks are not a good look. You know not to get electrical things wet, dont you?
If you do end up getting an electric shock then its the post it note treatment for you; assuming you survive.
2 - Alter the pipe so the boiler will not go off again
A very practical way to solve the problem is to re-route the condense pipe into a bucket or tray. It should be relativly simple as the connection of the condense pipe into the bottom of the boiler is not usually permanant and can either be pulled out or the compresion fitting loosened to allow the pipe to be removed. You will then be free to put another piece of pipe in its place, terminating in your bucket. Another alternative is to cut the condense pipe with a junior hacksaw. You are then able to add a 90 degree elbow and extra pipe needed to make a temporary termination. If you look on the picture opposite you will see the white plastic pipe This is the one you are looking for. The only possibility of there being another white pipe is if the hot and cold have been fitted with speed fix. In this instance you will be able to tell the condense pipe by the size. The one you want to cut is 21mm where as the hot and cold water ones will be in 15mm. If you are not certain, then make sure that you know where to turn the water off BEFORE STARTING.
3 - Reduce freezing : upgrade the condense pipe.
Lagging the pipe is the cheapest and easiest remedial action. 22mm pipe insulation is availible from most Plumbers merchants and DIY stores. for larger bore pipes use spiral wrap which looks like silver coated bubble wrap, it is very good. It is the equivalent of 33mm of polystrene and has an operating temperature of -20.
The next level of upgrade is to increase the size of the pipe. Only the external pipes need to be upgraded. The ideal size would be 42mm waste pipe, if this was also lagged then the chances of it freezing are minimal. You can choose the size of pipe to use on the basis that bigger is better. Even with upsizing the there is still a possibility of the pipe becomeing frozen when the water trickles down the pipe and freezes slowly over time but i'm sure you can see the advantages to having a larger bore pipe as this problem is much less likely to happen and would operate for longer before the boiler shut down.
The next upgrade is called trace heating and involves a heated cable running the length of your condense pipe. It has an external sensor that starts the trace heater when it gets to 2 degrees c. They are quite economical to run as they only turn on at times of extreme weather. They start at about £100 and only cost a few pounds a week to run. To install one would take a maximum of two hours, ideally a Plumber with part'p' electrics.