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Condensing central heating boilers and freezing

Postby ericmark » Tue Dec 07, 2010 5:46 pm

Condensing central heating boilers and freezing. My parents have a new Wooster central heating boiler, and the condensate pipe filled up with ice. The boiler made gurgling noises and then tripped out. Lucky the weather was not too bad and I was able to get there, and heat the pipe so removing the frozen condensate. However it would make sense to fit some form of trace heating. It seems the pipe goes through the wall near horizontal then about 30 degrees fall to drain and it was the horizontal section which caused the problem. Since this is in the wall putting any trace heating on outside of pipe will not be easy. This makes me ask what about inside the pipe. There will be a problem with acid I know and any element which can get wet would need to be supplied from a SELV supply. But here is the point. There must be thousands of people with the same problem and it seems inconceivable that an answer has not been found with some special pipe with trace heating built in designed for this very job!

So what have others used to keep the condensate pipe free from ice.
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Postby sparx » Wed Dec 08, 2010 8:06 pm

daughter has same problem!
talked to plumber/gas fitter mate today, he's been to 4 this week!!
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Postby bb700 » Thu Dec 09, 2010 8:51 pm

My Vaillant `ecotec plus` condenser boiler is fitted with a syphonic trap ;the syphon collects the condensate to a quantity of about 200 ml & then directs the entire content to the drain pipe ( thus resulting in minimal freezing problems). For boilers with a normal condensate drain pipe :-- the discharge pipe should have a fall (45mm per metre)& preferably be installed & terminated within the building to prevent possible freezing.
All boiler manufacterers will state all this info. in their installation guide.
It is up to the installer to comply to make the product more user `friendly`. or install the easier way with the possibility of freezing (although acceptable).
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Postby ericmark » Fri Dec 10, 2010 6:42 pm

It is fitted with symphonic trap. The problem now we have been able to remove the pipe cover is three fold.
1) The cover has resulted in the liquid in the condensate pipe to be colder.
2) The size of the pipe does not comply with the minimum 32mm requirement stipulated for pipes which may freeze.
3) There is no fall in the pipe going through the wall.
Cures can be done in a number of ways.
1) Renew the undersize pipe with correct size moving from around 20mm to 32mm.
2) At the same time a fall would be included.
3) Remove the aesthetically pleasing cover.
4) Fit some trace heating.
5) Fit a cover outside to encapsulate both the waist pipes.
6) Fit lagging outside.
I would like to retain the aesthetically pleasing cover. Also I would want to follow the regulations and have a fall and correct size pipe. Fitting a cover and lagging also seems a good option although not really needed in a hurry. The lagging does worry me a little. Although it would to begin with stop the condensate freezing as the temperature dropped it could still freeze and if it did then getting at the pipes to de-frost would be a problem. So fitting a cover so the heat from the sink waist pipe is directed up the length of the condensate pipe seems a good extra but don’t think I would include lagging.

As to trace heating I don’t think it would be required once the other alterations were completed.

However I did finally find the installer and it says “Total Trade Services core values of Quality, Safety and Care are at the core of everything we do.” Considering the fight I had during the install when a combi boiler was connected to a power shower. Plus wrong radiators fitted. Plus we had to insist they fitted pipes between ceiling and floor not exposed just under ceiling in kitchen I think it would be better to pay for a competent plumber rather than ask them to correct their workmanship.

The post on a number of different forums has done a good job. I had expected to find there was a trace heating kit. However I had not realised until I got replies that the installation did not comply with regulations. So seems likely with the house just 200 m above sea level approx that once the regulations are complied with we will have no further problems.

Thank you all for your help.
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