30 October 2011

DIY - Money Down the Drain

Well, I owe B&Q an apology.  In my previous post I implied that they were less than helpful.  I retract that accusation and apologise unreservedly.

We have a condensing combi boiler.  For those of you who may not know what that is, the combi bit means it produces heat for the central heating system and hot water on demand, with the consequence that one has no need of combination thermal underwear when indoors.  The system needs neither a hot water reservoir tank nor a cold water header tank.  The condensing bit means that its efficiency is improved by using a heat exchanger in the exhaust gases from the burners to scour heat that would otherwise be wasted on the atmosphere.  This means that I make better use of the calories in the LPG we have to use where we live, and as a result have a smaller carbon footprint. A side-effect of the heat exchanger is that water vapour in the exhaust condenses, hence the term.

This condensate is not really any use for anything as other substances from the exhaust are dissolved in it.  It has to be piped away to a convenient drain.  At our house, the condensate pipe passes through the wall at boiler height and then drops about 1.5m to the drain.  Normally, this works fine but our last two winters have been cold enough to freeze the condensate on its extremely long and exposed journey to the drain, thus blocking the pipe.  Herein lay my problem. Once the pipe is blocked, the boiler stops working.  To get the boiler going again, you have to boil kettlesful of water and pour it over the pipe to remove the blockage.  This is, of course, only a temporary solution, one that is reversed on the next cold snap.

One more useful solution would be to route the pipe inside the house and into a larger outflow, such as from the kitchen sink.  That had been my intention but the position of the breakfast bar and other kitchen units made the task impossible without dismantling the kitchen.  Since the kitchen cost me 8 grand I did not feel like wrecking it.

Another solution was to make permanent a temporary measure I had adopted last winter (and which seemed to work) in a desperate attempt to avoid boiler shut-down: lagging the pipe.  Hence my visit to B&Q.

I had hoped to find some pipe lagging that was made specially for the job, unlike the only stuff that was left in B&Q last winter, when everyone else was having the same problem and the same idea.  Unfortunately, it turned out that the pipe is of a larger diameter than anything B&Q stocks insulation for.  This is not a fault on their part; I don't think anyone would have it.  So, I spoke to an assistant in the insulation aisle, explaining my problem.  I mentioned that the only option I thought I had was to box the pipe in and fill the boxing with loft insulation or some such material.  'Which would be the best?' I asked.

'Don't do anything with wood,' he said, 'or you'll have to weather-proof it.  Use some square-section electrical conduit.  It's PVC and you can screw it to the wall and fill it with lagging.'

Brilliant idea!  Only problem was, B&Q's example of square-section electrical conduit was only about half the size I needed.  The assistant told me where a couple of electrical wholesalers could be found.  Very helpful.  Thank you, whoever you were.

I found a wholesaler nearer to home than the assistant had suggested.  I acquired a 3m length of 75mm square conduit (only 1.7m of which was necessary) and stood it in the back garden for a couple of weeks.  That was not a necessary part of the job. It just resulted from having other things to be done, bad weather and procrastination, a skill which I perform to a remarkably high level of expertise.

Anyway, today saw me with time and opportunity to get the job done.  I'd already spent a few days fretting about how to cap the end of the conduit to keep precipitation out (rain, snow, fallout from the local children's water cannons), with schemes involving self-tapping screws and cuts at various cunning angles.  However, this morning as I lay in bed procrastinating (I'll thank you not to snigger at this point) I realised that I had in my toolbox a remarkable adhesive called 'Pipe Weld' for PVC pipes which would make it remarkably easy to fix in place angle brackets and an end cap fabricated from the excess length of PVC conduit.

To cut a long story short, having avoiding cutting the conduit too short, the whole venture went off exceedingly well for a total cost of around £33.  The pipe is now nicely encapsulated in square-section electrical conduit.  It is not yet packed with insulation as it started raining while I was buying loft insulation at B&Q.  I need dry weather when installing that to give it the best chance of working.  Then I have to paint the shiny white conduit black so that it blends in with other external pipework and ceases to lower the tone of the neighbourhood.

Maybe tomorrow...