how/where to install connection points for DIY power flush machine?

16 Jun 2013
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West Midlands
United Kingdom

Ive read a lot on the net on possible locations to connect a power flush machine for my central heating and have decided its best to connect it directly to the supply and return 22mm pipes from the combo boiler as the pipes to and from the rads are all 10mm micro bore.

I don't really have blocked radiators or pipes, everything heats up really well. only thing is my diverter valve keeps clogging up every few months. so I want t do a power flush myself.

Now the boiler is in the loft (bungalow) and the supply and return come straight down and are easily accessible via the airing cupboard on ground floor, before they terminate into many 10mm pipes underground to all rads.

I am thinking of cutting these supply and return 22mm pipes and putting some sort of T compression joints so i can connect the pro flush machine from HSS.

But I am right in thinking a normal T won't be good as the water will be pushed both upwards and downwards along the pipe by the machine?

any help or advice on the right type of compression joints to add will be much appreciated.

P.S. I don't really want to connect the machine by detaching the boiler pump as 1) i don't like messing too much with my boiler and 2) its in the loft so makes it a lot riskier if water gushes everywhere.

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The Scottish Gas guy who did mine cut the return pipe to the boiler, connected both ends of the powerflush machine to the cut pipes, then fitted a magnaclean style filter where he had cut the pipe. He said to always do it before the boiler so you're catching the sediment before it hits the boiler.
If that's how you want to do it then just stick two full bore lever ball valves on the pipework upstream from the boiler and isolate it from the system that way it will only be able to flow around the system and will not force more carp into the boilers hex.
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the 22mm pipes will be the best place to do it from. (use two elbows rather than tees or as above fit some isolating valves above the tees.

However, on 10mm pipes, its unlikley to get the flow rate up high enough to dislodge proper amounts of dirt from the rads to flush it well, allowing future sediment to break off and make their way back to the boiler.

What you need is a good filter on the 22mm return pipe, by all means if you are confident flush the system out as you plan to but dont just hook it back up to boiler with out a filter to catch what WILL make its way to the boiler in future

(filters dont catch 100% first time either by the way, but gives the boiler a fighting chance)

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