DIY Doctor

New Combi on old system?

Postby pitza » Thu Jan 21, 2010 7:04 pm

Hi, Can a new combi boiler be fitted on an old system? A local plumber has told me that if I have a new combi fitted I will have to have all the pipework and rads renewed because of the added presure and the age of the system (23 years plus) is this right? Two other plumbers have quoted but mentioned any of this only a system power flush and mag cleaner.
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Postby NeilMar » Sat Jan 23, 2010 12:15 am

Depends on a few factors. I you have copper pipe, you can keep the pipework, however the valves (Thermostatic and the Lockshield) will need to be changed on each radiator. It is very very important that the engineer (most plumbers bodge this part!) powerflushes the system correctly. This on an old system can take 2-7hrs! This should be done before the new boiler is installed if the system is old. This will remove (i done correctly all the magnite and limescale that will cause your new boiler damage, reduce efficency and invalidate warrenty.Once the new boiler connected it should be filled and hot cleansed with sutable chemicals to get rid of the corrosive flux in the pipes used to solder. If the radiators are very old, changing the radiators to is advised. This is a brief description but the powerflush is very very important and will add years onto your new boiler etc
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Postby Steve the gas » Sat Jan 23, 2010 6:47 am


The ball is in your court.
Yes you can put a combi on old pipework but it will find any weak spots.
So its a suck it and see, I've done quite a few with no probs and some where there has been but they have been easily fixed.

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