Leak in Worcester boiler on water heat exchanger, advice please

I have a Worcester Highflow 400 which is only 3 years old and it has suddenly developed a leak. It seems to be dripping below the "water to water heat exchanger" towards the aft end of it away from the 2 manifolds firrted on the front face of it.
Struggling at the moment to get someone out to repair it so getting the feeling that I will be doing it.
Has anyone on here replaced one, how easy, how long to do it and is it a common fault?
Are these also called the plate exchanger?
cheers
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On Mon, 20 Nov 2006 15:23:22 +0000, jack wrote:

Try calling Worcester they have a service dept. A fair bit of dismantling is required although I've not done one. Looks like you need a lot of new O-rings.
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Ed Sirett - Property maintainer and registered gas fitter.
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Hi I did call out worcester Bosch to do the repair, well worth it. Two fixed prices, 185 for a minor repair, 245 if a heat exchanger is faulty. In my case the water to water heat exchanger was changed, then noticed that the heating not switching correctly, so traced the fault to a braided hose going to the expansion vessel, totally blocked. Also changed the diverter valve and relief valve which were also sticking. Think I had my moneys worth there, as it took 41/2 in total.
He thinks that the main problem is due to some black sludge in the heating system. This was all flushed when the boiler was fitted 3 1/2 years ago, but he reckoned that this is the normal cause with combi boilers malfunctioning. About 5 radiators have also been fitted new since the boiler was installed. He recommended having the system power flushed which I know is very expensive, but is it really worth it?
Surely it would be easy enoughto flush it through myself selectively closing radiator valves after leaving it for some time running with Fernox restorer? The boiler is also situated on the upper floor so would that help?
cheers
On Mon, 20 Nov 2006 23:32:44 +0000 (UTC), Ed Sirett

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