vaillant ecomax pro 18 "noisy fan ???"

[Agile]

But the Vaillant should be the least likely to attract dirt because its piped from underneath.

The Halstead Eden is piped upwards with the same HE but does not seem to have a particular problem.

Although a different HE, the Viessmann heat only is also piped from above but does not seem to suffer either.

But then I have not met a dirty Vaillant yet so perhaps I am biased?

Tony

 

[jono44]

The one I'm working on has flow and return connection at top of boiler.

 

[mickyg]

Tonys thinking of the 600/800 series boilers that have an insulated coil, plastic sump and bottom entry connections. As you point out yours are at the top. I've fitted quite a few Glowworm Ultracoms(same boiler different case) on open systems without any issues, but its essential the system is clean, the pipework is properly designed with a decent head of pressure and the pump is left on maximum speed.