"Andy Hall" wrote in message
...
I've always used Invensys/Drayton TRV4s and had good results. In
general, I think that you could expect good behaviour from any of the
branded products like Honeywell or Pegler.

It's generally reckoned that the heads have a life of about 7 years.
I've never had less than about 12 from a TRV4 so am pretty happy with
them.

It is important in any case to have a clean system, so while you are
doing replacements, it is worth giving the system a thorough flushing
and filling with corrosion inhibitor.


And when they fail ...?




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