Posted without comment.....
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From: steve robinson Subject: Re: Repairing rust on a panel. Date: Fri, 15 Apr 2011 19:25 Newsgroups: uk.rec.cars.maintenance
>> It may be now for potable water. But you can still used leaded
> >> stuff for heating, etc.
> >
> > Not if its exposed or is accessable .
> >
> > They certainly dont like it in the new heating systems , they run
> > alot hotter and because of the galvanic action.
>
> Like how? The temperatures on the water circuits of a modern
> condensing boiler are lower than that of the non condensing boilers > previously used.
>
> Flow temperatures have dropped from 80deg C to about 70 and return
> temperatures from 60 deg C to around 45 -55
Not all boilers installed are condensing units
The boilers i have had fitted run a dam site hotter than the older boilers
One of the reasons we have pressurised systems now is to prevent boil off causing air to enter the system , causing cavitation and rust