A plumber speaks....

[Dave Plowman (News)]

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

[ARWadsworth]

But most new boilers are condensing and should opereate at a lower temperatue and there are plenty of unsealed sytems still installed (I assume he meant sealed not pressurised systems).

[YAPH]

I'd say it's because we don't have to faff around installing a tank in the attic with associated F&E, supply & overflow pipework. Keeping down air ingress to the system and consequent corrosion, and not having kettling where you get boiling in hot-spots in the boiler due to the low pressure in the system, are bonuses.

[ARWadsworth]

So you mean lazy then:-)