Aluminum block boilers with cast iron rads

Jason Horner

What do you think of using alumimum boilers with cast iron radiators with/without boiler manufacturer approved moly additives? I've heard mixed opinions and am not sure whether I should be offering my iron rad customers these aluminum block boilers when installing new boilers for them.

Are we stuck not using Weil-McLain, Buderus, Dunkirk, et al. aluminum block condensing boilers in homes with iron rads?

Would appreciate hearing opinions from all but especially from the boiler manufacturers lurking here.

Thanks.

hr

I'd worry

more about rust and scale plugging the small HX passages then water quality itself.

Keep the ph in the 7-8.5 required by most aluminum block boilers, a dash of Rhomar inhibitor, and sleep soundly.

I think a Y strainer is very important. As is the frequent inspection of such

What's in your wallet, er I mean water.

hot rod

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Boilerpro_3

I believe the Dunkirks have large passages

since there is very little pressure drop across the boiler, so rust and scale shouldn't be much of a problem on these.

Boilerpro

Jason Horner

Weil-McLain has a filter/strainer they recommend for use with the Ultra and I think it may be similar to the one I saw the other day at a HeatLink course.

The one I saw looks like a domestic water filter enclosure and has a stack of plastic disks inside about 8" tall. Filter disk stack is removable and washable - supposedly filters to 55 microns.