I was recently advised "heat exchanger scaled" on a Worcester Bosch SiII combi boiler. There was a DW intermitent problem - sometimes DHW ran cold after a short while - other times worked okay. Gas installer diagnosed scaled hex. Options were to have new hex (mega cost) or replace boiler. As boiler was get ting on a bit, opted for new boiler. I retained old boiler and for curiosity, extracted the hex and cut open to see what a scaled hex looks like. See pics attached. One of the pics is of the DHW f & r pipes. I could see straight through all the pathways of the main part - including the pipes within outer pipes although difficult to show this in a photo.
Does this look like it should have caused the problem . Comments please.
Does this look like it should have caused the problem . Comments please.