The efficiency of condensing water heaters or boilers has made them a popular choice for new installations and as plant replacements. Recognising this, A.G. Coombs has issued an advisory note providing advice on the design, selection, installation and maintenance of such units.
“Condensing boilers achieve higher efficiency by using the waste heat in flue gases to pre-heat the water entering the boiler,” the note explains. “In doing this they also emit significantly less carbon monoxide and sulphur dioxide than comparable atmospheric boilers. Typical efficiencies of 90 per cent and over are achieved compared with 70–80 per cent for conventional heaters.
“Heat is recovered using extra-large heat exchangers within the boiler; these maximise heat transfer from the burner and recover useful heat which would normally be lost with the flue gases. Gas usage reductions of 15–30 per cent are possible compared to standard-type water heaters.”
But A.G. Coombs also warns that installation and operation need to be carefully considered for trouble-free operation and to ensure the expected service life – hence the advisory note.