sqeeking/sqeeling noise when boiler is running, 3way diversion valve????

sound like the dhw heat exchanger is blocked up you can take it off, run cold water through it shake it about till the black bit stop comeing out, refitt it should be ok now

erj
October 2009

wd40 tends to dry things out, it removes moisture, i would avoid it, get a proper spray grease or fan lubricant. Squealing/hissing on full flame is a pretty big sign that heat/ex is scaled up pretty badly but an engineer will be able to tell straight away location of noise and obviuosly check all gas pressures to make sure boiler operating as designed. One of them...need to be there type questions

ste
October 2009