Oz07 Posted October 14, 2017 Share Posted October 14, 2017 (edited) My 18month old combi has recently started to whistle on heating. No such sound on hot water. Really high pitched. Got told could be air so bled every rad. None had any air apart from towel rail (highest so seemed to make sense). Was quite a bit in. This hasn't stopped it whistling though. Could there be air in the pump? Why only on heating and not hot water? One thing I did do for the summer is turn off all rads at TRV apart from one where room stat was (no trv) and towel rail. Came on for around 3/4 hour each night to dry towels. Now all rads are back on. Thanks in advance Edited October 14, 2017 by Oz07 Link to comment Share on other sites More sharing options...
ProDave Posted October 14, 2017 Share Posted October 14, 2017 I wonder if the CH flow rate has dropped and you are getting localised boiling (kettling) inside the boiler? Link to comment Share on other sites More sharing options...
Brickie Posted October 14, 2017 Share Posted October 14, 2017 Any particular tune? Link to comment Share on other sites More sharing options...
Oz07 Posted October 14, 2017 Author Share Posted October 14, 2017 I wish! seems to be coming out the flue though. Just been outside and is as loud as inside. Link to comment Share on other sites More sharing options...
Oz07 Posted October 14, 2017 Author Share Posted October 14, 2017 Definitely coming from the flue. @Nickfromwales any ideas? Link to comment Share on other sites More sharing options...
Nickfromwales Posted October 14, 2017 Share Posted October 14, 2017 4 minutes ago, Oz07 said: I wish! seems to be coming out the flue though. Just been outside and is as loud as inside. Sounds gas valve or fan related to me. 4 hours ago, Oz07 said: Why only on heating and not hot water? A combi has two settings for the gas valve, giving less heat ( low flame ) for CH, and max heat ( full flame ) for DHW production, hence the change in state when delivering one or the other which helps narrow down the fault finding. What make / model? What about warranty? Link to comment Share on other sites More sharing options...
Oz07 Posted October 14, 2017 Author Share Posted October 14, 2017 Pm'd Link to comment Share on other sites More sharing options...
Nickfromwales Posted October 14, 2017 Share Posted October 14, 2017 Check that the condensate trap is clean and you can confirm it runs freely to drain. Download the manufacturers service guide for details. Sometimes the whistling noise can be caused by the condensate trap being blocked and the heat exchanger getting waterlogged. I can ring their technical support if you want ? What kw is it ? Can you post the GC number of the boiler data plate ? It'll be in the book ( installation guide ) that came with it 1 Link to comment Share on other sites More sharing options...
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