Glowworm 18 HXI

26 Jun 2018
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United Kingdom
Hello, I've recently experienced a problem with the above boiler. Boiler is 10 years old and has become noisy. Gas engineer put Fernox F2 boiler silencer into system. This exposed a noise which sounds like drums being played inside the boiler! This only occurs when the boiler is fully surging in power, usually around 70 degrees. The HEX has been cleaned, fan replaced and now system is being cleaned with Fernox F3. The diverter valve is sticking slightly and is being replaced next week. I took a video illustrating the noise this pm after the cleaner had been applied. Here the boiler is surging before it cuts out. Can anyone identify the noise?!Aq7r42kkeO1ngs4GzkON-AfGf-qs_A

Thanks for any advice

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At a good guess I would say the problem lies not with the boiler but an iron oxide blockage probably with the flow or return around the cylinder area.
Ask your plumber to run a magnet all over the the flow and return pipes in the cylinder cupboard, see if the magnet pulls at a certain point(s).
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The burner door was removed and scale removed using a nylon brush with a mixture of strong white vinegar and limescale remover. All surfaces were smooth and scale free when the door was replaced. Now running Fernox F3 through the system for a week.

Many thanks

What's the bypass valve set to and the pump setting? If the boiler is installed correctly it should be across the flow and return after the ensures a minimum flowrate through the boiler.
The heat exchanger was removed and cleaned with chemicals internally I hope. Removing the cover and polishing the combustion surfaces will do SFA to reduce noise.
Not sure about the bypass valve setting, pump is on maximum. Fernox F3 is running in system at the moment (leaving up to 7 days) to remove limescale
And you're not going to check it or post a pic of the setting?
I'm a novice, not a plumber/gas heat engineer so not sure where bypass valve is
It will be a coil in the heat exchanger partly blocked, hxi heat exchanger has coils. You can not clean heat exchanger, new heat exchanger required just done 2 , I cut them open scale/debris wedged in coil.
Hopes this helps
Many thanks for your response. Have discovered that cold feed and expansion pipes are partially blocked (used powerful magnet). Work being done next week.
Many thanks for your response. Have discovered that cold feed and expansion pipes are partially blocked (used powerful magnet). Work being done next week.
Be prepared to shell out for a new heat exchanger then. If the system was dirty as it sounds like it is, the waterways in the giannoni hex are tiny and block up very easily.

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