I'm getting a low droning sound coming from within the boiler (Keston
condensing). It sounds like a small, low flying aircraft!This happens
even when the boiler is "off" with the pump "on".    We've just had a
new bathroom fitted, so the system was drained down but it was all well
- for about 4 weeks, just using the HW side of things.  It is a sealed
system, under pressure.  Then  I bled all the radiators & checked they
all worked.  Ironically this probably introduced Fernox MB-1 which was
introduced via a new towel rail radiator.  Once the cycling water gets
hot enough, it resonates from within the boiler . .  I've vented the
system, there doesn't appear to be any air in it . . . any ideas?  It
is an old system but as I've mentioned, it's worked extremely well
until I checked out the CH part . .?

Cheers

Steve

In article ,
	"zarkov"  writes:

>I'm getting a low droning sound coming from within the boiler (Keston
>condensing). It sounds like a small, low flying aircraft!This happens
>even when the boiler is "off" with the pump "on".    We've just had a
>new bathroom fitted, so the system was drained down but it was all well
>- for about 4 weeks, just using the HW side of things.  It is a sealed
>system, under pressure.  Then  I bled all the radiators & checked they
>all worked.  Ironically this probably introduced Fernox MB-1 which was
>introduced via a new towel rail radiator.  Once the cycling water gets
>hot enough, it resonates from within the boiler . .  I've vented the
>system, there doesn't appear to be any air in it . . . any ideas?  It
>is an old system but as I've mentioned, it's worked extremely well
>until I checked out the CH part . .?


Sounds like a radiator or towel rail was the bypass and now no longer
is due to having a TRV fitted, and maybe the locksield closed down too
much. What did you have in the bathroom before in the way of radiators
and TRVs, and what have you got in there now? Does the top right red
light start flashing on the Keston? Another possibility is a TRV has
been fitted which is directional (good ones aren't) the wrong way
round. Does the system pressure dial needle also vibrate in sympathy?

Kestons can also make this noise if the gas/air mixture is too weak at
low modulation level, but you said it does it when the burner is off,
so this can't be the cause in this case.

-- 
Andrew Gabriel

In message , 
zarkov  writes

>I'm getting a low droning sound coming from within the boiler (Keston
>condensing). It sounds like a small, low flying aircraft!This happens
>even when the boiler is "off" with the pump "on".    We've just had a
>new bathroom fitted, so the system was drained down but it was all well
>- for about 4 weeks, just using the HW side of things.  It is a sealed
>system, under pressure.  Then  I bled all the radiators & checked they
>all worked.  Ironically this probably introduced Fernox MB-1 which was
>introduced via a new towel rail radiator.  Once the cycling water gets
>hot enough, it resonates from within the boiler . .  I've vented the
>system, there doesn't appear to be any air in it . . . any ideas?  It
>is an old system but as I've mentioned, it's worked extremely well
>until I checked out the CH part . .?
>

A washer is acting as a reed ?


-- 
geoff