ravenheat rsf 820/20t humming

[peter roberts]

i have a ravenheat 820/20t the boiler is fine but just one little thing i bugging me when the hot water tap is running and then the boiler starts up a humming noise .it lasts for about 5 seconds till the water in the boiler is hot again .there is no air in the central heating as i have bled a the rads when the heating is off as i was told to is there anybody out there that can give me some advice please thanks

 

[chrishutt]

Could be slight overheating of the heat exchanger. Could you describe more accurately when the noise starts and stops in relation to the hot tap being turned on and off?

 

[peter roberts]

thanks for the reply as soon as the tap or shower is turned on the boiler fires up to heat the water the humming starts up .then as soon as the water is hot enough in the boiler it stops then it will start again basically it starts every time the boiler has to heat the water up . if you want it discribing better let me know thanks

 

[chrishutt]

as soon as the water is hot enough in the boiler

That's the bit I don't understand. Do you mean the primary or secondary water? What signals that "the water is hot enough"? Do you mean "when the burner flame cuts out or reduces?

 

[peter roberts]

wot do you mean about primary or secondary .sorry .the thermostate on the boiler signals when the water is hot enough then the humming stops and then the flame reduces

 

[chrishutt]

As far as I understand what you're saying, it still sounds like the heat exchanger might be generating the noise as a result of overheating. I suspect that it is either scaled up (on secondary HW) side or sludged up on primary (CH) side. But really you need an experienced engineer familiar with Ravenheats to look at it.

 

[peter roberts]

just one more thing when the boiler is off it reads 0.5 bar when its on it reads 2 bar i9s that ok thanks alot for your replys

 

[chrishutt]

when the boiler is off it reads 0.5 bar when its on it reads 2 bar

You have a defective expansion vessel too. This may be related to the noise problem. Do a search of this forum for more details.

 

[peter roberts]

cool thanks i will get a plummer out soon as pos

 

[chrishutt]

Heating engineer would be better.

 

[peter roberts]

sounds like the exspansion vessel as you said .the other day it was reading 0.5 then i topped the boiler up to 1 bar then after about 15 mins it shot up to 2.9 bar then i had to bleed the radiator till it sat at 2 bar while it was running .it now reads 0.5 when its off then 2 bar when its on is that correct ?thanks

 

[chrishutt]

is that correct ?

No -see my post above!