midas bolier noisey

[dom2466]

i have a very noisey Midas combi boiler. the noise is like a pumping which can be heard all round the house.
i have replaced the C.H pump, vented the system but still no joy.
my Midas has 2 pumps. 1 for ths C.H and one for the D.H.W.

could it be the A.A.V ?
or the heat exchanger ?
can anyone one help ?

cheers

 

[Slugbabydotcom]

I wouldn't quite say that this is a stab in the dark. More like 'Use the force Luke' when wearing a blindfold
These Midases had a problem with the combustion chamber cover resonating. For the last one I found something to wedge against the cover to stop the noise. Now from what you have told us thats all that can be said as it could really be anything.
We need as much info as possible, such as what function you are using when the noise occurs.Also a better description of the noise and where you think it is coming from. Some have even managed to post a link to a recording hosted on their personal webspace!

 

[dom2466]

well. the noise is like a pumping or wooshing noise.
when i turn the C.H on it noisey
when a hot tap is turned on its noisey.

does this help ?

 

[Slugbabydotcom]

Is the 'dust cap' on the AAV open one turn and is it functioning correctly?
It could be air as you suggest
When did the problem arise? Was it gradual or sudden? Was it related to anything else that you did or had done to the system?
Do you have sufficient pressure in your system? As a rule 1 bar when cold is considered sufficient
Do you live in a hard water area?
Are there any leaks in your system and do you have to keep topping up?
Anything else you may feel is relevant?

 

[dom2466]

i have turn the dust cap 1 turn. but i dont know if its working or not. should air come out off it and then do i have to turn it down ??

the noise happened gradually, louder as each day went on.
i had been doing some minor repair in the house. i had a leak out side in the garden so i was turning the internal stopcock off and on a few times.

i live a soft water area.

the pressure seems fine. 1 bar when cold then rising to 2.5 - 3 bar when hot. this is when the noise starts to occur. when the system starts up and the pressure rise's.

 

[Agile]

You need to repressurise the EV to 0.9 bar with the system pressure opened to atmosphere.

Tony

 

[Slugbabydotcom]

the pressure seems fine. 1 bar when cold then rising to 2.5 - 3 bar when hot. this is when the noise starts to occur. when the system starts up and the pressure rise's.

That was the bit we needed to hear
As Tony says there is a problem with your expansion vessel. You could try pumping it up as suggested. I would be inclined to add another pressure vessel to the system if the problem recurs or perhaps as a cure if you have any difficulties.
It is much cheaper and easier to add another EV than replace the existing one so long as you can spare a bit of space for it

should air come out off it and then do i have to turn it down ??

Leave the AAV cap one turn open is the rule, as closing it often prevents the air getting out.

 

[dom2466]

cheers lads. ill try that and ill get back to you and tell you what happens.

tar

 

[dom2466]

how do i go about pumping up the E.V.
i can see a little 'nozzle' on the bottom of the expantion vessel.
i also have a mini-expantion vessel too.

( can i upload photos onto here)

 

[Slugbabydotcom]

how do i go about pumping up the E.V.
i can see a little 'nozzle' on the bottom of the expantion vessel.
i also have a mini-expantion vessel too.

( can i upload photos onto here)

Does the 'little nozzle' look like a schrader valve on a car tyre?

See the eighth post HERE

The bit about having the system open to the atmosphere is crucial.

I use photobucket.com to host my pics then post the img tags.

Mini EV is a shock arrestor for the DHW and not relevant to your problem

 

[dom2466]

followed the instructions for RE-PRESURISING E.V.

when i got the nozzle of the E.V (where u would pump it back up), i pressed in the little pin inside the nozzloe and water came out. do i need a new E.V

 

[kevplumb]

in a word YES

 

[dom2466]

ok. so i need to replace the E.V


i think my A.A.V might not be working. is there anyway to check if it still operating ???

 

[kevplumb]

i pressed in the little pin inside the nozzloe and water came out.

usually works

 

[dom2466]

what do you mean. "usally works"

when i pressed the pin in the little nozzle on the E.V, water comes out. could i still try and represurise the E.V ??

how do i find out if my A.A.V is working ?