Screeching from somewhere in plumbing- Megaflo?

[The OP]

Hi All,


This is my first post on the forum, and I'd be very grateful for your thoughts on a problem we have had for a month, and which we have spent several £100s on, with no success.


Despite visits from 3 plumbers/engineers, we cannot get rid of a loud screeching/groaning noise occuring in our plumbing, which seems to emanate from, or near, or Megaflo unvented indirect cylinder. We have almost run out of ideas!


When the noise is loud, the pressure gauge wobbles slightly. But it never exceeds 1.4 bar, even when noise is at loudest.


The pressure relief and pressure reducing valves have been changed, and a shock arrester installed. All to no success. A heatrae sadia engineer said it wasn't the tank (though it really sounds like the noise comes from the megaflo, especially when you put your ear to it). He suggested we have the two zone valves looked at.


Before I spend yet more money- has anyone any ideas?


Many many thanks.

 

[The OP]

Here is a video (filmed at 2am, so forgive the shakiness).

[video]http://m.youtube.com/watch?v=YEAJaz8o1dg&feature=youtu.be&deskt op_uri=%2Fwatch%3Fv%3DYEAJaz8o1dg%26feature%3Dyout u.be[/video]

 

[Dave Walker]

I would look at the zone valves as well remember the sound will travel through the pipe work in to your cylinder.

 

[PlumbBobBob]

does this noise happen after you have flushed the toilet?

 

[The OP]

does this noise happen after you have flushed the toilet?

No- it regularly happens when there is no water related activity in the house at all (that I'm aware of). It happens sometimes very early in the morning when we have all been in bed for hours.

 

[galaxy_plumbing]

sorry, can't see video. can you post link again?

 

[The OP]

Video -
[video]http://m.youtube.com/watch?v=YEAJaz8o1dg&feature=youtu.be&deskt op_uri=%2Fwatch%3Fv%3DYEAJaz8o1dg%26feature%3Dyout u.be[/video]

 

[Killy Bing]

Turn the power off to your boiler tonight and see if you still get the noise.
if you do then you can rule out zone valves.
if you dont then do this for the following night too and see if there is still no noise.

 

[Killy Bing]

Ok, have your plumber inspect your three port valves and pump.

 

[BLOD]

When it's makng the noise try opening the grey knob a little

 

[The OP]

Thanks for all your help.

BLOD, no grey knob I can see- pictures below- but all of the valves in the first picture have been replaced since the noise started. We did have the TPR replaced over 3 months ago after a slight leak, but that predates the problems by 2 months. A heatrae engineer recharged the pressure bubble last week, but that has made no difference.

Which knob do you mean?

 

[galaxy_plumbing]

sounds like pump to me. could you try to change pump speed and undo nut in the front of the pump to see if any water coming out of it.

 

[The OP]

Ok, have your plumber inspect your three port valves and pump.

Thanks- will do.

 

[The OP]

sounds like pump to me.

Thanks- whereabouts in the set-up would I find the pump so I can had a good listen next time I hear the noise?

 

[galaxy_plumbing]

sorry, its in your cupboard , blue with BG multihead sign on. It shouldnt be hot when nothing is on anyway so if its spinning something is probably not switching off as it should. But, try pump first, just doesnt make sense why this happening only during night. Do you have heating/hw set off during night?