Can somone help with air in central heating problem cheers

[Saltda]

We had air in our central heating system last year, it started as a whistling air sound in the boiler but eventually got so bad the pipes started banging and the heating was failing constantly. I had to bleed the pump and radiators to keep the heating on but we eventually had to get an engineer in who replaced the pump.

Well the whistling air sound in the boiler is back. It seems to only happen if only the heating is on. If I switch the heating off and switch the hot water on, the whistling air sound goes away.

If I have the heating on itself, and the whistling air sound in the boiler starts, I can switch the hot water on too and the whistling air sound goes away!

Any ideas what's going on its driving us nuts lol

 

[Saltda]

Untitled

• Saltda
• 16 Sep 2014
• 1

Untitled

• Saltda
• 16 Sep 2014
• 1

Untitled

• Saltda
• 16 Sep 2014
• 1

 

[45yearsagasman]

Is the middle pic displaying the correct way up? If so the pump is fitted incorrectly. That would not necessarily explain your noise though, just that it's wrong. The motor should be horizontal.

 

[Saltda]

Yeah the middle pic is displaying correctly. The original pump was in the same position too.

 

[Justin Passing]

Try adjusting the light-grey-topped valve in the middle picture, while you have the whistle. I'm assuming it's an automatic bypass valve, I can't quite see well enough. It would be adjustable between about 1 and 5. What's it on?
What model of pump is that and what's it set to? (Speed?)

 

[Saltda]

I'll try adjusting the valve but there are no numbers on it?

Untitled

• Saltda
• 17 Sep 2014
• 1

The pump is a Grundfos UPS2 15-50/60, it's set to speed number 2 (the middle one)

 

[Saltda]

I switched the heating on this morning and it was running quiet, but that's normal, it runs quiet when its cold. Its only when it starts to get warm the whistling sound is there.

Sure enough as it slowly starts to build temperature this morning, the whistling noise/air is creeping in.

I have adjusted the light-grey-topped valve and the pump speed but it makes no difference, the whistling air in system sound is still there.

 

[Saltda]

does anyone have any ideas what the problem could be? thanks in advance

 

[regsmyth]

Have you bled the system? Where did all the air come from that caused the problem last time? Maybe the pump only needed replacing because of all the air.
I guess the system is clean, but maybe they didn't drain the system when they changed the pump.
You need to check that the system is filling and keeping pressure properly.
You need to check if the system is leaking at all.

I had a strange tinkling sound from a previous boiler that turned out to be a gate valve rattling in the flow - it just needed undoing a fraction more to stop the noise. But you say a whistling noise....

 

[kbdiy]

I would still be suspicious of the pump. As mentioned above, it should not be at an angle but horizontal. I can see why it is in that position but I think it could be damaging the bearing - which could be the source of the noise.

Also as this is the second occurrence of the noise - and that was cured by a new pump - maybe?

Just my thoughts, that's all.

 

[Saltda]

Have you bled the system? Where did all the air come from that caused the problem last time? Maybe the pump only needed replacing because of all the air.
I guess the system is clean, but maybe they didn't drain the system when they changed the pump.
You need to check that the system is filling and keeping pressure properly.
You need to check if the system is leaking at all.

I had a strange tinkling sound from a previous boiler that turned out to be a gate valve rattling in the flow - it just needed undoing a fraction more to stop the noise. But you say a whistling noise....

I don't know where the air was coming from the last time. The pump was noisy and I suspected it was on its last legs but I wasn't convinced it was the pump that was causing the air in the system. The engineer said the pump was needing to be replaced and he said he could hear the air in the boiler, but that was it. He bled the system when he was here, well at least he said he did (I was out at the time) but I spent the few days after bleeding air from the radiators.

The water from the radiators is always clear. I have checked the water going into the tank in the loft and there is good pressure from the mains pipe, the water level never goes below the feed pipes at the bottom unless we turn all the taps showers etc on at the same time.

The water tank is in the loft and the boiler is on the ground floor. If I turn the cold water tap on in the downstairs toilet I sometimes hear what sounds like gurgling coming from somewhere up stairs, when that happens the air in the boiler seems to subside too, is there a blockage in that pipe? I dont think its connected to the central heating though its a cold water tap?

I cant find any leaks anywhere.

 

[kbdiy]

I have checked the water going into the tank in the loft and there is good pressure from the mains pipe, the water level never goes below the feed pipes at the bottom unless we turn all the taps showers etc on at the same time.

The water tank is in the loft and the boiler is on the ground floor. If I turn the cold water tap on in the downstairs toilet I sometimes hear what sounds like gurgling coming from somewhere up stairs, when that happens the air in the boiler seems to subside too, is there a blockage in that pipe? I dont think its connected to the central heating though its a cold water tap?

I cant find any leaks anywhere.

I think you're looking in the wrong tank to start with. Water to your taps etc has nothing to do with the heating system, which is fed from a much smaller header tank. Water pressure has nothing to do with it either. So long as the header tank has sufficient water in it to keep the heating system topped up and it isn't full of gunk then that isn't your problem.

Have you tried to get close to the various parts of the heating system to try and find the source of the whistle? You don't seem to have mentioned where the noise is worse, which might help find the problem.

 

[Saltda]

I have checked the water going into the tank in the loft and there is good pressure from the mains pipe, the water level never goes below the feed pipes at the bottom unless we turn all the taps showers etc on at the same time.

The water tank is in the loft and the boiler is on the ground floor. If I turn the cold water tap on in the downstairs toilet I sometimes hear what sounds like gurgling coming from somewhere up stairs, when that happens the air in the boiler seems to subside too, is there a blockage in that pipe? I dont think its connected to the central heating though its a cold water tap?

I cant find any leaks anywhere.

I think you're looking in the wrong tank to start with. Water to your taps etc has nothing to do with the heating system, which is fed from a much smaller header tank. Water pressure has nothing to do with it either. So long as the header tank has sufficient water in it to keep the heating system topped up and it isn't full of gunk then that isn't your problem.

Have you tried to get close to the various parts of the heating system to try and find the source of the whistle? You don't seem to have mentioned where the noise is worse, which might help find the problem.

There is a much smaller tank in the loft but the water looks quite stagnant, could it be blocked or something?

I havent tried no will give it a go thanks

 

[kbdiy]

The water in the header tank (yes, it is the smaller tank) may well look stagnant as there shouldn't be much movement of that water in a well maintained system. It can get dirty because heated water circulating through the system may overflow into the header (referred to as 'pumping over') due to a blockage or restriction caused by sludge - magnetite.

However, for the moment concentrate on finding the source of the whistle if you can narrow it down to an area or component of the system. Just saying 'a whistle' is far too vague for any meaningful diagnosis.