Heatline Vizo 24 Combi Boiler - intermittent problem

[proxide]

Hi all,

We've got a Heatline Vizo 24 Combi Boiler at home installed at the end of 2006. It has been running fine up until recently.

It now only works intermittently. It'll work one morning and then it won't be working in the evening or vice versa and any variation on this.

When it doesn't work, you can hear the pump go on and you can see it sparking so it's trying to light up. Once it's tried this a couple of times the gas/flame fault LED starts to flash. If you try it again a while later it might work.

When it does work, it makes an unusual noise which my wife originally thought was jet planes flying over! Also, when it's working and running hot water the boiler stops heating occasionally for a couple of seconds and then kicks back in again. I don't recall the cutting out happening before all this started.

It was installed by a CORGI registered fitter and the system was power flushed before commissioning. The water pressure to the system is at the correct level.

Hope you can help

Jon

 

[Agile]

It seems to be showing all the symptoms of a sticking gas valve if its a SIT 845 unit. Obviously needs a gas registered engineer to confirm and repair.

As far as the cutting out is concerned that sounds like a blocked plate heat exchanger but further tests would be needed to confirm that.

Tony

 

[proxide]

Thanks for the advice! I had a quick look and it seems to have been a dodgy contact on the leads to the Gas valve so that's working fine now.

Have you got any idea on it sounding like an aeroplane? Could it be that the system needs some sort of additive to reduce noise?

Thanks

Jon

 

[Agile]

I would need to know exactly under what conditions and on what use it makes this noise.

Tony

 

[bambibasher]

i had the same problem with an halstead ace he making noises like an aeroplane. checked it with a fga and gas valve was out of adjustment.

 

[bengasman]

i had the same problem with an halstead ace he making noises like an aeroplane. checked it with a fga and gas valve was out of adjustment.

How do you adjust the gasvalve on a Halstead Ace with a fga?

 

[bambibasher]

the c0 ratio was way out. run the boiler 10 minutes and check reading on fga and the use the adjustment screw on gas valve to bring back to spec in mi

 

[proxide]

Thanks for all your comments

In answer to the questions:

The sound only occurs when running the hot water. The noise starts high and then drops in tone, disappears and then starts high again, just like a small plane flying past.

Interestingly enough, we haven't used the central heating for a while and when I tested to see if it made a sound and then tried the DHW again, the aeroplane noise on the DHW was greatly reduced although not entirely gone. Any thoughts?

 

[bengasman]

Yep, you need a pro.