Baxi 105e howl

[Robhackney]

After repressurising my heating system yesterday everything seemed to be working fine.
Tonight, the boiler started making an intermittent howling noise. It seems to be when the burner kicks in to push the temperature back up when it drops to 70 from 80. It lasts a few seconds, until the boiler gets back up to max temperature.
Otherwise, everything seems fine.
Should I be worried, or is it something simple?

 

[shaneo]

does it sound like a kettle

 

[kevplumb]

check previous threads seem to remember something about o rings in the diverter valve

are you sure the cats not asleep on it

 

[Robhackney]

If we had a cat, the microwave would do a better job.

When the burner kicks in to boost the temperature from 70 to 80, there's a bit of a bubbling noise, then a loud 'hunting horn' kind of sound which lasts a couple of seconds and then fades. The burner then stays on for a bit, and everything seems fine. When the temperature drops again, the cycle repeats.

The boiler is three years old, and hasn't done this before. It's only happened since I drained and refilled the system, yesterday.

I did set the pressure at 2 bar, and I've now dropped it to about 1 to see if that makes a difference, but it doesn't.

The HW side seems to be fine. No strange noises there!

I had read the comments about the o rings, but it didn't quite seem to fit my symptoms.

 

[kevplumb]

sounds like a flow prob try flushing the system

 

[Robhackney]

I knew you'd say that.

Can I flush it through with water. If not, how do I get the cleanser into the system?

 

[kevplumb]

there is a thread but i cant remember where (altzhimers)fernox restorer the instructions come with it get the cartridge that fits a mastic gun

 

[Robhackney]

Thanks for the comments.

The system did have Sentinel inhibitor in it. When I drained it, yesterday, the water was pretty clean, with a gold/brown tinge. I was going to buy some new inhibitor this weekend, so I refilled without any temporarily. Water I have bled off since (hot) has been slightly milky with very slight frothing.

Is this good or bad?

 

[kevplumb]

bad its flux residue

 

[Robhackney]

I put some cleanser (Tower xxx) into the system tonight, the noise stopped immediately. I'll leave it in for a week or so to let it do it's job.

Hopefully that'll sort the problem.

 

[Robhackney]

I was a bit premature there.

It's better, but not gone completely. The noise is intermittent and not so loud. I'll see how it goes for the rest of the weekend, and give Baxi a call on Monday.