Hot water Issues

[charlottem]

Good morning,
I am after some advice please.
About a month ago our hot water system started making some horrible vibration noises, our next door neighbour is a heating engineer, so invited him to have a listen. I couldn't make it do it while he was around, but from me describing it, he suggested a change of pump, which he did.
Couple of days later it started again, called him over again and after some trial and error we realised it was the thermostat on the boiler not cutting the boiler off and therefore causing 'kettling' in the hot water tank. We had noticed the hot water out of the taps was scolding.
He fitted a new thermostat one night last week, and it has worked perfectly ever since. Had the heating on for a few hours too during the last week or so.
When he removed the thermostat it was melted, so it was obvious its had been getting very warm.
However this morning I woke to the sound of a waterfall, the sound came from the hot water tank in the airing cupboard and when I walked downstairs to the boiler, you can hear the noise a little clearer.
Only way I could stop it was to switch the hot water off. After 10mins or so I switched it back on and ran 2 hot water taps downstairs for a while. The boiler fired back up and all sounded fine. I switched it off before I came to work.
Any idea and advice would be greatly appreciated please.
Many thanks
Charlotte.

 

[ianmcd]

Gas or electric you may have an electric immersion heater that you have switched on by mistake, very easily done

 

[charlottem]

I am on gas and have no immersion.

 

[dilalio]

Pump speed setting and/or air in the coil in the cylinder. Do you have an air vent on the pipework going into the cylinder coil?

Like this one (which is an auto air vent)?

Underneath the label (72183) on the tank above. Yours may be a manual vent which you would have to unscrew to let any air out, then screw tight again when water starts to come out... It may be hot water so take care.

 

[charlottem]

We have adjusted the pump speed which didn't make any difference, will have a search for a vent, see if it can be manually bled.
I was up this morning so I heard to boiler kick in for the hot water. I listened to it and it was faultless, so it is very much an intermittent problem.
I had the heating on for an hour yesterday evening and it was faultless, but I presume this is because it is a different system?! Excuse my poor knowledge,...I'm learning!

Thanks

 

[dilalio]

It may be that the air has worked its way out, around the rest of the primary flow/return.

Just monitor it for a few days...

Most times air ends up at the top which may be your f&e tank (or there is an auto air vent somewhere) that's done its job and you'll be all good.