Boiler Noise - Need a bit of advice please....

[Azazal]

Hello,

I'm a complete novice to boilers etc so need a bit of advice please. I've read a post below that sounds exactly the same as my problem, with a loud 'knocking' noise and then boiler shutting down.

A user comment was: "No air in the expansion vessel, no room for hot water to expand and causing a rise in pressure and then blow out. If this is the case you will be constantly topping up the system water pressure"

I do have to check the water pressure daily at the moment, to make sure its between 1 and 2, When it gets low I top it up a bit. After its been topped up its fine for a week or so. Checking it this morning it was at zero!? first time its been that low!?

I have also noticed the 'overflow' (?) pipe outside the house is constantly dripping (never seen it do that in 5 years!)??

Questions:
What is the expansion vessel?
What are the causes of these symptoms listed above, and how would it be fixed??

I'm not going to attempt it myself, dont fancy blowing me or my house up, but want to know 'roughly' what I'm talking about when calling a plumber in.... or I'll attempt it if there's a 'simple' suggestion??

Thanks in advance people!

 

[ChrisR]

See Boiler Pressure problems in the FAQ section please

 

[Azazal]

Thanks to the person who wrote that section (and the plumbing for dummies one!). I've got a much better picture of what is going wrong now, and also understand my heating system a lot more.

I've narrowed it down to a few things that could be a problem, with a list of things to check. still probably cost me a small fortune to fix though!?

Good, helpful site. Well done.