Ideal Response 120 boiler -- pressure problem

[friedel]

Our Response 120 combi boiler was installed with the flat in 2001 and has worked perfectly until now.

This morning, I went to run some hot water in the kitchen sink when the pressure started rising beyond the 2 mark on our gauge (normally it sits at 1.5) and the safety button turned off the burner as a result. It also made a rattling noise.

I am still getting hot water out of it, but only in limited amounts as the pressure gauge causes the burner to cut out after a minute at most.

Any hints as to what could be wrong?

 

[ollski]

probably the expansion vessel has either got a leak or needs repressurizing...lots of posts on here about it.

 

[friedel]

probably the expansion vessel has either got a leak or needs repressurizing...lots of posts on here about it.

So, a boiler can need repressurizing, even when we haven't drained any radiators to do decorating?

Sorry if it's a daft question. This is all new to me.

Thank you for your help.

 

[ollski]

It's not the water, it's the air in the expansion vessel which allows the water to expand on heating. It is seperated from the water by a diaphram(?). If somehow the valve (like a car tyre valve) has let the air out the whole system will be filled with water which will not have anywhere to expand to and will raise the pressure in the system until it blows out of the pressure relief valve. If that is the fault you can pump the vessel back to the recommended air pressure and you're ok, if the diaphram is split you will have the same symptoms but need a new pressure vessel ( the big red tank).

 

[friedel]

Any idea what it should cost to fix the expansion vessel? We are going to call in a plumber.

 

[breezer]

i have no idea as to cost, but you want a heating engineer not a plumber, also you cant fix an expansion vessel, you either replace it (can be alkward) or install "an extra one" (making old one redundant)
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perhaps some one could tell me (one day i will get an old expansion vessel my self (to cut it open), but untill then...........)

does it have a "ballon" inside it or is it a large diaphram covering one side (water being on one side air the other)