expansion vessel

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timmyquick

Hi all

My Girfriend has had a plumber out today and he has said that he wants to intall an expansion vessel to the worscester combi boiler. Yet it has not had one for the last five years. Would like to know how this decision was made by the plumber. What determines wether a expansion vessil is required, as this plumber says that it will stop heating cutting out. He has also turned a screw on some sort of valve between to great big pipes which i know do the central heating. whats that about?
 
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wilhelm

:eek:

sound like the script to "carry on plumber" .....but they never got round to it, i know :cry:

:LOL:
 
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The only reason I can think is that the membrane in the expansion vessel is perforated which will then lead to the pressure rising to 3 bar and all the pressure being dumped out of the pressure relief valve. That would leave the pressure when the boiler cools down at zero which would prevent it from firing up due to the low pressure cut off switch.
The valve between the pipes is a bypass.
 
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timmyquick

i have the original manual here and there is no expansion vessel in the heating instalation at all. The problem is that its always cut aut from when my girlfreind moved in. Just had bonus from work, thus got a plumbmer to look at it
 
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If it's a Combi its very old or has a BUILT IN expansion vessel.
Plumber is presumably intending to fit a SECOND vessel because the first has failed and can't be dug out of the boiler at economic cost.
 
T

timmyquick

The combi boiler is a worcester bosh 240. The central heating is sealed system. From the manual and looking at the plumbing, the central heating circuit is in 22mm pipe running around the house then returning to the boiler with all the radiators connected into the 22mm pipe with 15 mm pipe with tees, to return & flow (i've had floorboards up for electrics). When turned off or cold boiler is at 1 bar on gauge. Keeps cutting out, this does appear to be when it gets hotter and the pressure rises. I then have been pressing the reset button, so have now got some money for plumper he messed around a bit and gave estimate for works, i was not there at the time but it clearly state on estimate, installation of expansion vessel. My girlfriend and i have not got back to this plumber as we don,t know what the expansion vessel is for as this boiler did work well at one time. All radiators do seem to get hot evenly. They have all been bled a few times and definitely don't have any air in the system as the plumber also confirmed this with my girlfriend. Have noticed cut out of boiler is less often if the temp control is on low, but it takes an eternity to get warn. Also the plumber unscrewed a big screw on what i now know is the pump as my girlfreind watched everything he did ( must be a nightmare for you plumbers!)
 
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this boiler must have an expansion vessel inside it like most combi boilers do.

The expansion vessel allows the hot water inside the heating system to expand when it heats up. If the expansion vessel is broken the pressure will go up and it will keep cutting out, and you will have to reset it all the time.

The plumber could replace the expansion vessel inside the boiler but this will be an expensive part and take hours to do. An easier and cheaper way to solve this problem might be to fit an expansion vessel onto the heating pipework that is outside the boiler.

Now phone that plumber back and tell him I want commission
 
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timmyquick said:
He has also turned a screw on some sort of valve between to great big pipes which i know do the central heating. whats that about?

timmyquick said:
Also the plumber unscrewed a big screw on what i now know is the pump as my girlfreind watched everything he did

:) :) :)
 
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ever get the feeling

deadhorse.gif
 

COG

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The 240 was never available without an expansion vess , but as kev said fitting an external one can be cheaper and qiicker. Thai "big" screw must be the by pass screw, bet it leaks now.
 
T

timmyquick

kevplumb said:
big screw and pump :LOL:

theres a gag there somewhere ;) ohh errrr missus :LOL:

Thanks made me laugh.

Ok so now i understand that all combi boilers have a built in expansion vessel. However that big screw he turned was done on the inside the boiler 100% certain which according to what i can find in the manual ( i still have the original ) is the pump. He also messed with what i now think is the bypass valve from your suggestions plus in the manual it does have a diagram and on the return and feed on the central heating circuit it clearly shows a valve labeled bypass which is by the side of the boiler as my girlfriend showed me what he done plus the paint has come off with the plumber messing.

So if this new expansion vessel is installed it will allow for expansion of heated water and hey presto cutting out solved?
 

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