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Expansion vessel in a domestic house

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Discuss Expansion vessel in a domestic house in the Central Heating Forum area at Plumbers Forums

Steve weightman

Steve weightman

Gas Engineer
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185
Any reason why this cold water expansion vessel would be found in a domestic house it's massive

20190103_110843.jpg
 
Sounds like an accumulator then. Is pressure not too clever where you are?

Alternatively it could be simply what it says on the tin - a darn great pressure vessel in order to give good pressure without drop off until 'much' later...
 
Steve weightman said:
Do You think it's acting as cold water storage the thing is there's no outlet just cold water inlet connected
Click to expand...

No then it won't be. That why I asked.
Sounds like it's simply as I said later on. A huge pressure vessel. The only way you'll know how it impacts performance, is to take it out of the supply or to let all the charge out of it. Hope you have a compressor cos if its a bike pump you're gonna end up like Stretch Armstrong :D
 
At that size I'd imagine like said previously, it's an accumulator simply boosting the cold water pressure, it would only have the one connection ,
 
accumulator will be connected to the water mains
 
I thought he said it was???
 
I bet they get a good power shower out of it! May be historical, might have had water pressure problems in the past. That might have improved since, but never taken pressure vessel out.
Make sure it has the correct diverter in the supply connection into the vessel so that there is no static water in it that could breed bacteria. It should send some if the flow into the vessel and back out, but some filters don't know what it is and therefore don't fit it. From the outside looks like an ordinary tee, but it has a clever sort of scoop inside it.
 
Gasinspect said:
I bet they get a good power shower out of it! May be historical, might have had water pressure problems in the past. That might have improved since, but never taken pressure vessel out.
Make sure it has the correct diverter in the supply connection into the vessel so that there is no static water in it that could breed bacteria. It should send some if the flow into the vessel and back out, but some filters don't know what it is and therefore don't fit it. From the outside looks like an ordinary tee, but it has a clever sort of scoop inside it.
Click to expand...
All I can see is a cold feed to it will a lever valve for isolation. The pressure drops slightly with the valve isolating the tank is off. I can't imagine how it's meant to increase the pressure as the pressure in the tank will only be the same as the incoming mains .
 
As above,
ie. the water flows in both directions along the pipe tee'd into the mains water pipe.
When water pressure is higher than the air charge in the vessel it flows into the vessel & is stored.
When the air pressure is greater it pushes the water back out into the system to boost the flow rate.

Question is how do you know what the air charge should be to achieve this ???
 
Ive got a 300L one at home, the manual says to basically measure the static pressure of the incomer (2.3 Bar for me) then set the empty accumulator to 1 to 1.5 Bar below mains pressure (Minimum Accumulator pressure is 0.5 Bar to 0.8 Bar). Im sure other manufacturers have their own rules but that what my ColdStream said.

Mines set at 1.3 Bar and has worked very well to improve flow rates for me for the last couple of years. Very noticeable difference if I close the isolator off. Great bits of kit where you have space. Still considering a pump to get it up to 3 Bar to improve the showers, but thats another days game.
 
So all I can see with this tank is a cold inlet with lever valve and nothing else I can't see how this can increase the mains it must only charge the vessel to what the mains is coming in at. Love where the boiler filling loop is around the back of it
20190123_091157.jpg
20190123_091145.jpg
 
will use the same pipe bi directional
 
It doesn't increase the static pressure it increases the flow rate. But static pressure is not useful at all on its own, in fact it's better lower to avoid strain on the system.
Accumulator it's only useful where the dynamic pressure is a lot lower than the static pressure, basically you need more oomph from the pipes. Think of it like a cold water storage tank only 30m above the house rather than in the loft.
 

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