The twin swirl pot - header finally fitted
Discussion
Swirl pot encourages coolant to spin around as it flows through causing any air trapped in the coolant to separate out to the top.
The header or expansion is for holding expansion water which is 'sucked in' and 'pushed out' as the temperature falls / rises and contains 'air' in the space to be expanded into such that the system doesn't lose coolant when fully expanded at high temps, or starve of coolant when very cool.
Two separate tanks are really to do with size and space available. one 'biggun' could do the job of both, if at the right height size location etc.
I went for two side by side as you can connect the top of the swirl pot to the bottom of a side by side header tank, which is like having a really tall tank :-)
The header or expansion is for holding expansion water which is 'sucked in' and 'pushed out' as the temperature falls / rises and contains 'air' in the space to be expanded into such that the system doesn't lose coolant when fully expanded at high temps, or starve of coolant when very cool.
Two separate tanks are really to do with size and space available. one 'biggun' could do the job of both, if at the right height size location etc.
I went for two side by side as you can connect the top of the swirl pot to the bottom of a side by side header tank, which is like having a really tall tank :-)
Alan461 said:
Expansion & contraction.
Otherwise you would loose a cup full of coolant every time it was used.
Never fully understood this, once the water has expanded, blown the "cup full of coolant" out surely there is then space for it to expand the next time so no further loss?Otherwise you would loose a cup full of coolant every time it was used.
Older cars with pressure cap direct on the radiator never had expansion tanks?
How about an expansion vessel, like used on closed central heating systems
phillpot said:
Alan461 said:
Expansion & contraction.
Otherwise you would loose a cup full of coolant every time it was used.
Never fully understood this, once the water has expanded, blown the "cup full of coolant" out surely there is then space for it to expand the next time so no further loss?Otherwise you would loose a cup full of coolant every time it was used.
Older cars with pressure cap direct on the radiator never had expansion tanks?
How about an expansion vessel, like used on closed central heating systems
The drawback to this is that bubbles will then start to upset the water pump.
An expansion vessel would in theory be an answer to this but manufacturers never use one so it must cause further problems.
The pressure cap has a two way valve that allows coolant back in to the system at maybe 50mbar (very low) so that the hoses don't collapse under the weak vacuum when cold.
Edited by Alan461 on Thursday 2nd October 21:30
Top Gear TVR said:
i've always loved the word 'CAVITATION'
Cavitation is where a void is pulled into a liquid under mechanical load and reaches the vapour point.Bubbles in the coolant are stretched and become an emulsion, this prevents good circulation and is not true cavitation.
The damage from cavitation is caused when the void slams shut when the mechanical load is reduced, not the case with bubbles in the system which just circulate.
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