Would be grateful for an explanation to a y plan

[sinc9603]

Hi, basically I'm reading up about Y plan systems and got my missis to take a pic of our airing cupboard layout (as I'm away working)

So the airing cupboard is on the first floor, boiler downstairs. Now the picture ive posted shows the pump and layout, and the arrow ive drawn on is the direction I'm assuming the water is being pumped. Is this correct? I'm assuming it is because the pump should be before the mid position valve shouldn't it? Only reason it got me wondering is the pipe above the pump feeds into the loft and im stumped as to how the hot water would come from above if the boiler is below if that makes sense?

Please could someone explain the operation or give me some direction please? Purely from someone trying to expand their knowledge whilst sitting in a desert bored as...

Thanks

Lee

 

[MANDATE]

The Y plan is based on the use of a 3 port mid position valve.
The valve is supplied with water from the boiler using the pump. There are three positions the valve can be in.
Hot Water only or Central Heating only or with the valve in mid position both HW and CH get the water shared.
The valve has a valve head/actuator containing a motor and a geared quadrant.The quadrant is spring loaded so without any power the valve springs to the HW position.
The CH position is dependant on two actions. First the valve has to move to mid point and then from mid point to CH.
Moving from HW to midpoint requires power from programmer via the room stat to the white wire of the valve.
Having arrived at mid point the power to the motor is cut off and replaced by power through the grey wire.
This drives the motor on and a 'stop' prevents the valve going further than CH position.
Note. The grey wire must remain live so the motor, although not turning remains energised.
Also note a micro switch is used to feed power from the valves orange wire to light the boiler whereas with HW the boiler receives power from the cylinder stat.
The mid point position is when the quadrant reaches mid point but the grey wire is not live soit cannot continue so is held at midpoint using a modified voltage. This is only a temporary situation until either HW or CH becomes satisfied. When satisfied the valve will move and block the relevant port and opening up the other port

 

[picasso]

Picture is worth a thousand words

 

[sinc9603]

Thank you Mandate and Picasso for the explanation and the picture. Makes sense now so much appreciated

 

[stardanny]

You need to refix that cylinder stat

Daniel

 

[Dan Robinson]

 

[sinc9603]

Cheers danny will get on it when I get home