Hot water cylinders - what's the difference?

[D_Hailsham]

Can any one explain to me the difference between the older cylinders, which used to be covered in yellow or green foam and the modern ones which use blue foam? I know that the allowed heat loss has been tightened up but the insulation material seems to be identical, apart from the colour and thickness has not changed. So how are they achieving the lower heat losses?

 

[kirkgas]

will be to do with the density of the material as well as the thickness, but most new cylinders have a quick recovery coil which heats the water quicker therefore shutting down the boiler sooner, basically the diameter of the coil is larger so there is more surface heat transfer, but the coil is significantly longer to really make a difference

 

[Agile]

I think that the yellow ones had less insulating effect and a pretty poor heating coil but usually 28mm for gravity.

The green ones were much more insulation ( and I thought the same level as the latest blue ones ) and usually a 22 mm coil for pumped systems.

I think the blue ones have the same insulation value as the green but the better heat input to the coil.

Tony

 

[D_Hailsham]

will be to do with the density of the material as well as the thickness,

I thought that they all used urethane foam insulation, so it's only the thickness which will make any difference.

The (green) foam jacket on my cylinder is about 32mm thick. A Range Hercal has a jacket which is 25mm thick; and it meets the current heat loss requirements. Does that mean my cylinder, which is over five years old (in situ when I moved in) is better than the current requirement?

I think that the yellow ones had less insulating effect and a pretty poor heating coil but usually 28mm for gravity.

The green ones were much more insulation ( and I thought the same level as the latest blue ones ) and usually a 22 mm coil for pumped systems.

I think the blue ones have the same insulation value as the green but the better heat input to the coil.

I have never had a yellow cylinder so can't comment about the insulation.

However the current Range cylinders are blue and Albion are green. So it may just be a brand thing.

most new cylinders have a quick recovery coil which heats the water quicker therefore shutting down the boiler sooner, basically the diameter of the coil is larger so there is more surface heat transfer, but the coil is significantly longer to really make a difference

I did know that, but thanks all the same. However I was more interested in the heat loss aspect.