Shower pump problems and bar pressure

[cliff1010]

Hi can someone offer some advice on the following :

my Shower pump packed up last night so at present don't know if its simple such as a fuse or a complete replacement. I have a combi boiler ( LPG Greenstar ) but also a hot water tank in an airing cupboard and a cold water tank in the loft. I assume I have a gravity fed system how do I tell what bar pressure I have ? googled on the train this morning on the B&Q site it said if you have a combi you have a high pressure system and if you have a hot water tank and cold in the loft you have a low pressure system.
The pump is old so assume it will need replacing but only seemed to have 3 pipes going into it,
everyone I have seen had 4 ? I want to make sure I get the right replacement

Thanks in advance.
Cliff

 

[muggles]

Sounds like you're on a split system with a mix of high and low pressure hot water. There's no such thing as a pump for high pressure systems, it's pumping the low pressure side (or, at least, it should be!). The pressure is calculated by measuring the vertical distance between your tank and the outlet - 1 metre = 0.1 bar. Never seen s pump with only three connections before though, they're either two or four

 

[cliff1010]

Ok thanks for the info maybe me checking at 6am this morning missed a connection and it is 4. I will measure the distance and work out the bar pressure. So if I am right the lowest one I could buy to fit my system if 0.1 bar would be a 1 bar or 1.5 bar ? is that right. do you go to the next size up
Thanks