Which of these pics it correct.

I assume it must be the second one as many people block off the heater matrix circuit.

I can't see your pic. Clicking on the link gives the pop up appeal then back to your question. maybe if you put it in your Photo archive, I could look at it from there ?

does this work?? don't know how to insert it:

http://farm1.static.flickr.com/214/460143790_f410ae3593.jpg?v=0

One on right looks ok to me.

I just stripped my Sierra and pipes were:

Large water pump -> Rad bottom hose
Large thermostat -> Radiator top hose
Small tee off on large thermostat to radiator top hose above -> Top of header tank
Header tank bottom -> radiator, half way up offside

Small water pump -> Heater matrix
Heater matrix return -> inlet manifold

Personally, I wouldn't blank off the heater matrix feeds as I think correct thermostat function depends on flow through heater and you also probably want flow of water through inlet manifold.

If I don't use a heater, I will loop from water pump to manifold to maintain flow.

Hope this helps

(Hope it's accurate
)

this is exactly what i wanted to know.

Have had the heater matrix blanked for a while now but am re-doing the water system and wanted to know if i should put a loop in.

As you cannot see inside the engine block i had no idea how the water flows through it

rupert