Heating - One Loop?

[scrivomcdivo]

So, I switched my first radiator (next to hot water tank) off as the last radiator (downstairs) was cold and was hoping to flush out any air within system. Now, when I switched off the first radiator by the TRV, all the other radiators in the system were cold. It was like the hot water couldn't pass though the first radiator (as it was switched off) and as such, all the others had no feed of hot water to them.

Are certain systems set up in this way?

 

[Softus]

Not on purpose, and certainly not competently.

 

[scrivomcdivo]

I reckon my system may have been installed around 1990.

Is there anyway I can verify if my system has been set up this way? As said, I turned off the TRV on the first radiator nearest to the hot water tank and subsequently, the second and third radiator were cold (there are only three radiators in the loop).

 

[Softus]

That sounds like verification enough, but the only way to be sure how the pipework runs is to look at the pipework.