M
mysteryman
Forgive me for this - but the last two are getting their definitions wrong.
Secondary circulation means a pumped circulation of domestic hot water to keep instant hot water at all taps.
The device between a primary circuit for one or more boilers and the various heating circuits and cylinder primaries is called a low loss header. These are not, contrary to popular belief, just welded up boxes with connection sockets on them. There is much more to their design and construction if they are to work properly.
Reverse-return connections are used when you connect several devices in parallel - you take the return from the far end, and bring it back from there with the flow. This keeps the branch lengths to and from each device the same, so the flow rates should be the same.
Secondary circulation means a pumped circulation of domestic hot water to keep instant hot water at all taps.
The device between a primary circuit for one or more boilers and the various heating circuits and cylinder primaries is called a low loss header. These are not, contrary to popular belief, just welded up boxes with connection sockets on them. There is much more to their design and construction if they are to work properly.
Reverse-return connections are used when you connect several devices in parallel - you take the return from the far end, and bring it back from there with the flow. This keeps the branch lengths to and from each device the same, so the flow rates should be the same.