double check valves

[ianchall]

thank you "onetap",the cause is about right, could you explain further your solution as the ground floor central heating forward flow is from pump upstairs the ground floor return is also upstairs (down & up) then to boiler return on the way picking up HW return then upstairs radiator return then down to boiler

original request
how can I stop the hot water return feeding down the ground floor central heating radiators, as for many years i have had problems when hot water tank return is feeding back down stairs to rediators, i was advised to fit a check valve on the down stairs return. now there is no hot water flow down stairs, I beleive due to lack of pressure on its return & as up stairs flow is not restricted it takes the easy route. what alternatives do I have to stophot water return

 

[Onetap]

Sort the pipework out. It is usually caused by the upstairs CH R being connected to the HW cylinder primary return and then one common return pipe dropping to the ground floor where the ground floor CH R is connected.

The upstairs CH R should drop and connect to the ground floor CH R. The HW cylinder primary return then connects to the common return. Anything else is wrong and a bodge.

 

[Onetap]

could you explain further your solution as the ground floor central heating forward flow is from pump upstairs the ground floor return is also upstairs (down & up) then to boiler return on the way picking up HW return then upstairs radiator return then down to boiler

As stated, you should join up the two (or more) heating returns and only then connect the HWS cylinder primary return. This is a common error by DIYers or 1st year plumbing students, but not one you'd make twice.