Why are the outlets on the radiators hotter than the inlets? Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

[chrisonedog]

We have had a number of 4 radiators fitted and finding that 3 of them are hotter at the outlets than the inlets. Is it possible that the engineer has put the TRVs on the wrong ends? Thanks

[htg engineer]

what makes you think the inlets are hotter than the outlets ?
The hottest pipe is the flow and the cooler one will be the return. With many TRV's now - it doesn't matter what side of the radiator they're fitted to. They can be fitted to the flow or return.

[marrtin]

Modern TRV's are reversible and therefore can fit in either the flow or return.