Offset is of little use to counteract the effect of radiant heat from the radiator. This is because the radiant heat is a significant variable and offset is a constant.
I would suggest that the best policy with current hardware is to fit SRT's in the horizontal plane (rather than in the vertical plane) in such a way as to minimise the effects from radiated heat. In those rooms where this does not work sufficiently well due to proximity of adjacent walls or other items for example, then adding a wireless temperature sensor may be your best option..
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