An automated bellows volumometer has been used to obtain volume ratios for 2,2,2-trifluoroethyl difluoromethyl ether (CHF2OCH2CF3, RE245) and 1,2,2,2,-tetrafluoroethyl-difluoromethyl ether (CHF2OCHFCF3, RE236) for pressures up to 380 MPa in the temperature range (278.15 to 338.13) K in the liquid phase. The fractional accuracy of the volume ratios is estimated to be +/-(0.0005 to 0.001) for the experimental temperatures up to the normal boiling temperature of both fluids and better than +/-0.0015 for higher temperatures. Isothermal compressibilities, isobaric expansivities, and internal pressures have been evaluated from the volumetric results. The volume ratios have been represented by Tait equations which enable accurate predictions of liquid densities along the (liquid + vapour) coexistence boundary. The experimental values for both liquids over the complete range of experimental temperatures can be combined by modifying the Tait equation representing the volumetric properties of CHF2OCH2CF, to allow for the contribution of the additional fluorine atom to the volumetric properties of CKF2OCHFCF3. The modified equation appears to be suitable for predicting the volumetric properties of other linear fluoroethers with a molecular composition based on three carbon atoms.