From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Comparison of noise and performance between different car heater models.
| Identifier | ExFiles\Box 137\2\ scan0074 | |
| Date | 7th May 1938 | |
| To J.L.E. from Rm{William Robotham - Chief Engineer}/Std. c. Hn.{F. C. Honeyman - Retail orders} Y 1158 Rm{William Robotham - Chief Engineer}/Std.1/MH.{M. Huckerby}7.5.38. Referring to your Le.10/C.29.4.38 and LE.10/C.3.5.38 we have tested the two heaters returned to us ("CC" type and "S.2.C.A." type) and agree with you that the "CC" type is impossibly noisy. Actually the heater you sent us is more noisy than the "CC" type heater we have here, but the "CC" type is in any case more noisy than the S.2.C.A. type, not being fitted with a rubber mounted motor. We have compared the S.2.R.A. type heater which you sent us with an S.2.C.A. type which we have here and find that the S.2.C.A. type is more noisy than the S.2.R.A. type, but much quieter than the CC. type. The S.2.C.A. type is similar to the S.2.R.A. type (has rubber mounted motor etc.) but has a different motor giving a higher fan speed, and gives a greater heat output. By turning down the rheostat switch and reducing the fan speed (of the S.2.C.A. heater) to that of the S.2.R.A. at maximum speed, the noise is reduced to the same level as that of the S.2.R.A. heater; at this speed the heat output of the two heaters should be the same. Since we supply a rheostat with the heater, irrespective of which type is used, it seems to us to be most logical to use the S.2.C.A. type, which can be used at maximum speed to warm the car up from cold, at the expense of a certain amount of noise, and which can be subsequently throttled down to whatever noise or heat level is desired. Since you state that with the S.2.R.A. type which you have used in the past you have had no complaints of lack of performance, then the S.2.C.A. type should give ample heat for customers' requirements and the reason for using the "CC" type disappears. Accordingly, we have returned to you the "CC" type heater which you sent us, and also an S.2.C.A. type heater in place of the S.2.R.A. type which we have retained. We would like you to try this heater and let us know whether you consider it suitable - if so we will retain the S.2.R.A. heater here - if not, we will return it to you in exchange for the S.2.C.A. one. | ||