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 different car heating and ventilating methods, detailing their respective disadvantages.
| Identifier | ExFiles\Box 137\3\ scan0023 | |
| Date | 21th January 1939 | |
| -9- (C) Combined heating and ventilating scheme as outlined above - this has been fitted up on 25.S.VI Wraith car, but has no thermostatic control as yet. Considering method (A), this is attractive from the standpoint of obtaining fresh air supply while heating and because it is cheap to construct, but suffers from two serious disadvantages:- (1) Noise transmission through walls of duct and also through radiator matrix, when heater grille is in "heat on" position - this appears to be difficult to entirely eliminate. (2) This scheme cannot be used for fresh air supply in summer since the air would always be heated. As a side issue, it is difficult to avoid the duct from radiator to dash being unsightly. Method (B) is that most commonly used at present and has been used by R.R. Ltd. on chassis which customers have requested car heaters. There are numerous heater units of this type, English, American and German, on the market at the present, but the only ones manufactured in this country are the Clayton, the Smith 'Malwes' and the AC-sphinx Co's heater. This method suffers from the disadvantage that it provides no ventilation, needs occasional alteration of fan motor control rheostat to maintain an approximately constant temperature, costs slightly more than method (A), and usually necessitates some demisting device to remove "steaming" from the interior of the car windscreen, particularly in wet weather. A further disadvantage is electric fan and motor noise, but the latter noise can be overcome by putting the motor on the engine side of the dash. Method (C) is obviously the ideal one, but suffers from the following disadvantages:- (1) Cost - It is bound to cost slightly more than either (A) or (B), but if the cost of the spinney ventilator, (which can be dispensed with, by using scheme C), is taken into account, we think that it can hold its own against the other two on a cost basis. | ||