Could you please provide full details as to the thermostat settings for air cooling and heating on S7 and S8 stock trains on the Underground? Including for instance, what is the target temperature set for heating in cold weather and cooling in hot weather? Is this a non-linear function for output based on current temperature, and where on the train (or otherwise) is this measured from? Is there a particular timing mechanism for activation (for instance, does output increase at stations or with doors open?) These technical details have much practical importance for passengers suffering uncomfortable temperatures on those trains, as they provide specificity for any adjustments that might be required to improve this.

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TfL Ref: FOI-0659-1920

Thank you for your request received by Transport for London (TfL) on 3^rd June 2019 asking for information about the temperature on London Underground trains.

Your request has been considered in accordance with the requirements of the Freedom of Information Act and our information access policy. I can confirm that we hold the information you require.

You asked:

“Could you please provide full details as to the thermostat settings for air cooling and heating on S7 and S8 stock trains on the Underground? Including for instance, what is the target temperature set for heating in cold weather and cooling in hot weather? Is this a non-linear function for output based on current temperature, and where on the train (or otherwise) is this measured from? Is there a particular timing mechanism for activation (for instance, does output increase at stations or with doors open?)”.

The saloon heating system is split into two areas, Heating Ventilation and Air Conditioning (HVAC) system, and the low level heaters.

Saloon HVAC system

In normal operation the saloon HVAC units independently control the temperature in the saloons by heating, cooling or ventilating as necessary to achieve a pre-set temperature for passenger comfort.

Heating start up is when interior temperature drops below 19 degrees. Cooling start up is when interior is above 21 degrees.

Saloon Low Level Heaters

Within the saloon are low level heaters that are controlled by the HVAC controllers, dependant on the mode of operation. Bodyside fan heaters are located underneath the longitudinal and tip-up seats, and gangway fan heaters are located in the intermediate ends of the cars. The saloon low level heaters are all fitted with over temperature protection.

Heating will carry on until the saloon temperature reaches 25 degrees, at which point heating will stop. This is measured at the probe in the HVAC unit. At a point 1.5m above the saloon floor the temperature will be 5.5 degrees below this.

The automatic door close function helps the HVAC to preserve the interior ambient environment of the train. The automatic door close function will close a door 45 seconds after it has been opened by the Train Operator or by a customer or staff via door leaf push button. Condition of the HVAC system is monitored by the train’s on-board monitoring system and if defects are identified technical staff are informed and the train is subsequently investigated.

It should be noted that when the doors are open and closed the temperature in the saloon may be difficult to maintain.

If this is not the information you are looking for please do not hesitate to contact me.

Please see the attached information sheet for details of your right to appeal as well as information on copyright and what to do if you would like to re-use any of the information we have disclosed.

Yours sincerely,

David Wells

FOI Case Officer

FOI Case Management Team

General Counsel

Transport for London

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