How cold should aircon be set on public transport?

[dk1]

I bet you miss the 360s… Not!

Never signed or even travelled much on them. The hauled sets could be bad & the 170s patchy.

 

[AgeoftheTrain7]

The GWR IET Class 800s have always been well cooled trains in my opinion. I changed onto one from an XC Voyager, which while it had good air conditioning, had a much higher internal temperature than the 800.

 

[Bletchleyite]

The GWR IET Class 800s have always been well cooled trains in my opinion. I changed onto one from an XC Voyager, which while it had good air conditioning, had a much higher internal temperature than the 800.

I did all the way from Bodmin Parkway to London on an 80x on one of those two "hottest ever" days, the aircon was absolutely lovely throughout.

 

[Dougal2345]

Will just mention the oft-heard idea of painting roofs white - astonishing that, even now, it isn't mandatory.

 

[cf111]

The Scotrail HSTs and LNER 801 I travelled on last week were wonderfully cold. The Scotrail 158s, as per usual, were too warm.

 

[Bletchleyite]

Will just mention the oft-heard idea of painting roofs white - astonishing that, even now, it isn't mandatory.

Yes, this helps hugely and has quite low cost, though as the railway doesn't often clean them (as the wires are in the way of doing so) the effect may be reduced compared with buses.

 

[61653 HTAFC]

When the train is moving at speed, probably. But not so much if there's disruption and the train is either moving very slowly or stopped for an extended period.

In addition to the increased resistance mentioned upthread, the hopper windows that everything from the late 1970s onwards had fitted were utterly terrible at circulating the air anyway. They just generate a load of extra noise. All because some people weren't smart enough to not stick various body parts out.

 

[tiptoptaff]

Count yourself lucky you weren't on my GWR 166 earlier with no air con and the heating on full blast!!

I can assure you that wasn't the case. It would have been AC blowing hot, rather than the heating. Pedantry, but the HVAC system on 166s mean that current, heating isn't running.

 

[westv]

2 1/2 hours on a cold train isn't much fun.

 

[jupiter]

Ridiculous. Cold trains? You're complaining?

This was taken on 1/8/22, GWR 2C73, Cardiff to Penzance. It was flippin' roasting. I emailed the picture to GWR asking for a comment. Needless to say I'm still waiting for a reply. The train crew were brilliant, goodness they shouldn't have to work in those circumstances.

Cold trains?

 

[Purple Train]

I like a nice cold train. (Possibly because I'm very attached to my coat.) I agree with @jupiter - we should be worrying far more about making sure that trains don't get too hot on warm summer days than making sure they don't get too cold for the "t-shirt and shorts brigade".

 

[Peter Mugridge]

When the 460s were first introduced on the Gatwick Express, I was on one once which was most definitely set far too cold.

There was a thick build up of ice at the lower edges on the inside of the windows... and yes, this was in summer.

 

[Bletchleyite]

That just makes me want to be there, now. Lovely. Or on an aircraft, their aircon is generally lovely and cold (largely due to the compressors being those two massive noisy things on the wings and thus not lacking in power).

 

[Purple Train]

When the 460s were first introduced on the Gatwick Express, I was on one once which was most definitely set far too cold.

There was a thick build up of ice at the lower edges on the inside of the windows... and yes, this was in summer.

All right, perhaps that is slightly too cold...

 

[Dr_Paul]

I was on a 150 when it was the record temperature heatwave that head the heater on!

That happened to me once, on a 455 from Waterloo: a hot day and the heating on full. About the only saving grace was that one can open the windows a little on 455s, so there was some relief when the train got moving.

 

[Envoy]

People in summer hot weather clothes should not be blasted with freezing air. They need to set a comfortable temperature.

 

[Bletchleyite]

People in summer hot weather clothes should not be blasted with freezing air. They need to set a comfortable temperature.

"Comfortable" is a matter of opinion. First thing I do when I get into a Premier Inn on a hot day is set the aircon to 19 degrees. You can put clothes on, I can't strip off.

(I'm not proposing setting train aircon to 19 degrees, but I would say 20-21 is about right).

 

[trebor79]

That just makes me want to be there, now. Lovely. Or on an aircraft, their aircon is generally lovely and cold (largely due to the compressors being those two massive noisy things on the wings and thus not lacking in power).

Not really. It's because the outside air is at about -45! Most aircraft bleed air from one of the engine compressor stages. That air is at about 150-200 degrees, so it's cooled (easy, just dump the heat to atmosphere) before being mixed with cabin air.
The 787 doesn't bleed air from the engines and instead uses ram air from outside. I believe it still requires cooling due to the temperature increase that occurs when it is compressed.

 

[Bletchleyite]

Not really. It's because the outside air is at about -45! Most aircraft bleed air from one of the engine compressor stages. That air is at about 150-200 degrees, so it's cooled (easy, just dump the heat to atmosphere) before being mixed with cabin air.
The 787 doesn't bleed air from the engines and instead uses ram air from outside. I believe it still requires cooling due to the temperature increase that occurs when it is compressed.

To be fair, plane aircon is still lovely when it's 35 outside and running off the APU or GPU, so it's partly due to it being up to spec!

 

[greyman42]

I hope so! Nothing better than arctic air con on a hot day

We have about 9 months of winter in this country, can we not just enjoy the summer heat?

Decent aircon is lovely. If you don't like it, put on a jumper.

Who goes out with a jumper on a glorious summers day?

2 1/2 hours on a cold train isn't much fun.

I travelled from York to Kings Cross on Sunday on a 8xx and it was nice to step of the train at Kings Cross into a lovely warm station. The temperature on the train was too low.

 

[Welly]

I love a cold train in hot weather so I despise the Mark 3s, Mark 4s and 158s for their flakey aircon!

 

[Ediswan]

Not really. It's because the outside air is at about -45! Most aircraft bleed air from one of the engine compressor stages. That air is at about 150-200 degrees, so it's cooled (easy, just dump the heat to atmosphere) before being mixed with cabin air.

The figure usually quoted for outside air temperature at cruise altitude is -56 degC.

The 787 doesn't bleed air from the engines and instead uses ram air from outside. I believe it still requires cooling due to the temperature increase that occurs when it is compressed.

Ram effect increases that to around -30 degC. Then it is further compressed (electric), with more resultant heating.

 

[DanNCL]

Count yourself lucky you weren't on my GWR 166 earlier with no air con and the heating on full blast!!

We have that on the Tyne & Wear Metro all the time. The new Stadler units couldn't come soon enough.

I love a cold train in hot weather so I despise the Mark 3s, Mark 4s and 158s for their flakey aircon!

Mark 4 air con can be very unreliable, but when it works it's very good I've always found.

 

[MattRat]

Something to add is that with the weather so hot, even set at the same level of aircon it usually is, it'll feel colder due to the greater temperature difference between inside and outside.

 

[Annetts key]

There’s a couple of points here. I’m not an air conditioning engineer, far from it. But have experienced and seen many situations of failed or inadequate air conditioning installations.

Air conditioning systems, specifically, each compressor, has a maximum capacity. If the system is operating at its rated capacity, it will be unable to cool the air in the carriage/car/cabin/room/whatever to the set temperature.

Secondly, the system must be well maintained. If a system is not in good condition, it will be unable to get to it’s rated capacity.

If a system is at it’s maximum capacity, is operating poorly due to poor maintenance, or has faults, the compressor will be unable to cool the refrigerant sufficiently, so the circulation fans/blowers will circulate the warm/hot air without cooling it much or at all. This will be even worse if the system mixes in ‘fresh’ (warm/hot) air from outside… Hence this air will feel warm/hot.

As the system is not cooling the air, as long as the sun is shining and humans are producing heat themselves (about 100W per person) the air temperature will continue to increase.

So the important point here, is that if the specifications of the air conditioning system are inadequate for the combination of the ambient air temperature, the heat from the sun and the heat from the people, it will fail to provide the wanted performance.

Because in this country, we are not used to such hot weather, how many air conditioning systems are actually specified for the hot weather that we are experiencing? Have the designers planned to fail?

And with trains, the priority for maintenance depots is getting the stock in service, the maintenance of the air conditioning systems is likely to be secondary…

And finally, as each carriage/car has it’s own air conditioning system, if you are not happy with the temperature in the carriage/car you are in, if possible, explore the other carriages/cars. On really hot days, I normally walk through the train looking for somewhere where I’m happy with the temperature.

 

[JamieL]

Another vote for cold trains here - much more pleasant on a hot Summer's day than the other way around. During the last heatwave I went from Bristol to Paddington and the coach was far too hot, in contrast the Euston to Glasgow train was lovely and cool - much more pleasant.

 

[Bletchleyite]

Who goes out with a jumper on a glorious summers day?

Someone who knows they find air conditioned trains a bit cold?

 

[Mojo]

Standing at the platform at Reading just now whilst about a metre and a half away from the train I really noticed the difference in temperature as the doors closed compared to when they were open.

 

[RPI]

The GWR 158's are far better than they used to be, the 166s are awful though. Problem is guards are too quick to open the windows which just knackers the air con, today on a 158 that was lovely and cool and yet the windows had been opened in one coach despite ice cool air blasting out

 

[tiptoptaff]

The GWR 158's are far better than they used to be, the 166s are awful though. Problem is guards are too quick to open the windows which just knackers the air con, today on a 158 that was lovely and cool and yet the windows had been opened in one coach despite ice cool air blasting out

Don't get me started on this. I have to argue with guards about it. They know best though, despite our traction knowledge being far superior to theirs.