myotis
29-05-2010, 12:08
I asked some time ago on here if anyone thought the Eta heat exchange pots would provide any benefit, when using a Trangia, no one responded.
I've now had an opportunity to try this out with a Trangia 25. Not exactly a definitive test, and it was using a replica trangia burner, but I boiled 600 ml of water three times in a 1.7l Primus Eta pot, and a three times in 1.75 Trangia aluminium pot. the lid from the Eta pot fitted the Trangia pot, so was used for all the tests. The burner was allowed to heat up, and although the starting temp of the water wasn't measured, it was left to equalise with ambient for half an hour before being used.
All six trials took around 9 (plus or minus 30s - 40s) minutes to boil, with neither pot showing any clear lead. The fastest individual boil was in fact from the Trangia pot.
My guess is that the Trangia wind shield, is doing a similar job to the heat sink in the Eta pots, and maximising the heat exchange cross the pot sides. But when the Eta pot is used in the trangia the heat that would normally go up the side of the pot and trapped by the windshield, is trapped by the heat exchanger and any gains from the heat exchanger is offset by the reduction in heat going up the side of the pot.
Interestingly, 600mls in a Tatonka 1.5l kettle took 12 minutes to boil, which I am guessing is due to the poorer heat transfer properties of Stainless steel compared to aluminium.
Graham
I've now had an opportunity to try this out with a Trangia 25. Not exactly a definitive test, and it was using a replica trangia burner, but I boiled 600 ml of water three times in a 1.7l Primus Eta pot, and a three times in 1.75 Trangia aluminium pot. the lid from the Eta pot fitted the Trangia pot, so was used for all the tests. The burner was allowed to heat up, and although the starting temp of the water wasn't measured, it was left to equalise with ambient for half an hour before being used.
All six trials took around 9 (plus or minus 30s - 40s) minutes to boil, with neither pot showing any clear lead. The fastest individual boil was in fact from the Trangia pot.
My guess is that the Trangia wind shield, is doing a similar job to the heat sink in the Eta pots, and maximising the heat exchange cross the pot sides. But when the Eta pot is used in the trangia the heat that would normally go up the side of the pot and trapped by the windshield, is trapped by the heat exchanger and any gains from the heat exchanger is offset by the reduction in heat going up the side of the pot.
Interestingly, 600mls in a Tatonka 1.5l kettle took 12 minutes to boil, which I am guessing is due to the poorer heat transfer properties of Stainless steel compared to aluminium.
Graham