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Last Night Lowest temperature since 1955?


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Like many others, I have a C11xlt permanently sited  under a dome. Last night was so cold the main mirror was fogged up on inspection this morning. I don't think a dew heater would have made much difference even if it had been on all night. Any comments welcome.......Dave

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5 minutes ago, DAVE AMENDALL said:

Like many others, I have a C11xlt permanently sited  under a dome. Last night was so cold the main mirror was fogged up on inspection this morning. I don't think a dew heater would have made much difference even if it had been on all night. Any comments welcome.......Dave

No, I don't think dew heaters would have made any difference there.  The problem surely has to be water vapour in the warmer air inside the OTA condensing on the mirror as it cools even further?  Fans to keep exchanging the air in the OTA with ambient might help, but even then the mirror can presumably cool even further because it's facing the open sky.

James

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21 hours ago, skyhog said:

Never had that, got an obsy mounted 12 lx200gps. I have a little 300w Heater on a thermostat in there. Set at a few degrees. 

I think you may have the answer with the little 300w Heater. It would be ideal if the heater was battery operated because I am not keen on leaving mains electrics on overnight. I will do a google and see if I can find one.......Dave

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On 12/02/2021 at 12:00, JamesF said:

No, I don't think dew heaters would have made any difference there.  The problem surely has to be water vapour in the warmer air inside the OTA condensing on the mirror as it cools even further?  Fans to keep exchanging the air in the OTA with ambient might help, but even then the mirror can presumably cool even further because it's facing the open sky.

James

Yes that seems to be the root of the problem or at least a pretty accurate assumption

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1 hour ago, DAVE AMENDALL said:

I think you may have the answer with the little 300w Heater. It would be ideal if the heater was battery operated because I am not keen on leaving mains electrics on overnight. I will do a google and see if I can find one.......Dave

I think you're unlikely to find a battery-powered heater of 300W. Worst-case, it runs for (say) 10 hours "on" time - that's a 3kWh battery, which is about the capacity of an electric moped (moped, not bike) battery. If you can actually find one, you won't like the price!

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19 hours ago, wulfrun said:

I think you're unlikely to find a battery-powered heater of 300W. Worst-case, it runs for (say) 10 hours "on" time - that's a 3kWh battery, which is about the capacity of an electric moped (moped, not bike) battery. If you can actually find one, you won't like the price!

You are so right. The best I could find was 150w and that  had poor write ups

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12 hours ago, Frank the Troll said:

A little tip I use for the greenhouse

A tealight under an old clay flower pot

In a snow hole or igloo one candle with an air hole will keep you alive.

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5 minutes ago, Cyril said:

In a snow hole or igloo one candle with an air hole will keep you alive.

I don't have a dome , but if I did,  I'd be sorely tempted when there's a good snow covering to build a little  faux doorway on it from snow blocks to male it look like an igloo ...

  • Haha 3
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Same here.  It was over 8C on Sunday and almost 13C yesterday after a week of mostly sub-zero temperatures (even in the daytime), and the minimum temperature overnight last night was 8.5C.

James

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