Getting Ready for Winter

[aardvark]

I don't think it should as the sensor for the temp.humidity is below the rain plate and if it flows out the drain holes as it should, it should be no issue,  hopefully.   

[aifan27]

I don't think it should as the sensor for the temp.humidity is below the rain plate and if it flows out the drain holes as it should, it should be no issue,  hopefully.   

I think that Trevor meant the temperature readings being incorrect (heat from the light bulbs), and therefore the humidity readings.

--Tim

[trevor]

Yep, I did, well actually a bit of both, the heat maybe creating evaporation and affecting humidity.

[aardvark]

well  then we should hope that the moisture rises to the top of the cone,condenses a bit and flows out .  I guess you will have the task of testing it out and seeing what happens.   The fun of invention is yours

[weatheroz]

Any sign of it distorting temperature/humidity readings from the ISS?

I would think that unless the bulbs are that hot that they are nearly melting the plastic, having the temp/humidity sensor BELOW the level of the globes, then I don't believe you'd have any problems, as heat rises drawing ambient air past the screen.

[MNflyer]

Greetings,
The heat from the bulbs should not be an issue as the Davis heater is much hotter than the 2 bulbs.
The rain gauge funnel comes down to a very small opening ( size of the little pinky) so all the water stays away from the bulbs. I found the humidity inside the rain gauge to be much much drier than the ISS. 45 % compared to the ISS 79 %. I don't know if that really is a case as I have checked it only a couple of times.

I also have a Heathkit 4001 just below the tower ( tower is 150 feet for your info, 4001's wind cups are at the top) and the temp is very close to the ISS.

Does anyone know how warm the Davis heater gets the inside of the rain gauge? Outside air here is zero and inside RG is about 23. Open to any questions or ideas. Just thought we'd give this a try since I had a 12 volt power supply and $3 for bulbs/sockets.

24 inches of snow the past 4 days. Later,

[weather_nc]

Not sure how warm it gets with the Davis heater, but if you are using the 27W filaments in the 1157 bulbs and running both bulbs, then you are kicking out twice the wattage as the Davis heater which is 25W.  Now, the big difference is that Davis' kit includes the insulation around the inside of the outside perimeter of the funnel which would make quite the difference since that's a large area to be un-insulated.

If you were able to insulate that, I would expect you would be able to get down to 0F and be at or above freezing inside.  The other thing would be to replace the clear bulbs with colored bulbs which would convert more of the light to heat....

I will be using Purple Bulbs I found at Autolumination.com

[aardvark]

be sure that the bulbs aren't red or your neighbors might think your business has expanded in a unique way.....

[administrator]

The other thing would be to replace the clear bulbs with colored bulbs which would convert more of the light to heat....

Is that correct? Do coloured bulbs really make that much difference? I'd have thought that having the bulbs totally enclosed in a black enclosure would mean that all the light energy is captured anyway.

http://www.newton.dep.anl.gov/askasci/eng99/eng99273.htm seems to suggest that you might get slightly different amounts of heat out of different bulbs due to the coloured glass absorbing some of the IR. If that's the case, then presumably a clear bulb is the best way of getting the most heat out, i.e. no dyes/chemicals in the glass to absorb anything?

[weather_nc]

Is that correct? Do coloured bulbs really make that much difference? I'd have thought that having the bulbs totally enclosed in a black enclosure would mean that all the light energy is captured anyway.

http://www.newton.dep.anl.gov/askasci/eng99/eng99273.htm seems to suggest that you might get slightly different amounts of heat out of different bulbs due to the coloured glass absorbing some of the IR. If that's the case, then presumably a clear bulb is the best way of getting the most heat out, i.e. no dyes/chemicals in the glass to absorb anything?

In that situation, the question dealt with heating a surface via energy transfer to that surface which would dictate two conditions: 1) Use of an infrared light such that the majority of 'heating' energy is transfered to the surface and 2) minimal or no lamp surface covering/coloring to convert the directed (reflector light) energy to heat on the bulb itself.

In the case of the rain bucket, you want to heat the internal Air more than try to heat a surface since you are trying to solve two problems - first is to ensure that snow/freezing precip. melts in the funnel/cone and seconds, to keep the tipping buckets and drains melted.

In essence, you want to duplicate what the original Davis design does, which is to generate heat not light...  Now, as to whether the colored coating is capturing or converting IR energy to heat.  Only a thermometer next to the bulbs, both clear and colored, would be able to prove that theory.

[MNflyer]

I do have a red light on the outside of my observatory (telescope) and everyone knows when I am out there. How does Davis insulate the inside? I wrote it down on things to do. I don't think I have the bright side of the 1157's hot. I'm only pulling about 1.4 amps total.

[weather_nc]

I do have a red light on the outside of my observatory (telescope) and everyone knows when I am out there. How does Davis insulate the inside? I wrote it down on things to do. I don't think I have the bright side of the 1157's hot. I'm only pulling about 1.4 amps total.

If you go back and look at the first post in this related topic, you can see the insulation material (shiny silver) in side the cone...  Also, if you are only using the low-wattage filaments of the bulbs, then you are only generating about 16W of light/heat or about 2/3rds of what the Davis heater does.  Combine that with the lack of insulation and that would explain why it only works down to about 10F.  You have 2 options, add insulation or use the high-wattage filaments in one or both lights.  Another thing to try is to connect the high-wattage filaments in series across the 12V....  Each high-wattage filament draws 21W so if in series, the total output for both bulbs should be 21W vs. the 17W you are getting for the low 8W filaments in parallel....  That would put you closer to the Davis Heater's output. 

I would try the series approach and measure the total current draw.  It will probably be around 1.8Amps...  You could always add the low wattage filaments, in series, across the high-wattage filaments for almost 30W of heat/light.


Using the thermal switch I mentioned in a post in the previously mentioned topic would prevent the inside getting too warm when the temperature is not that cold....

[daveq]

Using the thermal switch I mentioned in a post in the previously mentioned topic would prevent the inside getting too warm when the temperature is not that cold....

Do you have a source for those?  Don't have a lot of snow around here but what the heck.  The 12v bulbs seem to be a reasonable approach.

--Dave

--Dave

[weather_nc]

Do you have a source for those?  Don't have a lot of snow around here but what the heck.  The 12v bulbs seem to be a reasonable approach.

I was going to hold off on posting the source until they actually arrived but will post the link here and folks can decide...  I ordered 10 since I figured I would have a use for them in different application and considering shipping was almost $5, I wanted the product to exceed the shipping ....

It's part number #36TO15-L10-9C at site http://www.hoffind.com/thermal.htm

[MNflyer]

Today for grins and lack of something to do I lined the inside of the RG with foil. The temp in the RG now raises the temp to about 32 degrees above outside temp. So if that holds true I can hopfully melt snow down to about zero now. Trying different bulbs next. We will see. Later,