Beemaster's International Beekeeping Forum
BEEKEEPING LEARNING CENTER => GENERAL BEEKEEPING - MAIN POSTING FORUM. => Topic started by: mushmushi on August 30, 2011, 12:20:24 pm
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What are the advantages and disadvantages of heating a hive in northern climates ?
Hypothetical advantages:
- Decreased moisture
- Faster Spring build up
- Faster curing of syrup in Fall
- Less sugar/honey consumed
- Better overwintering rates
- Overwintering weaker colonies
Hypothetical Disadvantages:
- Difficult to control the heating levels (needs monitoring)
- Risk of cooking the bees
- Cost (cables, heating unit, power, etc)
- No overwintering gains
- Dryness inside the hive (little water left for the bees?)
- Electromagnetic radiation
- More work for the beekeeper
- Increased consumption of sugar/honey
Has anybody tested this ?
What kind of heater would be suitable ? Would a 25W infrared heater on a timer work ?
Cheers
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As many know and are probably tired of hearing about; I’m an infamous bee hive heater :-D
My experience would concur with the advantages Mushmushi listed.
As for the disadvantages, here’s what I found:
Concern: Difficult to control the heating levels and worry about cooking the bees.
Response: This depends upon what your goals are. If you only want to give the bees a break from a forecast week of an arctic blast (ie -20C to -30C spell) you could simply plug in a 10Watt heater (or incandescent light bulb) and let it run day and night through an extreme cold spell and never have to worry about cooking the bees when it is so cold outside. 10watts doesn’t warm a hive by much when it’s -20C outside! However the warmer convection currents rising up around the bees cluster may be greatly appreciated. If your goal is to minimize honey/stores consumption in the winter, then you would need a little controller to maintain the hive temp around 5 or 6C (low 40sF). If you’re trying to baby a small colony through winter, then 15C (60F) works well.
Concern: Cost.
Response: Yes, there is cost with electric heating, but there is also cost with buying new packages every spring. All my electrical parts cost less in total than a single new package of bees. I use an old computer power supply for power and some homemade cement/resistor things for heat. Total cost for a simple system is the cost of a bag cement, about $1 of resistors, and an extension cord. Plumbing heater cables have also been used by some for heaters. Cabling is the most expensive part. If you want to control a hive to a fixed temperature then you need a thermostat for the heaters. For DC heaters you can make one of those out of a simple op amp circuit (no programming needed) for under $5 in parts. If you want a more sophisticated controller and know how to program a micro controller, you can select from a ton of low cost 8-bit micros that are more than capable of reading temps from a thermistor and controlling the heaters with FETs. An 8 bit micro costs $1 to $4 depending upon what you want.
Concern: No overwintering gains?
Response: You lost me here, I don’t know what you mean.
Concern: Dryness in the hive.
Response: Yes, this can be a problem in the spring. Heated hives are very dry. You never have to worry about wet bees in a heated hive. Come brood season, I think you would want to add water to your hives somehow. A sponge, a coffee/food lid filled with water, or water poured into comb.
Concern: Electromagnetic Radiation
Response: EM radiation is generated by large current flows (your power company lines) and high frequency noise where there is a conductor that acts like an antenna and impedances are not matched. You really have to TRY to build a transmitter if you want to make a significant level of EM radiation. There will be more EM from cell phones and power transformers than bee heating equipment. If you go with a simple Christmas light heater, how much EM is in that? My stuff is powered by a computer power supply. Those use switching in the low MHz range to generate DC voltage. That does generate some noise, but you need a pretty long wire (antenna) to radiate 1MHz.
Concern: More work for the bee keeper.
Yes.
Couple of items you didn’t list:
Concern: A warm hive will be more conducive to pests like wax moths.
Response: Yes. Unless you’re babying a nuc, it may be unwise to heat the hive above 12C (55F).
Concern: What if the power goes out? Do my bees die?
Response: If the power goes out, your bees will have to cope with the cold like all the other bees out there. An extended period of cold may do them in, just like all the un heated bees. However a power outage does not mean immediate death to your bees!
Concern: The bees will keep brooding all winter long.
Response: I have not seen this with my carniolans or Italians, but I never say never.
Concern: Electrically heated hives will run my electric bill through the roof.
Response: No it won’t. Running a 10watt bee heater will be under 5 cents per day in most of the USA. So $1.50 per month. Most of us don’t have -20C all winter long, maybe you just run a heater for a month or put it on a timer? The power cost depends upon how many watts of heat you want to pump into your hives and for how many hours. Say you add a 10 watt heater to your hive and run it 24 hours a day during a cold spell. That is 10w x 24hour = 240watt-hours of power you need to buy from the power company per day. Electric power is priced by the kilowatt hour used in the USA. In the Midwest power usually costs about 12 cents per kw-hour (can be double that on the east coast, or Calf). So 0.240kw-hours x 12 cents/kw-hour = 2.88 cents per day to run a 10watt bee heater. How much does it cost for new packages of bees from the south? How much is a pound of sugar? Electricity is cheaper.
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Not worth it unless you insulate a lot!- a small bare wooden hive dissapates around 5w per degree C. 25w = 5 degree C. (thats 9F). The Artic blast of -20C is only going to come upto -15C.
You can insulate down to 0.3W per degree C using standard(in the UK at least) building materials. Your 20W now gets you 60C difference.
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BlueBee, thanks for the tips.
By "No overwintering gains" in the hypothetical disadvantages category I meant that the rate of overwintering might not change.
How many hives are you heating every year ?
Do you have your heated hives on 1 or 2 deeps ?
I would like to know more about your cement heaters.
Do you put them underneath the bottom screen ? How much heat can be produce ?
I was thinking of wrapping my hives with the bee cozy wraps. Link is here (http://www.miteaway.com/Bee-Cozy/bee-cozy.html).
I would put the heater under the sealed screen board.
Also, I was thinking of monitoring the temperature of one or two hives and based on those readings the heat would be on or off.
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I have heated hives 7 years. I put terrarium heater cables into every hive in spring.
Heaters are 15 w - 7 w.
3 w has no inlfluence.
I have wintered small colonies with electrict aid. Heating is like a bigger cluster.
Last winter was very bad. When I trickled my hives in December, I noticed that varroa had demished 5 hives too much. I put to them 7 w heating.
The winter was unespectedly hard, but thse weak colonies were in good condition in spring.
I have wintered 2 frame colonies with electrict and the nuc in a firewood shelter.
The colony has only value of queen and trouples begin in spring - from where you get 5 frame colony tothe queen?
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Concern: what if one of the kids gets electrocuted sledding in slush over the 200 foot extension cord? :roll:
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"Concern: what if one of the kids gets electrocuted sledding in slush over the 200 foot extension cord?"
Same concern if one of the kids gets hit by a meteor on the way to the school bus. Greater concern if (god forbid) the kid walks to school.
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I think Scads raises a valid concern. We all view risks differently so one shoe doesn’t fit all.
I will just stick with the facts. Yes 120VAC is deadly. It only takes about 50milliamps of current going through your heart to stop it. That’s just a little more current than is used to light a little LED indicator. It doesn’t take much to kill you IF it flows through your heart muscle. Muscles are controlled by nerves which are controlled by electrical potentials. If you mess up the nerves (with external voltage), you mess up the muscle. If that muscle happens to be your heart, then warm bees is no longer your biggest problem.
An electrically safer way to provide power to bee hives would be to use a 12Volt DC power source like a battery, or a long feed cable feeding 12volts DC to the hives. I have tried feeding 12volts DC back to my hives through long heavy gauge landscape lighting wire (10 or 12 gauge, I can’t recall which). However you just get too much voltage drop over the cabling to be efficient; even with thick wires. By the time my 12volts DC got back to my hives, it was down to 9volts when flowing a few amps (actually about 9 amps). That means I was loosing 25% of my heating power just in the feed cable!
I ended up switching back to a 120VAC extension cord because of the voltage drops in the wire. If you drop a few volts over 120VAC you can still get 12VDC out the other end. However as Rick points out, it is more dangerous. It is also dangerous to use Christmas lights, but that is for a different discussion.
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Hypotetical risk list is not real.
It is easy to see how the bees react on heating.
For winter put the heater over the top bar or on side. So it doest not break the wintering cluster. Another place is a side.
Once I bought two heating cables which irritated bees so that bees stung the cable full of sting. It was like a tail of squirrel.
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As Derekm, points out, you waste a lot of energy (bee heat and electrical heat) if your hive isn’t insulated. 19mm thick wood has almost no insulation value. It would seem sensible to me to add insulation before playing with electric heat.
I listen to Finski when it comes to heat and insulation. He has more years in than I do. I just started experimenting with electric heat last winter. My full sized hives were all mediums last year, 3 mediums per hive and insulated in 2” foam. My nucs were 2 to 3 frames of bees going into winter. They didn’t build up as much as I hoped before winter. Everything survived winter, even the 2 frame nucs. The reports I heard was that Michigan lost at least 60% of their hives last year. I can definitely attribute the 2 frame nucs survival to electric heat, I suppose the rest could be debated (maybe I was lucky)
As Finski preaches, the bees themselves make heat energy, probably on the order of 10 to 40 watts. So we already have an energy source to keep the bees warm if we provide them with good insulation. Electric heat really comes in useful if you end up with a weaker than hoped for colony going into winter.
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http://www.bushfarms.com/beesnucs.htm#overwinternucs (http://www.bushfarms.com/beesnucs.htm#overwinternucs)
Here are some pictures of overwinter nucs with a small space heater in the gap at the back. 2" of Styrofoam top, bottom and ends.
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Here’s a photo of my heaters. Each heater is a shade over 10watts. This whole stack cost maybe $10 to make. (http://i1082.photobucket.com/albums/j365/MichiganBee/Bee%20Equipement/StackOfHeaters.jpg)
Here is a forum link how to make these things here. http://forum.beemaster.com/index.php/topic,32037.0.html (http://forum.beemaster.com/index.php/topic,32037.0.html)
The bottom unit of my full sized hives is actually a heater box. There is a screen on top to keep the bees out of the heater area so I can manipulate things in there as desired. The brood boxes sit over top of the heater box. Since heat (actually hot air) rises, putting the heater box on the bottom of the stack makes the physics work easier, but other configurations would also work. Convection currents will distribute heat.
I didn’t find any photos on the computer of my full sized heater boxes, but here is a photo of a smaller heating box used in another hive configuration. I add the brood boxes on top of this and add foam shells over the whole thing for insulation.
(http://i1082.photobucket.com/albums/j365/MichiganBee/Bee%20Equipement/HeaterBoxMatingHive.jpg)
Last winter I wintered in 3 mediums. I decided to stop using mediums for brood chambers this summer so I will have different winter configurations this year. I switched back to using deeps and extra deeps for brood chambers. So this winter, I will be wintering in 1 deep + 1 medium configurations. I also have some half frame hives (for mating) and nucs I will be wintering.
My foam nucs look like this. This design does NOT have a heater box in them. The bottom deep is brood/stores, the super medium is more stores if they get too big before winter.
(http://i1082.photobucket.com/albums/j365/MichiganBee/Bee%20Equipement/Gen1Nuc.jpg)
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My only concern w/ artificially heating hives is that I 'believe' it fools bees into thinking its warmer outside than it is, causing some to venture out (or maintain a loose cluster when a tight one is needed) when perhaps they should just stay put. Can't prove it but its what I believe. I also believe bees will consume more when hive is heated.
That said I remain very interested in the discussion and any other methods folks are experimenting with to keep bees alive and healthy. Dif strokes for dif folks, Right.
thomas
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Has anybody tested this ?
What kind of heater would be suitable ? Would a 25W infrared heater on a timer work ?
Cheers
Here is a thread from a few years discussing my use of 7watt night lights.
http://forum.beemaster.com/index.php/topic,11721.0.html (http://forum.beemaster.com/index.php/topic,11721.0.html)
I found anything more than 15watts was to much and made the bees too active. I found it to work reasonably well, but ultimately found the switch to polystyrene hives works best for me.
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My plan for this winter is to use electric heat as an insurance policy just in case we have a super cold winter. I may or may not use it since my hives are already highly insulated. I may just do like Finski and try to boost the spring buildup with electric heat.
Thomas raises a good concern: Does heat fool the bees into thinking it is warmer outside than it is?
It might, I still don’t know for sure. If you play with electric heating, my current advice (subject to change) would be to set the thermostat of your heaters at 55F (12C or less) when it is colder than 45F (7C) outside during the winter. I would also highly recommend using a landing board on a heated hive.
Last winter my hives had landing boards, but my nucs did not. If it is relatively mild inside the hive (heaters on), some bees will definitely hang around the entrance soaking up the sun, snow, or just investigating. I had bees roaming around the entrances when temps were 20F (-6C) outside. This did not appear to cause problems with the big hives, but it did the nucs.
The nucs did not have a landing board, so when the bees crawled out to check on the weather, more than a few fell off the nuc entrance hole and into the snow. A bee that falls into the snow is dead within about a minute. There is no recovery. The cold snow sucks energy from their bodies so they can no longer fly to get back in the hive. If a bee falls in the snow, it is doomed.
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It is easy to see, what the heating causes to bees or to cluster.
You just lift the cover and look.
It is important that that bees have a cluster, loose or compact. when bees are in "cluster sleep", they survive over winter. If they are running inthe hive here and there, they are not in rest mode.
It is you who arrange the system. It no one else.
It is interesting to read what you have met in heating.
To me most important has been that electrict heating has teached the meaning of heat to bee colony.
That puts a mesh floor in a different light in spring.
Some say that a mesh floor is absolutely the best, but on another hand I may see the influence og heating.
One basic factor is the size of bee colony. It is much more easier to rear a big colony in late summer than in spring.
It is almost ridiculous that biggest hives get biggest advantage from heating.
the basics comes from the volume of ball and the growth of radius with aid of heating.
.we ray "brood area" but it is a ball.
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BlueBee quote; "If a bee falls in the snow, it is doomed." Not so, I've been picking bees up from the snow for a few years now and there have been many that have come back after just a few minutes in my hand. I just push them into the entrance if they're real lively and its above freezing outside. Not sure how long some were there in the snow but it had to have been more than a minute on some occasions. Try it sometime. 8-)
Finski; Aren't you the one who is always telling beeks to leave their hives alone during winter months :-D (I remember you told me not to even listen w/ a stethoscope as it would cause too much disturbance :-\). Now your advising to just lift the cover and look????
At what temps do 'you' stop lifting the lid and looking? Does artificial heat cause bees to be 'running in the hive here and there' when they should be in cluster? Just asking.
thomas
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Beak,
The whole body suffers from stupid head. I am so sorry.
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>Thomas raises a good concern: Does heat fool the bees into thinking it is warmer outside than it is?
With or without heat some fly out and die in the snow. I see no difference in the amount.
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>Thomas raises a good concern: Does heat fool the bees into thinking it is warmer outside than it is?
With or without heat some fly out and die in the snow. I see no difference in the amount.
you must set the heat in proper way that the heat does not disperse cluster and winter rest.
Actually I saw last spring that in heated hives bees had less poo, and they did not need to make desperate cleansing flights on snow.
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BlueBee, thanks for the all information. :-D
I've read your older forum post about the heaters.
Do you put one or 4 heaters into every hive ? Or it does not matter since you control the power with the board you made ?
Are wrapped hives (using the bee cozy stuff) considered to be insulated enough ?
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We all justify our actions/behaviors/beliefs and can call the results 'proof' as it benefits our particular positions. It's part of what make humans human. We find what we're seeking, whether consciously or not.
Keeping it all civil is the hard part and I endlessly thank my bees for teaching/reminding me :).
thomas
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BlueBee quote; "If a bee falls in the snow, it is doomed." Not so, I've been picking bees up from the snow for a few years now and there have been many that have come back after just a few minutes in my hand. I just push them into the entrance if they're real lively and its above freezing outside. Not sure how long some were there in the snow but it had to have been more than a minute on some occasions. Try it sometime. 8-)
thomas
I've done the hand warming thing...to a few bees. The hundreds others out there on that day were doomed. And that was only that day. So I think doomed is a fair statement for the 99.9999% that fall in the snow and don't get picked up;) Unless you are far far more dedicated to them than I am.... :-D
I thought that the heat would mess up my observation hive - it is near my fireplace and the warmest spot in my house. But they were just fine - loosely clustered, they very rarely moved, they flew less on sunny days than my other hives. Low honey consumption, although in fairness that they had tiny clusters.
The heat did cause a problem in the spring - they expanded their brood nest more than they could defend, and the beetles and moths that overwintered in there easily overwhelmed the hive. This is in April/May.
Have you ever seen that problem in the spring when heating hives?
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Mushmushi, I have run up to 4 heaters (about 40 watts) in a full sized hive in the dead of winter.
Keep in mind I just started playing with electric heat last winter so I haven’t had a lot experience testing out different hive temperatures. I go by the old books (CC Miller) when speculating about what might be a good wintering temperature and then experiment from there. They did fine last winter and were probably warmer than they needed to be.
My controller can turn on and off individual heaters since they’re each on a separate FET (Field Effect Transistor). If the thermistor says it’s getting hotter than my set point in a hive, then the controller would shut off a FET which cuts power to one of the 4 heaters. So the system allows for variable heat from 0 to 40 watts, but in discrete steps. My controller did not have PWM capability last winter, so the heating levels were really in pretty big steps: 0, 10, 20, 30, 0r 40 watts. With PWM controls, you could generate any level of heat between 0 and 40 watts if you wanted.
Are wrapped hives (using the bee cozy stuff) considered to be insulated enough ?
I don’t know the R value of the cozy’s, but you can use heat with anything, it’s just not going to warm the whole hive up like thick insulation would. Warm air from the heaters would still rise if you place them below the bees. The warm air should bath the winter cluster even in a wood hive, but to a lesser extent. I have never tried putting a heater in an un-insulated wood hive so I don’t know all the pros and cons.
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The heat did cause a problem in the spring - they expanded their brood nest more than they could defend, and the beetles and moths that overwintered in there easily overwhelmed the hive. This is in April/May.
Have you ever seen that problem in the spring when heating hives?
Yes, I have had wax moth problems in my heated nucs in the spring. I think this is the biggest problem with adding too much heat. Wax moths don’t multiply like rabbits when the temperature in a hive is on the cool side (40 to 55F / 4-12C). The bees can keep them under control if they aren’t multiplying exponentially.
It is my belief based on observations that wax moths are always present in a hive, no matter how strong a hive is. I could be wrong, but that is my belief. Strong hives keep them in check in the summer. The spring is a different beast though. If conditions become more favorable in the hive for overwintered wax moths than for the bees, then you may have some big problems to deal with.
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The heat did cause a problem in the spring - they expanded their brood nest more than they could defend, and the beetles and moths that overwintered in there easily overwhelmed the hive. This is in April/May.
Have you ever seen that problem in the spring when heating hives?
Of course not. How brood are could be bigger than occupied frane area - never...
Heating gives only heat, nothing . How heat can make troubles.
When sun heats the hive, does it bring troubles?
When day temp rise to 17C bees star activate ventilation.
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I have heated 8 years in spring. I have not noticed any problems, only good to say. With patty feeding spring build up is 3 times faster than in natural colonies.
One problem is that hives swarm more, because big hives swarm first.
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Mushmushi, I have run up to 4 heaters (about 40 watts) in a full sized hive in the dead of winter.
That I do not understand.
Normal size hive does not need heating = one box occupied or more. It makes possible to make large brood ball.
40 W is surely too much,.
Like Robo says, my experience is that 15W is enough and 11W makes the same result.
15W is the cheapest heating cable. It tried 25W but it was too much.
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Mushmushi, I have run up to 4 heaters (about 40 watts) in a full sized hive in the dead of winter.
That I do not understand.
Normal size hive does not need heating = one box occupied or more. It makes possible to make large brood ball.
40 W is surely too much,.
Finski, I agree with you! I was just experimenting with 40watts to see what I could learn. I know strong colonies in full sized insulated boxes do not need heating.
Last winter I was experimenting with VERY warm hives. I wanted to see what would happen. I’m talking 60 to 70F (15 to 21C) in the dead of winter. I have learned that 40watts is probably more heat than I want to give them :-D
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Once I put a cable to the 2 frams nuc. It was too much, and every worker went away from combs. They went to the corners and walls of the hive and searched colder places.
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..Heating over winter
Winter hester should be at least half that of spring heathing.
Winter heater is on side or on top bars. - NOT on the bottom.
Bottom heater disturbs cluster formation and winter rest.
If you have a langstroth size colony, 7W is enough to add wintering heat.
If your heater is bigger, you may add a timer, which cut off the part of electrict. For example 15 w caple heats every two hours or you take half of cable off and put it half of it to the next door neighbour. Cable is 10 feets long.
Here is some examples. 15 W heater cable is cheapest.
These plate heates are double price compared to cable.
http://www.namibaterra.de/kataloge/dateien/Katalog2010EnglischWEB.pdf (http://www.namibaterra.de/kataloge/dateien/Katalog2010EnglischWEB.pdf)
cables page 14 and mats page 15
This in USA?
http://www.reptilesupply.com/popup_image.php?pID=2702 (http://www.reptilesupply.com/popup_image.php?pID=2702)
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My controller did not have PWM capability last winter, so the heating levels were really in pretty big steps: 0, 10, 20, 30, 0r 40 watts. With PWM controls, you could generate any level of heat between 0 and 40 watts if you wanted.
You dont really need PWM in your setup. You have a timer. 1 sec on / 9 sec off to give one watt of power. Your concrete blocks filters out the the 0.1 Hz fluctuation.
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Cheap every boy's timer has 15 minutes intervals to set on or off.
1) You may connect 10 15 W cables to the times and you get 4 W heating easily per hour.
2)Another way is to draw a camble through several hives.
Cable is 4 metre long and each metre gives about 3 wats. Part of cable is outside the hives.
3) to weak nucs you make a big styroks box, half cubig metre. The floor is ventilating and not much closed.
Then you put into box several nucs.
My friend have made into a firewood shelter a big styrox box where he puts 10 one-box langstroth hives.
Hives generate so much heat that other heating is not neeeded.
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IF the winter is mild and frost is under -10C, 3 W heater is enough to 3 frame nuc, including that the nuc is in a shelter where wind does not reach.
Last winter was bad. I put into a 2 frame nuc first 3 W heater but it affected nothing.
Then I put 7W heater. Near freezing point cluster was widely open, but they were not walking and moving. In -20C temp they clustered nicely along the heater.
If the nuc is too warm, bees are in movement, which tells that they have not winterest.
In spring in 2 frame nuc they had half bees alive. One frame is not able to rear brood. That is why I must take a frame of bees from a big hive. Dead bees were on bottom board. So they did not came out to die during winter.
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Finski, my controller is cheap too; you just have to know a little programming :-D
Finski, I’m hoping not to use electric heat this winter. My hives are highly insulated already. I will probably only turn on the electric heat if it gets REALY cold. Electric is my insurance plan.
How warm do you think it is inside your polystyrene hives in winter?
How warm do you think it is inside your electric nucs (2 or 3 frames) in winter?
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Boca, you are CORRECT!
My cement heaters do have a long thermal time constant and hence I can control them exactly as you suggest; On for 1 sec, Off for 9 sec, and variations thereof. Implementing the controls in that fashion would allow me to use a simpler micro controller. That might save a little money and give you a wider selection of micros to pick from. Most 8 bit micros have a couple 8 bit PWM capable channels, but less have 4 PWM channels. The 32 bit micros are a little nicer because they usually have four 16 bit PWM channels.
The only downside I really see with the manual control of the duty cycle is a little more code in your task scheduler. But the additional code needed would be very minimal. On the other hand, if your micro has dedicated PWM hardware, all you have to do then is program your desired duty cycle into a register and forget about it.
There is one other issue which I have run into with the more modern computer power supplies. The high efficiency ones seem a little more stringent upon maintaining a minimal load current. If you don’t always draw enough current they can shut down. I discovered that little problem when fooling with my bumble bee hives this past spring. How you execute your PWM controls (software vs hardware) may be a factor to analyze when using high efficiency switching power supplies (ie computer supplies).
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Cheap every boy's timer has 15 minutes intervals to set on or off.
1) You may connect 10 15 W cables to the times and you get 4 W heating easily per hour.
This will be my first winter with experimenting the electric heating, so none of my statements come from experiment.
The 15 min on-off interval I think makes the temp fluctuation too large. I believe the more constant the temperature the better the system is. Therefore my timer will use short intervals which makes the fluctuation not detectable by my temperature sensors, about 0.1 C. (accuracy 0.5 C)
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I discovered that little problem when fooling with my bumble bee hives this past spring. How you execute your PWM controls (software vs hardware) may be a factor to analyze when using high efficiency switching power supplies (ie computer supplies).
Yes computer power supplies have unexpected behaviour and they are all different. I'm a bit reluctant to use them. I would be mad if one day I find my nucs frozen because of a nasty power supply.
Probably I will go to the 230V AC option, keeping in mind the risks of electric shock and fire.
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The only downside I really see with the manual control of the duty cycle is a little more code in your task scheduler. But the additional code needed would be very minimal. On the other hand, if your micro has dedicated PWM hardware, all you have to do then is program your desired duty cycle into a register and forget about it.
I use solid-state relays. The hardware PWM frequency probably is to much to respond by my SSR. So in my case the PWM is not an option probably anyway, even if many are available in the hardware.
http://futurlec.com/SSRAC.shtml (http://futurlec.com/SSRAC.shtml)
(http://futurlec.com/Pictures/SSRAC_300.jpg)
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How warm do you think it is inside your polystyrene hives in winter?
How warm do you think it is inside your electric nucs (2 or 3 frames) in winter?
Bees control their own heat. What I have pushed digital thermometers sensor into the hive, winter cluster has 23C temp. If I disturb the hive only walking outside, the hive may rise its temp up to +40C.
Before cleansing flight bees start brood rearing in late February and rise core temp to +36C.
In my climate under 5 frame hive does not survive over winter.
In wood shelter it makes better.
It is vain to measure "how warm inside" because the out door temperature fluctuates +5 C--- 5C, -10C -- 20C, sometimes -30C.
In Spring winter temp may be near zero by day and -20C at night.
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In practical problem may be that if you have electrict current cutters, how many times they stand on-off mechanics.
Guys have bought thermocabel from chops and made their own thermometers.
Stuff is used in warmed floors.
http://www.pistesarjat.fi/index.php/front/heatingcables?gclid=CKS37f-R_qoCFSt-mAod1T7iyg (http://www.pistesarjat.fi/index.php/front/heatingcables?gclid=CKS37f-R_qoCFSt-mAod1T7iyg)
Pistesarjat Oy
Karvaamokuja 1 | 00380 Helsinki
puh. +358 10 4238 770
fax. +358 9 346 3095
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I'm planning to run fragments of exactly those cables at 230V.
It seems the most cost efficient ($/W).
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Of course not. How brood are could be bigger than occupied frane area - never...
If the heating system works at a constant power, or switched on-off not in line with the outside temperature, then it can make damage.
With temperature fluctuation the cluster size expand/shrinks. With careful control fluctuation can be attenuated, with not careful heating it can be amplified. Then brood can chill.
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Of course not. How brood are could be bigger than occupied frane area - never...
If the heating system works at a constant power, or switched on-off not in line with the outside temperature, then it can make damage.
With temperature fluctuation the cluster size expand/shrinks. With careful control fluctuation can be attenuated, with not careful heating it can be amplified. Then brood can chill.
That needs imagination.
temp fluctuates normaly quite much.
Bad weathers makes damages to brood if half of field bees die in spring. The sun invites out and then a rainshower hits bees down.
Chalkbrood hits often into brood area.
This has nothing to do with heating.
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Boca, it sounds like you’re going to have an interesting winter! I like the looks of your AC switching board.
You might get a kick out of this photo :-D One of the problems with using a computer power supply.
(http://i1082.photobucket.com/albums/j365/MichiganBee/Bee%20Equipement/InsulatedPowerSupply.jpg)
There is a computer power supply in this nuc, under the snow. The orange wire going in is a 120VAC extension cord. The black wire coming out is 12volts DC. Inside the nuc is my 500W computer power supply. There are NO bees in this nuc. This insulated nuc is just used to keep the power supply from FREEZING up!
Semiconductors tend to run better at cold temps, but the electrolytic capacitors don’t like the cold :( There are some big electrolytics on the output filtering stage in a power supply. Hence I needed a foam hive just to keep my power supply warm last winter.
Power supplies are not 100% efficient and most computer power supplies are probably going to waste 15% of their input energy as heat. So if you just put a power supply in an insulated box, the thing will warm up the box so the caps don’t freeze up. If you’re drawing 120watts from the power company, the power supply itself is going to be a 18 watt heater.
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Finski, what do you think the temperature is inside your poly hives at the walls? What about the electric nucs, at the walls? I know the bees themselves are warm, but what I’m wondering about is the warmth of the environment inside your hives (around the bees). How much warmer than the outside air in general would you guess?
If I do any experiments with electric this winter, my goal is going to be to program my controller to hold the temperature in the hive (near the walls) to about 50F/10C.
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I answered to that allredy
Bees control their own heat. (if they can)
I have pushed digital thermometers sensor into the hive, winter cluster has 23C temp. If I disturb the hive only walking outside, the hive may rise its temp up to +40C.
Before cleansing flight bees start brood rearing in late February and rise core temp to +36C.
In my climate under 5 frame hive does not survive over winter.
In wood shelter it makes better.
It is vain to measure "how warm inside" because the out door temperature fluctuates +5 C--- 5C, -10C -- 20C, sometimes -30C.
In Spring winter temp may be near zero by day and -20C at night.
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If I do any experiments with electric this winter, my goal is going to be to program my controller to hold the temperature in the hive (near the walls) to about 50F/10C.
When beekeepers winter bees in cellars, there temp must be under 7C. That keeps bees in winter cluster.
It is near the temp where a bee goes into choma without external heating aid.
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Since this thread is about electric heating, let me throw this idea out :-D Has anybody ever considered cooking their bees with enough heat to kill mites and other pests? With all the insulation in our hives if we were to add a few more watts of heating power to our systems, you could raise the temperatures in the hive to 115F / 46C if you wanted to.
Finski, have you ever tried to cook your bees to kill the mites?
I read in another forum some beeks in Uzbekistan do this to kill varroa! Yeah, I’m going to have to get out my globe again to remember exactly where Uzbekistan is located...
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>Has anybody ever considered cooking their bees with enough heat to kill mites and other pests?
As soon as the bees get overheated they regurgitate honey all over and make a sticky dying mess... if you could stop precisely before that point, then maybe it might work.
If you do it for any length of time you'll just over work the bees trying to cool it down.
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Has anybody ever considered cooking their bees with enough heat to kill mites and other pests?
Of course! How can you not think about come up with a method of keeping in control such a pest. I could not experiment seriously this year, because I had only two hives. Every single worker bee is a treasure. Next year if I still have bees I will take a more courageous approach.
(by the way; the whole summer I have not seen a single varroa fallen to the bottom, so I am not treating with formic acid, only oxalic acid in December)
I have the feeling that heating the whole brood nest above its normal temp makes more harm than benefit.
I read in an article that slightly higher temperature applied on sealed brood for a short time kills lowers the number of mites significantly without serious damage for the pupae.
So the plan is:
- The object of the experiment is not a colony but a frame of sealed brood. The cells can be counted, statistically more accurate.
-The pupae have to be very close in age (resticting the queen to the frame for a short time).
- In an incubator different temperatures are applied for various time.
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Cook bees?
I enjoy enough when I read beemaster forum.
Too much fun to process....
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Control of Varroa: A Guide for New Zealand Beekeepers (http://homepage.ntlworld.com/gandboss/BeeginnersFAQ/Problems/control-of-varroa-guide.pdf)
Page 62:
Studies show that if the brood is heated
to 44oC for 4 hours, 100% of the mites in the capped brood will be killed. Only about 5%
of the brood itself is killed in the process, mostly in the form of older larvae that crawl out
of the cells. Heat can also cause some deformities in adult bees that develop from old
pupae that have been treated. There is no noticeable affect on the life-span of bees
emerging from heat treated comb.
It does not say where the studies are.
It must be a fun when larvae crawl out :)
Otherwise does make sense to me. Bees kill hornets by generating heat in a cluster.