Heating hives

[mushmushi]

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 ?

[T Beek]

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

[Scadsobees]

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?

[BlueBee]

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.

[BlueBee]

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.

[Finski]

[  

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.  

::::

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.

[Finski]

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.

.

[BlueBee]

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

[Finski]

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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.

[Finski]

..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

cables page 14 and mats page 15

This in USA?


http://www.reptilesupply.com/popup_image.php?pID=2702

[boca]

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.

[Finski]

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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.

*****
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.

[BlueBee]

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?

[BlueBee]

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).

[boca]

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)

[boca]

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.

[boca]

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

[Finski]

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.

[Finski]

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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

Pistesarjat Oy

Karvaamokuja 1 | 00380 Helsinki
puh. +358 10 4238 770
fax. +358 9 346 3095

[boca]

I'm planning to run fragments of exactly those cables at 230V.
It seems the most cost efficient ($/W).