a black bucket update

We are getting better at managing our heat sink.  BSH (before supplemental heat) the morning would find our barrels and buckets with a layer of ice formed across the surface and sometimes down the insides of the containers.  I had a single stock tank de-icer--an electric heater that would float in the tank and keep the water from freezing.  It is a farm product meant to keep the water for livestock from freezing.  It would not heat the water, the water would still be cold but it would keep it above freezing.  The barrel with the de-icer would be thawed but the others would have a layer of ice on them.  Sometimes the ice layer would be very thin, other times it could be up to 1/2 inch thick.  The sunlight coming into the greenhouse would spend much of it's energy trying to melt the ice before it could warm the water.  I would help the process along but breaking up the ice and moving the de-icer from barrel to barrel.  Unfortunately the stacked buckets received little attention.

When we verified that the south side of the greenhouse near the glazing was significantly colder than the rest of the greenhouse and that the buckets there received no direct sunlight hitting them, the buckets were all moved to the north wall.  As we began moving the buckets to apply the black tape to them we discovered varying amounts of ice in the buckets.  Bucket near the floor had heavier ice production than the top row of buckets.  Buckets with tables in front of them blocking some direct sunlight had thicker ice than buckets hit fully by the sunlight.  Buckets in the corners of the greenhouse had thicker ice than those in the middle of the room.

As the sun hits the greenhouse first thing in the morning the west side is in sunlight and the east is in shadows.  As the sun moves across the sky the sunlight moves across the greenhouse from west to east.  I have been trying to notice on sunny days and yesterday at 9:15 the west 2/3 was sunny and the east 1/3 was still in shadows.  Today at 10:00 the west 3/4 was sunny and the east 1/3 was still in shadows.  By 11:00 the sun had hit the far east corner of the growing room.

In the winter the sun crosses the sky at a low angle.  The growing room is 11 feet from the south glazed side to the north wall.  Today the south six or seven feet were in shadows at the level of the floor and sun was directly hitting the wall and only the north 3-4 feet.  at the height of the tables there was sunlight over most of the area.  This should change as we move into spring and the angle of the sun becomes more over head.

northeast corner in shadows at 10:15 a.m.

Yesterday when taping the buckets there were still buckets with ice in them.  Most of these were near the floor and the corners.  When applying the tape I rearranged the buckets so that the thawed ones were on the floor and the ones that still contained some ice were on the top.  I taped a few more buckets but they started to have some condensation and I worried about the tape not sticking well.  I restacked the buckets so that the top bucket on each stack had ice.  I did not stack another bucket on top as I wanted to make sure that all of the buckets were thawed.  In the picture below the each of the top buckets still have some ice in them and if it does not thaw I will remove the ice so that all the buckets are thawed.  Common sense says that a thawed bucket will absorb the sun's energy more efficiently than a bucket with a mix of ice and water.  Common sense also says that if I can get all the buckets thawed and keep it above freezing overnight I should not have new ice forming. 

After discovering that some of the buckets still had ice in them after a couple sunny days and several days since it was below freezing in the green house, I decided to check the white buckets as well for the presence of ice.  Those buckets had been taped on December 29 and restacked in no particular order and not checked for the presence of ice.  There are two stacks of white buckets, one group to the east of the door and one group to the west of the door.  In checking the buckets for ice every bucket to the east of the door was thawed.  In the stack to the west of the door the top row was thawed but many of the the middle and bottom row buckets had ice.  Now the east group is more centrally located and probably receives more hours of sunlight than the west group but the other possible reasons for the difference could be that the area of wall behind the buckets east of the door is insulated and the insulation to the wall behind the west group has yet to be installed.

My goal for today was to make sure all of the buckets were thawed and to finish taping the last few buckets.  Some of the buckets had thawed and those that had not I fished the ice out of the bucket, replaced the water.  I stuck what ice would fit in a barrel with the de-icer so that it could melt.  The rest of the ice is pictured here:

 And here are the finished buckets all lined up:

 It is a sunny day and warm in the greenhouse.

The ventilation fan has kicked in and I am running the box fan to circulate the air.

I have a little concern about the sensitivity of the thermometers as the electronic thermometer is quite a bit warmer than the inexpensive plastic thermometer right next to it.  Both were in the sun.

Yesterday it was not quite as warm in the greenhouse and I had the box fan circulating the air and it did bring down the temperatures in the upper areas and evened out some the temperatures in the lower areas.  I think on sunny days the box fan will help to moderate the climate inside.  Right now it is at one end of the room sitting on a table.  It may benefit from some tweaking.

supplemental heat--it's working

Today is January 6.  We started using the milk house heater at night on New Year's Day.  Today, like the past couple mornings it is above freezing despite overnight temperatures outdoors in the single digits or near zero.  Today at daybreak:

The little seedlings aren't showing growth yet but I have hope.  BSH (before supplemental heat) our electronic thermometer which reads the current temp but records the highest and lowest temperatures attained during the 24 hour period would almost always read LL overnight.  The potting mix in the planters would be frozen and there would be a layer of ice in the blue barrels on the surface and sometimes around the inside perimeter.  I do not know for sure at what point the thermometer switches from reading numbers to reading LL but I do know that there have been some number readings in the mid 20s.  Since adding the milk house heater the water in the blue barrels has had no ice form overnight.  Once the current ice melted it has not reformed and there has not been any LL readings recorded overnight. 

Other factors  that must be taken into consideration is that November and December are traditionally less sunny.  In fact, according to the weather calendar on Weather dot com for our zip code December had only one sunny day and less than half of the month was even partly sunny.  There were also nine days where the low was single or double digits below zero.  So far we haven't had a -15 to really test our heater.  January shows a couple of 0 readings but the -12 on New Year's Day was it 1 a.m. (BSH)!

We are also working to fine tune the managing of our heat sink but that deserves it's own post...

supplemental heat in the greenhouse

It has been cloudy and cold and the greenhouse is not always warming up during the day and is getting below freezing at night.  The seedlings are not getting bigger.  Our plan was to try to keep the greenhouse at or above freezing without supplemental heat.

Our efforts so far:

We have containers of water to use as heat sink.   Right now we have 36 cat litter boxes and 30 mushroom boxes filled with water.  We also have four 55 gallon barrels filled with water.  We are in the process of covering the fronts and sides of the boxes  with black tape to hopefully help the water absorb more heat.  We are also hoping that the porcelain tile floor and the dirt in the planters will absorb warmth.  We have passed the solstice and the days will be getting longer and the nights shorter.

We have scattered five thermometers around the growing area looking for cold spots and warm spots. The thermometers are sitting in different locations and at different heights.  So far they don't have permanent locations.  There is one near the glazing at table height, one in a planter at about six feet in the air, and three that have been moved around trying to measure the east and west corners and the north wall at different heights.


What we know:

On a cloudy day the temperatures throughout the greenhouse are pretty consistent. On a sunny day the temperatures can vary significantly, as much as 20 degrees or more of difference when it is moderately sunny. Since we added the additional thermometers we haven't had any really sunny days yet, so it may vary even more.

When there is a difference it is consistently cooler near the glazing.  The warmest area that was measured is in the center of the room at about six feet in the air. It is probably warmer still near the rafters and roof.

When we had heat sink buckets on the south wall below the glazing, those buckets had more ice than the buckets on the north wall.  The air temperature in that area is lower and that area is not hit directly by the sunlight coming in through the glazing.  Plan A had been to line the area below the glazing with the pallet tables and put the heat sink buckets under the tables and plants on top of the tables.  As the greenhouse filled with plants the gutter planters would be hung from the rafters and the table would hold larger containers with bigger plants. Now that we know that is the coolest part of the greenhouse at least in the cloudy short days of late fall and early winter, we may have to rethink that plan.

All of the heat sink buckets are now on the north wall. They are stacked three deep.  In moving them around to apply the tape it is apparent that in the buckets that I was working on, the top row of buckets have no ice or less ice than the bottom row of buckets.  I did not check all of the buckets only the few in the center of the room that I was taping.  A new question then is why the lower buckets are colder.  Is it because they are closer to the floor?  Is it because there were tables with planters in front of the stack that prevented direct sunlight from hitting the lower buckets?  Now the tables have been moved into the middle of the room to allow greater exposure to the sun.  I think there will be a lot of trial and error in finding our way this first growing season.

On New Year's Day we purchased this:

Commonly known as a milk house heater, this is a small electric heater used to provide supplemental heat to farm buildings.  It has two settings, high and low, and a dial type thermostat.  Even on high it doesn't put out a large amount of heat but I am hopeful that between this heater and the heat sink we can keep the growing area above freezing on most nights. 

hanging planters

The greenhouse plants are seeded into planters made from recycled rain gutters.  Above is pictured an attempt to suspend the gutters using chain and double end bolt snap hooks.  It seems to be working so the plan will be to hang more of the planters.  The multiple thermometers were recently added to allow for greater monitoring of the temperatures in the greenhouse.  Near the bottom of the glazing it was nearly 20 degrees cooler than along the north wall or in the suspended planter.  It will be interesting to scatter the thermometers around learning the greenhouse's hot spots and cool spots and where are the best places to put the planters in the different seasons of the winter.

snap hook and chain

When this picture was taken it was single digits above zero outside and partly cloudy.  Earlier it had been sunny and this thermometer was reading 85 degrees.

Arugula

black buckets

Mom's greenhouse is a passive solar greenhouse.  The goal is to grow cold tolerant greens and vegetables without a supplemental heat source.  This fall our family completed the tile floor which was the last of the insulating projects.  This allows for our first real winter of  crops.  Our goal is to keep the temperature in the greenhouse above freezing.  We are using containers of water as heat sink.  We have had the overnight temperatures drop into the 20's or lower on some nights.  The seedlings in the planters are still alive but not thriving and growing.  We are adding additional containers of water.

In an effort to improve the heat absorption quality of the water containers used for heat sink in the greenhouse the exposed sides of the containers will be covered with black duct tape.  We currently have 34 yellow cat litter boxes (thanks Lisa and Jack) and 30 new white mushroom boxes (thanks Nathan and Michelle).  Today the new white boxes were covered on three sides with the duct tape.  Each box required three wider strips and one narrower strip of the tape. 

The boxes are placed along the North wall of the greenhouse where the sun can hit them, warming up the water inside.  After the sun goes down and the greenhouse begins to cool the boxes will release their heat, slowing the cooling of the greenhouse.  The yellow boxes still need to be covered and that is a project for another day.  Thank you Caitlin for your help in covering the boxes today.

the greenhouse floor--the last major project

In this picture: Nikole, Michelle, Nathan and Reese

 The last major project to be completed in the Mom's greenhouse is the insulating and tiling of the growing room floor.  The above photo shows three steps in preparation for tiling.  In the back of the photo can be seen the floor joists and insulation.  That is covered by the plywood which is seen on the left side of the picture.  The plywood is covered by the cement board which is seen on the right.  Once these surfaces are in place the floor is ready for tile.

Nikole and Michelle begin laying the tile at the drain.  This will determine the placement of the tiles for the rest of the room.  Not pictured: Lisa and Nathan.

 The tiling process is coming along.  The spacers can be seen as well as the portable heat source necessary to keep the room sufficiently warm so that the mortar can properly set. 

Last tile!!

Nikole placing the final tile

In this picture the seedling mat can be seen

 After the tile sets overnight the grout is applied.  Since our project has big temperature extremes every eight feet the grout is replaced with caulk as an expansion joint.  Here the tile still has a little of the haze that needs to be cleaned from the tile as a final step in the grouting process.

The finished drain

These plant benches are made from recycled pallets.  The pallets originally held a specialized product that required a plywood top instead of the standard spaced boards.  They are smaller than a conventional pallet--20 X 33 and only needed legs attached to make benches to hold the plants.

To see Nathan's take on the greenhouse construction check out his blog Northland Phoenix here
for more pictures, video and commentary. 

the cornfield

This newly dug up spot will be additional garden space for sweet corn, pumpkins, melons and squashes.  The ground will mellow over the winter and then be tilled in the spring.  The corners will be squared up and it will eventually be a 40 x 140  garden plot.