Homemade Bottom Heat Supply

DennisinPa · March 11, 2007

Hello everyone,I had a store bought heating mat fail after only two seasons sooooo I built my own

The box is 29"x16"x11 1/2" high,it is painted white on the inside bottom and sides and the inside bottom of the top is painted black.

There are two light fixtures inside with low profile 40 watt flood light bulbs controlled by a dimmer switch.

I use a remote food test thermometer inside the plant tray to monitor the soil temp.

NCTIM · March 11, 2007

Very, very nice. I made one also this year. It did the job but controlling the temp was tricky.

I will not be posting any pics.

Tim

DennisinPa · March 11, 2007

Second picture

dcarch · March 11, 2007

Nice work.
Just a suggestion: Although the bulbs are floods, they do have reflectors. As a result, heat will be focused directly above. this will also add to the direct convection heat from the bulbs. The white interior will help to even out the heat a little, but may not be enough to eliminate hot spots.

1. Try changing to non-reflectorized bulbs.
2. Try putting a small fan inside to circulate. BTW, the electricity of operating the fan is not wasted. All the watts in operating the fan is completely converted into heat inside the box.

dcarch

dcarch · March 11, 2007

For those who can handle a soldering iron, here is an elecronic thermostat kit you can build:

dcarch

http://www.youdoitelectronics.com/id23.htm

General purpose low-cost thermostat with NTC temperature sensor. Output relay with LED-indicator.
Specifications
temperature range : +5°C to +30°C approx. (41°F to 86°F)
relay power rating : 24VDC/AC 3A
power supply : 12VDC / 100mA
dimensions : 54 x 62 x 28mm (2.1" x 2.4" x 1.1")

MK138 YDI Price $9.90
Thermostat

Rena · March 12, 2007

My Dad uses an old WATER BED HEATER

!! I would if I could find one.

DennisinPa · March 12, 2007

dcarch,Thanks for the operating tips

Dennis

March 11, 2007	#1
DennisinPa Tomatovillian™ Join Date: May 2006 Location: Pa. Posts: 24	Homemade Bottom Heat Supply Hello everyone,I had a store bought heating mat fail after only two seasons sooooo I built my own The box is 29"x16"x11 1/2" high,it is painted white on the inside bottom and sides and the inside bottom of the top is painted black. There are two light fixtures inside with low profile 40 watt flood light bulbs controlled by a dimmer switch. I use a remote food test thermometer inside the plant tray to monitor the soil temp. Last edited by DennisinPa; March 11, 2007 at 11:04 PM.

March 11, 2007	#2
NCTIM Tomatovillian™ Join Date: Jan 2006 Location: zone 8 NC Posts: 286	Very, very nice. I made one also this year. It did the job but controlling the temp was tricky. I will not be posting any pics. Tim __________________ "You can observe a lot by just watching." - Yogi Berra

March 11, 2007	#3
DennisinPa Tomatovillian™ Join Date: May 2006 Location: Pa. Posts: 24	Homade Bottom Heat Supply Second picture

March 11, 2007	#4
dcarch Tomatovillian™ Join Date: Jun 2006 Location: NY Posts: 2,618	Nice work. Just a suggestion: Although the bulbs are floods, they do have reflectors. As a result, heat will be focused directly above. this will also add to the direct convection heat from the bulbs. The white interior will help to even out the heat a little, but may not be enough to eliminate hot spots. 1. Try changing to non-reflectorized bulbs. 2. Try putting a small fan inside to circulate. BTW, the electricity of operating the fan is not wasted. All the watts in operating the fan is completely converted into heat inside the box. dcarch __________________ tomatomatomatomatomatomatomatomatomatomatomatomato matomato tomatomatomatomatomatomatomatomatomatomatomatomato matomato tomatomatomatomatomatomatomatomatomatomatomatomato matomato

March 11, 2007	#5
dcarch Tomatovillian™ Join Date: Jun 2006 Location: NY Posts: 2,618	For those who can handle a soldering iron, here is an elecronic thermostat kit you can build: dcarch http://www.youdoitelectronics.com/id23.htm General purpose low-cost thermostat with NTC temperature sensor. Output relay with LED-indicator. Specifications temperature range : +5°C to +30°C approx. (41°F to 86°F) relay power rating : 24VDC/AC 3A power supply : 12VDC / 100mA dimensions : 54 x 62 x 28mm (2.1" x 2.4" x 1.1") MK138 YDI Price $9.90 Thermostat __________________ tomatomatomatomatomatomatomatomatomatomatomatomato matomato tomatomatomatomatomatomatomatomatomatomatomatomato matomato tomatomatomatomatomatomatomatomatomatomatomatomato matomato

March 12, 2007	#6
Rena Tomatovillian™ Join Date: Feb 2006 Location: Warm Springs, GA Posts: 1,421	My Dad uses an old WATER BED HEATER !! I would if I could find one.

March 12, 2007	#7
DennisinPa Tomatovillian™ Join Date: May 2006 Location: Pa. Posts: 24	Homemade Bottom Heat Supply dcarch,Thanks for the operating tips Dennis