Circuit Panel

The circuit panel contains the electronics that are not directly connected to either the Constant Level/Preheat Tank or to the burner. The goal of this webpage is to show you step by step how to build and connect the electronics contained in this circuit panel. If you have any questions feel free to contact me.

In this build, the panel was created from a piece of scrap aluminum. It could also be made from sheet metal. The metal also provides some cooling for the two Solid State Relays that mount on it so thicker is better. The main goal in creating this panel was to place as many of the electrical parts on a single panel that has quick connect/disconnects for ease of removal/servicing of the panel, burner and/or preheat tank. This webpage will take you step by step through the construction and wiring of this panel.



Panel after mounting components. The PID for the burner is the one in the middle.

One the back side you wil also see the Solid State Relays (on right side) and the electrical wire connection busbar (near center)




This panel will be built according to the following circuit diagram. Note: The thick lines represent 14 gauge wire and the thin lines 16 guage.

White wire - typical 120VAC Nuetral/ground wire. Used in conjunction with a Black or Orange wire to supply power to a device.

Black wires - "HOT" wire 120VAC power from furnace

Brown wires - 120VAC - power supplied to heating elements when PID turns on the appropriate SSR.

Orange wires - "HOT" power from Primary Control on Burner - this supplies 120VAC ONLY when the burner is running

Red, Blue, Yellow wires - connections to the thermocouples

Purple, Green wires - PID to SSR control


In the following descriptions, the word LONG will be used to describe those wires that get connected to either the Burner connector or Preheat Tank connector. The length will vary depending on your placement of this panel with respect to the burner and the preheat tank. For this panel and my project I am using 2 ft.

Now let's begin wiring up the panel. First we will connect a LONG piece of white wire (14 guage) to busbar pins A1 and A2, as well as white 16 guage wire to A3, A4 and A5. In the first few pictures shown I forgot to connect the white wire to A5, but you will see it connected in later pictures.

Here you can see a close-up of the A1-A4 bus bar connections. Notice that A1 is physically connected to B1, A2 to B2, etc..


Next, connect a single LONG piece of 14 guage white wire to B1. Then connect one of the electric air solenoid wires to B2. Then connect a 16 guage white wire from B3 to pin 2 on the Tank PID, and similarly another white wire from B4 to pin 2 of the Burner PID.

Now connect a 16 guage white wire from B5 to the minus(-) terminal of the Hour Meter.

Close up of the Bus Bar connections. Here you can see that A1 connects to B1, A2 to B2, etc..

Next connect the other air solenoid wire to B6 and a 16 guage orange wire from B7 to the plus(+) terminal of the Hour Meter. The Hour meter is optional. I include it so I can see how long the burner has been running between maintenance. Next connect a LONG piece of 16 guage orange wire to A6 and A7 as shown.


You may notice that the fuse holders have some wires attached. These were fuse holders from another project. I will remove the old wires from them and connect new ones as we proceed. As can be seen above, most of the busbar connections are complete.


Now connect a LONG piece of black 14 guage wire to A8. This is the incoming 120VAC from the Burner connector. Also connect 14 guage wire from B8 to both appropriate pins of the DPST main power switch as seen in the bottom left of the picture. This completes the bus bar connections.

Now connect the purple and green PID to SSR control wires. Green wires go from PID pin 7 to SSR pin 4. Purple ones go from PID pin 6 to SSR pin 3. Notice that for most of the PID controller connections from here on out that I don't use crimp connectors. I just "tin" (put solder on) the end of the stripped wire and then screw them down.


Now connect wires from the Main Switch terminals as shown to the side connectors on the fuses. I took these fuse holders out of some old electronics. They need to be rated at 120VAC.

Next connect the other side (top center) of the fuses to the SSR's.

First connect a piece of 14 guage black wire from the top center of Fuse 1 to pin 2 of the Burner SSR .

Similarly, connect a 14 guage piece of black wire from the top center of Fuse 2 to pin 2 of the Preheat Tank SSR.


Notice that pin 2 of the Burner SSR has a 2nd connection (red crimp connector under the blue one). This 16 guage black wire goes to the Burner SPST PID switch which is shown in the following picture. Then the other connector of the SPST switch is connected to pin 1 of the Burner PID with another piece of 16 guage black wire.


Again, notice that pin 2 of the Preheat Tank SSR has a 2nd connection (red crimp connector under the blue one). This 16 guage black wire goes to the Preheat Tank SPST PID switch. Which is shown in the following picture. Then the other connector of the SPST switch is connected to pin 1 of the Preheat Tank PID with another piece of 16 guage black wire.

A red & blue 16 guage wire pair is used for the burner temperature sensor and a red, blue & yellow 16 guage set of wires are used for the preheat tank sensor. These LONG wires become part of the wiring bundles for the burner and preheat tank connectors as shown. Notice which LONG white and orange wires go to each bundle. There will be brown wires that we connect next that also go to the appropriate bundle.

Now a quick disconnect type air hose fitting is added to the air pressure regulator. This part was less than $3 at Home Depot and the SKU number is shown.

The next picture shows a piece of air hose attached to the electric solenoid valve on one side, and female quick disconnect air fitting on other end. At both ends of the hose a 3/8" hose barb by 1/4" NPT male fitting was used (as well as a small stainless steel hose clamp) to connect from the air hose to the solenoid valve and to the female air hose fitting.

Also notice that the brown wires have now been connected - one in each wire bundle.

Closeup of the brown wire connections to pin 1 of the Solid State Relays.


In the following picture, a backet was made from some scrap angle iron welded together for the Preheat Tank to sit in. A couple holes were then drilled into the side of the furnace and the frame bolted to it. The Circuit Panel was then bolted below the frame to some tabs that were also welded onto the frame. Notice the air hose and wire bundle running into the side of the furnace. The other wire bundle from the Circuit panel is dangling on the bottom right of the picture.

Next the Preheat Tank is placed in the bracket.

Male quick disconnect style connectors are crimped to the ends of the wires that go to the burner. These connectors handle both 14 and 16 guage wire. Be sure to get the right size. The burner shown has not yet been modified and is running heating oil. Notice the clear PVC lines allow viewing of the current heating oil running into and out of the oil pump.


Crimp connectors are also connected to the other wire bundle. Here the red ones are female crimp connectors for 16/22 guage wire which work well to directly plug into the connectors on the Preheat Tank temperature sensor.


Next a pigtail was added to the heating element and connected to the wiring bundle. The connectors from the Preheat Tank temperature sensor were also connected to the appropriate wire bundle connections.

Then the wires were tied to the air hose (or whatever you like). This completes the Preheat Tank wiring connections.

I would also recommend putting a shield over the exposed Preheat Tank heating element as seen above. The white/black "hot" wire pair will have 110VAC and one can get shocked if they touch it.

Listed below is information taken directly from my personal file showing costs of parts I found.

If you find a better deal, let me know and I can update the list


Socket Set Screw 1/4-28 x 1/4 (for small threaded nozzle block holes): 100ea $3.55 + $3.95 = $7.50 EBay

Crimp Connector style Wire Spades 1/4"
American Terminal E-FFB250N-100 16/14-Gauge Economy Nylon Fully-Insulated Female Quick Disconnects 100 pack $6.59 Amazon
Seismic Audio - SAPT209 - 50 Pack of Fully Insulated 16/14 Gauge Female Quick Disconnect Wire Connectors $6.78 Amazon SAPT209
Seismic Audio - SAPT210 - 50 Pack of Fully Insulated 22/18 Gauge Female Quick Disconnect Wire Connectors $6.78 Amazon SAPT210

1/4" NPT drain valve = $2.48 Home Depot

Watts 3/8 in. Brass Short-Rod Flare Nut = $1.96 Home Depot

1/4" brass 1/4 turn valves - Female/Female = $3.99 Harbor Freight

1/4"NPT bronze muffler/breather = $1.29

3/16" & 1/4" compression sleeves = $0.29 Wilco

1/4 NPT - 3/8 hose barb = $1.51 Amazon (Dixon BN32)

1/4 NPT - 1/2 hose barb = $2.69 Wilco Farm Store

1/4 NPT - 3/16 compression (Nozzle oil input) = $

1/4 NPT - 1/4 compression (Nozzle Air input) = $2.89 Wilco

#48 O-ring P/N 9D0035762B = $0.69 Ace Hardware

Action AFI-1.0-50 1" 50-Mesh Irrigation Filter = $46.45 (40.36 + 6.09Shipping)
9/21/12 - $33.47 + shipping

Hour meters
EBAY - New Electromechanical Hour Meter Counter - AC 100~250V $.99 + $6.99 shipping = $7.98 = $6.91

Ordered from on 12/22/2011 Hour Meter and Sensor probe = $7.09 + $4.67 - $2 discount = $9.76

18 gauge wire - $26.55 (free shipping) 8 colors 50 ft each. = $.0664/ft EBay
14 gauge wire - $31.30 (free shipping) 2 colors (I chose black & white) 100ft each = $.1565/ft EBay

3/16" compression by 1/8" NPT (tank connector for oil feeed to burner) = $2.29 Wilco

1" metal conduit locknuts (use with heating element) - $0.55/2 = $.275 each Home Depot

AMMO Box = $10 - used from local guy in Tigard, Oregon

Drain Valve
Powermate 1/4 in. NPT Tank Drain Valve Model 072-0001RP = $2.99 Home Depot

Heating elements
1500 Watt 120V screw in water heating element - Home Depot Camco model 15896 = $8.57 Home Depot

Float valves
WATTS FLIPPEN FLOAT VALVE C1/4TF-1 X 12" = $11.27 (EBAY bought 2 for $22.53 = 2*$8.27 + SH$4.99 + SH$1)
3/8" compression Dial 4164 ( = $15.50 - I like the 3/8" compression size better as it matches the size of the copper conduit I use.

PID controllers
Dual Display PID controllers 110VAC - China - product #tcqbn2006p = $28.19, $24.35, $25.56,,, $27.21 EBay

Power Switch
toggle switch used to turn PID on/off - $??? pulled out of some used electronics

New Solid State Relay SSR-25DA 25A /250V 3-32VDC $4.77 + free shipping = $4.77 EBay

---------------- = $4.48


Air pressure regulator & filter
Air pressure regulator with filter AFR2000 = $12.32 - 20%off($2.46) = $9.86

Cartridge Heater
1/2"diameter x 4"long,230volt 1000w $6.00 each QTY = 4 -> $24.00 + $6.95 (Shipping) = $7.74 each
1/2"diameter x 3"long,120volt 300w = $10.00 Ebay
1/2" dia x 4", 120V, 750W = $20 Zoro (less with coupon code TRYZORO10)

HD Cartridge Heater - 5/8"OD 4"L 120V 750W 109 Density T9FB382577 = $20.75*4 min. + 11.75 S/H -> $23.69 each

Zoro Tools, TEmpco 5/8" OD 4"L 120V 750W 109 Density HDC00775 = $22.28 + ??? S/H (Free S/H on $50 or more) Tempco Hd Cartridge Heater 1/2"Od 4"L 120v 750w 136 Density = $19.50 + ??? S/H (min. purchase of 5!)

Delavan Waste Oil Burner Nozzle #30609-7 = $21.00 EBay, $29 on Amazon

PID controllers
Same as Preheat tank

Power Switch
same as Preheat tank

Same as Preheat tank

AC 110V 1/4" Electric Solenoid Valve Water Air N/C Gas Water Air 2W025-08 brass = $14.50 EBay
DC 12V 1/4 Inch Electric Solenoid Valve for Air Water / High Quality Replacement Brass Valve for Use with Pipelines in Water, Air and Diesel Applications = $11.37 Amazon

Thermocouple Temperature Controller Sensor probe K type = under$2 EBay (free with some PID's)

Same as Preheat tank

Fuse holder & fuse

----------------------------------------------------------------------------------------------------------------------------------------- discount coupon 1012942321 15% off $10 or more
1012947827 20% off
1012874322 $2.00 off $10 or more
1012875075 $5.00 off on $25 or more

Order the following from Zoro Tools - free shipping if over $50
Cartridge Heaters - 120VAC, 1/2" dia, 750W
coupon codes - TRYZORO10 ($10 off $50+), TRYZORO ($10 off $50+), 15GEN75 ($15 off $75+), ZT35H ($35 off on $60+??)

Order the following from and use 20% off coupon, everything has free shipping
Hour Meter - $6.91
Temperature Sensor Probe PT100 - $4.48
Air pressure regulator with filter AFR2000 - $12.32

Amico AFR-2000 Pneumatic Filter Regulator Air Treatment Unit w Pressure Gauge = $10.77 Amazon

380V 10A 12-Position Wire Connector Barrier Terminal Block - $1.99