David Lawyer

Oct. 1994, to hypertext 1997, Dec. 2000
Covers furnaces and blowers in the Furnace Basement for heating & ventilation. The broken evaporative cooler.









Throop Memorial Church is heated & ventilated by 3 @ blower-furnace pairs in the furnace basement below the Fireside Room. This is a "forced air" system using natural gas for heating. To ventilate only, the blowers are turned on but the gas is kept turned off. The 3@ blower-furnace pairs are for: 1. Sanctuary (large blower to W) 2. Throop Hall (blower nearest doors) 3. Upstairs (blower near SW corner). To understand the ventilation system air flow and system problems at Throop read the file hvac_system. All hardware mentioned in this document is in the furnace basement unless otherwise noted. To better understand this document, inspect the hardware as you read this.

Each blower is driven by an electric motor (3-phase). Control voltage is 24 VAC with the following exceptions: 240 VAC is used for: 1. The motor contactor magnets. 2. The timer motors. The 24 VAC is used for various gas valves, relays, control switches, and thermostats. The use of both 24 VAC and 240 VAC as control voltage complicates the situation and requires the use of extra relays to "convert" 24 VAC signals to 240 VAC signals.

1.1 Furnace Specs

All furnaces in the furnace basement are Hayes model SED and are 80% efficient. Input BTU/hr are: Throop Hall Furnace: 480K, Sanctuary Furnace 600K, Upstairs Furnace 520K. Output BTU/hr are 80% of this. Hayes is reputed to be a top quality furnace.

1.2 Flues

The 3 circular vents leading to the S. wall ceiling are furnace flues (exhaust) and exit the building at the top of the main chimney which also serves the fireplace in the fireside room.

1.3 Pilot

The pilots have a flame going out in three directions. One of these 3 flames is to heat a thermocouple which generates about 30 mv of electricity. The voltage is supplied to the pilotstat (see Pilotstat via a thin wire encased in a thin metal tubing. At first sight, it doesn't look an electrical conductor.

To remove the pilot and the thermocouple first pull back the apron that is about 1" above the mixer part of the burners. It's a rusted sheet about an inch high and a few feet long. Prop it up with a stick, etc. With this up, access to the pilot is much better. Then outside the furnace, disconnect the aluminum pilot gas line tubing and the electrical conductor tubing. Then unscrew the 2 small screws (size 4-40) that hold the pilot assembly to the furnace. One way not to drop the screws is to unscrew them a little with a screwdriver and then grab the heads with a pickup tools and continue unscrewing.

When the pilot assembly is free, there is still a problem in removing it since the 1/4" tubing will not go thru a narrow area. So pull the assembly toward you and then use a 7/16" flare wrench to remove the 1/4" tubing from the pilot. Other types of wrenches don't work. After this it's easy to remove the pilot assembly and tubing.

If the pilot gets clogged up, the flame will be weaker and may not generate enough voltage to keep the pilotstat on. One way to try to remove the clog is by using a piece of tubing or a hose and then blowing thru it, with the nozzle end aimed down at the top of the pilot. The mixing air enters a down-tube right next to the pilot up-tube. This down-tube uses the pilot up-tube as part of its wall. This is where you want to blow.


2.1 Introduction

The furnaces & blowers are controlled by toggle switches at the top of the basement stairs. See the circuit diagram on the next page. There is a toggle switch for each of the 3 furnace-blower pairs. Each switch has 3 positions: heat, off, vent. In the vent position only the blower is on and no heat is supplied. There are also timers on the N. wall (Minn. Honeywell Da-Nite Timeswitch) for each of the 3 furnaces/blowers but they are "set" up for "always-on" by allowing the timer wheels to not turn by loosening a screw. Thermostats in the sanctuary, social hall, and N room (upstairs) regulate the temperature.

2.2 24 VAC Control Voltage

24 VAC control voltage is supplied by 3 transformers low on panel B, the primary (240 VAC) being supplied by the corresponding fused safety switch above. Thus if one pulls the lever on a safety switch, control voltage is shut off and both the gas turns off and the blower stops. Control voltage from a transformer is first fed to the timer and from there to the toggle switch. Depending on the position of the toggle switch, the control voltage is then fed to: 1. nowhere if toggle in the "off" position. 2. the motor relay if the toggle is in the "vent" position. 3. both the motor relay and the "gas valve" (via thermostats) if the toggle is in the "heat" position.

2.3 Gas Valves_1

The control voltage is fed to the "gas valves" by brown two-conductor cables. 24 VAC must be present for the gas valve to operate. The 24 VAC doesn't go directly to the gas valve but to a small box on top of the "Modutrol Motor" where it must first pass thru some thermostat circuits before reaching one of the actual gas valve. In addition, each furnace has a 2nd gas valve (Modutrol) which is activated by an input air thermostat. See "Gas Valves_2", etc. for more details.

2.4 Blower Motor Contactors (Relays)

Each such motor is turned on and off by magnetically operated contactors. The control voltage to operate the contactor electro-magnet is 240VAC, but the control voltage used for switches, thermostats, and timers is only 24VAC. To allow 24VAC to operate a 240VAC contactor-magnet requires a 10-fold step up of voltage. This is done by relays in at box near the door labeled 240 V. Since the contactor for the main motor current is actually a relay, there are two relays involved for starting or stopping a blower motor.

Thus to turn on a motor 24 VAC is supplied to the first relay which closes a 240 VAC contact. This 240 VAC then operates the second relay (contactor) which closes 3@ 240 VAC contacts for feeding 3-phase power to the motors. The first relay (24 VAC control voltage 240 VAC contact voltage) are located in the orange box next to the basement door labeled 240 V. See "Motor Controls" for a description of the second relays (3-phase contactors which are part of the "magnetic starters"). All of these relays make audible clicking noises when they operate and this can help in trouble-shooting.

2.5 24 VAC Terminals

Many connections for wires using the 24 VAC control voltage are made in an orange box near the door labeled 24 V. In this box, all terminal block screw connections are numbered using the numbers 1-5, 11-15, and 21-25 (except connection 21 is made with a wire nut). #1 (Sanctuary) uses 1-5, #3 (Upstairs) uses 11-15, and #4 (Throop Hall) uses 21-15. In case the terminal labels fall off (they must be removed to turn the screws), the left terminal block (from top to bottom) is: 11,3,13,23. The right terminal block is (from top to bottom): 4,1,5,3,15,13,14,25,23,24,2,12,22. Only 1-5 will be described here since the others are similar (24 and 14 are like 4, etc.). 1-5 will be shown in parentheses.

2.6 24 VAC Control Wiring

The 24 VAC circuits may not be grounded so voltage should be measured between other points. One side of the 24 VAC supply goes to (2) a black timer and then to (3) the toggle switch at the top of the stairs. Each toggle switch is double pole, double throw with jumpers connected so that in the vent position (3) is connected to (4) feeding a 24-to-240 V. motor relay in the orange box labeled 240 V. In the heat position (3) connects both to the motor relay (4) and the gas control line (5). The other side of the motor relay connects to the other side of the 24 VAC supply transformer (connection made in the 240 V. box). The other side of the gas control line also connects (1) to the other side of the 24 VAC supply.

                            Terminals 1-5 in    
Basement                    24 VAC Orange Box        Top of Stairs
_______. 240VAC ._______                              ____________
Motor  |--------| 24 VAC|---2-------Timer-------3---- |Toggle Sw. |
Fused  |        |Xformer|                             | Connects: |
Safety |--------|Supply |---|-----Motor_Relay----4----|Vent: 3-4  |
Switch |        |_______|   |                         |Heat: 3-4-5|
_______|                    |---1---Gas_Control---5---|___________|

Gas_Control Details:    (1,5 runs to T in a 2-cond. brown cable)
(Sequence of elements in series not always as shown below.)  Both
the Modutrol and Magnet Value (gas valves) must be on for the heat to
                             1 (or 5)     ( In 24VAC Orange Box)
              _______T_______|            ( T-terminal on Modutrol)
              |          Magnet_Valve     ( In gas pipeline, 2 blk.)
_______   ____|____          |            ( Wire-nut on Modutrol) 
 Input |--|Modutrol|    Room_Thermostat   ( In a church room, white)
Thermo-|--|Xformer |         |            ( Wire-nut on Modutrol) 
 stat  |--|& Valve |   Output_Thermostat  ( On output ducting)
_______|  |________|         |            ( Connection in Output_Therm)
              |           Pilotstat       ( Low on side of furnace)
              |              |            ( Connection in Output_Therm)
              |______T_______|            ( T-terminal on Modutrol)
                             5 (or 1)     ( In 24VAC Orange Box)

2.7 Thermostats

There are 4 thermostats for each furnace, all of which must be calling for heat in order for the furnace to operate. Three of these are connected in series with a magnet gas valve (or just "magnet valve"): 1. The output air thermostat. 2. The room thermostat. 3. The "pilotstat" at the pilot. The 4th thermostat is the input air thermostat and is connected directly to the "Modutrol" gas valve.

Room thermostats

There is a "room" thermostat for each of the 3 areas of the church. The upstairs thermostat is on the W wall of the North (Red) Room. The sanctuary thermostat is on the sanctuary N. wall to the W. The Throop Hall thermostat is on the hall's W wall. The cables to these thermostats are oval, beige-colored and run thru the crawl space at a diagonal.

Output and input thermostats

There are 2 more thermostats mounted on each furnace: 1. Output thermostat to shut off the heat if the output air temperature gets too high (>150 Deg. F => air flow too slow, etc.). 2. Input thermostat to reduce heat if the input air temperature is too high (>80 Deg F => fan not turning, air already warm due to summer heat, etc.). The input thermostat is Honeywell T991A (One is missing a knob which is no longer available as a spare part). All thermostats control 24 VAC.


The pilots are gas. A "Pilotstat" mounted near the floor will sense if the pilot goes out. The cable from this goes to the output (safety) thermostat. They are wired in series (open circuit shuts off the gas). There is an indicator to show "off" if the pilotstat has tripped (is open). There is no automatic valve to shut off the pilot so if the pilot blows out the pilot will still keep drawing gas (but the gas for the main burners will not come on). One pilotstat uses a Jade Controls thermocouple 83-25.

The pilotstat gets voltage (about 25 mv) from a thermocouple placed in the pilot flame. The resulting current operates an electro-magnet inside the pilotstat which holds back a spring-loaded rod. If the current becomes weak (due to the pilot flame going out), the spring is able to push the rod away from this magnet and the rod linkage then pushes down on a switch button which breaks the control voltage to the gas magnet valve. This shuts off the gas. To bring the rod back so that it will be held by the electro-magnet (inside the Pilotstat) one needs to push on the rod on top of the pilotstat. After lighting a pilot this must be done to get the furnace to work.

The switch inside the pilotstat may get corroded contacts and work erratically. To clean it, remove the cover of the pilotstat and then remove the black switch by removing a thin cotter-key on the left side of the switch. This black switch comes apart without tools and thus it's easy to clean the contacts, but take care not to lose the spring inside the switch.

The thermocouple can also go bad or the flame may not adequately heat the thermocouple. The open circuit voltage of the thermocouple should be about 25 mv. Fix/replace if under 18 mv. For how to remove the pilot and thermocouple see Pilot.

The Pilotstat is Honeywell C418A1 and in 2001 was not listed in their parts catalog. Such a device would be made by Honeywell's "Home & Building Control" division. There is likely a replacement for it.

2.8 Gas Valves_2

The regulation of gas flow is by a small magnet valve and a larger (Modutrol) motor operated valve. Both of these operate with 24 VAC control voltage. All components are made by Minneapolis Honeywell (now named just Honeywell). Each "Modutrol" unit has 3 components: 1. Motorized Valve Linkage Q601B3X1 with a large indicator dial 2. Modutrol Motor M904E100 behind the above linkage. 3. valve moved by 1 & 2 above (on 1 1/4" pipe). Separate from the Modutrol is Magnetic Valve A3DJ8-AT (on 1 1/4" pipe) (magnet valve). The motorized valve (Modutrol) is capable of opening only part way. If one counts the manual shutoff valve there are thus 3 valves in series, any one of which can shut off the gas to a furnace.

2.9 Cables to Modutrol

Most of the multi-conductor cables lead to the motorized valve terminal block from: 1. All 4 thermostats (3 cables): output (includes Pilotstat), input, room 2. magnet valve (2 separate wires) 3. 24 v control voltage (on a 2-conductor-cable) via toggle switches and timers (in series). There are thus 4@ pairs (3 twin-cables plus 2 individual wires) plus one 3-conductor-cable (from the input thermostat) entering each motorized valve. There are 5 contacts (24 VAC), all of which must be closed for the magnet valve to operate: 3@ thermostats (including the Pilotstat), the timer, and the toggle switch at the top of the stairs. The remaining input air thermostat (3 conductors) controls the Modutrol motorized valve.

2.10 Wiring at Modutrol

The 3 conductors from the input thermostat are connected to 3 terminals labeled "thermostat". The 24 v brown pair (from the 24v terminal box on Panel B: terminals x1, x5) is connected to the T (transformer) terminals. The rest of the 2-conductor lines are connected in series with wire nuts with the extreme ends going to the 24 v terminals (which gets its 24 v from the T terminals). Since the magnet valve is one of the devices in series, its operation (24 v) depends on the closure of all contacts except the input thermostat.

2.11 Modutrol Operation

The input thermostat will operate the motorized modutrol valve (provided 24 v is present). In the summer when the intake air from outside may be hot but the building cool and calling for heat, the Modutrol may operate. It might also operate if the return air (recycled) is too hot. But since only part of this recycled air comes from the area being heated by a given furnace (and since heated air to the upstairs is not recycled) this method of regulation is not optimal. It is thus possible that hot air recycled from downstairs could turn off heat needed for a cool upstairs. The modutrol has actually been observed to operate.


3.1 Introduction

The forced air system uses 3@ centrifugal blowers, each driven via fan belts by 3-phase induction electric motors. The sanctuary blower is in the NW corner: "Buffalo Duplex Conoidal" made by Buffalo Forge Co., Size 9, Shop Order No. A31091. Patented 1915, 1916, & 1917. The other two blowers are "Utility Heavy Duty Blower" made by Utility Fan Corp., Los Angeles. Size is 4 1/2 S-B, models 5-1420 (Throop Hall) and 5-1430 (upstairs). "Utility" is out of business but parts are said to be available. "Buffalo Forge" was purchased by the Howden Fan Co. in 1994 but parts are not available per letter from Howden Fan.

3.2 Pulley Removal

For all blowers: First remove the belt guard. Then remove the 3 screws from the hub and install 2 of them in the threaded holes of this hub. Alternately tighten them until the pulley-to-shaft seal is broken and then slide off the hub and pulley. No gear puller is required. The Buffalo blower has a Browning pulley.

3.3 Blower Motors

These are 3 phase: 2 @ 1.5 HP, 5.2 amps and 1 (the sanctuary) @ 5 HP, 13.8 amps, service factor 1.15. Both are 220V but are connected to a 240V (line-to-line) 3-phase system. The air washer pump motor is not now being used. In 1994 it turned OK after being turned with a pipe wrench to unfreeze it. Thus there are 4 electric motors which are fed thru fusible safety switches, magnetic contactors, and thermal overload relays on the N. wall. The safety switches are all together on the panel by the door. There is another safety switch in the electric basement which feeds all 4 of the above mentioned safety switches. The location of the magnetic starters (contactors and thermal overload relays) are spilt, with half of them (2) being located on the middle of the N wall. See "Motor Controls" (this document) for details.

3.4 Fuse Sizes

For ordinary class H fuses (non-time_delay), the amp rating should be a little under 300% of the nominal motor current to allow for high starting currents. Thus 15 amps is used for the 1.5 HP motors and 40 amps is used for the 5 HP motor (Sanctuary). If a time-delay fuse were used, they should be 125% to 175% of the nominal motor current. Time delays fuses might be better but since thermal overload relays are also in the circuit to handle overheating, time-delay fuses are not essential. Non-time_delay fuses are cheaper and easier to find.

3.5 Fans

The Buffalo fan (including shaft) is estimated to weigh about 300 lb. Lifting up the shaft at the S. bearing seemed to take about 100+ lb. There is a strong reverse flow of air around the edge of the fan, especially at the top right. Some of this is due to leakage around the edge (adjust for closer clearance).

3.6 Blower Bearings

                                        Buffalo   Utility  
Date Made                               1920 ?    1950 ?
Fan shaft Dia.                          2 11/16"  1 11/16"
Pillow to frame mounting bolt spacing   9"        6 1/2"  c-c
Mounting bolt dia.                      3/4"      1/2"
Bearing metal (all plain bearings)      babbitt   bronze
Mounting base to center of shaft        3 5/8"-   2 3/8"  2 5/16"(new)
Mounting base width                               3" - => -1/32
Buffalo: Set screws: Top 2" ,  Sides 3/4".  ID Nos.: O 15 No. 5.
Utility: Bronze sleeve OD 2", length 4", 


B & D says don't use graphite oil since bearing will wear out faster??? Use SAE 30 oil (someone suggested Mobil 1 synthetic but others say it makes no difference).

Future Replacement Bearings

One may use ball, roller, or plain bearings as replacements for the existing plain bearings. However, plain bearings are said to be superior due to the low pressure. It's also claimed that plain bearings reduce any tendency to vibration. However plain bearing have higher starting friction and re-babbitting (Buffalo Forge only) is expensive .

3.7 Utility Bearings

A replacement ball bearing was installed in 1995 in the Utility Throop Hall blower, pulley side: Koyo UCPX 09-27LJ (self-aligning) purchased from Thompson Industrial since they didn't have Browning VPS 327. 2 5/16" height is too low, but no shim was used since shaft is level at this height (possibly due to the opposite original bearing being worn). Had to pound on bearing, but slipped too easily over worn spot (where old bearing rubbed). No noticeable play so didn't use any Locktite although there could be say .002" play. Set screws keep it from slipping. To remove new bearing only from pillow block, remove pillow block (pound off) and then twist out bearing and pull out thru 2 notches. It should be lubricated every year with a grease gun.

Inspection: To inspect the intake bearings of the Utility blowers look inside the duct. For the upstairs blower remove the filter and enter the intake plenum chamber. For the Throop Hall blower, remove the west-most filter and look inside (with binoculars at close focus) using a flashlight, etc.

3.8 Buffalo Forge Bearings

The 2 11/16" shaft size is not too common but some replacement bearings are made for it. The old bearings may be drained (drain plug). Change oil every several years?? Since the housing holds a quart or two of oil, one needs to use a pump-oiler in order to fill it rapidly with oil. It's easy to put too much in so check the level with a flashlight while oiling.

The bearing is lead Babbitt, an alloy of tin, antimony, copper, and lead. The percentage of lead for low cost bearings ranges from 25% to 90% and we don't know what ours is. Other types of Babbitt bearings are tin based and are better quality but in the 1920's lead was cheaper than tin. Lead is softer and readily tolerates misalignment. In May 1996, David Lawyer removed the top housing (14" long) of the S. bearing by removing 4 bolts with 1 1/16" nuts and 7/8" heads.

The internal bearing itself is in 2 halves, each 10" long with 2@ 10" long notched shims separating them. The top half of the housing has a 2" setscrew to hold down the top half of the bearing. It has a 3 1/8" locknut. Use a 3' or 4' pipe wrench to turn it (2' with a "cheater" pipe barely worked). There is a 3 1/8" socket made for 1" drive socket wrench sets, but it costs over $100 for the socket (3 1/2" is the largest socket). The side setscrews position the transverse location of the bottom half of the bearing. There may be an internal height adjusting screw underneath the bottom half. Since the positioning of the bearing is at its longitudinal center (5" from each end) the bearing will align itself to the direction of the shaft (it does not need to run exactly parallel with the housing). At present the S. bearing has a lot of skew within its housing and this has even damaged the shaft slightly (a small groove has been cut).

Two solid lubrication rings rest on the shaft and turn as the shaft turns (but at less rpm) to bring oil up to the top of the shaft by drawing up drops of oil from the bearing case bottom. In May 1996 the S. bearing (but not the N. one) had these rings positioned over the top of the bearing inserts and thus didn't provide any lubrication. These rings may be seen by removing the top oil plugs and then looking straight down thru holes in the top bearing half. This past mistake is a major cause of excessive bearing wear. It may have been done to prevent oil leakage out of the bearing case and seal. The bearing case needs a gasket or Permatex so as not to leak.

The two bearings halves are steel with lead alloy Babbitt inside (at least 1/4" thick). The S. bearing had (as of May 1996) about 1/16 clearance (wear). But since the bearing may have been adjusted in the past to compensate for previous wear, the total wear could be greater. Thus the bearing is likely less than half worn out. One may replace the shims to compensate for wear (must fabricate such shims with a few notches). The bearing must have a clearance of a few (say 5; see Machinery's Handbook, 1941) thousands of an inch for an oil film. Thus one can't just remove the shims and tighten down the large top setscrew resulting in no clearance in some spots. The old wood shims (original ?) were 3/16" (= .187) thick. To compensate for wear (as of 1996) ones about .135" thick are needed. Use 1/8" (.125") sheet rubber plus .010" duct tape? In the future, still smaller ones will be needed. In 1996 a .090 linoleum shim was placed on top of one wood shim. The amount needing compensation was .102 = 2(.187 - .135) so the bearing is now still a little loose but better than what it was.

The seals are half rings of felt, about 1/4" thick by 1"+ wide, by about 6" long (arc length). They are held in place by 3 screws which pierce the felt and have a metal backing ring to hold the felt better than just the screws alone. To make seals, cut them from 1/4" felt sheets (about 5" square). Due to wear, the top seal may need to be larger. The felt for seals should be SAE F-1 (500 psi tensile) or SAE F-3 (400 psi). Roll width and % wool: F-1: 72", 95+% F-3: 80", 85+%. The collet that prevents outboard movement of the shaft is held in place by 2@ set screws (1/4" hex key). National non-wovens is a source.


There are 4 motors numbered B1 thru B4: 3 motors drive blowers and one drives a water pump for the air washer.

4.1 Magnetic Starters

Each of our "magnetic starters" consists of 2 devices: a magnetic contactor and a thermal overload relay. The contactor (3 or 4 large contacts) switches on and off the current to the motors and is operated by a built-in electromagnet. The thermal relay contain an analogue model of the heating of the actual motor and shuts off the motor if the "model" (and presumably the motor also) gets overheated. This shut off is achieved by cutting off the holding current to an electromagnet. With no magnetic force to hold the the main contacts closed, spring force opens (breaks) the contacts. Note that the term "magnetic starter" is somewhat of a misnomer as ours only switch on and off the motors and provide thermal overload protection. There is no provision in our "magnetic starters" for reducing the voltage during starting (as happens in "reduced voltage starters"). Other types of magnetic starters (combination starters --not at Throop) also include fuses and a manual switch so that no "safety switches" are required. The simplest type (not at Throop) is a manual starter that uses human energy to move the contactors.

4.2 Starter Locations

We have a "magnetic starter" for each of the 4 basement motors (3 blower and 1 water pump). The locations are split. The magnetic starters for the sanctuary blower and the water pump are located on the middle of the N wall. The magnetic starters (General Electric) for the other 2 blowers are also on the N wall but located next to the stairway door just below the safety switches for all 4 motors. The sanctuary blower (mid-wall location) has its magnetic contactor in one box and its thermal overload relay in a smaller adjacent box. These 2 boxes of old (1920's) hardware constitute the "magnetic starter" for the sanctuary blower. Just to the left of this inside a box formerly containing a magnetic contactor is the magnetic starter for the water pump.

4.3 Newer GE Magnetic Starters

The panel by the electric basement door contains 4 safety switches but only 2 GE "AC Magnetic Starters with thermal overload relays" (CR7006 B101B). Each has a reset button which resets the 2 thermal overload relays inside it. Only 2 legs of the 3 phase circuit are thus protected. More modern designs protect all 3 legs. The heater elements are 81D 547 (#3 blower) and 81D 548 (#4 blower) rated at nominal motor currents of 4.7 to 5.1 amps and 5.2 to 5.6 amps respectively. Since both our motors are 5.2 amps, one heater is not exactly correct but since the trip current is 115% of 5.1 amps, 5.2 amps should not trip it. Also, the rating is likely for a high ambient temperature, but since the basement is cool the relay is less likely to trip. It might be wise to buy a higher amp heater element.

The contacts may be easily cleaned by removing 4 screws and then removing the bottom contact holder and the front part with the GE logo.

4.4 Newer GE Starter Wiring

The covers may be removed. Inside the cover is a small circuit diagram (but no wiring diagram). The main contacts are within the top part (with the red GE logo). The magnet which moves the contacts is in the lower part between the two red reset buttons (rectangular).

L1, L2 and L3 terminals for the input Line power AC voltage (240v) are just above the red GE logo. The output terminals of the contactor are directly behind the front L1-L3 terminals (and a couple of inches away). Each output terminal has 2 screws for wires with only one of these screws clearly visible (the 2nd one is hidden behind the 1st one).

T1-T3 are the final 240V outputs, T2 is behind L2, T1 is in the lower left corner, and T3 is in the lower right corner. Wires from these feed the 3-phase motor. The T1-T3 and L1-L3 symbols are stamped on terminal lugs (but some are missing). Turn on is obtained by shorting a pair of wires (via the 240V relay box) connected to terminals 3 and L1 (and not as suggested in the text of the circuit diagram). If the control is calling for the blower on, terminal 3 should be at L1 voltage. Wires from L1 and L3 go to the terminals at the top of the thermal relays via thin #14 wire (should have used larger wire ?). If a thermal overload relay trips, the control contacts (shown normally closed) open, thereby deenergizing the magnet coil resulting in the opening of the main contacts.

2 red wires going down supply power to the 240v-to-24v transformers. 2 black wires going down are control wiring and go the the 24v-to-240v relays in the 240v box.

4.5 Other Starters

The other 2 magnetic starters are located in the middle of the N wall. One is an old (1922, 50 cycles) GE CR7005 A2 "magnetic switch" (= magnetic contactor) along with a GE CR2824-TC121A overload temperature relay. This is for the sanctuary blower. The thermal relay has a screw adjustment for setting trip current and is reset by opening the box and moving insulated levers. New heater elements are said to be not available (they are bimetalic strips) but one doesn't need them if the nominal current falls within the range of the trip adjustment. Inside the magnetic switch box are empty fuse holders. No fuses are needed since the fuses in the safety switch near the door protect the motor.

Inside the 2nd box for a GE CR7005 "magnetic switch" is a more modern magnetic starter for the water pump for the air washer which is not used (1993) due to leaks. There is no toggle switch for this and the water pump is started by a push-button switch on the wall below the magnetic starter.

4.6 External Control Circuit

The control voltage for all motor contactor magnets is the same as line voltage (240 V). This 240 volt circuit is made/broken by relays located in an orange box on the main panel labeled 240 V to the right. These relays coils are energized by only 24 VAC. The 24 V circuits go thru both the toggle switches at the top of the stairway and the timers. The red wires supply the timer motors with 240 VAC. The top box to the right labeled 24 V contains only terminal blocks for interconnection of 24 VAC control wiring which is used to turn on the gas as well as to start the blowers. See "Toggle Switches, Timers & 24 VAC Terminals" for details.


5.1 Introduction

Alias: Air Washer, Humidifier. This broken device is as large as a small room and is in the SW corner. This cooler is only for the Sanctuary (unless air is recycled). The nameplate says this is a Carrier type C Air Washer (made c. 1922), Size 5C, Serial No. 30813. It has 3 doors which a person can use to walk inside it although only the center door leads to the washer compartment. It sprays a water mist into the intake air before the blower. Then excessive moisture is removed by baffles (the eliminator). This both cools and washes the air. Bill Adamson at (818) 854-4500 knows a little about it.

5.2 Leaks

As of 1991 it had many large (a few in. dia.) and small leaks in its water tank (at floor level) as may be seen by walking inside it (enter its 3 "rooms" via each of the three access doors). Worst of all, the floor (pan) is likely badly damaged by rust. Thus a new pan may be needed (custom made). One spray nozzle is missing (not available from Carrier). Some internal support posts are badly rusted, broken, or loose (for both spray piping and eliminator louvers).

A new sheet metal pan and sides may be the best solution but if patching is feasible then: Some holes could be patched with Mr. Mac's Metal Fix (uses Polymer ACT-91 and fiberglass cloth) or Bondo, etc. One could also use sheet metal patches welded (or soldered) in place. Tiny leaks might be fixed with plumbers Goop. See the hvac_system document for discussion of the air washer's utility.

5.3 Water Circulation

The water is circulated by a water pump driven by an electric motor, both mounted on the floor in front of the air washer. The GE motor is a 3 phase induction motor, 3 HP, 9.2 amps, 1728 rpm (design is 1440 rpm at 50 Hz, but we have 60 Hz). If the power required is proportional to the velocity cubed, then at the higher speed 72% more power is used to pump the water. This may both waste energy and overheat the motor.

The water level is maintained by a float (like in a toilet tank) and fresh water is added to compensate for evaporation. But the dirt collected in the water also needs to be drained out periodically and the only drain is into the nearby sump (water operated).


Slots exist in the air duct for filters, all located in the basement. The duct was cut for them around 1980? Thus the duct is weak at these points. All filters are 2" thick. The sizes marked on the duct are not always correct. The sizes are (incorrect sizes inside ()) Upstairs 16 3/8 x 35 3/8 (15 x 35). Throop Hall 2@ 19 3/4 x 28 (19 x 28). Sanctuary 2@ 20 x 25. Only 20 x 25 is a standard size. The others must be custom made. The filters obtained in the 1980's were "Servodyne" brand (Santa Rosa, CA) but are not of very high quality as the few staples holding the sheet metal grille to the cardboard sometimes broke, allowing the filter pads to crash into the fans. A washable polypropylene filter cost $93 (too high). Efficiency is only about 30% for "Arizona road dust".

The filters restrict the air flow since they directly occupy the cross section of the duct. Dwyer Instruments Inc. of Anaheim makes air velocity meters. Cat. # 460 costs $ 20 and can be obtained from A. Biederman of Glendale (246-8431).


(Use Business-to-Business Yellow Pages)

American Metal Bearing, Garden Grove (714) 892-5527.  Makes custom
   made bearings but cost is about $500/bearing.
Ashcraft Co., 1392 Lincoln Ave., 797-6021 (Keith does repair work
@ $52/hr) (formerly tinsmiths, stocks some bearings).
Bearings & Drives (B & D), 9506 Rush St., S. El Monte, 443-0251.
Sells bronze bushings for Utility Blowers.  OD`s:
1 15/16 to 2 1/4" for 1 11/16 id.
Carrier Corp. 800-937-7222, (Know little about our equipment.)
Filter Supply Co., Anaheim, (213)567-1264. (Basement air filters)
Heating & Cooling Supply, El Monte, 443-7181.  Don't stock bearings.
Honeywell Corp. (800) 328-5111.  Local Rep.: Refrigeration Supplies,
Monterey Park (213) 264-2800
Howden Fan Co. (formerly Buffalo Forge) 110 Broadway (zip 14203-1695),
or PO Box 985 (zip 14240-0985), Buffalo NY.  (716) 847-5121.
HVAC Supply (Monrovia, etc., Parts for Henry House Air Conditioning).
King Bearing, 5735 E. Washington Blvd., Commerce CA, (213) 724-5111
Magtrol (for motor magnetic starters & thermal relays), Commerce CA,
(213) 685-9310
Thompson Industrial supply, 1310 Santa Anita Ave., S. El Monte,
579-4330.  Have bearings and seals.
Toro Aire, Compton (310) 632-6000.  Glendale 956-7511. Rep for Howden
Fan.  (now in Ahaheim ?)