SERIES 20/30SERIES 20/30 INSTALLATION INSTRUCTIONS and ...ordanthermal.com/products/maxitrol/pdf/selectra/s... · regulator in manifold and adjust 2 or 3 turns to compensate for pressure

SERIES 20 Amplifiers:SERIES 20 Amplifiers:SERIES 20 Amplifiers:A1010A - single furnaceA1010B - w/ high fire ignition

SERIES 30 Amplifiers:SERIES 30 Amplifiers:SERIES 30 Amplifiers:A1011A - multiple furnaceA1011B - w/ high fire ignition

Modulator-Regulator Valves:Modulator-Regulator Valves:MR410 (3/8" and 1/2" pipe size)MR510 (1/2" and 3/4" pipe size)MR610 (3/4" and 1" pipe size)

Selectrastat: Selectrastat: selector and integral sensingT120 - (60o to 85o F) - supersedes T107A-1

or optional pair to replace Selectrastat...

Space Temperature Selector:Space Temperature Selector:Space Temperature Selector:Space Temperature Selector: selection onlyTD120 - (60o to 85o F) - supersedes TD107AOptional: ETD-1 enclosure,

EFP-1 cover plate only - no enclosureSpace Temperature Sensor:Space Temperature Sensor: remote sensingTS120 - supersedes TS2003A

System Components

SERIES 20/30SERIES 20/30SERIES 20/30SERIES 20/30SERIES 20/30 INSTALLATION INSTRUCTIONSand field service check list

SelectrastatSelectrastat TemperatureTemperatureSelectorSelectorSelector

Temperature SensorTemperature Sensor

BULLETIN MI2044-01/04REPLACED MI1080

A1010 AmplifierA1010 Amplifier ValveValveA1011 AmplifierA1011 Amplifier

The Selectra SERIES 20/30 electronic gas flamemodulation systems are designed primarily for commercialand light industrial space heating, as components ofindirect fired units with atmospheric burners. All fuel gasesare compatible.

The SERIES 20 is designed for single furnace operation,and the SERIES 30 is capable of handling up to fourfurnaces. They may be field installed on existingequipment or specified for new equipment installation.

The systems utilize Modulator-Regulator valves.Amplifiers are available with high-fire ignition. A wallmounted Selectrastat senses space temperature and hasan integral selector with a 60o to 85o F range. Optionally, aremote Temperature Sensor paired with a separateTemperature Selector (60o to 85o F) can be substituted forthe Selectrastat.

Introduction

Page 2 Specifications and DimensionsPage 3 Installation of Components

Preliminary Circuit AnalysisPage 4 & 5 Field Service ChecklistPage 6 Performance Check

Extended High-Fire IgnitionLow Limit Stat

Page 7 Wiring DiagramsPage 8 Temperature Calibration

Valve Adjustments

Table of Contents

CAUTION: Operation of combustion equip-ment can be hazardous resulting in bodilyinjury or equipment damage. Each burnershould be supervised by a combustion safe-guard and only qualified personnel shouldinstall, make system adjustments and per-form any required service.

NOTICE: Maxitrol practices a policyof continuous improvement in the de-sign of its products. It reserves theright to change the specifcations atany time without prior notice.

ORDAN THERMAL PRODUCTS LTDCombustion Equipment & Controls for Industry

Tel: (905) 475-9292 Fax: (905) 475-3286 www.ordanthermal.com

T 21 Amber St # 9, Markham Ontario Canada L3R 4Z3

Specifications and DimensionsGases: All fuel gases.Pressure Limits:Inlet (maximum) MR410 / 510 / 610.....1 psi / 69 mbar

Outlet (maximum fire)standard spring*.....3.0" to 5.0" w.c. / 7 to 12 mbarH - models.....7.5" to 12" w.c. / 19 to 30 mbar

(Max. set point not to exceed 10" w.c. above min.set point)

Outlet (minimum fire)standard spring*.....0.2" to 1.2" w.c. / .5 to 3 mbar(-1) spring*.....1" to 2.8" w.c. / 2.5 to 7 mbar(* other spring ranges available - consult factory)

Power Requirements:Single Furnace.....24V AC, 40VA capacityMultiple Furnace.....24V AC, 100VA capacityNOTE: Transformer secondary must not be groundedin any portion of the circuit external to a Maxitrolamplifier. If existing transformer is grounded, aseparate isolated transformer must be used. Electricalinterference may effect performance and/or damageequipment.

Temperature Control Range: 60o to 85oF

Ambient Limits: -30o to 125oF / -34o to 52oC

(TS120 dimensions same except without front dial)

A1011A1011

ETD-1ETD-1

A1010A1010

T120T120T120T120T120

TD120TD120TD120TD120TD120

Power Requirements:Pressure Limits:Gases:

Outlet (maximum fire)

Outlet (minimum fire)






Installation of ComponentsSpace Temperature Selector:Space Temperature Selector: Install in control cabinet orother chosen location. Remove cover and wire as shownin diagram, page 7 - reassemble.

Note:Note: For systems using up to four automatic gas valveswith 0.8 amp maximum current each, a 100VA transformerwill be adequate.

In the event that an automatic valve's current exceeds 0.8amps, it would be advisable to wire according to the'Independent Power Supply' diagram, page 7. Thetransformer for the modulating power - terminals 8 and 9 -should be 40VA, and the automatic valve transformershould be capable of handling required loads up to 3.5amps maximum. If exceeding 3.5 amps, it will benecessary to operate an auxiliary relay with contact ratingsufficient to handle the automatic valves.

Amplifier:Amplifier: Slide or snap out circuit board from amplifierbase. Mount base with two screws in chosen locationprotected from weather or contaminated atmosphere.Amplifier is ready for wiring when circuit board is replacedon base - protective cover need not be removed. Controlwires connecting the Selectrastat or Space TemperatureSensor must not be run close to or inside conduit withpower or ignition wires. Doing so may cause the unit tofunction erratically or may destroy the amplifier. If shieldedwires are used, shield must be insulated and grounded atthe amplifier location only.

Selectrastat:Selectrastat: Pull dial and cover outward. Loosen screwsin terminal strip, tilt out and lift up. Install in area whererepresentative space temperature is to be sensed. Wireas shown in diagram, page 7 - reassemble.

Space Temperature Sensor:Space Temperature Sensor: Remove cover and install inarea where representative space temperature is to besensed. Wire as shown in diagram, page 7 - reassemble.

Valve:Valve:Valve:Valve:Valve: The MR valve must be in upright position, in a horizontal run of pipe only, with pilot gas supply upstream.

If diaphragm type automatic gasvalve is used with separate regulator,install MR valve downstream fromdiaphragm gas valve. Retainregulator in manifold and adjust 2 or 3turns to compensate for pressuredrop of MR valve.

If full combination control is used,install MR valve downstream. Adjustregulator in combination control 2 or 3turns to compensate for pressuredrop at MR valve.

If solenoid type automatic gas valveis used with separate regulator,replace regulator with the MR valve.

Automatic Valve Function - when temperature atSelectrastat or Sensor is less than 60°F (16°C) orgreater than 85°F (29°C):Disconnect the wires at amplifier terminals 10, 11 and 3.DC modulating voltage across terminals 1 and 2 should bezero. Ohm reading across terminals 10 and 11 should bezero ohms.

Reconnect wire to terminal 3 of amplifier.Carefully connect a piece of jumper wireacross the thermistor as shown (makeonly temporary connection). Ohm readingat terminals 10 and 11 should be infinite(open circuit). Modulating voltage atterminals 1 and 2 should be greater than17 volts.

Reconnect wires to terminals 10 and 11. Amplifier is notfaulty if the above conditions are met.

Preliminary Circuit AnalysisIn order to diagnose the cause of problems in this systemit is necessary to determine certain values. It is helpful tohave an AC and DC voltmeter and an ohmmeter capableof reading 0 to 15,000 ohms.

Modulating Function Test - when temperature atSelectrastat or Sensor is 60° to 85°F (16° to 29°C):Connect a DC voltmeter to amplifier terminals 1 and 2. Ifmore convenient, the meter may be attached to the MRvalve terminals. Rotate temperature selection knob tomaximum setting. The DC volts should read zero. Thevoltage should gradually increase to at least 20 volts whenthe temperature selector is slowly rotated to its minimum(generally over a 3°to 4° range).

Automatic Valve Function - when temperature atSelectrastat or Sensor is 60° to 80°F (16° to 29°C):Disconnect the wires at amplifier terminals 10 and 11, andconnect an ohmmeter. Rotate temperature selector tomaximum setting - ohmmeter should show continuity.Rotate temperature selector to minimum setting -ohmmeter should show open circuit. Reconnect the wiresto terminals 10 and 11.






Aut

omat

ic c

ontr

ol v

alve

will

not

clo

sede

spite

full

rang

e of

mod

ulat

ing

volta

ge a

t ter

min

als

1 an

d 2.

1. F

aulty

aut

omat

ic co

ntro

l val

ve.

2. I

nsta

llatio

n w

iring

erro

r.

3. A

mpl

ifier

is fa

ulty.

1. R

emov

e w

ire fr

om va

lve,

if va

lve

does

not

clos

e - v

alve

is fa

ulty.

2. R

emov

e w

ire fr

om a

mpl

ifier t

erm

inal

10

or 11

. If v

alve

rem

ains

ope

n, c

heck

for m

isw

iring

.

3. If

AC

vol

tage

will

not d

rop

to z

ero

at te

rmin

als

8 an

d 11

- w

hen

DC

vol

tage

at t

erm

inal

s 1

and

2 is

abo

ve 2

0V

DC

- am

plifi

er is

faul

ty.

If sp

ace

tem

prea

ture

is le

ss th

an 6

0° o

r gre

ater

than

85°

F (<

16° o

r >29

°C),

see

Prel

imin

ary

Circ

uit A

naly

sis,

pag

e 3.

1. R

epla

ce a

utom

atic

cont

rol v

alve

.

2. C

orre

ct w

iring

.

3. R

epla

ce a

mpl

ifier

.

Aut

omat

ic c

ontr

ol v

alve

won

’t op

ende

spite

full

rang

e of

mod

ulat

ing

volta

ge a

t ter

min

als

1 an

d 2.

4. F

aulty

aut

omat

ic co

ntro

l val

ve.

5. O

pen

wire

to a

utom

atic

valve

.

6. A

mpl

ifier

is fa

ulty

.

4. R

ead

volta

ge a

cros

s va

lve

term

inal

s. If

24

V AC

, val

ve is

faul

ty.

5. R

ead

volta

ge a

cros

s te

rmin

als

8 an

d 11

on

ampl

ifier

. If 2

4 V

AC. c

heck

for o

pen

circ

uit t

o au

tom

atic

val

ve.

If sp

ace

tem

pera

ture

is le

ss th

an 6

0°or

gre

ater

than

85°

F (<

16° o

r >29

° C),

see

Prel

imin

ary

Circ

uit

Anal

ysis

, pag

e 3.

6. I

f AC

vol

atge

read

ing

rem

ains

zer

o - w

hen

DC

vol

tage

at t

erm

inal

s 1

and

2 is

bel

ow 1

4 V

DC

- am

plifi

er is

faul

ty. I

f spa

ce te

mpe

ratu

re is

less

than

60°

or g

reat

er th

an 8

5°F

(<16

° > 2

9°C

), se

e Pr

elim

inar

y C

ircui

tAn

alys

is, p

age

3.

4. R

epla

ce a

utom

atic

cont

rol v

alve

.

5. C

orre

ct w

iring

.

6. R

epla

ce a

mpl

ifier

.

No

gas

Flow

7. F

aulty

pow

er su

pply.

8. M

R va

lve

inst

alle

d ba

ckw

ards

7. R

ead

volta

ge a

t am

plifi

er te

rmin

als

8 an

d 11

(24

V AC

).

8. A

rrow

on

MR

val

ve s

houl

d po

int in

one

dire

ctio

n of

gas

flow

.

7. P

ower

supp

ly m

ust b

e 24

V A

C.

8. In

stal

l pro

perly

.

Con

tinuo

us h

igh

fire.

9. O

pen

circ

uit i

n se

nsin

g an

d se

tting

circ

uit.

9. D

isco

nnec

t and

mea

sure

acr

oss

wire

s co

nnec

ted

to a

mpl

ifier

term

inal

s 3

and

4 (A

1010

mod

els)

.Sh

ould

read

bet

wee

n 8,

000

and

12,0

00 o

hms.

9. If

abo

ve 1

2,00

0 oh

ms,

che

ck c

ircui

t for

ope

n or

loos

e w

ires.

Con

tinuo

us h

igh

fire

but a

utom

atic

valv

e cy

cles

.10

. Ope

n ci

rcui

t in

wiri

ng to

MR

val

ve.

11. P

lung

er ja

mm

ed o

r ins

talle

d up

side

dow

n.

12. F

aulty

MR

valv

e.

10. C

heck

wiri

ng fo

r def

ects

.

11. P

lung

er s

houl

d be

sm

ooth

and

cle

an a

nd o

pera

te fr

eely

in s

olen

oid

slee

ve. M

ust b

e in

stal

led

as s

how

n in

“Val

ve A

djus

tmen

ts” f

igur

e, p

age

8.

12. M

easu

re v

olta

ge a

cros

s M

R v

alve

.

10. R

epla

ce w

iring

if n

eces

sary

.

11. C

lean

or r

epla

ce p

lung

er.

12. I

f mod

ulat

ing

volta

ges

are

obta

ined

but

no

gas

mod

ulat

ion,

MR

val

ve is

faul

ty. R

epla

ce if

nece

ssar

y.

Furn

ace

won

’t ac

tivat

e du

e to

cons

tant

hig

h m

odul

atin

g vo

ltage

.(a

bove

17

V D

C)

13. S

hort

circ

uit i

n se

nsin

g an

d se

ttlin

g ci

rcui

t.13

. Dis

conn

ect a

nd m

easu

re a

cros

s w

ires

conn

ecte

d to

am

plifie

r ter

min

als

3 an

d 4

(A10

10 m

odel

s).

Shou

ld re

ad b

etw

een

8,00

0 an

d 12

,000

ohm

s.13

. If b

elow

8,0

00 o

hms,

che

ck c

ircui

t for

sho

rts o

r

m

isw

iring

.

Con

tinuo

us lo

w o

r med

ium

fire

, but

auto

mat

ic v

alve

cyc

les

corr

ectly

.14

. Inc

reas

e te

mpe

ratu

re s

ettin

g 10

deg

rees

.

15. C

heck

for p

arts

( se

e “V

alve

Adj

ustm

ents

” fig

ure,

pag

e 8)

.

16. E

xam

ine.

Plu

nger

shou

ld b

e cl

ean,

smoo

th, a

nd o

pera

te fr

eely

in so

leno

id sl

eeve

.

17. R

emov

e w

ire fr

om M

R va

lve.

18. R

emov

e sp

ring

5 fro

m M

R v

alve

(see

val

ve fig

ure,

pag

e 8)

pus

h do

wn

on p

lung

er.

Insu

ffici

ent m

anifo

ld p

ress

ure

with

furn

ace

oper

atin

g in

dica

tes

supp

ly is

too

low

.

14. H

eat l

oad

requ

ires

low

fire

onl

y.

15. P

lung

er a

nd/o

r max

imum

spr

ing

mis

sing

.

16. J

amm

ed p

lung

er.

17. O

ther

valv

e fa

ults

.

18. I

nade

quat

e su

pply

pre

ssur

e.

14. I

f hea

ter g

oes

to h

igh

fire,

sys

tem

is w

orki

ng

cor

rect

ly.

15. I

nsta

ll cor

rect

par

ts.

16. C

lean

, or r

epla

ce p

lung

er if

nec

essa

ry.

17. I

f MR

valv

e re

mai

ns o

n lo

w fir

e, va

lve

may

be

faul

ty.C

heck

item

19

belo

w, th

en re

plac

e va

lve

if nec

essa

ry.

18. C

heck

for o

bstru

ctio

n in

gas

pip

e ah

ead

of c

ontro

ls.

Incr

ease

gas

pre

ssur

e if

poss

ible

.

Inco

rrec

t dis

char

ge a

ir te

mpe

ratu

re.

19. C

alib

ratio

n19

. Che

ck se

al o

n ca

libra

tion

pote

ntio

met

er.

19. R

ecal

ibra

te p

er “T

empe

ratu

re C

alib

ratio

n” p

roce

dure

.

SY

MP

TOM

POSS

IBLE

CA

USE

FIEL

D T

EST

REM

EDY

Fiel

d Se

rvic

e C

heck

list

Erra

tic o

r sev

erly

pul

satin

g fla

me.

20.

Dirt

y or

stic

king

plu

nger

.

21. I

nter

mitt

ent s

horti

ng in

wiri

ng

22. F

aulty

am

plifie

r.

20. E

xam

ine.

Plu

nger

shou

ld b

e cl

ean,

smoo

th, a

nd o

pera

te fr

eely

in so

leno

id sl

eeve

.

21. I

nspe

ct w

iring

.

22. O

bser

ve D

C v

olta

ge a

cros

s am

plifi

er te

rmin

als

1 an

d 2.

20. C

lean

, or r

epla

ce p

lung

er if

nec

essa

ry.

21.

Cor

rect

wiri

ng.

22.

If er

ratic

or p

ulsa

ting

DC

vol

tage

is o

bser

ved

and

wiri

ngsh

ows

no d

efec

ts, r

epla

ce a

mpl

ifier

. If e

rratic

or

puls

atin

g vo

ltage

con

tinue

s, c

onta

ct M

axitr

ol.

*Con

trol

cir

cuits

ext

erna

l to

the

Ser

ies

21 a

nd 3

1 ca

n ca

use

burn

er m

alfu

nctio

n.

Alw

ays

chec

k m

anua

l va

lve

to b

e ce

rtai

n ga

s is

on,

and

che

ck l

imit

cont

rols

for

nor

mal

ope

ratio

n.

A. B.

C.

D. E. F. G. H. I.

With the modulator-regulator valve installed as instructed(voltages are approximate)...Minimum fireMinimum fireMinimum fireMinimum fireMinimum fire is obtained above 14 volts DC.Manifold pressure can be adjusted as follows: Standardspring 0.2" to 1.2" w.c. (.5 to 3 mbar), MR*10B10L-1 spring1" to 2.8" w.c. (2.5 to 7 mbar),Maximum fireMaximum fire is obtained at zero volts DC.Use manufacturer's pressure specifications when available.Maxitrol standard factory settings are 0.5" w.c. (1.25 mbar)minimum and 3.5" w.c. (8.75 mbar) maximum. H-1 models1.75" w.c. (4.35 mbar) minimum and11" w.c. ( 27 mbar) maximum.

At Selectrastat / Temperature Selector:At Selectrastat / Temperature Selector:1) Set below room temperature and slowly increase settinguntil furnace begins operating. Furnace should ignite andremain on low fire. If high fire ignition is being used -(A1010B or A1011B amplifiers) the furnace will ignite at highfire for a duration of either 5 or 25 seconds (see ExtendedHigh Fire Ignition below), then modulate to low fire. At lowfire (manifold pressure about 0.5" w.c. [1.25 mbar]), areading of approximately 14 or more volts DC should beobtained.2) Rotate 3° higher.3) Furnace should now be at high fire, manifold pressureabout 3.5" w.c. (8.75 mbar). Less than 2 volts DC shouldread across Modulator-Regulator valve terminals. Rotateslowly to a lower setting. Furnace should modulate to lowfire, with voltage at modulator approximately 15-17 volts,internal relay will trip and solenoid automatic control valvewill close.

If the preceding readings are obtained,proceed with Furnace Adjustments.If the preceding readings are not obtained:4) Recheck wiring to ensure system is consistent withappropriate wiring diagram.5) Check power source for 24 volts.6) Some automatic control valves require as much as 20seconds to open. In this case, check for 24VAC output atautomatic valve terminals.

Furnace Adjustments:Furnace Adjustments:For space heating, first calculate heat loss. If reduction offurnace input is indicated, consult furnace manufacturerabout changing to smaller orifices. Do not try to reduce bypressure adjustment or throttling the gas supply.

An oversized furnace input is easily identified, particularlyduring cold weather. If outdoor temperature is low and thesystem cycles on and off instead of maintaining a low input,the furnace is oversized. Consult furnace manufacturer.

Performance Check

On A1010B and A1011B amplifiers, the high fire startduration is approximately five seconds. To extend it from 5seconds to approximately 25 seconds, remove 100K(brown-black-yellow-gold) resistor from board as shown.

On furnaces equipped with slow opening automatic valves,it is recommended to make this modification.

Extended High-Fire Ignition

LOW LIMIT DUCT STAT(not furnished by Maxitrol)

A1010A1010A1010A1010A1010

Snip Off Resistor

Low Limit StatWhen fresh outside air is introduced and the space beingheated is up to temperature, the furnace will shut off. If therecirculated air should be too cool, temper it by wiring aduct-stat, as shown.






Wiring Diagrams

Single Furnace Operation - Series 20COMMON POWER SUPPLY

INDEPENDENT POWER SUPPLY

COMMON POWER SUPPLY

INDEPENDENT POWER SUPPLYREMOTE TEMPERATURE SENSORW/SEPARATE SELECTOR

REMOTE TEMPERATURE SENSORW/SEPARATE SELECTOR

Multiple Furnace Operation - Series 30

MR VALVEMR VALVE24V-40VA24V-40VA24V-40VA

24V-40VA24V-40VA24V-40VA24V-40VA24V-40VA




(Wire Selectrastatsame for Series 20and Series 30)


T120T120

A1010A1010A1010A1010A1010



A1011A1011

A1011A1011A1011A1011A1011

A1011A1011A1011A1011A1011

A1011A1011A1011A1011A1011

A1010A1010A1010A1010A1010

MR VALVES MR VALVES MR VALVES MR VALVES MR VALVES 4 MAX.

GASGASGASGASVALVEVALVE

GASGASGASGASGASVALVEVALVEVALVEVALVEVALVE

A1010A1010 (Series 20)

(wire A1011 A1011 A1011 A1011 A1011 samefor Series 30 below)

WIRED IN PARALLEL

GAS VALVES (4 MAX.) 3.5 AMPS MAX.

GAS VALVES (4 MAX.) 3.5 AMPS MAX.

TS120TS120TS120TS120TS120

TS120TS120TS120TS120TS120






Temperature Calibration

High Fire Adjustments:High Fire Adjustments:High Fire Adjustments:High Fire Adjustments:High Fire Adjustments:A) Using maximum adjustment screw (4), set manifoldpressure to furnace manufacturer's specifications.B) Replace cover plate (2) on Modulator-Regulator valveand reconnect wire to amplifier terminal 3.

Low Fire Adjustments:Low Fire Adjustments:Low Fire Adjustments:Low Fire Adjustments:Low Fire Adjustments:A) Remove maximum adjusting screw (4), spring (5), andplunger (8). A small magnet is useful for this purpose.CAUTION - The plunger is a precision part. Handlecarefully to avoid marring or picking up grease and dirt.Do not lubricate.B) Using minimum adjusting screw (9), set manifoldpressure to furnace manufacturer's specifications.C) Replace plunger and spring retainer, spring, andmaximum adjusting screw in proper order.

If needed - amplifier potentiometer adjustment -If needed - amplifier potentiometer adjustment -If needed - amplifier potentiometer adjustment -If needed - amplifier potentiometer adjustment -If needed - amplifier potentiometer adjustment -for space heat sensing with eitherfor space heat sensing with eitherfor space heat sensing with eitherSelectrastat (T120) orSelectrastat (T120) orSelectrastat (T120) orSelectrastat (T120) orSelectrastat (T120) orpaired Selector (TD120) and Sensor (TS120):paired Selector (TD120) and Sensor (TS120):paired Selector (TD120) and Sensor (TS120):paired Selector (TD120) and Sensor (TS120):paired Selector (TD120) and Sensor (TS120):Install a thermometer or other temperature measuringdevice at the room sensor. Set the temperature selector atthis sensed temperature. Place DC voltmeter on MR valveor amplifier terminals 1 and 2. Adjust potentiometer (A)until a voltage of 14V DC is obtained.

AAAAA

1. TOP HOUSING2. COVER PLATE3. SEAL GASKET4. MAXIMUM ADJUSTMENT SCREW5. MAXIMUM ADJUSTMENT SPRING6. SOLENOID7. MINIMUM ADJUSTMENT SPRING8. PLUNGER9. MINIMUM ADJUSTMENT SCREW10. MINIMUM ADJUSTMENT SCREW STOP

21

9

6

5

3

4

8

7

10

Note:Note:Note:Note:Note: High Fire Adjustment should be checked whenever Low Fire Adjustment is changed.

Disconnect wire from amplifier terminal 3, remove cover plate (2).

(See bulletin MT2035 for additional M/MR valve information)

Valve Adjustments











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SERIES 20/30SERIES 20/30 INSTALLATION INSTRUCTIONS and ...ordanthermal.com/products/maxitrol/pdf/selectra/s... · regulator in manifold and adjust 2 or 3 turns to compensate for pressure