I Nstall Room Therm Ostat; Outdoor Air Sensor ( Oas) Electrical Connections - UTICA BOILERS MAHF-75 Installation, Operation And Maintenance Manual

8 .5 I nst a ll Room Therm ost a t
I nst all room end swit ch on inside wall. Do not inst all
where it will be influenced by drafts, hot or cold water
pipes, lighting fixtures, television, sun rays or near a
fireplace.
Dry contact only - do not apply 24 volts between 6 and 7.
A. Con n e ct Room Th e r m ost a t
• turn power off to boiler;
• access t erm inal block M 2 ;
• connect room end swit ch t o t erm inals 6 ( R) -
7 ( W ) - 8 ( C) ; Do not apply dry volt age bet ween 2
t erm inals. Dry cont act only.
• t urn boiler power on;
• verify room end swit ch operat es per end swit ch
m anufact urer inst ruct ions.
N OTE: m axim um load allowed is 10 m A
Dry cont act end swit ches from various m anufact urers
can be at t ached t o boiler cont rol PCB.
8 .6 Out door Air Sensor ( OAS) Elect rica l Connect ions
A. 1 K Ohm ( 1 K Ω) Optional Outdoor Air Sensor (OAS)
To connect t his accessory, see Figure 8- 5, t erm inals
4- 5, and inst ruct ions supplied wit h
inst ruct ions supplied wit h
B. Set t ing " Kt " Clim a t e Curve
1.
Boiler aut om at ically recognizes OAS sensor when
wired t o M2 t erm inal block. Display changes t o show
current default " Kt " value ( 80) . Not e display value.
2.
When operat ing in CH m ode, boiler set point is
det erm ined by t he Kt value select ed and act ual
out side air t em perat ure. Refer t o applicable ° F ( or
° C) chart , ( pg. 30) for set point inform at ion.
• Select Kt range which will sat isfy t he desired
boiler delivery t em perat ure based on out door
t em perat ure range expect ed for your locat ion. For
exam ple: if you need 176° F wat er when t he out side
t em perat ure is 20° F and colder, select 35 for your
Kt set t ing.
• To change" default " Kt value on boiler cont rol use
or CH Heat ing but t ons.
• Rest rict t he upper lim it of t he Kt curve by using
Param et er P16 t o set t he m axim um boiler wat er
t em perat ure. P16 Default is 176° F.
3.
When scrolling has st opped, boiler will aut om at ically
" SAVE" value as new Kt default value and
aut om at ically ret urn t o CH m ode when no Kt
adj ust m ent act ivit y is sensed. Kt values can be
changed in + / - 1 point increm ent s.
4.
To ret urn, t o verify or change current Kt " default
value, depress one of t he CH set point adj ust m ent
but t ons ( once) ,
st andby m ode. Adj ust Kt value t o obt ain desired
com fort level.
8 - ELECTRI CAL CON N ECTI ON S
1 K Ω
sensor.and
1 K Ω
sensor.
or , while in any heat ing or
FI GURE 8 - 4 Therm ost a t Connect ions
FI GURE 8 - 5 Out door Sensor Connect ions
1k Ω
Sensor s used for t his boiler ar e pr opr iet ar y
N o t e
t o t he m anufact ur er. Use of aft er m ar ket
sensor s w ill dim inish boiler per for m ance.
4 4
A
Room Th e r m ost a t
240013503 REV A, [ 03/ 15/ 2022]