Install Instructions

Page 50
4.18 DIP Switches
System Control Setting
DIP switches 6 and 7 have to be set in the OFF position when the boiler is running normally.
DIP switches 1, 2, and 3 are system switches and are factory set to the boiler model and size
and should not be touched.
Maximum ame detecting voltage 2.4V
Pre-purge time Tp Maximum 10s, minimum 1s
Safety Time (igniting time) Ts 1.5s
Igniting interval time 10s
Post-purge time Tip 120S (1st : 60s + 2nd 60s)
Over-heating 1,2,3 protection detection time <2s
High & Low Water Level detection time <5s
High & Low Water Level Recover time <5s
Temperature sensor anomaly detection time <3s
APS sensor detection time <3s
800.900.9276 • Fax [phone] (Customer Service, Service Advisors)
20 Industrial Way, Rochester, NH 03867 • 603.335.6300 • Fax [phone] (Applications Engineering)
1869 Sismet Road, Mississauga, Ontario, Canada L4W 1W8 • 905.238.0100 • Fax [phone]
www.Laars.com
Document 4296D
The FT Series, Heating Only, Gas Conversion Kit
pg 3 of 4
Table B DIP Switch Settings
MBH 80 100 120 140 N/A 199
These 3 bottom switches must be set per unit SIZE.
9.
Per Table B, set DIP Switch
5 to OFF
for LP Propane.
10.
Turn ON the GAS and WATER supply to the FT.
11.
Turn ON the FT.
12.
Connect a manometer to the manifold pressure port. For dual port manometers, use the positive pressure
side. Check for proper manifold gas pressure. Refer to Table C.
ON OFF
MIN Fire Normal Operation
MAX Fire Normal Operation
NG Natural LP Propane
3” Vent Size
2” Vent Size
ON OFF ON OFF ON
ON
OFF ON ON OFF OFF
ON
OFF OFF OFF ON ON
ON
Figure D
Gas Valve for 80 to 140 MBH
Gas Valve for
199 MBH
The gas valve on
the smaller models is
mounted vertically.
Manifold Pressure Port
Manifold Pressure Port
Table C
Manifold pressure Propane Gas (LP) Natural Gas (NG)
MFTHW 80/100
-0.102 ˝ WC -0.102 ˝ WC
0.00 ˝ WC 0.00 ˝ WC
MFTHW 120/140
-0.216 ˝ WC -0.216 ˝ WC
0.00 ˝ WC 0.00 ˝ WC
MFTHW 175
-0.169 ˝ WC -0.129 ˝ WC
-0.015 ˝ WC -0.015 ˝ WC
MFTHW 199
-0.173WC -0.134 ˝ WC
-0.015 ˝ WC -0.015 ˝ WC
CO
2
value
Propane Gas (LP) Natural Gas (NG)
2˝ VENT 3˝ VENT 2˝ VENT 3˝ VENT
MFTHW 80/100
120/140/175/199
9.5~11% 8.5~10.5%
9~10.5 % 8~10%
Refer to the below table.
Manifold pressure Propane Gas (LP) Natural Gas (NG)
MFTHW 80/100
-0.102 ˝ WC -0.102 ˝ WC
0.00 ˝ WC 0.00 ˝ WC
MFTHW 120/140
-0.216 ˝ WC -0.216 ˝ WC
0.00 ˝ WC 0.00 ˝ WC
MFTHW 175
-0.169 ˝ WC -0.129 ˝ WC
-0.015 ˝ WC -0.015 ˝ WC
MFTHW 199
-0.173WC -0.134 ˝ WC
-0.015 ˝ WC -0.015 ˝ WC
CO
2
value
Propane Gas (LP) Natural Gas (NG)
2˝ VENT 3˝ VENT 2˝ VENT 3˝ VENT
MFTHW 80/100
120/140/175/199
9.5~11% 8.5~10.5%
9~10.5 % 8~10%
Refer to the below table.
13.
Establish a call for heat. You may need to disconnect the outdoor reset if you are making this gas
conversion during warm weather.
Shown is a
Model 140
with 3"
Venting and using
Natural Gas