Mod Con MODCON500, Installation Manual

Page: 7 / 68

LP-446-r4 Rev. 10.12.16
7
Part 2 - Before You Start
CAUTION
VWH units must be connected to a storage tank. You must not have a direct connection of the potable water system into the heat
exchanger. This could cause flow issues, short cycling, and an increase of mineral build-up in the unit. This system is designed
to have incoming potable water flow through the storage tank first, then through the heat exchanger. Failure to connect the
VWH boiler to a storage tank of the minimum size requirements (119 gallons for a single 500VWH; 175 gallons for a single
700/850VWH) will result in property damage and/or premature boiler failure. Damages resulting from incorrect installation or
from use of products not approved by HTP, Inc. ARE NOT covered by warranty.
∆T
(Delta T)
(
o
F)
500VWH 700VWH 850VWH
Gallons
Per Hour
First
Hour
Rating
119
Gallon
Tank
First
Hour
Rating
175
Gallon
Tank
First
Hour
Rating
200
Gallon
Tank
Gallons
Per Hour
First
Hour
Rating
119
Gallon
Tank
First
Hour
Rating
175
Gallon
Tank
First
Hour
Rating
200
Gallon
Tank
Gallons
Per Hour
First
Hour
Rating
175
Gallon
Tank
First
Hour
Rating
200
Gallon
Tank
First
Hour
Rating
300
Gallon
Tank
Contact HTP for Available
Storage Tanks
Contact HTP for Available
Storage Tanks
Contact HTP for Available
Storage Tanks
40
o
1414 859 883 894 1980 1206 1217 1260 2404 1449 1459 1502
50
o
1131 872 902 915 1584 1225 1238 1292 1923 1467 1481 1534
60
o
943 884 920 937 1320 1244 1260 1324 1602 1486 1502 1566
70
o
808 897 939 958 1131 1262 1281 1356 1374 1505 1524 1599
80
o
707 910 958 979 990 1281 1303 1388 1202 1524 1545 1631
90
o
628 923 977 1001 880 1300 1324 1420 1068 1542 1566 1663
100
o
566 935 995 1022 792 1319 1345 1453 961 1561 1588 1695
110
o
514 948 1014 1044 720 1337 1367 1485 874 1580 1609 1727
120
o
471 961 1033 1065 660 1356 1388 1517 801 1599 1631 1759
130
o
435 974 1052 1087 609 1375 1410 1549 740 1617 1652 1791
140
o
404 986 1070 1108 566 1394 1431 1581 687 1636 1674 1824
Table 2 - VWH Ratings with Storage Tanks - NOTE: Gallons Per Hour Does Not Take a Storage Tank into Account
Min Tank Size (Gal.) = Required Flow (GPM) X 10
Mixing Factor (M
f
) = VWH Outlet Temp - Inlet Temp
70
First Hour Rating = Total VWH Output X VWH Efficiency + .75 X Total Storage X M
f
[
(VWH Outlet Temp - Inlet Temp) X 8.31
]
Example:
2 500VWH Boilers - Total Output = 1,000,000 BTU @ 94% Efficiency
VWH Outlet Temp = 140
o
F - Inlet Temp = 40
o
F
2 Storage Tanks (119 Gallons Each) =Total Storage = 238 Gallons
Mixing Factor (M
f
) = 140 - 40
= 1.43
70
First Hour Rating = 1,000,000 X .94 + .75 X 238 X 1.43
[
(140 - 40) X 8.31
]
First Hour Rating = 940,000 + 179 X 1.43
[
831
]
First Hour Rating = [1,131 + 179] X 1.43
First Hour Rating = 1,310 X 1.43
First Hour Rating = 1,873 Gallons