Lochinvar CW 645, CW 745 manual Water Connections, High Altitude Applications

4.A manual main gas shutoff valve is provided outside the jacket, upstream of the main gas valve.

5.In Canada, derated10% from 2,000 - 4,500 ft., over 4,500 ft. derate must be in accordance with local authorities. Consult factory for installations at higher elevations.

High Altitude Applications

Atmospheric pressure decreases as the height above sea level increases. At any altitude above sea level, a cubic foot will contain less gas than a cubic foot at sea level. Thus, the heating value of a cubic foot of fuel gas will decrease as height above sea level increases.

Specific gravity of a gas with respect to sea level also decreases with altitude. These changes in heating value and specific gravity tend to offset each other.

However, as elevation above sea level is increased, there is less oxygen per cubic foot

of air. Therefore, heat input rate should be reduced in an appliance above 2000 feet. Ratings should be reduced at the rate of 4 percent for each 1000 feet above sea level.

(TABLE E) – INLET GAS PRESSURE

MODELS	NAT. GAS	LP GAS
CW 495-745
Minimum Allowable	4”	8”
Maximum Allowable	10.5”	13”
CW 986-2066
Minimum Allowable	4.5”	8”
Maximum Allowable	10.5”	13”

WATER CONNECTIONS

Inlet and Outlet Water Connections

For ease of service, install unions on inlet and outlet of the water heater.

The connection on the unit marked “Inlet” should be used for return water from the storage tank. The connection on the header marked “Outlet” should be connected to the inlet of the storage tank. (See Appendix A for Water Heater Piping Diagrams).

EXAMPLE OF HIGH ALTITUDE APPLICATIONS

For example, if a unit’s input is 100,000 Btu/hr at sea level, the rated input at 4000 feet of elevation can be calculated by derating input 4% per 1000 feet above sea level.

[Btu/hr Input]

[1.00 - (Elevation/ 1000 ft. x 0.04)] = Btu/hr Input at specified elevation. [100,000][1.00 - (4000 ft. /1000 ft. x 0.04)]

=Btu/hr Input 4000’ elevation. [100,000][0.84] = 84,000 Btu/hr Input at 4000 ft. elevation.

(TABLE D) – GAS SUPPLY PIPE SIZING

Length of Pipe In Straight Feet

Nominal Iron
Pipe Size, Inches	10	20	30	40	50	60	70	80	90	100	125	150	175	200
3/4	369	256	205	174	155	141	128	121	113	106	95	86	79	74
1	697	477	384	328	292	267	256	246	210	200	179	164	149	138
11/4	1,400	974	789	677	595	543	502	472	441	410	369	333	308	287
11/2	2,150	1,500	1,210	1,020	923	830	769	707	666	636	564	513	472	441
2	4,100	2,820	2,260	1,950	1,720	1,560	1,440	1,330	1,250	1,180	1,100	974	871	820
21/2	6,460	4,460	3,610	3,100	2,720	2,460	2,310	2,100	2,000	1,900	1,700	1,540	1,400	1,300
3	11,200	7,900	6,400	5,400	4,870	4,410	4,000	3,800	3,540	3,300	3,000	2,720	2,500	2,340
31/2	23,500	16,100	13,100	11,100	10,000	9,000	8,300	7,690	7,380	6,870	6,150	5,640	5,130	4,720

Maximum capacity of pipe in thousands of BTU’s per hour for gas pressures of 14” Inches Water Column (0.5 PSIG) or less and a total system pressure drop of 0.05 Inch Water Column (Based on NAT GAS, 1025 BTU’s per Cubic Foot of Gas and 0.60 Specific Gravity).

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