Roberts Gorden CRV-B-2 Manual Do Utilizador

14 

The flow unit capacity of the pump is indicated on 
Page 14, Table 2, as a function of installed altitude. 
When the CRV-Series system is designed in accor-
dance with this set of instructions and is in proper 
operating condition, a vacuum from 2-3" w.c. will be 
obtainable at each end vent (i.e. at all burners).

There are a number of design requirements which, if 
not met, will reduce the vacuum obtainable and 
thereby the effective flow capacity of the pump. These 
include:

• Minimum Length of Tailpipe - If less than the 

minimum length of tailpipe is provided per radiant 
branch, there will be insufficient cooling of the com-
bustion gases and improper operation of the pump.

• Line Loss Check for Tailpipe is applicable to 

sections of tailpipe which are common to two or 
more radiant branches (i.e. shared lengths). See 
Page 14, Figure 15.

• Excessive back pressure on discharge line of 

pump can be caused by partial blockage or too 
much flow for length. See Section 5.3.1

• More than maximum number of burners or flow 

units per radiant branch. See Page 14, Table 2.

• Excessive number of elbow or tee fittings 

which increases vacuum loss.

Excessive flow loading in a single section of tailpipe 
can cause low vacuum and lower effective pump 
capacity. For the pump to develop the proper vacuum, 
the length of tailpipe must not be excessive for the 

number of flow units carried in the tube.

See Figure 15. Readings for length and flow when 
plotted on the graph must fall on OK side to avoid 
excessive vacuum losses.

FIGURE 15: Vacuum Loss Curve for 4" Shared 
Tailpipe

NOTE: For 6" (15 m) tailpipe, length is limited to a 
maximum of 100’ (30 m). See Page 16, Section 6.3 
for more details.
Lengths shown include allowance for 1 elbow every 
50' (15 m); deduct 15% of length for each additional 
elbow used per 50' (15 m) length.

The tube length on the exhaust side of the pump is 
considered excessive if not within the following condi-
tions:

Installed Altitude

Maximum Flow Units

Feet Above

Sea Level

Meters Above 

Sea Level

EP-100

EP-200 

Series

EP-300 

Series

0

'

 - 2000

'

0 m - 609 m

66

112

224

2001

'

 - 3000

'

610 m - 914 m

63

105

215

3001

'

 - 4000

'

915 m - 1219 m

60

100

206

4001

'

 - 5000

'

1220 m - 1524 m

57

95

197

5001

'

 - 6000

'

1525 m - 1828 m

54

90

188

6001

'

 - 7000

'

1829 m - 2134 m

51

84

180

7001

'

 - 8000

'

2135 m - 2438 m

48

80

170

8001

'

 - 9000

'

2439 m - 2743 m

45

75

161

Pump Series

Exhaust Tube Length Exhaust Tube Diameter

EP-100

Up to 25' (7.6 m)

4" 3 Elbows

EP-100

Up to 50' (15 m)

5" 3 Elbows

EP-200

Up to 10' (3 m)

4" 0 Elbows

EP-200

Up to 25' (7.6 m)

5" 3 Elbows

EP-200

Up to 50' (15 m)

6" 3 Elbows

EP-300

Up to 10' (3 m)

6" 1 Elbows

EP-300

Up to 25' (7.6 m)

7" 3 Elbows

EP-300

Up to 50' (15 m)

8" 3 Elbows

10

20

30

40

50

60

70

80

90

100

120

130

30 40 50 60 70 80 90 100 110 120