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Contractor > Proper Tank Sizing > Hydronic Systems

Online Tank Sizing

To properly size your Flexcon hydronic tank you will need to obtain the following information:

  • Total system water content including boiler, piping and terminal units
  • The initial system fill water temperature
  • The maximum water temperature
  • The system fill pressure in PSI
  • The maximum operating pressure (use 10% below the relief valve setting)
  •  

Once these factors are known, the following calculations will determine, in most cases, the correct model to meet your specifications.*


Required Information

1. Total system water content

Gallons
2. Initial fill water temperature

F
3. Maximum water temperature

F
4. System fill pressure

PSIG
5. Maximum pressure (10% below relief valve)

PSIG

Tank Selection

6. Enter total system water content (form line 1)

Gallons
7. Enter Expansion factor from Table 1
8. Expanded water volume( line 6 X line 7)

Gallons
9. Acceptance factor from Table 2
10. Total tank volume required (divide line 8 by line 9)

Gallons

Hydronic Tank Chart

Select a Flexcon tank below which satisfies both line 8 and line 10. For larger systems, multiple tanks may be manifolded together to meet system requirements. For systems containing propylene glycol please contact customer service.

Model Total
volume
(gallons)
Maximum
Acceptance
(gallons)
Dimensions
Diameter
(inches)
Length
(inches)
Weight
(lbs.)
ASME* Non-ASME
N/A HTX15 2.1 1.0 8.0 12.5 5.5
N/A HTX30 4.5 2.5 11.0 14.0 10.0
HTC 60 C HTX60 6.0 3.0 11.4 17.2 11.5
HTX 90 C HTX90 15.0 6.0 16.0 20.8 28.0
SXHT 30 C SXHT30 15.0 6.0 16.0 21.7 32.0
SXHT40 C SXHT40 20.0 8.0 16.0 28.8 39.0
SXHT 60 C SXHT60 33.0 13.4 16.0 42.8 57.0
SXHT 90 C SXHT90 44.0 17.7 21.0 36.2 72.0
SXHT 110 C SXHT110 62.0 25.0 21.0 47.9 112.0
SXHT 160 C SXHT160 81.0 32.6 21.0 62.0 123.0
SXHT 180 C N/A 90.0 36.0 24.0 52.0 283.0
SXHT 210 C N/A 115.0 46.0 24.0 66.0 325.0
SXHT 250 C N/A 140.0 56.0 24.0 78.0 362.0

*Dimensions for HTC 60 C thru SXHT160C are different from this chart.
Please refer to the ASME section.

Table 2
Acceptance Factors
 Hydronic and Thermal tanks
Po Maximum Operating Pressure (PSIG) Pf-Minimum Operating Pressure at Tank (PSIG)
  12 20 25 40 50 60 70 80 90
27 0.36 0.168              
30 0.403 0.224 0.112            
50 0.587 0.464 0.386 0.155          
70 0.685 0.59 0.531 0.364 0.236 0.118      
90 0.745 0.669 0.621 0.478 0.382 0.287 0.191 0.096  
110 0.786 0.723 0.682 0.561 0.481 0.401 0.321 0.241 0.16
130 0.815 0.76 0.726 0.622 0.553 0.484 0.415 0.346 0.277
150 0.838 0.789 0.759 0.668 0.608 0.547 0.486 0.429 0.365
Table 1
  Expansion Factors
Final Temp Initial Temperature
  40 50 60
100 0.00575 0.00569 0.0052
110 0.00771 0.00765 0.00716
120 0.01004 0.00998 0.00949
130 0.01236 0.0123 0.01181
140 0.01501 0.01495 0.01446
150 0.01787 0.01779 0.0173
160 0.02092 0.02086 0.02037
170 0.02418 0.02412 0.02363
180 0.02763 0.02757 0.02708
190 0.03127 0.03121 0.03072
200 0.0351 0.03504 0.03455
210 0.03911 0.03905 0.03856