Grundfos · ASME Buffer Tank
GCBT Chilled Water Buffer Tank
30 builds: 6 capacities from 120 to 1,040 gallons, each with 3 to 10 in flanged connections.
125 PSI Max Working Pressure
ASME Section VIII Div. 1
Up to 450°F
120-1,040 Gallons
3 to 10 in Flanged System Connections
Steel, Red Oxide Primer
3/4 in Top Vent, 1 in Bottom Drain
Overview
Grundfos GCBT tanks add water volume to chilled water and process cooling loops. A small loop turns over too fast for a chiller’s controls, so the compressor short-cycles and loop temperature swings. A buffer tank adds thermal mass: the chiller runs longer, steadier cycles and supply temperature holds tighter.
GCBT tanks are ASME-built steel vessels in 6 capacities, each with 3, 4, 6, 8 or 10 inch flanged system connections, a 3/4 in NPT top vent and a 1 in bottom drain. They ship in red oxide primer, ready for insulation and finish paint on site.
What Ships and What It Needs to Run
Included: the GCBT tank with flanged system connections, vent and drain connections.
Ships: about 410-2,138 lb by model, by LTL freight to a commercial dock; liftgate or residential delivery is a paid checkout option. Larger tanks ship on their own skid or base ring.
Needed to install: isolation valve and drain at the system connection, a pressure gauge or tire gauge to set the pre-charge, and a level floor or pad rated for the full-of-water weight.
Genuine Grundfos equipment, factory-new in original packaging — sold and supported by Watermain Supply, an independent industrial supplier.
Specifications
| Tank type |
Buffer (thermal mass) tank, no bladder |
| Code |
ASME Section VIII Division 1 |
| Max working pressure |
125 PSI |
| Max temperature |
450°F |
| System connections |
3, 4, 6, 8 or 10 in flanged (the model suffix, e.g. -6F) |
| Vent and drain |
3/4 in NPT top vent, 1 in bottom drain |
| Finish |
Red oxide primer |
Models, Part Numbers and Weights
| Model |
Part no. |
Gallons |
System connection |
Dia. x height (in) |
Weight (lb) |
| GCBT-120-10F |
99470392 |
120 |
10 in flanged |
24 x 60 |
410 |
| GCBT-120-3F |
99444064 |
120 |
3 in flanged |
24 x 60 |
410 |
| GCBT-120-4F |
99470388 |
120 |
4 in flanged |
24 x 60 |
410 |
| GCBT-120-6F |
99470390 |
120 |
6 in flanged |
24 x 60 |
410 |
| GCBT-120-8F |
99470391 |
120 |
8 in flanged |
24 x 60 |
410 |
| GCBT-200-10F |
99470397 |
200 |
10 in flanged |
30 x 72 |
555 |
| GCBT-200-3F |
99470393 |
200 |
3 in flanged |
30 x 72 |
555 |
| GCBT-200-4F |
99470394 |
200 |
4 in flanged |
30 x 72 |
555 |
| GCBT-200-6F |
99470395 |
200 |
6 in flanged |
30 x 72 |
555 |
| GCBT-200-8F |
99470396 |
200 |
8 in flanged |
30 x 72 |
555 |
| GCBT-300-10F |
99470403 |
300 |
10 in flanged |
36 x 72 |
690 |
| GCBT-300-3F |
99470398 |
300 |
3 in flanged |
36 x 72 |
690 |
| GCBT-300-4F |
99470399 |
300 |
4 in flanged |
36 x 72 |
690 |
| GCBT-300-6F |
99470400 |
300 |
6 in flanged |
36 x 72 |
690 |
| GCBT-300-8F |
99470402 |
300 |
8 in flanged |
36 x 72 |
690 |
| GCBT-500-10F |
99470270 |
500 |
10 in flanged |
42 x 90 |
1,150 |
| GCBT-500-3F |
99470404 |
500 |
3 in flanged |
42 x 90 |
1,150 |
| GCBT-500-4F |
99470405 |
500 |
4 in flanged |
42 x 90 |
1,150 |
| GCBT-500-6F |
99470406 |
500 |
6 in flanged |
42 x 90 |
1,150 |
| GCBT-500-8F |
99470407 |
500 |
8 in flanged |
42 x 90 |
1,150 |
| GCBT-850-10F |
99471473 |
850 |
10 in flanged |
54 x 96 |
1,945 |
| GCBT-850-3F |
99471465 |
850 |
3 in flanged |
54 x 96 |
1,945 |
| GCBT-850-4F |
99471468 |
850 |
4 in flanged |
54 x 96 |
1,945 |
| GCBT-850-6F |
99471470 |
850 |
6 in flanged |
54 x 96 |
1,945 |
| GCBT-850-8F |
99471472 |
850 |
8 in flanged |
54 x 96 |
1,945 |
| GCBT-1040-10F |
99471494 |
1,040 |
10 in flanged |
60 x 96 |
2,138 |
| GCBT-1040-3F |
99471478 |
1,040 |
3 in flanged |
60 x 96 |
2,138 |
| GCBT-1040-4F |
99471479 |
1,040 |
4 in flanged |
60 x 96 |
2,138 |
| GCBT-1040-6F |
99471480 |
1,040 |
6 in flanged |
60 x 96 |
2,138 |
| GCBT-1040-8F |
99471493 |
1,040 |
8 in flanged |
60 x 96 |
2,138 |
Weights are Grundfos’s published figures (approximate shipping weight). Dimensions in inches. Tanks over 150 lb ship by LTL freight.
Before You Buy — The Limits That Decide the Fit
| Sizing |
Most chiller makers state a minimum loop volume in gallons per ton; the tank makes up the difference between that and the piping volume. |
| Pressure |
125 PSI max. Higher pressures, NPT connections (1 to 2-1/2 in) and flanges up to 20 in are factory options: call for a quote. |
| Insulation |
Insulate on site for chilled water to prevent condensation. |
Applications
Chilled water plants with small loop volume, process cooling, heat pump and data center cooling loops, and hot water systems that need added thermal mass.
Materials of Construction
| Shell and heads |
Steel |
| Finish |
Red oxide primer |
