Solar Products
Vessel Installation Kits
The kit is designed for expansion vessels to be locted on to a suitably stable and load bearing wall. It is normally recommended that the biggest expansion vessel to be located in this way is a 25 ltr.
The kit also contains an isolation valve that enables the vessel to be taken out of the system for inspection or re-pressurisation, without the need for draining the system of its glycol mix fluid.
The kits A1 and A200 have automatically closing valves. When the expansion vessel is removed, the spring load valve shuts and closes the system. The A200 has a double closure system that compensates for if the installer disconnects the vessel and the valve union or on the vessel itself, either way, the system is safe from draining fluid.
Part code SOVK-A200 supports the vessel with a substantial steel bracket, and comes comes complete with wall fixings. A SS flexible pipe is supplied to connect the vessel to the provide male connection port on the pump station.
The M1 valve is a lock shield manual valve. The same result is achieved by manual closure of the vessel isolating valve, with the advantage that any fluid remaining in the vessel (and still under pressure) can be drained off on the valve’s drain valve – less mess!
The M1 valve is also available separately, and in a 1" version, part code SOV-3M001. See the Intaeco price list.
The Expansion Line
In brief:
- The British Standard BSEN 12976-1 does not identify any method for calculating size or length of what it calls the 'expansion line'.
- It does state that the length of pipe between the expansion vessel and the system should not cause the working pressure to exceed safe working limits due to resistance in that pipe line.
- It does say in passing that expansion lines should be laid in such a way to avoid future blockages by debris or scale.
Flow resistance or pressure drop issues for the expansion line (Annular Tube)
| DN16 |
DN20 |
| Pressure drop (mbar/m) |
Flow rate (l/m) |
Pressure drop (mbar/m) |
Flow rate (l/m) |
| 1.44 |
2.13 |
1.40 |
2.68 |
| 2.28 |
2.67 |
2.24 |
3.25 |
- The expansion line does not exist in 'flow conditions', so on DN16 and larger, pressure drop is marginal.
- The best orientation of the vessel is vertical, with the fluid chamber and system connection point uppermost. This is to eliminate areas of the chamber being capable of trapping air. Trapped air with minimal amounts of water will cause corrosion on the vessel. The expansion vessel however will work in any orientation.
Volume of expansion
A formula is available to calculate the amount of volume for expansion (as laid out in the Zilmet SolarPlus download from
Zilmet). Intaeco also provide a calculator for vessel sizing estimation.
Volume of the expansion line. Again the guidelines are in the BSi doc (should not cause an increase in working pressure due to resistance in the pipe line)
Volume in that line is dramatically increased by the introduction of an Intermediate Vessel, i.e. a vessel installed in-line with the expansion vessel to facilitate heat loss, and cool the liquid in the expansion chamber to protect the expansion diaphragm – see the Intaeco information sheets for further explanation.
Intaeco Best Practice Summary
- The expansion line should not be smaller in diameter than the largest diameter section of flow & return pipe used in the system. General rule 22mm or DN16.
- The connection to the vessel should allow the vessel to be mounted vertically, without the use of manufactured elbows or bends. General rule, use DN16 flexible SS pipe
- Heat dissipation on the expansion line is to be encouraged. General rule, do not insulate, or better still incorporate an intermediate vessel
- The expansion line should be a short as possible, but be able to facilitate the above. General rule to apply, the length of pipe should be less than 1M. (Intaeco use 520mm of DN16 in both SOVK-A1 and SOVK-M1 expansion vessel connection kits).
