Solar water heating – The aztec pumping station
The Aztec Solar Water Heating pumping station
We currently manufacture the manifold (where the pressure gauge is mounted and the pipes are connected to) on the pumping station in Woodbridge, Suffolk and are in the process of getting castings made in High Wycombe to replace the silver soldered unit made in Suffolk.
We have developed the solar pumping station ourselves so that we can insure that we can provide a quick and reliable solar heating installation, the unit is pressure tested before being taken to the customers site for installation to reduce the likely hood of leaks.
Starting at the top you will see the AVV, auto vent valve. We have placed it hear instead of on the solar collector for a very good reason. Some existing installations place the auto vent valve next to the header on the solar water heating panel on the roof on the there is one problem with this. When the solar collector vapour locks in extreme temperatures over one hundred and forty celsius the ball inside of the AVV will drop and allow some vapour out and a small amount of system fluid behind it, clearly over time you can lose enough system fluid to stop the solar water heating system from working. This is why we have placed our AVV down on the pumping station away from the vapour that can build up in the solar water heating panel.
Next you will see a chamber above the pressure gauge this is used to trap and collect any air that enters the solar heating system when you first install the unit and to remove any gas that would be released from the high heat transfer system fluid when the fluid gets hot (this usually occurs after the first two weeks of operation after the initial install. Once the gas or air is trapped in the chamber you can remove it using the AVV and tap above and top up using the hand pump on the left with the high heat transfer fluid and hose pipe that we provide.
We have used a hand pump so that this unit can be placed anywhere and so that we can use the high heat transfer fluid in the solar water heating panel, some units use mains water for the system which would does not have the same properties as the fluid and would possible mean you would have to install a long run of pipe to the mains supply which may limit where you can site the pumping station.
At the top right there is a non return valve that will prevent any hot system fluid backing up and damaging the pump, (grunfoss pump in red), when the temperature on the solar water heating panel exceeds one hundred and forty celsius. On the top left you can see a pressure relief valve which is standard in all types closed circuit installations. The pipe coming into the bottom of the grunfoss pump connects to the secondary coil in the new hot water cylinder and the non return valve (on the top right) connects to one side of the solar water heating panel on the roof. The other side of the solar water heating panel connects directly to the second coil in your hot water cylinder.
We have used a standard grunfoss pump found in any normal central heating system in this unit so that it can be sourced from any DIY shop should you need to replace. It should last far longer than a pump in a boiler as it is doing less work, it only operates when there is a 5 degree difference between the hot water cylinder and the solar water heating panel. The four horizontal connections coming out of the manifold above the pump can be connecting in any way to suit your current plumbing in your house and the resol controller that regulates your solar water heating system can be removed from the backing board and place somewhere more suitable for yourself.
The last connection coming from the manifold (bottom right of the pressure gauge) is connected to the expansion vessel.