Quality, Innovation, Simplicity taswildlife@gmail.com

Connecting the tubes to your MH panel.

Fittings to connect your Heliatos Panel

Choosing the Right Fittings

The Heliatos MH-38 panels have (two) X 3/8 inch copper tube compression outlets. Not all 3/8″ brass compression fitting supplied in Australian plumbing shops will fit the MH-38 panel’s brass compression nuts. The nuts are manufactured so they can rotate but they are fixed permanently to the panels outlets. SolaExchange supplies a range of 3/8″ brass compression fittings that have the correct thread for these nuts enabling Australian installers to adapt or go directly to any Australian plumbing system.


SolaExchange offers two types of brass fittings for this purpose. The first type has 3/8″ compression at both ends. These come in a straight union and a 90 degree elbow                          1a) The straight union is used to; join two or more panels together. A straight union will be needed every time an extra panel is added.                                                                                                                       1b) The straight union is also used to join either 3/8″ copper tube or 3/8″ John Guest tube to the panel. A tube insert and nylon ferrule are added to modify the union’s conversion to 3/8″ John Guest tube.                                                                                                                                                                                        1c) A 3/8″ compression elbow can also be used to join 3/8″ tube to the panel where the tube needs to go directly down from the panel or to run parallel to the panels side. The elbow can be swivelled and fixed at any point that is at 90 degrees to the outlet.


A)   Used to join panels together

B)   Used to Join 3’8″copper or 3/8″ John Guest tube to the panel

C)  Used to Join 38″ tube to 3/8″ tube





Replaces the straight union and used in the same way as B) and C) above. Can be used with 3/8″ copper tube or 3/8″ John Guest tube when modified with a tube insert and nylon ferrule.




The second type of fitting is 3/8″ compression to BSP. These fittings allow one end to be joined to the panel and the other has a BSP thread that is compatible with Australian plumbing systems. This means any Australian plumbing system can be joined to the Heliatos MH-38 panel. This allows the outside connection to be as neat as possible without the need for extra adaptors SolaExchange stocks four BSP thread compression fittings. These are:

3/8″ compression to 3/8″ BSP male. Also available in half inch BSP male thread







               Connecting 3/8″ John Guest Tube

The same brass compression fittings are used for 3/8″ John Guest tube as for copper tube but they are modified to work with heat resistant John Guest 3/8″ plastic pipe. A nylon ferrule (olive) replaces the brass one supplied with the fitting and a brass tube insert is fitted into the end of the tube to reinforce it for hot water applications.

John Guest compression union. Showing the nylon ferrule and tube insert

John Guest 3/8″ Tube and Fittings                                                                    Approved for use with potable (drinking) water. This tube is rated to 150 psi (6 bar) at 150 degrees Fahrenheit (65 Celsius) That’s 30 psi (5 bar) higher than the 12 mm John Guest tube that is sold in boat and caravan supplies stores. This tube curves to a fairly tight radius especially when gently heated with a heat gun or hair dryer. It can be more easily routed than the 12 mm version. It is suitable for the Heliatos Solar Water Heating Panel when there is no more than 5 meters distance from the panel to the hot water tank. That’s a total return length of 10 metres. 12 metres being the outside maximum

If you would like buy the 3/8″ John Guest tube and fittings or the RV Plumbing Kit from SolaExchange there is is some important information you should consider first.

3/8″ John Guest tube and fittings are not “watermarked” as is the 12mm John Guest system. The tube and fittings in both systems are made from the same materials. If you search the specifications you will find the 3/8″ tube is rated to a higher pressures at same temperatures as the 12 mm. Both are rated for use in drinking water applications

The RV Kit is designed for owners who wish to install their own Heliatos Solar Water Heating System on their own vessel, vehicles.and caravans. If you take responsibility for your own installation you may consider the 3/8″ John Guest plumbing as a viable option

If you need your Solar Hot Water System system to meet the Australian Standards for domestic (home) installations then you will probably need to use copper tube, install a tempering valve and have your system professionally installed by a plumber.

SolaExchange freely provides this information with the clear intent of offering the best available options to its Australian customers. By offering 3/8″ John Guest tube and acetel plumbing fittings SolaExchange takes no responsibility in the case of failure of the 3/8″ tube or fittings or any fault due to its installation

This product is supplied for use with the Heliatos solar water heating system only !. Although the 3/8″ John Guest system is made from the same materials as the 12 mm John Guest tube and fittings that are available in stores stocking boating and RV accessories and the tube is rated to higher pressures at the same temperatures but it is not “water marked” as is the 12 mm JG system. Therefore the responsibility for installing this product rests solely with the customer and those persons installing it