N.Design Studio

Pond heating

Pipe unions
View of complete union When lengths of pipe are attached to items such as the heat exchanger and the pipe connections are joined with solvent then it is important that some type of union is used so that the pipes can easily be disconnected if it is necessary to remove the unit for any reason.
90<sup>o</sup>elbow (plain/threaded) These three black & white photos show the three elements that make up the union as shown above.
The union bush X is glued on to one length of pipe.
90<sup>o</sup>elbow (plain/threaded) The union end Y is then glued on to the other length of pipe. When it is mated together with element X then the O-ring will create the seal.
90<sup>o</sup>elbow (plain/threaded) The union nut Z passes over the union end Y, and then screws on to the thread on X. This is tightened up until the seal is made. Do not over tighten.
This assumes that the other end of the pipe is free. If it has already been attached to a fitting then the nut Z must be passed over the pipe before element Y is glued in place.
   
TIP. These unions are expensive at almost £10 for the 2 inch size. If possible leave at least two inches of pipe between the union and the next fitting. If you have to change the pipework at a later date then you can cut the pipe two inches away from the union and use a straight socket to join it to a new length of pipe and so use it again. New O-rings can be purchased.