Selgas
1. The purpose of the limiting valve is to ensure that the cylinder is not subjected to excessive cold water inlet pressure which can affect the operation of the TPR valve.
2. The purpose of the cold water relief valve is to ensure that should the pressure applied within the system exceed the valve setting it will discharge colder water thus saving you energy in running costs.
3. Fit the pressure limiting valve first if this does not stop the hot water relief valve from continually discharging you will have to replace the HW TPR valve as well.
4. Fitting a cold water relief is a manufacturers recommendation and is not compulsary, however I would strongly recommend you do in fact fit one – remember to get on rated at 70% of that of the hot water relief valve. 
Selgas Services Ltd
Craftsman Gasfitters, Plumbers, Electrical Service Technicians
