Online support - cylinders
We’ve collated a set of frequently asked questions to help you to diagnose any system issues. If you’re still experiencing any problems, please contact our technical support team via email@example.com or give them a call on 01404 540745 (available from 8am to 5pm, Monday to Friday).
Faulty Flow switch
When the hot water tap is opened does the shunt pump operate and when the tap is closed does the shunt pump stop?
Shunt Pump – Boiler pump on older systems – Gate valves closed
When a hot water tap is opened does the 2 port zone valve open and start the boiler pump?
Blending valve fault
Can you alter the input temperature to the manifold? If not remove the white head and check that the pin valve is moving freely.
Air in the top of the cylinder – Faulty AAV
Make sure that the black cap on the AAV is always on loose – remove the red cap and poke a small screw driver down the hole to rapid purge. If air is present then replace the AAV.
Heat exchanger blocked or restricted
Double check the inline strainer – remove all pipework and blow down the HX with your hand over the hole to check resistance. If the HX is blocked then an acid cleaner can be used to unblock it
Cylinder thermostat faulty or temperature set incorrectly
Make sure that the cylinder thermostat is set at least 5°C higher than the boiler setting. Turn the thermostat up and down and listen for a click. If it will not click then replace.
Call a gas safe engineer
Zone valve faulty
Remove the actuator head and exercise the mechanical valve underneath. Otherwise replace the whole valve.
Faulty wiring connection on wiring board
Remake all connections
Faulty relay on wiring board
The relay will be either permanently on or off – replace the wiring board
Non return valve on DHW loop letting by
Replace the Non return valve with a new one
Pressure Loss on System
1. Visual check on manifolds, cylinder including PRV, AAV and expansion
2. Re-pressurize system and isolate all manifolds. Check which side drops in pressure
3. Temperature pressure relief valve letting by – check for a weep from the connected pipework
4. Check expansion vessel on boiler side
5. Check boiler blow off valve
Pressure Rise on System
1. Filling loop left on or letting by – double check that the filling loop has been left on – make sure that both black isolation valves are at 90°C
3. Expansion vessel failure
Circulation pump failure
Check the air side for pressure if no pressure try to repressurize using a foot pump it this does not work then replace the expansion vessel – With the system cold the expansion vessel should hold a charge slightly over system pressure.
Choose your cylinder from the list below to determine your spare part requirements.
Assembly for Nu-Heat 300 litre Solar EnergyMaster thermal store – (click to expand)
Assembly for Nu-Heat 300 litre EnergyMaster thermal store
Assembly for Nu-Heat 210 litre Solar EnergyMaster thermal store
Assembly for Nu-Heat 210l EnergyMaster thermal store