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EndoTherm – Installation Guide
EndoTherm is quick and easy to install into any wet heating system. Most installations can be completed without interruption and with no heating system downtime. Like an Inhibitor, EndoTherm can be installed into a heating system in a number of ways:
EndoTherm Installation Instructions

Dosing Pot
- Confirm boiler system is online, circulating and at operating temperature.
- Ensure fill valve A, drain valve D and vessel vent valve are all closed.
- Open inlet and outlet valves B & C.
- Wait for a few minutes and confirm vessel becomes hot, proving adequate circulation is available through the dosing pot.
- Close inlet and outlet valves B & C.
- Place a suitable container under the dosing vessel drain or confirm presence of a floor drain immediately below the vessel.
- Release pressure from the dosing vessel by either cautiously opening the vent valve or slightly opening drain valve D. CAUTION – emitted system water will be very hot.
- Once the pressure has been removed, fully open drain valve D and the fill valve A to fully drain the dosing vessel.
- Once drained, close drain valve D and the vent valve.
- Fill the dosing pot with product via fill valve A.
- Once the dosing vessel is full, close fill valve A.
- Slowly open inlet & outlet valves B & C fully.
- Depending upon flow rates the dosing vessel should be left in this position for several minutes until the dosing vessel surface temperature is equivalent to the system operating temperature.
- If multiple fill cycles are required to complete the dose, repeat steps 5-13.
On completion of required dosing it is common practice to leave the dosing pot in an isolated state with the inlet & outlet valves closed, however customer premises may have a different preference and leave the dosing pot circulating.

Normal Radiator
If you have a combi-boiler then you need to remove some water from the system. The system will be pressurised. Switch off the boiler and find a suitable radiator with a drain valve fitted or a drain valve at the boiler. Slowly vent the system to relieve the pressure. There will be a small screw at the top of the radiator for this purpose. When loosened, you will hear and see the water pressure drop. Use a cloth or towel to collect the small amount of water which is vented.
When vented, close the radiator inlet and outlet valves. You now need to make space for the EndoTherm to be added. On the radiator side of the inlet or outlet valve, release the valve joint with a suitable spanner. Collect a litre of water and then tighten up the joint.
Remove the plug from the top of the radiator. attached the provided EndoTherm installation kit (left), pour in the EndoTherm. Reinstall and tighten the plug. Ensure that the vent bleed screw is closed and tightened. Open the radiator inlet and outlet valves.
The system will now contain some air. Start up the boiler and gently bleed air from all of the radiators via the bleed screw. Re-pressurise the boiler system to the manufacturers’ recommended pressure (usually about 1 bar).
There are two dials one of which is the pressure dial and the other which is the temperature. Below the boiler is a filling loop which comprises of a flexible pipe, a handle and a double check valve. The double check valve prevents water from the central heating being sucked back into the cold water supply for the house.
The pressure dial should have a red line on it to signify the minimum pressure required for the boiler to work. This dial will increase in pressure when the combi is heating water so ensure that the central heating part is off and that no hot water is being drawn. If there is no red line then check the manual for the combi as putting too much pressure in the boiler will cause the blow off valve to blow, which will be vented outside of the property.
Most boilers require just over 1 Bar of pressure when switched off. If the pressure is below the minimum required for your boiler then slowly open the valve on the filling loop, this normally has a handle attached but a suitable tool may be needed. You should hear the water moving into the combi! Keep an eye on the pressure dial and when it reaches the correct pressure turn the valve off!
You can now use your boiler as normal.

Magnetic Filter Unit
- Turn off your boiler.
- Isolate the magnetic filter by closing the valves either side of it.
- Slowly open the valve at the bottom of the filter and drain the contents into a container, please use caution as this water may be very hot.
- When the vessel is empty close the valve just used for drainage, then open the filter by unscrewing the lower body.
- Fill the lower filter body with EndoTherm and re-attach.
- Re-open the valves either side of the magnetic filter once it is back in place. This will admit the boiler system water back into the magnetic filter.
- Switch the your boiler back on. The pump will distribute the EndoTherm throughout the system.
If your system requires more EndoTherm than the lower filter housing will accommodate allow 15 minutes for the initial charge to circulate then repeat the procedure until all EndoTherm required is installed.

Towel Radiator

Header / Expansion Tank
To drain the tank either tie up the ball valve or isolate the water feeding it, then drain off all of the water present in the tank via a radiator or drain valve at the boiler if present. If no drain valve is present, using a suitable spanner release the joint at the radiator inlet valve and collect the water in a container.
Pour the EndoTherm into the expansion tank and turn the water back on, bleed the radiators until all air is expelled from the system