This article will look at how to add inhibitor directly into a radiator via a pressure sprayer.
It’s common to use this method if you have a pressurised heating system and it’s also one of the more complex ways of adding inhibitor to your system. For this reason, we recommend that you tackle this job only if you have done some plumbing before and if you have fairly extensive knowledge of your system.
Before starting, remember to turn off your heating system, making sure the boiler is off and that it’s completely electrically isolated.
Firstly, turn the radiator you’ve chosen to add the inhibitor into off at both ends. Then use a standard radiator bleed key to open up the air valve and dissipate any pressure in the radiator. Use a towel to catch any drips or spillages.
Take a pair of adjustable spanners and remove the nut that houses the air bleed valve. If possible, be as quick as you can when removing the nut and replacing it with your adapter valves. This will avoid any water coming out and making a mess.
Attach your hose to the adapter, tighten it up and ensure your hose is firmly attached to your pressure sprayer. Pour your inhibitor into the pressure sprayer and open up one of the radiator valves. Start methodically pumping the pressure sprayer so that the inhibitor flows into the radiator and continue to pump a little air into the rad after all the inhibitor has gone into the system. Turn off the valve you previously opened and release the pressure valve on the pressure sprayer until all the air has escaped.
Remove your hose from the valve at the side of the radiator, unscrew and remove the valve and replace it with the bung that houses the air bleed. As before, do this as quickly as you can to avoid any water coming out. Again, use your radiator key to shut the air bleed valve and open up both of the radiator valves. Open up the air bleed valve again to allow the cushion of air you pumped in to escape, and have your towel close at hand to catch any water.
At this point you can turn your heating system back on and release more air via the air bleed if necessary. If you have a pressurised system, set the pressure to where you think it should be. If you have a feed and expansion system, it’s likely that you don’t need to do anymore, although you may wish to take a quick look in your loft just to double check everything is ok.
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Video - How to add inhibitor to your pressurised heating system
Article by Benjamin Clarke