Central Heating System Losing Pressure Or Leaking? - Fernox Leak Sealer F4 Express Via Radiator

[@simonw7284]

My advice applies to a combi-boiler/closed system. This is my experience! I think I would only recommend this (as in my case), if you know the leak is not your boiler which is easy to diagnose by isolating the central heating from the boiler. These are normally two red valves under your boiler. Using a screwdriver you turn off both the valves. The pipes are normally larger at 22mm in width). Turn these both off and wait 24 hours (without using the central heating! Turn the timer off (in my case I had on, off, timer, and boost. I used OFF) so no central heating is possible even if someone turns up the thermostat. You could also turn off the boiler completely but you won't have any hot water. If your pressure still drops after isolating the central heating after your period of time you have a leak in the boiler somehow. Quite simply water is escaping from the boiler when it is running. It will be leaking either from 1) the boiler (drips on the floor or the running down the wall where the boiler is) which indicates an internal leak, or a crack in the heat exchanger 2) A leak from the condensation pipe which will normally give off water during normal use. If it is dripping water when the boiler is cold you still have a problem 3) pressure release valve which is not normal to release any water unless the pressure in the central heating exceeds dangerous limits. The system will also lose pressure much more quickly if the expansion tank cannot expand. This "tank" is inside the boiler and helps to take the pressure as the central heating heats up. With heat the pressure will increase, thus this tank expands to take the increase in pressure. This tank should already be pressurised in order to take further expansion. If flat it cannot expand. Its like sucking on a flat balloon. Funnily enough, to expand this tank requires a bicycle pump! So if you think your boiler is leaking I would recommend getting someone in to investigate and not using a leak sealant unless temporary. If after determining your boiler is fine... It must be the central heating. It cant be anything else right? It cannot be if you have isolated the boiler. Its in the pipes feeding your radiators, or the radiators themselves. Check your radiators under each valve while cold or hot (both ends of a radiator). Put some kitchen towel wrapped under each valve (use some masking or other paper tape to make it easier to detect water). It doesn't take long to drop 1-bar of pressure in 24 hours with a slow drip. On hot the water may evaporate, but with some kitchen towel you may detect some evidence. Its obviously easier to detect leaks from upstairs then on the ground floor. I would say that some leaks may only occur when the central heating is either hot (expanded) or cold (contracted) so its worth checking both If after all this.. the leak is not obvious (i.e. on the ceilings or walls from upstairs) then its on the ground floor. If your pipes are buried in concrete on the ground floor (like my house) I have a slow leak. In which case use leak sealant to get you through a year. It will only work with a junction leak, or pinprick leak. To detect a leak will require specialist people whom use both heat detectors and also listening devices (which are much more accurate).

[@calvinlee1989]

In the boiler, why would you put it into the pipe where the water comes from rather than the pipe next to it where it goes to?

[@rikm555]

If your boiler is losing pressure and you can't find a leak it could be that your expansion tank needs repressurizing. You can lose water through the pressure relief valve if the tank pressure is too low.

[@DanielJohnHowTo]

thanks, out install is rather basic but that sounds like something to definitely check.

[@rikm555]

@@DanielJohnHowTo If you have a Combi Boiler the expansion tank is inside it.

[@Paul-mg7bh]

At the start of the video you turned off the radiator valve at the bottom. I watched the fernox video and it said to open this when using the sealant. Any help would be appreciated, thanks

[@rikm555]

@@Paul-mg7bh You need to close both valves initially. Then drain some water, which will come from inside the radiator and not the pipework. Then tighten it back up. Then add the leak sealer and close the bleed valve. Then open both radiator valves to their previous position. Then check and increase the system pressure. Then turn on the heating an the sealer will travel around the whole system.

[@Paul-mg7bh]

@@rikm555 Great, thanks very much

[@علیاکبرزارعی-ز4ض]

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