Bubling radiator after TRV fitted

[ivanov]

I have Keston Gas boiler with a pressurized central heating currently set to 1.2 bar. The system is 5 years old and I recently have drained to install 5 Drayton TRV. After running it with Fernox restorer for a week I add Fernox Protector and bled all the rads, pump multiple times (with the pump off and TRV set to Max) and I also have de-airiator (or whatever is called) next to the pump but 2 radiators upstairs are still making some bubbling noises when the CH starts. I've turned the pump to min (from III to I) and this has improved the situation but I can still hear the bubbling when the CH starts. Also I have realised that I've fitted some of the TRVs on the return part of the flow but this should not matter, based on Drayton instruction TRV being bi-directional. It seems to me that I'm getting air into my CH (because always one if the radiator downstairs close tot he boiler have air in it) but there are no leaks from anywhere OR there is an air that I can't get rid off. Any ideas of suggestions will be highly appreciated. Thanks

 

[ChrisR]

Did you flush out the restorer? Could be some sort of reaction?

Some systems DO take a few weeks to settle down - unsatifactory answer I know and I don't now why.

It's possible you have a Micro Leak taking air IN, this will be near the input side of the pump.
Try running it at higher pressure. There was a thread here where the system took air in until he set the minimum at 1.4 bar. Make sure it doesn't go above 2.5 though cos the release valve might start leaking then.

 

[ivanov]

ChrisR, I flushed the restorer by refilling the system few times and draining it, but it seemed that I haven't done a great job because now the water in the system is a bit coloured from the restorer.

 

[doitall]

Try turning the valve off one end when you bleed it then open it and turn the other end off and bleed again.

Does the air smell like rotten eggs.

Running the pump at its highest setting will shift air into the rads whereas the lowest speed may not.

 

[ivanov]

I've tried to increase the pressure as well as bleeding the rads with one valve open at a time. The air didn't smell nice and also from time to time instead of the normal water flow there was something like a "fizzy water" coming out from the bleed valve (is that air?). It seems to me that my system is getting air from somewhere because I can't get rid of the bubbling noise. Any ideas if Fernox"Leak Sealer" can cure the problem?

 

[ivanov]

Is it possible if I didn't flush properly the Fernox restorer, the small remainder can get into some chemical reaction with the water and/or Fernox protector and generate gas or air?

 

[bripl]

yes more than likely

 

[ivanov]

OK I guess I have to flush the CH properly then. The problem is that the drain valve is above my boiler, higher than all downstairs rads. What I've done is drain the system trough the drain valve, refill it , switch pump on for few minutes and drain it again. After I've done this for about 6 times I've drained all the downstairs rads one by one but still there was some leftover from the restorer. Any ideas haw to flush the system more efficiently so I can get rid of all the chemicals?