Furthest away rad not heating

[paddyhamill]

Hi everyone
I recently put fernox in my closed system through the pressure release valve in my burner. Since then the furthest away rad refuses to heat.
I had trouble with the same rad when i had an open system. This was the reason i put the red tank in the attic. Since i done this the rad heated up to a temp to take the chill out of the room, this was all i wanted as its only a utility room.
I should also mention that this rad is a drop feed, the feed pipe is warm all the way down the wall but no heat at the rad, the return pipe is freezing.
I have tried bleeding the rad but just getting water. I have also closed all the rads off and it has made the problem rad piping hot, so its not an air problem. I then turned the radiators on one at a time at seperate intervals, then the problem rad just goes cold.
I have also turned the gauge on the red tank up to 3, i know it should only be at 2 but i'm trying to get it to heat again.
Why would this rad have stopped heating after the introduction of fernox?
The pump at the burner is going because i can hear it and all the downstairs rads are working fine expect the drop feed one in the utility room.
I have tried balancing the system by judging the temp with my hand. None of the rads are turned up full but yet it still won't push the heat down again.

Please help me

Thanks
Paddy

 

[Agile]

What Fernox product?

Have you done a bucket test at each valve of the problem rad?

Have you balanced the rads?

Tony

 

[Boilerman2]

Your system needs balancing or a larger circulation pump may be required
more info on system would help

 

[paddyhamill]

thanks for the reply folks.

I am not sure what type of fernox i used, it was just a 1litre jar from the local plumbers. Would the type of fernox cause this problem??????

The pump is from CIRCULATING PUMPS. CP53
Code 8204E0602

Can you please tell me what the bucket test is?

The system is heating 9 rads. 5 of which are doubles. The system is 6 yrs old.

Thanks
Paddy