Towel rad needs constant bleeding

[diyisfree]

I recently fitted a towel rad in the bathroom and the top rail always goes cold after a day or 2.

I keep bleeding off small amounts of air but the pressure on the combi doesnt seem to be dropping ?

The rad is quite a fancy one and i did purchase one of those auto bleed valves only to find it bottomed out on the internalls of the rad before it can make a seal.

Is it normal to get all the air from the central heating in the highest rad ? and if so, how much longer should i expect to bleed it before it finally stops.

 

[Softus]

I recently fitted a towel rad in the bathroom and the top rail always goes cold after a day or 2.

I keep bleeding off small amounts of air but the pressure on the combi doesnt seem to be dropping ?

In that case you probably have a leak on the filling loop valve. Which boiler is it?

Is it normal to get all the air from the central heating in the highest rad ?

Yes.

how much longer should i expect to bleed it before it finally stops.

If it's still collecting air/gas after a couple of days, you have a problem.

 

[diyisfree]

Softus,

The boiler is a Baxi 105he instant. It was fitted 2 months ago.

The filling loop is disconected so it cant be topping up the boiler if thats what you are thinking.

The pressure gauge is set to 1.5 bar when its cold. Obviously it increases once the boiler kicks in and the temp increases.

I check every day and the pressure is the same. Its only the top bar of the towel rad that goes colder than the rest and its litterally open the bleed screw for 2 seconds and then water appears so it cant be much air.

Guess i'll keep bleeding till it stops, if it ever does

 

[ChrisR]

Corrosion will produce hydrogen gas. Test with inverted "test tube" as we all did at school (??).
(move the towels before lighting it!)

 

[diyisfree]

will it work if i just light the escaping air/gas when i open the bleed screw?

To be honest, The system is clean as a whistle. The water that comes out is clear and when i dropped the water to fit the rad, it was clear.

 

[JohnD]

But does the system contain a chemical corrosion inhibitor?

The black sediment will be hiding at the bottom of the old radiators, or possibly trying to collect inside your boiler and pump where it can cause a problem.

 

[diyisfree]

John,

If you recall a couple of months ago i posted on here regarding that i had fit my own new central heating. I fit a baxi 105 and replaced every radiator in the house for new ones.

I used a small section of the old pipework and replaced the rest. I flushed the system and each radiator in turn by filling through the loop and then draining each rad through the drain off lockshield ( i have fitted every rad with a drainoff)

I filled the system with sentinal flushing solution, the eone where you fire up the boiler for an hour then drain it all again. Once i did this i then repeated the flushing on each radiator. It looked rather funny with an hose pipe stuck out of the bedroom windows with watet gushing out

I then added the sentinal corrosion inhibitor and re filled the system. I had to drain down the system when i fitted the towel rad because it was going on a different wall of the bathroom and the water was clear. I then re filled again and added another sentinal inhibitor.

I have checked every rad for leaks, every connection, boiler connections and i cant find a leak.... I got an auto bleed valve BUT it is too long and bottoms out before it seals on the rad...

How are you by the way john ? You have always been very helpful with my problems in the past.... Do you still have the fetish about RCBO's

 

[JohnD]

Yes

It seems to me that the gas is either the product of corrosion (and will ignite if hydrogen) or air being sucked in from a tiny leak on the return side of the pump.

 

[diyisfree]

Ok here goes. I have my Rothenberger at the ready and a full face mask.....

Anyone got a fire extinguisher in case the place goes up