Radiator requires frequent bleeding

[talkingcats]

Hi, I live in a 4-bedroom detached house with 13 hot water radiators driven by an Ideal condensing boiler installed a couple of years ago.

Every radiator comes on uniformly hot when in operation except the radiator in my en-suite bathroom. This radiator is hot at the bottom and much cooler at the top. Typical symptoms of an airlock, right? So I bled the radiator. Some trapped air hissed out and the radiator was uniformly hot in operation again . But after a month or so the problem came back. I bleed the radiator again and everything is right again for a month then I have to bleed again.

This has been going on for some time. I think it was happening before the boiler was replaced but can't remember as I wasn't being proactive in bleeding radiators in those days

Can anyone suggest possible reasons why this airlock is continually coming back and whether fixing it is a suitable DIY job? Frankly if it expensive to diagnose or fix the problem then I'll just put up with it. Spending five minutes bleeding the radiator every month is not such an awful job. The problem does not happen with any other radiator in the house.

Any thoughts gratefully received

Thanks

 

[Jurassicspark]

Was corrosion inhibitor added?

Have you been noticing frequent pressure drops?

 

[HERTS P&D]

Open vented? Check the pump speed and /or fit an auto bleed on the radiator.

Aladdin Auto Airvent

• Eliminates manual venting• Easy fit, no need to drain system• Works vertically and horizontally• Fits 1/2" BSP tappings

www.toolstation.com

Andy

 

[talkingcats]

Was corrosion inhibitor added?

Have you been noticing frequent pressure drops?

Thanks for your reply. No I haven't noticed any water pressure drops. Every other radiator is very hot to the touch after the system has been on for an hour or so. I do';t think any anti-corrosion treatment was applied to the system at the time of the boiler installation

 

[HERTS P&D]

Ok, New auto bleed with x100.

Andy

 

[fixitflav]

Some trapped air hissed out and the radiator was uniformly hot in operation again .

Have you tried lighting the gas? If it burns it's hydrogen produced by corroding the steel. Do a bright wire nail test and if the result indicates it, add inhibitor.

 

[foxhole]

Would the affected rad be the highest point on the system ? Any leak on the system allowing air in migrates to high point .
Used to happen with my bathroom ladder rad , found a small leak on a compression joint , very slight and being soaked up by insulation and crud so never showed anywhere . Just luck I found it .

 

[DP]

Is the radiator a towel rail?
Quite common for these to act like that

 

[talkingcats]

Is the radiator a towel rail?
Quite common for these to act like that

Thanks for your reply. No I don't use it to hang a towel. There is a towel rail but I don't use it. All the towels hang in the master bathroom

 

[talkingcats]

Would the affected rad be the highest point on the system ? Any leak on the system allowing air in migrates to high point .
Used to happen with my bathroom ladder rad , found a small leak on a compression joint , very slight and being soaked up by insulation and crud so never showed anywhere . Just luck I found it .

Thanks. I can't see anything but I will secure a paper towel around it and see if I can detect any dampness after a couple of days. Logically the air must be getting in somewhere and a leak somewhere seems a likely way for tha to happen

 

[talkingcats]

Have you tried lighting the gas? If it burns it's hydrogen produced by corroding the steel. Do a bright wire nail test and if the result indicates it, add inhibitor.

Thanks. I might try that. I guess it is safe enough as the only H2 that would burn is the stuff that just been bled from the radiator?

 

[fixitflav]

Thanks. I might try that. I guess it is safe enough as the only H2 that would burn is the stuff that just been bled from the radiator?

That's right, it's not dangerous, if it is H2 there'll just be a small flame. Let us know the result.

 

[talkingcats]

That's right, it's not dangerous, if it is H2 there'll just be a small flame. Let us know the result.

Thanks I will wait three weeks for the 'air' to build up before trying again

 

[MNW67]

I have the same issue. My gas explodes. It's a very old open vent system and air collects in the bathroom radiator and it needs bleeding every week. I paid a plumber to come and drain the system a bit and put in two bottles of F1. But he wouldn't do it. He made it clear he didn't want to disturb such an old system. The only drain point is in the garage. What would happen if I just put two bottles into the header tank without draining? Presumably it would eventually disperse through the system. Could it do any harm, though, with such a high concentration in the header tank?

 

[HERTS P&D]

Start your own thread.

Andy