On my home heating system, I have to bleed 2 of the 7 radiators on a regular basis - ie every month or so. I have a Panda oil burner which I appreciate is pretty old but I'll keep it until it packs in. The system is the header tank / copper cylinder type and irrespective of what temperature the boiler is set at I can always release 10 sec or so of air from 2 of the rads. The water hasn't been changed for years. I can easily live with this but if anyone has any ideas / solutions I'd be pleased to hear them. Cheers and have a good day! John
Regular bleeding necessary!
- Thread starter Burnerman
- Start date
What colour is the water that bleeds out?
Most likely it has a fair bit of corrosion and sludge. The corrosion of the radiators produces gas.
have a look in the loft at the feed and expansion tank, bale out any mud and sponge it clean, set the depth to a couple of inches (only), fit a lid if it does not have one. Observe if there is any sign of leakage being made up with fresh water, or any sign that water is being pumped over from the vent pipe which is bent over the F&E.
Then give it a chemical clean and add corrosion inhibitor. This is quite easy if you can access the F&E and the drain cock. Sentinel and Fernox are good brands. If you clean it with Sentinel X400 which is a very mild cleaner that breaks up old sludge, you can leave it in for several weeks, so when you drain it out (say in a month's time) the weather will be warmer and you will not mind turning the heating off for the drain and flush.
You do not mention any other problems which can be caused by excessive sludging, so we will assume you do not need any more intensive cleaning. One of the signs of bad sludging is cold patches at the bottom of radiators.
Most likely it has a fair bit of corrosion and sludge. The corrosion of the radiators produces gas.
have a look in the loft at the feed and expansion tank, bale out any mud and sponge it clean, set the depth to a couple of inches (only), fit a lid if it does not have one. Observe if there is any sign of leakage being made up with fresh water, or any sign that water is being pumped over from the vent pipe which is bent over the F&E.
Then give it a chemical clean and add corrosion inhibitor. This is quite easy if you can access the F&E and the drain cock. Sentinel and Fernox are good brands. If you clean it with Sentinel X400 which is a very mild cleaner that breaks up old sludge, you can leave it in for several weeks, so when you drain it out (say in a month's time) the weather will be warmer and you will not mind turning the heating off for the drain and flush.
You do not mention any other problems which can be caused by excessive sludging, so we will assume you do not need any more intensive cleaning. One of the signs of bad sludging is cold patches at the bottom of radiators.
Many thanks for that JohnD - the water colour is a little discoloured on the worst radiator - the other one is new. The system has got Fernox in, header tanks are clean but I imagine there is a lot more grot in there than I think. What I didn't realise is that the sludge produces gas - thats a new one on me and I'm sure you're right. I'll do what you recommend by adding the Sentinel and flushing out when its warmer.
I really appreciate your comments! Cheers John
I really appreciate your comments! Cheers John
Good post by JohnD, as usual.
A few additional questions, because there are other caused or having to vent:
1. Did you start having to vent only after replacing the rad?
2. Which rads do you have to regularly vent?
3. Which rad did you replace?
4. Why did you replace it?
5. Was a TRV fitted to the rad where there wasn't one before?
6. Was any other work done at the time?
A few additional questions, because there are other caused or having to vent:
1. Did you start having to vent only after replacing the rad?
2. Which rads do you have to regularly vent?
3. Which rad did you replace?
4. Why did you replace it?
5. Was a TRV fitted to the rad where there wasn't one before?
6. Was any other work done at the time?
Answers to your queries -
1) I've had to vent the system ever since I restored the house in 1986.
2) The rads I have to vent are the kitchen (1000mm x 700mm) and the utility (1400 x 700) which are the ones closest to the boiler, as it happens
3) I replaced the kitchen rad (nearest to boiler) with a Screwfix one 2 years ago
4)I replaced it because the old one was rusty on the bottom, full of fluff and had 43 layers of paint on
5) I don't have any TRV's now or before - its so bloody cold up here in no way do we turn the heating down
6) I replaced the bathroom rad at the same time - it was a single row so I replaced it with a double.
Cheers for the interest! Look forward to any follow up. John
1) I've had to vent the system ever since I restored the house in 1986.
2) The rads I have to vent are the kitchen (1000mm x 700mm) and the utility (1400 x 700) which are the ones closest to the boiler, as it happens
3) I replaced the kitchen rad (nearest to boiler) with a Screwfix one 2 years ago
4)I replaced it because the old one was rusty on the bottom, full of fluff and had 43 layers of paint on
5) I don't have any TRV's now or before - its so bloody cold up here in no way do we turn the heating down
6) I replaced the bathroom rad at the same time - it was a single row so I replaced it with a double.
Cheers for the interest! Look forward to any follow up. John
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Check for air entrainment on the suction side of the pump!
Could also be vent pipe!
If it is system corrosion the venting gas should ignite if provided with a source of ignition!! (A bit like a fart but smells better)
Could also be vent pipe!
If it is system corrosion the venting gas should ignite if provided with a source of ignition!! (A bit like a fart but smells better)
Trying to light the venting gas sure is a new one on me, Terry....! Bit difficult to tell if any air is entering the system via the pump or whatever but there are no leaks outwards, for sure. I think I'll drain the system down and try to flush it with my garden hose connected to one of the rad valves and see what comes out - then I'll go for the Sentinel flush, leave it for a month or so and repeat the process again. Cheers for the comments! John
Result!! I did what Terrywookfit suggested and bled the rads, this time complete with fag lighter - resulting in a 3" flame! Guess thats all I need to know - drain down, flush out and refill with inhibitor....thank you all so much! 
Cheers John
Cheers John
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