'Popping' sound from Boiler when burning
- Thread starter Ian Seale
- Start date
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Quite common for old cast iron boilers to develop this sound. It indicates localised overheating in the heat exchanger caused by deposits of scale and corrosion products. Because free movement of water is impaired, temperatures of 100C can occur at certain points resulting in boiling of water. The steam bubble created promptly collapses as it contacts with cooler water, producing the popping sound. You can add chemicals to the system to break down scale deposits in the boiler.
Chris,
Thank you very much for your reply.
The paranoid in me thought it could be little gas explosions, fearing a bigger bang to come.
Yep it is an old boiler, and not one I'm keen to change out for a condenser. So I'll put up with the popping!
I'm surprised that there should be scale, I did fully flush the system about 8 months ago, de-scaled for 2-3 weeks, reflushed and refilled with inhibitor. Maybe I'll lower the boiler temperature a bit.
The reason I did the flush, was that I was getting air in my rads, which was tracked down to sludge build up in and aroud the (aerator?) and dragging in air from the expansion breather pipe. Again, diagnosing that problem was made easier and very helpfully aided by the guys on this website.
Thanks for being there to help.
Cheers,
Ian
Thank you very much for your reply.
The paranoid in me thought it could be little gas explosions, fearing a bigger bang to come.
Yep it is an old boiler, and not one I'm keen to change out for a condenser. So I'll put up with the popping!
I'm surprised that there should be scale, I did fully flush the system about 8 months ago, de-scaled for 2-3 weeks, reflushed and refilled with inhibitor. Maybe I'll lower the boiler temperature a bit.
The reason I did the flush, was that I was getting air in my rads, which was tracked down to sludge build up in and aroud the (aerator?) and dragging in air from the expansion breather pipe. Again, diagnosing that problem was made easier and very helpfully aided by the guys on this website.
Thanks for being there to help.
Cheers,
Ian
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sentinel X200 is very good just put it in and leave it 
It does take a while to start working depending on how badly scaled it is about 1 month
It does take a while to start working depending on how badly scaled it is about 1 month
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Gaz,
I can't remember what I used, but I followed the instructions exactly to the day on the maximum time to leave the de-scaler in (2-3 weeks I think), and I didn't scrimp on the stuff either. I used a couple of containers of descaler (3-4 litres) which was the right amount for the system, and the same for the inhibitor. It wasn't cheap!
Thanks for the advice though. I'll remember Sentinel X200.
Cheers,
Ian
I can't remember what I used, but I followed the instructions exactly to the day on the maximum time to leave the de-scaler in (2-3 weeks I think), and I didn't scrimp on the stuff either. I used a couple of containers of descaler (3-4 litres) which was the right amount for the system, and the same for the inhibitor. It wasn't cheap!
Thanks for the advice though. I'll remember Sentinel X200.
Cheers,
Ian
Moosehead,
Ahh, I'm not a plumber, but one of those dangerous people that knows a little bit.
The aerator (or a least my one) is about the size of a baked bean can and has the cold water (from the header tank) connected to it, as well as the hot water flow from the boiler (in on the cold water feed side and out the other). It also has the expansion pipe (running back to the top of the header tank) connected to it too.
In my case it was close to my boiler. The bolier a floor-stander, and is upstairs, with the header-tank directly above. The aerator is a ceiling level directly above the boiler, and directly below the header tank.
So, I guess in your case, if you trace the pipe runs from either the bolier or the header tank, until you find some thing that looks like a baked-bean can with pipes sticking out of it, you've found it.
Hears a tip:
If you system is really badly sludged up, not end of flushing and de-scaling is going to clear it properly.
What I did was to drain the system down, and cut the pipes around the aerator so that it could be withdrawn and (carefully) cleaned out by flushing and rodding with something like stiff electrical wire.
I also found the pipe from the boiler to the aerator particularly sludged up too, so I disconnected that end from the boiler at the same time and rodded/flushed that out too.
Then the whole lot was put back together using good old-fashioned compression joints where the pipes were cut, so that if it ever happened again (and it did 7 years later) it was an easier job to disconnect it all and flush it out.
So many people have helped me on this website, I hope this helps you.
Good luck.
Ian
Ahh, I'm not a plumber, but one of those dangerous people that knows a little bit.
The aerator (or a least my one) is about the size of a baked bean can and has the cold water (from the header tank) connected to it, as well as the hot water flow from the boiler (in on the cold water feed side and out the other). It also has the expansion pipe (running back to the top of the header tank) connected to it too.
In my case it was close to my boiler. The bolier a floor-stander, and is upstairs, with the header-tank directly above. The aerator is a ceiling level directly above the boiler, and directly below the header tank.
So, I guess in your case, if you trace the pipe runs from either the bolier or the header tank, until you find some thing that looks like a baked-bean can with pipes sticking out of it, you've found it.
Hears a tip:
If you system is really badly sludged up, not end of flushing and de-scaling is going to clear it properly.
What I did was to drain the system down, and cut the pipes around the aerator so that it could be withdrawn and (carefully) cleaned out by flushing and rodding with something like stiff electrical wire.
I also found the pipe from the boiler to the aerator particularly sludged up too, so I disconnected that end from the boiler at the same time and rodded/flushed that out too.
Then the whole lot was put back together using good old-fashioned compression joints where the pipes were cut, so that if it ever happened again (and it did 7 years later) it was an easier job to disconnect it all and flush it out.
So many people have helped me on this website, I hope this helps you.
Good luck.
Ian
This "aerator" is a "de-aerator". The object is to help entrained air to escape up the vent (not "expansion"!) pipe. They are rarely fitted and are arguably unnecessary in a well designed system.
In most cases the vent pipe connection and the feed & expansion pipe connections are a few centimetres apart and made to the flow pipe before the pump. These connections are liable to block with corrosion deposits, so having compression joints around them makes a lot of sense for ease of inspection.
In most cases the vent pipe connection and the feed & expansion pipe connections are a few centimetres apart and made to the flow pipe before the pump. These connections are liable to block with corrosion deposits, so having compression joints around them makes a lot of sense for ease of inspection.
Chris,
I did say that I was dangerous and knew a little!
But everything I said did work, even if I didn't use the correct terminology.
It was definitely a sludged up aerator, and the pipe from the boiler to it, that was the reason that the system was sucking in air through the vent/expansion pipe.
Cheers,
Ian
I did say that I was dangerous and knew a little!
But everything I said did work, even if I didn't use the correct terminology.
It was definitely a sludged up aerator, and the pipe from the boiler to it, that was the reason that the system was sucking in air through the vent/expansion pipe.
Cheers,
Ian
Bottel-shaped?
Oooo-errr! That doesn't sound like it.
My aerator is a copper can with soldered spigots for the pipe connections, I haven't seen, or heard of, a brass one with plastic knurled screws and hex nuts. It sounds more like a gas fitting, possibly a valve.
I'd get a little more advice, or pay a professional before I went there if I were you.
Altrernatively, following Chris's advice, you may not have an aerator, but a junction of pipes close together, which might be what you need to find if you can't find an aerator. The process is the same, follow the boiler hot water output pipe (22mm) or the cold feed pipe (15mm) from the header tank until you find a junction where they come together and are joined in close proximity by another 22mm pipe which acts as a vent/expansion which routes back up to the top of the header tank.
I'm assuming you have a traditional boiler and system.
You might need to post a question, giving all your system details, on the site, it won't be long before some kindful soul helps you out.
Cheers,
Ian
Oooo-errr! That doesn't sound like it.
My aerator is a copper can with soldered spigots for the pipe connections, I haven't seen, or heard of, a brass one with plastic knurled screws and hex nuts. It sounds more like a gas fitting, possibly a valve.
I'd get a little more advice, or pay a professional before I went there if I were you.
Altrernatively, following Chris's advice, you may not have an aerator, but a junction of pipes close together, which might be what you need to find if you can't find an aerator. The process is the same, follow the boiler hot water output pipe (22mm) or the cold feed pipe (15mm) from the header tank until you find a junction where they come together and are joined in close proximity by another 22mm pipe which acts as a vent/expansion which routes back up to the top of the header tank.
I'm assuming you have a traditional boiler and system.
You might need to post a question, giving all your system details, on the site, it won't be long before some kindful soul helps you out.
Cheers,
Ian
That's an Automatic Air Vent (AAV). It used on sealed systems were there is no open vent (not vent/expansion, Ian Seale) pipe, or on open systems where a high point does not vent naturally to a vent pipe or radiator.moosehead said:
Chris - I believe our system is closed. So how will the AV work? Does the knurled plasic screw on top have to be loose? Does the hex nut on the side have to be adjusted. They are both screwed down hard?
Tks as usual.
Tks as usual.
The top plastic screw on AAV should be loose to allow air to vent. If it's screwed tight it's probably because it leaked water. If it's still doing this you need to replace it. You can buy AAVs for £3 or so (BES) and they're easy to fit.
The other plastic screw is probably a fast vent screw, used to speed up initial filling. This should be screwed shut. (It's possible that the 2 plastic screws are the other way around to what I've said, so check.)
The other plastic screw is probably a fast vent screw, used to speed up initial filling. This should be screwed shut. (It's possible that the 2 plastic screws are the other way around to what I've said, so check.)
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