Sorry for the massive post but I thought it better to put as much info as possible.
I have an ongoing problem at a flat I rent out with 2 of the radiators needing bleeding.
The heating system was installed 29 years ago when it was converted to a flat. It’s an open vent system with copper pipes and a hot water cylinder where the water is heated by the boiler and stored in the cylinder but the cylinder can also heat water electrically by a switch next to the cylinder. The flat is on the top floor but is split level with 3 radiators on the upper level and 2 radiators and a heated towel rail on the lower level. The kitchen radiator (upper level) and the towel rail (lower level) are both new. The other 4 radiators are originals. The upper level radiators heat up first when the heating is turned on.
In May 2016, I spotted a small leak from the feed pipe from the header tank. I don’t know how long it had been leaking. The plumber came out and replaced this section of pipe.
The bathroom radiator was rusting badly and in July 2016 this was swapped for a heated towel rail.
The boiler broke and in October 2016 the boiler was changed for a Vaillant Ecotec Plus 415 ERP and a magnaclean was installed. The plumber did a manual flush of the heating system and put some inhibitor in the header tank. There was a lot of air in the radiators afterwards and you could hear air going round the system. I had to bleed the radiators several times.
The tenants told me the system was noisy. About 2 weeks later, the radiators on the upper level were full of air again. When I turned on the boiler, air was bubbling in the header tank (I think from being sucked through the vent pipe). The plumber told me to turn down the pump speed, so I changed it from 3 to 1 and bled the radiators again.
It was very cold and a few days later the tenants said the radiators on the lower level weren’t heating up. After doing some tests:-
1. When the pump was on 1 and both the heating and hot water were on, the 3 radiators on the lower level didn’t warm up. It was better when the pump was set to 2, but the lower 3 radiators only fully warmed up when I turned off the hot water.
2. I put the hot water and heating on separately. When only the hot water was on, the gurgling sound from the hot water cylinder and surrounding pipes was noisy (the header tank is above the cylinder in the loft). When they were both on, it was quieter. It was much quieter when only the heating was on.
3. The water in the header tank didn’t get warm.
I couldn’t turn the pump speed to 3 as the upper level radiators would get full of air within a few days.
In December 2016, the plumber converted the feed from the header tank into a combined feed and vent.
In February 2017 the radiator in the kitchen (upper level) was swapped for a new radiator.
Since October 2016, I have cleaned the magnaclean 4 times. The first time in November 2016 there was a massive amount of black sludge and a lot of debris in the debris collector. Each time since there has been less. The last time was a few days ago with a gap of 4 months from the previous cleaning. There was some sludge and no debris. The water in the system is now quite clear whereas it had been blackish before.
A few days ago I checked the radiators. Of the 3 on the upper level, the 2 original radiators were about ¼ to ½ full of water but the new radiator in the kitchen (which is much smaller than the other 2 radiators) was full of water. All the lower level radiators were full. The heating is off at the moment. I last bled the radiators 4 months previously.
The plumber said that if air was getting into the radiators after converting to a combined feed and vent, he would need to convert the system to a sealed (low pressure?) system which would mean installing an expansion vessel. Before doing this, I want to make sure the air in the 2 radiators is there because it is being drawn through the combined feed and vent as otherwise I presume it won’t help to convert the system.
I have read that other causes could be:-
• Hydrogen in the radiators from corrosion.
• A leak in the system is drawing in air.
Are there any other possible causes?
I have read I can check if it is hydrogen by lighting a match above the bleed valve when I bleed the radiator.
What should I do next?
If air is still being drawn into the system through the combined feed and vent, are there solutions other than converting it to a sealed system?
I’m wondering if it might be worth getting another plumber for a second opinion.
Thanks to anyone who reads and replies!
I have an ongoing problem at a flat I rent out with 2 of the radiators needing bleeding.
The heating system was installed 29 years ago when it was converted to a flat. It’s an open vent system with copper pipes and a hot water cylinder where the water is heated by the boiler and stored in the cylinder but the cylinder can also heat water electrically by a switch next to the cylinder. The flat is on the top floor but is split level with 3 radiators on the upper level and 2 radiators and a heated towel rail on the lower level. The kitchen radiator (upper level) and the towel rail (lower level) are both new. The other 4 radiators are originals. The upper level radiators heat up first when the heating is turned on.
In May 2016, I spotted a small leak from the feed pipe from the header tank. I don’t know how long it had been leaking. The plumber came out and replaced this section of pipe.
The bathroom radiator was rusting badly and in July 2016 this was swapped for a heated towel rail.
The boiler broke and in October 2016 the boiler was changed for a Vaillant Ecotec Plus 415 ERP and a magnaclean was installed. The plumber did a manual flush of the heating system and put some inhibitor in the header tank. There was a lot of air in the radiators afterwards and you could hear air going round the system. I had to bleed the radiators several times.
The tenants told me the system was noisy. About 2 weeks later, the radiators on the upper level were full of air again. When I turned on the boiler, air was bubbling in the header tank (I think from being sucked through the vent pipe). The plumber told me to turn down the pump speed, so I changed it from 3 to 1 and bled the radiators again.
It was very cold and a few days later the tenants said the radiators on the lower level weren’t heating up. After doing some tests:-
1. When the pump was on 1 and both the heating and hot water were on, the 3 radiators on the lower level didn’t warm up. It was better when the pump was set to 2, but the lower 3 radiators only fully warmed up when I turned off the hot water.
2. I put the hot water and heating on separately. When only the hot water was on, the gurgling sound from the hot water cylinder and surrounding pipes was noisy (the header tank is above the cylinder in the loft). When they were both on, it was quieter. It was much quieter when only the heating was on.
3. The water in the header tank didn’t get warm.
I couldn’t turn the pump speed to 3 as the upper level radiators would get full of air within a few days.
In December 2016, the plumber converted the feed from the header tank into a combined feed and vent.
In February 2017 the radiator in the kitchen (upper level) was swapped for a new radiator.
Since October 2016, I have cleaned the magnaclean 4 times. The first time in November 2016 there was a massive amount of black sludge and a lot of debris in the debris collector. Each time since there has been less. The last time was a few days ago with a gap of 4 months from the previous cleaning. There was some sludge and no debris. The water in the system is now quite clear whereas it had been blackish before.
A few days ago I checked the radiators. Of the 3 on the upper level, the 2 original radiators were about ¼ to ½ full of water but the new radiator in the kitchen (which is much smaller than the other 2 radiators) was full of water. All the lower level radiators were full. The heating is off at the moment. I last bled the radiators 4 months previously.
The plumber said that if air was getting into the radiators after converting to a combined feed and vent, he would need to convert the system to a sealed (low pressure?) system which would mean installing an expansion vessel. Before doing this, I want to make sure the air in the 2 radiators is there because it is being drawn through the combined feed and vent as otherwise I presume it won’t help to convert the system.
I have read that other causes could be:-
• Hydrogen in the radiators from corrosion.
• A leak in the system is drawing in air.
Are there any other possible causes?
I have read I can check if it is hydrogen by lighting a match above the bleed valve when I bleed the radiator.
What should I do next?
If air is still being drawn into the system through the combined feed and vent, are there solutions other than converting it to a sealed system?
I’m wondering if it might be worth getting another plumber for a second opinion.
Thanks to anyone who reads and replies!
