I know, yet another one!
My parents have an Ideal Mexico RS60 boiler (about 10 years old, fitted by BG) working a 30-year old pumped C/H system with gravity hot water,
in a four-bed detached house. When the boiler was replaced, the rest of the system was unchanged.
It all works OK, except for air gathering in the bathroom towel rail, about 1 'bar' per week. (It is air, not hydrogen.) This towel rail replaced the original bathroom radiator about 2 years ago. Before that, 1 or 2 upstairs radiators required bleeding about 2 to 3 times per year, but they are now OK, and it's just air in gathering in the bathroom towel rail (it is now by far the tallest).
Otherwise, the system is original, and has been flushed out and re-Fernoxed about every 5 years. (My father is obsessed with this.)
Testing found that when the C/H pump is started, there is a surge up both the feed and expansion pipe and the vent pipe at the same time. (Ripples could be seen in the header tank water, and air was pushed out of the vent pipe but no water came out.) The header tank only has a few inches of water in it, so the surge was easily seen.
The feed and expansion pipe and the vent pipe are as original and connected as per Ideal's instructions, on the gravity hot water circuit return and flow respectively. They are not on a pumped circuit.
The C/H pump is connected on the return pipe just before it enters the boiler. (However, Ideal show the pump in the C/H flow pipe just after leaving the boiler.) How it was connected before the boiler was replaced is not remembered.
The C/H header tank is about 500 to 600mm higher than the top of the bathroom radiator.
Could this air be being drawn in via 'microleaks' as the pump is 'pulling' the water round the C/H, or could it be connected to the 'surge', causing oxygenated water to be drawn in every time the pump starts? It appears as if the pump is causing an increase in pressure in the boiler chamber thus pushing water up both the gravity hot water pipes.
If the pump was on the C/H flow, would it have the opposite effect and suck water down the feed and expansion and vent pipes?
A professional plumber came, and suggested a combined feed and expansion/vent pipe might sort out the problem, but didn't seem too keen on doing anything regarding the pump.
Any (polite) suggestions please?
My parents have an Ideal Mexico RS60 boiler (about 10 years old, fitted by BG) working a 30-year old pumped C/H system with gravity hot water,
in a four-bed detached house. When the boiler was replaced, the rest of the system was unchanged.
It all works OK, except for air gathering in the bathroom towel rail, about 1 'bar' per week. (It is air, not hydrogen.) This towel rail replaced the original bathroom radiator about 2 years ago. Before that, 1 or 2 upstairs radiators required bleeding about 2 to 3 times per year, but they are now OK, and it's just air in gathering in the bathroom towel rail (it is now by far the tallest).
Otherwise, the system is original, and has been flushed out and re-Fernoxed about every 5 years. (My father is obsessed with this.)
Testing found that when the C/H pump is started, there is a surge up both the feed and expansion pipe and the vent pipe at the same time. (Ripples could be seen in the header tank water, and air was pushed out of the vent pipe but no water came out.) The header tank only has a few inches of water in it, so the surge was easily seen.
The feed and expansion pipe and the vent pipe are as original and connected as per Ideal's instructions, on the gravity hot water circuit return and flow respectively. They are not on a pumped circuit.
The C/H pump is connected on the return pipe just before it enters the boiler. (However, Ideal show the pump in the C/H flow pipe just after leaving the boiler.) How it was connected before the boiler was replaced is not remembered.
The C/H header tank is about 500 to 600mm higher than the top of the bathroom radiator.
Could this air be being drawn in via 'microleaks' as the pump is 'pulling' the water round the C/H, or could it be connected to the 'surge', causing oxygenated water to be drawn in every time the pump starts? It appears as if the pump is causing an increase in pressure in the boiler chamber thus pushing water up both the gravity hot water pipes.
If the pump was on the C/H flow, would it have the opposite effect and suck water down the feed and expansion and vent pipes?
A professional plumber came, and suggested a combined feed and expansion/vent pipe might sort out the problem, but didn't seem too keen on doing anything regarding the pump.
Any (polite) suggestions please?