I seem to have a problem, or combination of problems, with my central heating / hot water system. It is a fairly conventional pumped system, oil-fired boiler, pump, two 2-way valves, HW cylinder, radiators, F&E tank in loft (base same level as cold water tank, so F&E water level well below cold water tank level). Usually it works OK (rads and hot water).
For some time (months) the feed and expansion tank overflow has sometimes been dripping outside, and looking at the tank months ago, I saw that the expansion vent (inverted J) pipe was dribbling hot water, and the tank was full to the overflow level. I tried changing the pump speed, and that seemed to help a bit, but not cure it, but as the problem was intermittent, I couldn't be sure if it made much difference.
I have moved some radiators around over the last few months, but the problem occurred before and after, so I don't think it's relevant.
Last weekend I decided a bit more investigation was required, and replaced the F&E ball-valve, replaced the float (it had water splashing about inside), drained the system a bit, and adjusted the arm so that the tank (with the system cold) was perhaps less than a quarter full. My theory was that the water in the expansion vent pipe would be hotter (less dense) than in the feed pipe, and I needed a greater difference between the top of the vent pipe and the water level in the tank. I also bled the rads.
In the spirit of unjustified over-confidence and with the level steady in the F&E tank, I was pleased with myself.
Now the problem (or problems) seem to be worse than ever, and I could hear it dripping at midnight last night, and looking at the ceiling below the tank, I could see an ominous wet patch, right over "she who must be obeyed"'s clothes cupboard. Into the loft, where I found that I must have disturbed the overflow pipe, and it was no longer fully connected to the tank, and the tank had filled up again. I closed off the isolation valve for the ball-valve, switched the CH controller off, and drained the system, ideal pastimes for that time of night!
At the moment, I've closed off the drain valve, but kept the ball-valve off, and I'm waiting to see if the system fills up slowly, suggesting a leak in the coil in the HW cylinder.
I have checked other similar posts, and a frequent suggestion is the wrong arrangement of feed/vent/pump. I have got (as far as I can tell, as I didn't install it):
22mm from boiler to T piece
T piece has 22mm to vent over F&E tank and about 150mm of 22 mm to another T piece
This second T piece has 15mm to the feed in the F&E tank and 22mm to the pump
The pump goes to another T piece, then to the two 2-way valves
Another suggestion is wrong direction pump - mine has an arrow pointing from the boiler supply (via the T pieces) to the 2-way valves.
Another suggestion is blockage in the feed pipe. When I drain the system, the tank level drops quite quickly, so it's not blocked in one direction, but not sure about the other direction.
Another suggestion is the boiler is boiling, or at least too hot. When I refill the system, I'll try a lower setting.
I'll also flush the system.
Does anyone have a theory about how these all may be linked, or have I had several problems at once, and what should I try next?
Perhaps I should just do a loft conversion, as I'm spending so much time up there!
Thanks in advance for any assistance.
For some time (months) the feed and expansion tank overflow has sometimes been dripping outside, and looking at the tank months ago, I saw that the expansion vent (inverted J) pipe was dribbling hot water, and the tank was full to the overflow level. I tried changing the pump speed, and that seemed to help a bit, but not cure it, but as the problem was intermittent, I couldn't be sure if it made much difference.
I have moved some radiators around over the last few months, but the problem occurred before and after, so I don't think it's relevant.
Last weekend I decided a bit more investigation was required, and replaced the F&E ball-valve, replaced the float (it had water splashing about inside), drained the system a bit, and adjusted the arm so that the tank (with the system cold) was perhaps less than a quarter full. My theory was that the water in the expansion vent pipe would be hotter (less dense) than in the feed pipe, and I needed a greater difference between the top of the vent pipe and the water level in the tank. I also bled the rads.
In the spirit of unjustified over-confidence and with the level steady in the F&E tank, I was pleased with myself.
Now the problem (or problems) seem to be worse than ever, and I could hear it dripping at midnight last night, and looking at the ceiling below the tank, I could see an ominous wet patch, right over "she who must be obeyed"'s clothes cupboard. Into the loft, where I found that I must have disturbed the overflow pipe, and it was no longer fully connected to the tank, and the tank had filled up again. I closed off the isolation valve for the ball-valve, switched the CH controller off, and drained the system, ideal pastimes for that time of night!
At the moment, I've closed off the drain valve, but kept the ball-valve off, and I'm waiting to see if the system fills up slowly, suggesting a leak in the coil in the HW cylinder.
I have checked other similar posts, and a frequent suggestion is the wrong arrangement of feed/vent/pump. I have got (as far as I can tell, as I didn't install it):
22mm from boiler to T piece
T piece has 22mm to vent over F&E tank and about 150mm of 22 mm to another T piece
This second T piece has 15mm to the feed in the F&E tank and 22mm to the pump
The pump goes to another T piece, then to the two 2-way valves
Another suggestion is wrong direction pump - mine has an arrow pointing from the boiler supply (via the T pieces) to the 2-way valves.
Another suggestion is blockage in the feed pipe. When I drain the system, the tank level drops quite quickly, so it's not blocked in one direction, but not sure about the other direction.
Another suggestion is the boiler is boiling, or at least too hot. When I refill the system, I'll try a lower setting.
I'll also flush the system.
Does anyone have a theory about how these all may be linked, or have I had several problems at once, and what should I try next?
Perhaps I should just do a loft conversion, as I'm spending so much time up there!
Thanks in advance for any assistance.