I've posted here once or twice in the past about various problems concerning my central heating system but have never seemed to have sorted them out completely, or at best only to a limited degree.
The boiler is a Potterton Netaheat 10-16 Mk II F.
Pump is regular Grundfoss.
The controller is a mechanical/clockwork with a circular timer with little moveable segments to facilitate the on/off times, and two sliders for CH and HW.
I think the system is a 'W' plan whereby I can have hot water only or hot water AND heating, but not heating on it's own. And the hot water has priority.
Anyway, to my problem. I think it would be true to say that the heating has never really worked well, just better at times than others. We have been in the house for about 13 years.
By the look of things the heating looks a very diy effort, especially judging by the pipework routing in the airing cupboard, the only thing missing is a knot in the pipework!
Upstairs there are rads in all three bedrooms and one in the bathroom. Downstairs we have just one double rad in the living room, which is definately not adequate, and one rad, fitted by me, in the kitchen.
I have replaced the pump three times over the years, and the diverter valve once ( a second hand 3 position honeywell given to me and wired up for the 'w' sytem op).
I have also drained and mains flushed the system so many times I've lost count, removed the rads, taken them outside and flushed them both ways until the water has run clear as crystal and I've been blue in the face!
I've mains flushed the system backwards, forwards, upwards, downwards, turned off every rad in turn except one and done it all again, and repeated with every rad in the house several times over until I'm sure the system is surgically clean!
I have to fill the system from the bottom, (using a hosepipe as per mains flushing) to avoid airlocks, which I'm guaranteed to get if I just let it fill from the loft.
Anyway, after all this the heating is at best mediocre. By that I mean that the rads don't get too hot to touch by any stretch of the imagination, or to be more precise, the downstairs two don't. I can get the upstairs ones to get reasonably hot, and the bathroom rad to get very hot( its the first one off the feed plumbed into 22mm pipes) but if I do this the downstairs rads go cold, so I have to throttle the rest so that I get a bit of heat downstairs.
I have recently turned the pump up to 3rd speed (max) which improved things quie a bit, but only for a while it seems.
Now, the hot water is scalding......I mean it's almost boiling, so I edged the cylinder stat down a touch.......no difference... bit more.......still no diff, so I turned it down all the way......still no diff. Ahh, I thought, new stat and all will be well.......fitted new stat.....still no diff
I checked the operation of the motorised valve, and it seems it isn't responding to the cylinder stat at all. So I thought if it's stuck in the hot water position that would account for no or not very hot rads. So I moved the valve over to the manual position, which I assume is hot water AND heating position, but still no change.
My only thoughts now are that the rubber ball may have disintergrated and is partly choking the outlet to the heating side. I'm certainly not doing a drain down til the warmer weather's here, but would greatly appreciate any thoughts/advice/solutions from anyone of you guys.
The water from the rads is clear btw, I did put some anti-corrosion fluid in last year.
I apologise for the lengthy post, but I wanted to include all relevant facts, and a few irrelevant ones I guess.......but if anyone wants any more info just ask
Thanks for taking the time to read this far.
The boiler is a Potterton Netaheat 10-16 Mk II F.
Pump is regular Grundfoss.
The controller is a mechanical/clockwork with a circular timer with little moveable segments to facilitate the on/off times, and two sliders for CH and HW.
I think the system is a 'W' plan whereby I can have hot water only or hot water AND heating, but not heating on it's own. And the hot water has priority.
Anyway, to my problem. I think it would be true to say that the heating has never really worked well, just better at times than others. We have been in the house for about 13 years.
By the look of things the heating looks a very diy effort, especially judging by the pipework routing in the airing cupboard, the only thing missing is a knot in the pipework!
Upstairs there are rads in all three bedrooms and one in the bathroom. Downstairs we have just one double rad in the living room, which is definately not adequate, and one rad, fitted by me, in the kitchen.
I have replaced the pump three times over the years, and the diverter valve once ( a second hand 3 position honeywell given to me and wired up for the 'w' sytem op).
I have also drained and mains flushed the system so many times I've lost count, removed the rads, taken them outside and flushed them both ways until the water has run clear as crystal and I've been blue in the face!
I've mains flushed the system backwards, forwards, upwards, downwards, turned off every rad in turn except one and done it all again, and repeated with every rad in the house several times over until I'm sure the system is surgically clean!
I have to fill the system from the bottom, (using a hosepipe as per mains flushing) to avoid airlocks, which I'm guaranteed to get if I just let it fill from the loft.
Anyway, after all this the heating is at best mediocre. By that I mean that the rads don't get too hot to touch by any stretch of the imagination, or to be more precise, the downstairs two don't. I can get the upstairs ones to get reasonably hot, and the bathroom rad to get very hot( its the first one off the feed plumbed into 22mm pipes) but if I do this the downstairs rads go cold, so I have to throttle the rest so that I get a bit of heat downstairs.
I have recently turned the pump up to 3rd speed (max) which improved things quie a bit, but only for a while it seems.
Now, the hot water is scalding......I mean it's almost boiling, so I edged the cylinder stat down a touch.......no difference... bit more.......still no diff, so I turned it down all the way......still no diff. Ahh, I thought, new stat and all will be well.......fitted new stat.....still no diff
I checked the operation of the motorised valve, and it seems it isn't responding to the cylinder stat at all. So I thought if it's stuck in the hot water position that would account for no or not very hot rads. So I moved the valve over to the manual position, which I assume is hot water AND heating position, but still no change.
My only thoughts now are that the rubber ball may have disintergrated and is partly choking the outlet to the heating side. I'm certainly not doing a drain down til the warmer weather's here, but would greatly appreciate any thoughts/advice/solutions from anyone of you guys.
The water from the rads is clear btw, I did put some anti-corrosion fluid in last year.
I apologise for the lengthy post, but I wanted to include all relevant facts, and a few irrelevant ones I guess.......but if anyone wants any more info just ask
Thanks for taking the time to read this far.
