Hi
I really hope someone can help me out here. The story is as follows:-
I have a 1st floor flat which has mains pressure water to all CW outlets and low pressure HW to all hot outets. I also have a direct combination cylinder measuring 1200mm * 450mm which has recently started to leak.
So I ordered a new one which arrived the other day, so I removed the old one and found on removal that it was something called an IMI shower master or similar. The idea of the cylinder is that is provides mains pressure to the shower by utilising a mains cold feed to the cylinder. I have no idea how it does this, but my plumbers merchant says he cannot get one, also a search of the internet this afternoon revealed nothing.
The new cylinder has 3 usable tappings, 1 * 22mm and 2 * 15mm. I am using the 22mm for all the DHW except the shower, and one of the 15mm outlets for the HW supply to the shower.
My problem is this, I have negative pressure at the shower head and since I have a thermostatic mixer control, if I try and run the shower not only do I get no hot water coming out but even worse I have cold mains water back filling the cylinder, causing water to pour out of the overflow and top of the combined header tank.
For the moment I have capped the HW supply to the shower to prevent any more flooding disasters but I do not know what to do with regards to getting my shower working properly again.
I realise that I can fit a non return valve to the HW supply and thus prevent the back flow, but I cant see how a single impeller pump would ever work as surely turning the shower on would not result in the low pressure water supply being able to overcome the mains back pressure, even if the shower head was held at a lower level. I have not been able to find a negative head single impeller pump and am now at a loss as to what to do.
I hope I have explained this all logically and that my understanding of the problem is correct. Any help would be much appreciated.
Thanks
Mike
I really hope someone can help me out here. The story is as follows:-
I have a 1st floor flat which has mains pressure water to all CW outlets and low pressure HW to all hot outets. I also have a direct combination cylinder measuring 1200mm * 450mm which has recently started to leak.
So I ordered a new one which arrived the other day, so I removed the old one and found on removal that it was something called an IMI shower master or similar. The idea of the cylinder is that is provides mains pressure to the shower by utilising a mains cold feed to the cylinder. I have no idea how it does this, but my plumbers merchant says he cannot get one, also a search of the internet this afternoon revealed nothing.
The new cylinder has 3 usable tappings, 1 * 22mm and 2 * 15mm. I am using the 22mm for all the DHW except the shower, and one of the 15mm outlets for the HW supply to the shower.
My problem is this, I have negative pressure at the shower head and since I have a thermostatic mixer control, if I try and run the shower not only do I get no hot water coming out but even worse I have cold mains water back filling the cylinder, causing water to pour out of the overflow and top of the combined header tank.
For the moment I have capped the HW supply to the shower to prevent any more flooding disasters but I do not know what to do with regards to getting my shower working properly again.
I realise that I can fit a non return valve to the HW supply and thus prevent the back flow, but I cant see how a single impeller pump would ever work as surely turning the shower on would not result in the low pressure water supply being able to overcome the mains back pressure, even if the shower head was held at a lower level. I have not been able to find a negative head single impeller pump and am now at a loss as to what to do.
I hope I have explained this all logically and that my understanding of the problem is correct. Any help would be much appreciated.
Thanks
Mike