It's my first post so here goes.
I have been tasked with solving a low flow rate problem in a salon. The problem is that 2 wash basins have to be provided with sufficient hot water to cope with 2 basins for around 15 minutes each, sometimes simultaneously. The basins have mixers for hot & cold blending plus flow/ on/off.
The current setup is that a ZIP instaneous water heater has been fitted to an existing basin with 15mm copper pipe in and a 1.5M run of 15mm copper pipe out to the basin. The basin is about 6 inches lower than the ZIP heater's output connection. The problem is that when water is drawn off the supply from adjoining business's the flow drops and the water gets too hot naturally and the heater cuts out. I am told that the incomming pressure is 8 bars.
My first summation was that the pipe diameters are too small and should be increased to 22mm.
I designed a solution whereby a 22mm pipe feeds into a 25 gallon coffin type header tank through a float valve with two 22mm output pipes, one feeding 2 HYCO IN95 instantaneous water heaters and the other tank output is feeding the mixer valves direct. This provides a means of mixing water to attain the right temperature. Due to space constaints the tank is placed 1M above the heaters and in turn 1.6M above the spray heads. This gives us a 1.6M of head I believe. All piping is via 22mm Speedfit plastic pipe and fittings.
I thought this would be enough to give us sufficient head and flow but this proved to be wrong so I have installed a 1.5 bar NABIS twin impeller shower pump from PlumbCentre between the header tank and the heaters, thus drawing water from the tank and pumping it up 1.2M to the heaters to the heaters.When the water leaves the heaters it travells back down to the mixer taps at the basins. The pump is at ground level so has a head of 2.5M from the tank. It's a cheap and crappy pump in my opinion but I needed to keep costs down. I think I need to change it for a 2bar Salamander or something like that.
This has improved the situation so we have a flow rate at the spray heads of 4 L/min. The problem I have now is that the client informs me that after 15 mins of running the water gets cold because the heaters are cutting out. I have not witnessed this but believe this to be the pump which is not man enough for the job since it's designed to run for 20mins in any one hour. The pump is an induction type motor and is a centrifugal not a regenerative type.
Should I use a twin impeller still or can I use a single impeller and feed the basins and the heaters through the same line?
Any suggestions would be greatly apreciated.
I have been tasked with solving a low flow rate problem in a salon. The problem is that 2 wash basins have to be provided with sufficient hot water to cope with 2 basins for around 15 minutes each, sometimes simultaneously. The basins have mixers for hot & cold blending plus flow/ on/off.
The current setup is that a ZIP instaneous water heater has been fitted to an existing basin with 15mm copper pipe in and a 1.5M run of 15mm copper pipe out to the basin. The basin is about 6 inches lower than the ZIP heater's output connection. The problem is that when water is drawn off the supply from adjoining business's the flow drops and the water gets too hot naturally and the heater cuts out. I am told that the incomming pressure is 8 bars.
My first summation was that the pipe diameters are too small and should be increased to 22mm.
I designed a solution whereby a 22mm pipe feeds into a 25 gallon coffin type header tank through a float valve with two 22mm output pipes, one feeding 2 HYCO IN95 instantaneous water heaters and the other tank output is feeding the mixer valves direct. This provides a means of mixing water to attain the right temperature. Due to space constaints the tank is placed 1M above the heaters and in turn 1.6M above the spray heads. This gives us a 1.6M of head I believe. All piping is via 22mm Speedfit plastic pipe and fittings.
I thought this would be enough to give us sufficient head and flow but this proved to be wrong so I have installed a 1.5 bar NABIS twin impeller shower pump from PlumbCentre between the header tank and the heaters, thus drawing water from the tank and pumping it up 1.2M to the heaters to the heaters.When the water leaves the heaters it travells back down to the mixer taps at the basins. The pump is at ground level so has a head of 2.5M from the tank. It's a cheap and crappy pump in my opinion but I needed to keep costs down. I think I need to change it for a 2bar Salamander or something like that.
This has improved the situation so we have a flow rate at the spray heads of 4 L/min. The problem I have now is that the client informs me that after 15 mins of running the water gets cold because the heaters are cutting out. I have not witnessed this but believe this to be the pump which is not man enough for the job since it's designed to run for 20mins in any one hour. The pump is an induction type motor and is a centrifugal not a regenerative type.
Should I use a twin impeller still or can I use a single impeller and feed the basins and the heaters through the same line?
Any suggestions would be greatly apreciated.
