Shower Pump

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29 Apr 2008
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Croatia
My hot water is a gravity system and the shower has always been a pathetic trickle. Some time ago a friend gave me a couple of secondhand shower pumps, the sort with a central motor and pumps each end for hot and cold. He also gave me some hoses for connecting to the supply and shower mixer plumbing. These only fitted the newer of the two pumps, so that is the one I used. This unit had no markings for what pipe goes where so I looked at the manufacturers website where I found circuit diagrams. These showed the end connections as inlets and the top connections as outlets. I assumed that it did not matter which end of the machine was hot and which cold but now I am not so sure. I mounted the pump under the bath and connected the left end to hot and the right end to cold, to match the way the pipes enter the shower mixer. The pump works fine for a couple of minutes then the motor seems to slow down for a few seconds then shuts off completely, leaving the shower output the same trickle as it was without the pump. I decided to try the older pump so today I bought adapters for the hoses, 3/4 inch down to 1/2 inch. I just looked at the older pump, a Quantum and it is labelled cold on the left, hot on the right. Do you think these pumps are the same both ends or can the hot only go to the
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designated end?
 
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I just read this>
"A 'Surrey' or 'York' flange should be fitted in the outlet from the hot water tank. These fit into the standard hot water tank outlets but draw the water from below the very top of the tank to avoid drawing off the aerated water. Air in the water will cause problems with the pump."

Could that be the problem? When I originally put in the hot water system I simply drew off the water from the top of the cylinder.
 
Could well be sucking in air ,did the same thing happen with the Quantum pump ?
 
Not yet tried the Quantum pump but it looks like the first thing to try is this flange fitting. I live in Croatia but the indirect cylinder is one I brought with me from UK as they do not have them here. It is part of a solid fuel central heating system.
 
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It shouldn't matter which way round they are. They are designed to be fitted in airing cupboards though, as close to the hot water cylinder as possible, and the hoses on your outlets are bent far too tight. I wouldn't be surprised to see the hot one collapse and kink when it gets warm
 
Could well be sucking in air ,did the same thing happen with the Quantum pump ?
I am now wondering if these flange fittings would work in this case as the mixer is a combined shower and bath tap type. What happens when you run a bath, does it effectively reduce the capacity of the tank if you draw off water from a point below the top or does it make no difference?
 
Makes no difference if the pump is running to fill bath or shower ,it can draw in air regardless ,if it is not connected via a flange.
 
Sorry, I think you may have misread my question. I was asking if I would still get a full tub of warm water with the pump running off water drawn from below the top of the cylinder?
I have now had a new idea that I can try. The outlet at the top of my cylinder is a stub of thick walled copper pipe with a 22mm compression socket at the top. If I recall correctly, this fitting does not have a stop so it should be possible to use a longer pipe that pokes several inches into the cylinder. If I solder a disc of copper to the end of that pipe and drill side holes I will have something akin to a Warwick flange. This will obviously be supplying all the hot taps as well as the pump as I will not have the tee arrangement of the flange. I was not keen on having to run an additional hot pipe anyway as it would be a big job.
 
If I recall correctly, this fitting does not have a stop so it should be possible to use a longer pipe that pokes several inches into the cylinder. If I solder a disc of copper to the end of that pipe and drill side holes I will have something akin to a Warwick flange. This will obviously be supplying all the hot taps as well as the pump as I will not have the tee arrangement of the flange.

Now think where will all the released air and CO2 go to? Will it be trapped at the top of your cylinder and depress the hot water surface until the same aerated water emerges?
I'm afraid that extra run of pipe and a Surrey flange may be necessary after all.
 
Now think where will all the released air and CO2 go to? Will it be trapped at the top of your cylinder and depress the hot water surface until the same aerated water emerges?
Will it not go up the vent pipe?
 
I worked out what is happening. In preparation for draining the cold tank to do the plumbing modification, yesterday evening I turned off the mains water supply to the cold tank and used the cold bath tap to fill the watering can a few times to water my veg. patch. This morning I started draining the rest of the water off and the pump did not come on at all. The head of water must be only just enough to operate the flow switches in the pump and after a couple of minutes showering the head of water drops low enough for them to shut off. The mains pressure is quite low as it is a borehole supply, so the tank empties quicker than it can be refilled from the main. It looks like the only answer is to raise the cold tank higher into the roof space, it might only need half a metre or so.
 
I don't agree with your assessment I'm afraid. Once the pump is operating, it will provide sufficient head to be self-sustaining. The level of water in the loft tank is irrelevant unless it runs out completely
 
Perhaps I should rig up indicator lights for each flow switch so I can monitor what is happening.
 
Most of the budget shower pumps are only designed for intermittent use because they get hot, and when they do they may shut down, but it will take longer than "a couple of minutes" For the same reason, they usually have a specified maximum hot water supply of something in the region of 65 degrees C. So if your water supply is hotter than that, perhaps it maybe overheating more quickly.

Alternatively, if you are now emptying the hot water system feed tank faster than the supply can be replenished, you could simply be running out of water. As you are in Croatia, and although your cylinder is from the UK the supply plumbing maybe different to the UK.

I see that the pump is connected to the bath taps, these pumps are really just for a single shower, so if you have been trialing it with the bath taps open, maybe you are exceeding its design capacity.

EDIT:
Here's an alternative way to a fitting a flange to get an air free supply.

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Tanks stem. I did not know about the design temperature as I do not have any documentation for the pump. I could try turning down the thermostat on the immersion heater as the water is very hot. In winter the boiler heats the water but that does not get it so hot as it is set to default to central heating at high boiler temperatures. Normally the plumbing in Croatia is very different but I designed this system on UK lines. The indirect cylinder is one I brought with me from UK and the cold tank is a modified plastic lined solvent drum with a UK ballcock. I am not running out of water as the shower continues working at a reduced flow rate when the pump stops. The shower is only average for the couple of minutes it is working, not that powerful but adequate. The pump can be turned off with a switch in the hall so it can be left off when running a bath. I did see on the manufacturers website that it is designed for 10 minutes continuous operation. My tests have been with the shower head, not running the bath outlet.
 

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