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Alanw

Hi,
I would appreciate some advice please. My son has just bought an old rather large house. There are two pumped showers fed from a gravity fed cylinder. The distance from cold header tank to cylinder is about 10 metres (22mm pipe). From the cylinder to the first shower pump is about 25 metres (22mm) the run then continues about another 20 metres to the second shower pump (22mm).

I would estimate the total head to be about 3 metres (the header tank is on an 18 inch platform in the loft and the room height is about 7 ft 6. The problem is that when either ofthe showers is used they run for a minute or so and then start "hunting" and the water delivered slows to a trickle.

Now the elegant solution would be to shorten the pipe runs by re-siting the tanks, but since that would be major surgery, is the current pipe of a suitable size for this configuration? Would it be possible to increase the flow to the pumps by siting a third pump in the cold feed to the cylinder in order to boost the total head?

Any advice would be greatly appreciated


thanks

alanw
 
Read the manuals for the pumps all the info is in there, if not call them as they will diagnose.
btw, if the tank is 3m above it has not got 3m head. 3metres =0.3m head.
are the pumps at the base of the cylinder and are they positive head pumps?
most pumps require to be within 2 metres of supply hot and cold so unless stated otherwise that's too far away.
What make and pressure pumps are they? What size cold tank is it and are the pumps both connected via a dedicated supply from the cold and hot ( not shared )
 
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2 Questions. Just before the flow turns to a trickle, does the temp rise? Is the pressure and flow ok till this point?
pumps have strainers built into the flexi pipes so worth checking for debri.
Is it a thermostatic shower?
these have built in strainers too so check for debri. Old house, big tank, any screen on it?
 
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Hi craigy,
Thanks...i dont know what make the pumps are but one is fixed pressure and I have set the other down to minimum to try and alleviate the problem. One pump is about two ft above floor level and the other (far end) is at floor level. I suppose I was using head to mean the height of the water surface above the hot tank. The cold tank is a bit mean for two showers two baths and three basins .....65 litres !! Both pumps are fed from the same 22mm copper feed pipe from the hot tank. Normally they are never used at the same time.
I guess from what you say that he will have to rearrange what is essentially a very poor design so that the pumps are closer to the tank and the pipe runs are shorter!
 
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Hi craigy,
Thanks...i dont know what make the pumps are but one is fixed pressure and I have set the other down to minimum to try and alleviate the problem. One pump is about two ft above floor level and the other (far end) is at floor level. I suppose I was using head to mean the height of the water surface above the hot tank. The cold tank is a bit mean for two showers two baths and three basins .....65 litres !! Both pumps are fed from the same 22mm copper feed pipe from the hot tank. Normally they are never used at the same time.
I guess from what you say that he will have to rearrange what is essentially a very poor design so that the pumps are closer to the tank and the pipe runs are shorter!
Can you take some pictures of the pumps and post them up? If they are in the attic they should be negative head pumps. I can tell this from a picture. If you have a 65ltr/15gal cws then this is insufficient. 1 bathroom should be supplied by 50 gallon cws to supply cylinder and pump. Your setup,will almost run dry after 3-5 mins! Run the shower and watch the level of water in the cwsc and time how long before it gets really low. This wouldn't account for a trickle after 1 min but is important that you check this anyway.
 
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