Hot water pump help please?

[Trevor Austin]

I fitted some new waterfall taps to our upstairs bathroom this week, All went great, except the hot water pressure, which was never great, is now awful through the modern taps compared to the 30 year old ones I replaced.

Currently I have a hot water tank in the airing cupboard 1st floor and a feed cold water tank in the loft, so approx 2m head to the highest outlet.

22mm pipe outlet to 15mm feed pipes.

We only ever have been able to run a single outlet of hot at any time, including downstairs bathroom shower and basin.

So I decided to try this pump from screwfix, 2 bar single pump. Having done a fair bit of reading I am sure this is a positive head, so thought this pump would easily sort out a single outlet. http://www.screwfix.com/p/stuart-turner-showermate-eco-s-positive-head-shower-pump-2-0bar/58748

Very carefully fitted it but cutting the 22mm outlet pipe before it hit ANY of the supply pipe, put a 22mm to 15mm reducer in and placed the pump on the floor next to the hotwater tank, and turned all the water and tested outlets. Water flow was as before and couldn't see any problems even with placing the 15mm and a couple of bends to the new pump.

Then wired it up, putting the inlet to the connector next to the connector marked as inlet. Turned on a tap hoping for a huge flow improvement, and..... the pump started almost immediately made lots of pumping sounds and no flow improvement. Turned the tap off and the pump carried on running.

So took it all apart and this time primed the pump without connecting the outlet connector. Exactly the same result, even testing with downstairs outlets, there may be better flow to the downstairs bathroom but really not sure. But anyway the pump isn't turning off, turns on fine but hasn't turned off once, I have to use the electrical isolation switch.

I tested flow, to fill a 2 litre jug takes exactly 23 seconds in the upstairs bathroom both with and without the pump running.

So I know this isn't a whole house pump, but surely it should have worked for any of the single outlets?

Any pointers to what I've done wrong or have I just got a faulty pump? (float switch in the outlet is moving up and down freely)

I have now ordered this pump to fit tomorrow, but would like to know what I have done wrong, if anything?
http://www.screwfix.com/p/stuart-turner-showermate-eco-s-positive-head-shower-pump-2-0bar/58748

 

[picasso]

At 5 litres a minute the pump is being starved of water, I would check for scale in the cylinder or a valve not opened fully, the gate valve on the cylinder would be favourite for this.

 

[Trevor Austin]

At 5 litres a minute the pump is being starved of water, I would check for scale in the cylinder or a valve not opened fully, the gate valve on the cylinder would be favourite for this.

I'll check that thanks, however if that was the case wouldn't I have bad unpumped flow downstairs too? And the pump should still turn off, I'll go and do a comparison of the downstairs HW outlet........ 15 seconds unpumped, 13 pumped.

And I've found out why it carries on running. There is a valve on the cold water inlet to the hot tank, if I shut that off, the pump stops running, so that implies it is running in reverse and pumping water back into the hot tank and into the cold water tank!

so maybe I had the connections the wrong way round, but if I reverse them there is practically no flow unpumped. I don't get what is going on at all

 

[picasso]

Can you stick a few photos up ?

 

[Trevor Austin]

At 5 litres a minute the pump is being starved of water, I would check for scale in the cylinder or a valve not opened fully, the gate valve on the cylinder would be favourite for this.

Also checked the feed pipe to the pump, through the 15mm pipe added, that is running at over 15lps, so I'm lost, the hot water pressure was OK, but not good before fitting the new upstairs bathroom taps, but then as I understnad it modern taps do need higher pressure. Downstairs flow hasn't changed, but adding the pump has made almost zero flow difference and when the taps are turned off, somehow it seems to run in reverse.

 

[picasso]

So now you have 15 litres per second ?

 

[Trevor Austin]

Can you stick a few photos up ?

Sure here goes;

IMG_0971

• Trevor Austin
• 9 Oct 2016

Pump

IMG_0972

• Trevor Austin
• 9 Oct 2016

Take off

So the first picture is of the pump placement.

The second is the take off from the hot outlet at the top of the tank. Pipe from right is outlet, fed to the connector on the pump marked inlet (although as mentioned I did just try and reverse them) the pump then going to the left is the pump outlet, connected to the main hot water feed to all of my outlets.

 

[Trevor Austin]

So now you have 15 litres per second ?

15 litres per second into the pump...... oh whoops 15 litres per minute into the pump inlet, but only 5 litres per miute into the upstairs basin and about 10 litres per second to the downstairs kitchen tap.

 

[picasso]

You have managed to cut into the vent pipe for the cylinder which is a complete no no and it could be dangerous, first I would put the vent back the way it was and then we can go from there.

 

[Trevor Austin]

You have managed to cut into the vent pipe for the cylinder which is a complete no no and it could be dangerous, first I would put the vent back the way it was and then we can go from there.

Oh ****, thanks

I'll do that tomorrow after work, so now I'm completely lost, where the hell is the hot feed then? I can only see three pipes going into the tank, the one I have cut into, the cold water feed and the feed from the CH? I'm going to look again!

 

[oldbuffer]

I think you'll find you're pumping your hot water straight up the expansion pipe into the cold tank. And you've also broken the direct connection from the hot water cylinder outlet to the expansion pipe into the loft, which can be dangerous.

Check with others, but what I think you need to do is:

a. Break the connection below the "tee".
b. Reconnect the hot water cylinder hot outlet to the pipe going vertically upwards
c. Take a downward tee off the horizontal pipe from b. and connect it to the downward going pipe below the tee.

The above pre-supposes that the upward pipe from the tee does not feed any other outlets, but is purely the expansion pipe. It also does not comply with most pump manufacturer's instructions, but you might get away with it.

I would strongly advise you to get an experienced plumber in to do it properly and fit an Essex flange or similar to your hot water cylinder.

 

[picasso]

Its just a matter of moving the two elbows to the down pipe.

 

[Trevor Austin]

You have managed to cut into the vent pipe for the cylinder which is a complete no no and it could be dangerous, first I would put the vent back the way it was and then we can go from there.

So here's a couple of other pictures,

In the bottom picture are the only other two pipes I can see which I believe are for the hot water heating for the ch.

The top picture, the second pipe from the back is the one that tees onto the pipe I have cut into from the top connection on the hot tank.

The back pipe, behind the one I have cut into has a valve on it and connects to the bottom of the hot tank and I'm pretty sure into the cold water tank in the loft.

 

[Steelmasons]

FFS..

 

[Trevor Austin]

Its just a matter of moving the two elbows to the down pipe.

Ah OK,

So repair the pipe (vent pipe) that I've f'ed up. And then move the elbows to where I have marked in yellow?