Negative head pump

[V1k]

oh also forgot to mention, the taps in the bath (on the first floor of the house) are high pressure taps, I replaced this with a low pressure hot water tap and the water flows out perfectly well from this.

 

[echoes]

Ah, so good flow upstairs with proper tap, poor flow/no flow/spluttering downstairs? That may eliminate a blockage with the cylinder and CWS tank.

How long to fill a 1L container from this working tap? The flow may still not be as good as it could be.

Getting difficult to help now.

Even a high pressure tap downstairs should still give a steady, constant flow from a low pressure supply, even in 15mm - it just won't be very fast, and should certainly not stop & splutter due to low pressure alone.

 

[V1k]

Ah, so good flow upstairs with proper tap, poor flow/no flow/spluttering downstairs? That may eliminate a blockage with the cylinder and CWS tank.

How long to fill a 1L container from this working tap? The flow may still not be as good as it could be.

Getting difficult to help now.

Even a high pressure tap downstairs should still give a steady, constant flow from a low pressure supply, even in 15mm - it just won't be very fast, and should certainly not stop & splutter due to low pressure alone.

This is the strange bit you see, very very strange. The plumber put a push fit stoper on the pipe which comes from the top of the HW cylinder and goes up to the CW tank in the loft and drained the water from the cylinder. he then filled it up again and the ground floor WC tap worked fine. as soon as he took the stopper off of the pipe in the loft though, the spluttering and stalling started again.

not sure if it's the design of the pipework which has caused the problem? the hot water pipe comes out from the top of the HW cylinder goes into an elbow and turns horizontally right. It then goes into a T. The top of the T goes into the loft and into the CW tank in the loft and the bottom part of the T goes down into the floorboards and horizontilly accross the house into the bathroom.

Should a T be used in this way or should the pipe going into the loft be taken up from a different point before/after the pipe that goes down and supplies the rest of the house?

I will check later tonight how long it takes to fill a 1l bottle when I get home and post it when I've worked it out.

 

[echoes]

The T from the top of the cylinder goes (1) down to your taps and (2) up and over the CWS tank. This is correct.

So your plumber put a stop-end over the vent, and everything worked OK, but spluttering started as soon as the stop-end was removed. If the stop-end is left on, the vent cannot empty and remains full of water.

This seems to indicate that the vent is the source of the air.
Your upstairs tap works, but downstairs taps splutter.

Since your downstairs taps are at a higher pressure (more head), I would expect the flow to be greater than upstairs. It could be that the flow to downstairs is sufficient to empty the vent of water, but the flow to upstairs does not.
Which points to either
(1) cylinder not refilling fast enough, which plumber appears to have checked & eliminated; or
(2) a restriction between the top of the cylinder and the T.

After this, I'm out of ideas.

 

[V1k]

The T from the top of the cylinder goes (1) down to your taps and (2) up and over the CWS tank. This is correct.

So your plumber put a stop-end over the vent, and everything worked OK, but spluttering started as soon as the stop-end was removed. If the stop-end is left on, the vent cannot empty and remains full of water.

This seems to indicate that the vent is the source of the air.
Your upstairs tap works, but downstairs taps splutter.

Since your downstairs taps are at a higher pressure (more head), I would expect the flow to be greater than upstairs. It could be that the flow to downstairs is sufficient to empty the vent of water, but the flow to upstairs does not.
Which points to either
(1) cylinder not refilling fast enough, which plumber appears to have checked & eliminated; or
(2) a restriction between the top of the cylinder and the T.

After this, I'm out of ideas.

I think we're all out of ideas, including my plumber with his 20+ years of experience.... real head blower this one.

I also thought that the vent was pulling air into the system and was thinking of moving this vent to another point along hot water exit from the cylinder. Just didn't know where would be best? Any ideas?

I tried the taps when I got home just now - the ground floor WC taps don't stop working now but the flow deffinately slows down and still splutters....

0-2 litres - 18 seconds
2-4 litres - flow slows down but still going
4-6 litres - spluttering
6-8 litres - spluttering and it takes 49 seconds to fill up.

 

[echoes]

Where the pipe exits the top of the cylinder and goes horizontal via an elbow before the T - that horizontal bit should be either level, or rise slightly. A slight fall would tend to trap air.

Did your plumber ensure that the pipe from the top connection from cylinder to the T was clear, as well as checking that the bottom cold feed to the cylinder was clear?

 

[wundaboy]

When I did my first plumbing job some 23 years ago, raising a CWS tank from a first story airing cupboard up to the loft to provide extra head for a shower, I extended the feed pipe from the CWS with an appropriate fall, but did a cack-handed job of extending the vent pipe so that after rising up to the loft it then fell a little along the loft floor before rising again. This led to spluttering and gurgling at the lower floor taps, possibly of the sort you describe. Maybe a similar situation? Anyhow, I corrected the inadvertent fall in the vent pipe so that I had a continuous rise up to the CWS, which remedied the problem.

I'd offer the suggestion that even though your plumbing up to your CWS hasn't changed apart from your new feed pipe down to the hot water cylinder, maybe there was something like this pre-existing in your installation which didn't cause a problem before but which moving the hot water cylinder to its new position has exacerbated?