Boosting pressure for unvented cylinder (or stick to vented...)

[Ch_152]

Hello all.

[following is the edited version as apparently the original had too many words...].

My incoming supply is rubbish. I've looked into improving it through Thames Water and the management company of my flats, but I'm stuck with a little less than 1 bar (second floor flat), and a flow rate that is currently around 7 l/m at kitchen tap (checking stop taps to get this improved).

Currently cold water header + vented cylinder + pump for all outlets except mains drinking, and shower supply (electric shower).

Electric shower pressure is pitiful and I'd like to get rid of the pump and CWS. Plumbers have recommended unvented cylinder.

Reading on here, it seems like an unvented cylinder is going to be worthless at my current pressure.

I have electric only on E7 tariff. No radiators - so no boilers.

Is there any way (other than accumulator) to boost the mains into an unvented, or am I better off sticking with the header tank + vented + pump?



Cheers

 

[oldbutnotdead]

Not ploughing through all that lot.
First Q- are you saying there is a single supply pipe to the block which then splits into individual metered lines or does each unit have its own supply pipe back to the main?
Second Q- what size is the supply pipe where it comes into the building, what size is it when it gets to your flat?
Before you put time and money into appliances sort the supply out.

 

[Ch_152]

Not ploughing through all that lot.
First Q- are you saying there is a single supply pipe to the block which then splits into individual metered lines or does each unit have its own supply pipe back to the main?
Second Q- what size is the supply pipe where it comes into the building, what size is it when it gets to your flat?
Before you put time and money into appliances sort the supply out.

1) I think the guy from TW implied the latter, but I'm not sure in all honesty.
2) Not sure about under the manhole outside, but in the building it's 15mm.

It seems that the supply to my flat is what it is. TW consider themselves to be providing their minimum obligation (1 bar at ground floor), the management company aren't going to change the pipes inside the building. Even if there's a restriction in flow somewhere (early 70's building, old pipes, corrosion?), I assume I won't get any better pressure.

 

[Johntheo5]

Are TW saying they will supply 1 bar at where their pipe ends? and do they guarantee this at any flowrate?. How long is your piperun from where their one ends?.

 

[Ch_152]

Are TW saying they will supply 1 bar at where their pipe ends? and do they guarantee this at any flowrate?. How long is your piperun from where their one ends?.

Not sure regarding flow rate, but I spoke to a few people and all that was mentioned was 1 bar where the pipe enters the property. One chap mentioned that (given I had my own supply) this should be 1 bar at the entrance to my flat, rather than at ground floor. But the engineer didn't seem to agree with this, and nor did most of the other people I complained to.

Pipe run from the point the TW engineer measured at outside is probably 15-20m horizontally and then up to the second floor.

 

[Johntheo5]

If you assume a total length of say 20M of 15mm pipe to the second floor and only 0.75bar available after allowing for the ~ 2.5M head loss to the second floor then looks like you will only get a flowrate of ~ 15LPM and thats through a filling valve into a cold water water storage tank, so looks like you have to consider a pump from the CWST boosting the cold water with a unvented cylinder or suchlike.

 

[oldbutnotdead]

Gravity isnt your friend here- for every metre above street level you lose 0.1 bar of pressure plus the headloss in all that 15mm tube will be significant.
Definitely worth checking your stop taps as advised, no point doing much else yet.

 

[Ch_152]

Gravity isnt your friend here- for every metre above street level you lose 0.1 bar of pressure plus the headloss in all that 15mm tube will be significant.
Definitely worth checking your stop taps as advised, no point doing much else yet.

Indeed. Checks out if 1.7 bar outside and I'm getting ~0.7 to 1 in my property 6 to 7 m up (not to mention further 3m to the upper floor of my flat where HW and CW storage currently is).

What am I looking for when checking the stop taps? Is there going to be some external evidence of them being corroded/blocked etc.

Cheers

 

[oldbutnotdead]

First thing make sure they are all the way open (I say they- there should be one at the water meter and probably one in your flat somewhere). Yes have a look at them- the one at the meter will likely be a modern plastic quarter-turn thing but if it isn't then a pic or 2 will help the true gurus on here give you a rough age.
Next, close one (doesn't matter which you do first), make sure it actually closes all the way (as in isolates water supply to your flat), unless it is a quarter-turn type see how it feels as you turn it- stiff but smooth is fine, jerky/notchy is a bad sign as is really loose and sloppy and doesn't feel as if it is doing anything. Open it all the way again, do a quick flow check (bucket and stopwatch) to make sure it is the same (or better) than before you started. Repeat with the other one.
Is your water hard or soft (do you get lots of scum in the kettle)? It is possible your supply pipes (the copper anyway) are scaled up

 

[Johntheo5]

Indeed. Checks out if 1.7 bar outside and I'm getting ~0.7 to 1 in my property 6 to 7 m up (not to mention further 3m to the upper floor of my flat where HW and CW storage currently is).

Can you note those pressures at a known flowrate, say 10LPM or whatever you measure, also take them (static) at no flow.

 

[Ch_152]

First thing make sure they are all the way open (I say they- there should be one at the water meter and probably one in your flat somewhere). Yes have a look at them- the one at the meter will likely be a modern plastic quarter-turn thing but if it isn't then a pic or 2 will help the true gurus on here give you a rough age.
Next, close one (doesn't matter which you do first), make sure it actually closes all the way (as in isolates water supply to your flat), unless it is a quarter-turn type see how it feels as you turn it- stiff but smooth is fine, jerky/notchy is a bad sign as is really loose and sloppy and doesn't feel as if it is doing anything. Open it all the way again, do a quick flow check (bucket and stopwatch) to make sure it is the same (or better) than before you started. Repeat with the other one.
Is your water hard or soft (do you get lots of scum in the kettle)? It is possible your supply pipes (the copper anyway) are scaled up

Cheers. There are actually 3: The Thames Water one outside at the meter down a manhole; one at the ground floor in the corridor of the block of flats; and the one in my flat.

The TW guy checked out the one outside and it seemed okay to him. I had a go with the one in my flat and seems fine (isolates correctly, no change to flow before/after). It did start dripping ever so slightly for a while afterwards, but that has since stopped.

Need the maintenance guy to do the other one unfortunately, so that's a job for next week. I'll report back.

And the water is on the harder side, but not too bad... Though it's been in for 50 years, so could be a thing!

Can you note those pressures at a known flowrate, say 10LPM or whatever you measure, also take them (static) at no flow.

I'll see if I can get hold of a pressure gauge. Those quoted were tested by the TW guy (1.7 at ground) and a plumber (0.7-1 at 2nd floor. I think this was static but at the time I didn't know the difference, so not sure...).