Accumulator or cold water tank+pump

[sasha0120]

Hi

I own a flat on the third floor of a building. There is an issue with the building water supply due to which there is not enough water pressure and volume reaching our flat. At peak times of the day there is no water coming in the taps. Thames Water will not do anything about it because they guarantee supply of 1 bar at the building entrance and that is it. The building does not want to provide for a pump or tank to resolve the issue. Thus, I am left with trying to find a solution for my flat. I have a brand new megaflo boiler and have been recommended 2 options: 1) Install an accumulator that will provide a burst of 20-30min of water for a shower during peak times when the water supply is most impacted or 2) Install a cold water tank and a pump (or a pumped tank?) that will provide enough water supply. We have 2 bathrooms and showers in the flat. Option 1 is quoted at £1.5-£2.5k and Option 2 is significantly higher at £3-£4k. I do have the space in terms of cupboards for an accumulator or cold water tank. Attached pics of our current megaflo configuration. I would really appreciate some advice. Our new megaflo boiler cost us £3k last Decemeber so we dont want to spend on Option 2. However, I want to make sure that Option 1 works before committing to it. Any advice/help is much appreciated!

 

[ShaunCorbs]

How or what was the OP using previous to this megaflow installation?

Gravity cold tank and cylinder

 

[John.g]

Why not (OP) measure his actual shower flowrate(s), the DAB VS pump pressure can then be set to match this and he may find that a little or no compromise will result in no extra tank capacity required.

 

[John.g]

If the flowrate through a cold tap is measured during this bad morning period then that will give a good idea of what will be making up into the DAB tank and even if its as low as 6 LPM that will augment his storage and give effectively ~ 700 ltrs. (35 mins)

 

[ShaunCorbs]

If the flowrate through a cold tap is measured during this bad morning period then that will give a good idea of what will be making up into the DAB tank and even if its as low as 6 LPM that will augment his storage and give effectively ~ 700 ltrs. (35 mins)

0lpm he doesn’t have any water sometimes

 

[Chuck]

0lpm he doesn’t have any water sometimes

I'd have thought that this is an issue for the owners of the block to remedy rather than individual flat owners.

 

[sasha0120]

I'd have thought that this is an issue for the owners of the block to remedy rather than individual flat owners.

yes I thought so too but they are refusing to as the other flat at our level has its own tank and so its just our flat that seems to be impacted

 

[John.g]

When you had your own tank 7/8 years ago you would/should still have had one tap fed off the mains so did you still have zero flow through this tap at peak times?.

 

[ShaunCorbs]

I'd have thought that this is an issue for the owners of the block to remedy rather than individual flat owners.

Might be private owned also bit bad of the water supplier to say not our problem aswell tbh

 

[sasha0120]

When you had your own tank 7/8 years ago you would/should still have had one tap fed off the mains so did you still have zero flow through this tap at peak times?.

yes

 

[John.g]

Thanks, would IMO be a big help if you can measure your shower flows during normal supply times to help in sizing your tank.

 

[Chuck]

yes I thought so too but they are refusing to as the other flat at our level has its own tank and so its just our flat that seems to be impacted

Hmm, seems like a fairly complicated situation.

Anyway, you need a reliable supply of potable water. So, if you do decide to fix the symptoms rather than the cause then make sure that any tank and/or pump you install is certified as suitable for potable water and is properly maintained.

 

[sasha0120]

Thanks, would IMO be a big help if you can measure your shower flows during normal supply times to help in sizing your tank.

I have the pressure reading if that's of any use? It was a little less than 1 bar.

 

[John.g]

When you have your shower running normally at your desired flow and temperature hold a bucket or dish under it for exactly one minute and measure this amount in litres or pints. You can also note the pressure as well with shower running normally.

 

[SJB060685]

Max you can pump the mains without a tank is 12lpm which is not suitable for a property with 2 bathrooms.

Can you explain why 12lpm is the max mate. It's been a long time since I did my relavent courses.

 

[Chuck]

I've been racking my brain and have remembered something, e.g.

South West Water

Providing reliable, efficient and high quality drinking water and waste water services throughout Cornwall and Devon, plus servicing small areas of Dorset and Somerset.

www.southwestwater.co.uk

Water companies have "a statutory requirement to supply water by gravity continuously for domestic purposes at a pressure that will; ‘reach the top of the top-most storey of every building’ (Water Industry Act 1991 Section 65)."

This is in addition to the OFWAT minimum pressure at the end of the communication pipe. So, I think it would be worth going back to the water company and making a complaint about non-compliance.

@SJB060685 - I think that the 12 lpm limit is to stop you starving neighbouring properties.

 

[John.g]

If you had 3 floors even with each only 2.5M high then a pressure of 0.75 bar will reach the top of the the third floor so you might argue that 1.0 bar (dynamic) would be more than adequate and it would, if you had > 22mm piping. 1 bar should theoretically flow 20 LPM to each floor (total 60 LPM) with 22mm piping but if 15mm is used then ~ 2.8 bar is required for the same flow rates. 1.6 bar minimum is still required at a flow rate of 10 LPM to each floor with 15mm piping so surely there is a requirement (and not from the water board(s)) to install adequately sized piping for each application.
1.0 bar dynamic will only give ~ 6 LPM to each floor with 15mm piping, assuming in all cases that a storage tank is being filled, also IMO the op will receive 0 LPM if the two floors below are flowing ~ 10 LPM each @ 1 bar dynamic.

 

[Chuck]

If you had 3 floors even with each only 2.5M high then a pressure of 0.75 bar will reach the top of the the third floor so you might argue that 1.0 bar (dynamic) would be more than adequate and it would,

During the periods when when the supply is '0 lpm' the water company is not 'supply[ing] water continuously', is it?

 

[John.g]

No, are they then obliged to either run a separate supply to the OP (the owner) or pay to upsize the existing (3 flat) piping? They also state that "where our communication pipe joins your supply pipe you should be able to fill a 2 litre bottle in less than approximately 13 seconds." so does this imply that they are only obliged to supply 10.9 LPM continuously?,

 

[Ant87]

Am I right in thinking that an unvented cylinder requires a minimum of 1.5bar working pressure and around 20l/min so even if SWW meet their minimum obligations of 0.7bar (at pavement level) and 10l/min then issues will still be present?

Something like a Stuart Turner Flomate might be an option which is an all in one stored water (break) pump set.
Dab E.sybox are extremely good units but might be overkill?

You are correct in saying that legally you can pump up to 12l/min directly from the mains with no break tank. Salamander HomeBoost is a direct to mains booster pump which will pump at 12l/min (1.6bar i think) however would still not be adequate for an unvented cylinder.

 

[Timmy D]

Can you explain why 12lpm is the max mate. It's been a long time since I did my relavent courses.

Water regs. As Chuck mentioned, to stop the mains supply running dry during peak periods.