Accumulator or cold water tank+pump

sasha0120 · Sep 6, 2021

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!

John.g · Sep 8, 2021

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 · Sep 8, 2021

John.g said:
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 · Sep 8, 2021

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 · Sep 8, 2021

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.