Advice re pressure & megaflo

[Cazyan]

I have a studio apartment of 500 sqft on the first floor of a 5 floor house in Central London.

The building has had one Central heating system which serviced all three apartments. This is now being separated. As this is a studio apartment I will be installing a shower with a large showerhead. It is therefore essential I have very good pressure.

I am being given conflicting advice.

There is a cold water tank in the roof which I can access. I have space on the first floor for, if needed, a boiler and a cylinder.

The plumber who is also working for the lower two floors and therefore may have a vested interest in retaining the very major job downstairs - a total renovation/refurbishment of the apartment – maybe to my disadvantage & expense has suggested a new separate water supply and a Megaflo - I think he wants exclusive use of the cold water tank in the roof - He has also suggested a combi-boiler.

My understanding is you cannot fit a pump to either system - is that correct?

A new water supply will require me paying for the excavation of at least 20 feet of a stone floor and further disruption in the building.

The most important question bearing in mind the studio is on the first floor is what is the minimum bar for a 'drench' type shower for these systems? Will a new water supply come in a different bore or higher pressure - is thisa question Thames Water would answer?

What specification of boiler &/or cylinder do I need for a 500sq ft apartment with four radiators a towel rail, shower, washing machine?

To add a complication there is a wonderful 85 yr old lady who presently lives in the studio and she is horrified that we have to disrupt her home by lifting floorboards etc. I had hoped as the boiler is being placed outside her studio that it may be possible to use the existing pipes to connect to the new boiler/Megaflo and when she dies put in the new pipes and radiators meaning she would have v little disruption?
Is this possible?

I realise these questions may be answered elsewhere on this site and apologise but my head is now spinning, trying to find a solution and keep everyone happy without incurring enormous expense

 

[justlead1]

Hi I think your right to be concerned. Mains water can not be pumped to increase pressure. However being in central London the storage cistern you refer to is likely to be large (100 gallon min) in order to comply with old bye laws. Owing to the demand mains pressure will vary depending on time of day, effecting the shower performance. To overcome this i would be tempted to use the storage cistern and a pump set to deliver water to a mega flow for hot water and cold supply to shower room. Fit a combi to serve rads, heat mega flow and supply hot water to just the kitchen sink and washing machine. My reasoning being combi's are poor provider on the hot water side, but sufficient for a kitchen sink, simple to install, efficient, and will provide hot water on demand, allowing the storage of hot water to be scheduled according to personal needs. Good Luck

 

[Winston]

You wont get a drench like shower with a combi. Mega flow you will.

 

[Cazyan]

Hi I think your right to be concerned. Mains water can not be pumped to increase pressure. However being in central London the storage cistern you refer to is likely to be large (100 gallon min) in order to comply with old bye laws. Owing to the demand mains pressure will vary depending on time of day, effecting the shower performance. To overcome this i would be tempted to use the storage cistern and a pump set to deliver water to a mega flow for hot water and cold supply to shower room. Fit a combi to serve rads, heat mega flow and supply hot water to just the kitchen sink and washing machine. My reasoning being combi's are poor provider on the hot water side, but sufficient for a kitchen sink, simple to install, efficient, and will provide hot water on demand, allowing the storage of hot water to be scheduled according to personal needs. Good Luck

Do you mean 2 megaflos? Can this be fitted to the existing pipework .. presumably not which would mean serious upheaval for the old lady.
As I will completely redesign the whole system internally in the apartment when she leaves could there be an interim solution - she does not need the pressure for her existing bath - that would mean I do not have to buy a set of rads etc that I will inevitably replace and position differently at a later stage?

 

[justlead1]

Hi. It difficult to picture the property and sitting tenant situation. However the heating system to the flat may well come from flow and return risers from the boiler. If so it may be easy to hook up the flow and return feeding the flat and connect to a combi and provide hot water via the combi (as the old lady's needs are likely to be served with a combi ) for the interim period.
When in a position to fit mega flow, only one would be required.
A new supply pipe from mains will record the same pressure, but maybe better volume.

 

[Blackcatgas]

Hi I think your right to be concerned. Mains water can not be pumped to increase pressure. However being in central London the storage cistern you refer to is likely to be large (100 gallon min) in order to comply with old bye laws. Owing to the demand mains pressure will vary depending on time of day, effecting the shower performance. To overcome this i would be tempted to use the storage cistern and a pump set to deliver water to a mega flow for hot water and cold supply to shower room. Fit a combi to serve rads, heat mega flow and supply hot water to just the kitchen sink and washing machine. My reasoning being combi's are poor provider on the hot water side, but sufficient for a kitchen sink, simple to install, efficient, and will provide hot water on demand, allowing the storage of hot water to be scheduled according to personal needs. Good Luck

I like this idea, you could add another tank if the capacity isnt big enough, with a pump fed from this tank to a megaflow you wouldnt need to put in a larger mains cold water pipe.
having said that the existing mains cold water pipe even if 15mm might already be man enough, dont quote me on this but they will operate on a minium of 1.5mbar and 20litres a minute.

 

[Bernie2]

A lot swings on cold mains avaliable pressure and flow. I would imagine Justlead1's idea is probably best.