Advice on temporary shower feed before we move to megaflow

[Caveman]

Hi Everyone,

I'm moving to a megaflow from a regular immersion heater set up. The house has several showers and at the moment they are fed by gravity feeds from the immersion (hot water) and a top floor tank (cold water). All the showers are powered by (pressure drop) pumps which are fed by the immersion heater/top floor tank.

When we have the megaflow fitted we will feed direct from the megaflow and mains pressure cold.

I am re-doing a bathroom on our top floor and, knowing what is coming, have plumbed on the basis of mains water pressure cold water. Before we get the megaflow could the pump take just the hot water and I feed the cold water from the mains? I assume I cannot feed the pump (which pumps both hot and cold water) with mains pressure? Worst case I can just wait for the megaflow; we are lucky enough to have several showers. What are my options?

Thanks and regards,

David

 

[ShaunCorbs]

The bathrooms cold will need to be fed off the unvented balanced cold as well so will need piping back to the cylinder

single or twin impeller pump eg 2 or 4 pipes on it ?

 

[Caveman]

Hi Shaun,

Thanks for replying so quickly. I'm not a plumber s what do you mean by "fed off the unvented balanced cold so will need piping back to the cylinder"?

The pump is a twin impeller as four pipes - hot in, hot out and on other side - cold in, cold out

 

[ShaunCorbs]

Hi Shaun,

Thanks for replying so quickly. I'm not a plumber s what do you mean by "fed off the unvented balanced cold so will need piping back to the cylinder"?

The pump is a twin impeller as four pipes - hot in, hot out and on other side - cold in, cold out

The cold will have to come after the unvented pressure reducing valve to keep the supplies balanced eg like your pump both at the same pressure

You can’t just use only the hot off your pump on a side note needs to be both of them due to both impellers spin at the same time one shaft

 

[Knappers]

Is it best to only feed showers from balanced supply and everything else straight from main?
If you had a reducing valve on supply where it enters property and all outlets fed from it, would flow restrictions and pressure fluctuation become more of an issue again?

 

[Timmy D]

You say you have multiple showers. Have you tested your mains flow rate?

With your current tank and pump set up, you’ll likely get better flow than the unvented.

More often than not, unvented isn’t better than your current set up.