Electric Shower Pressure Problem

[Theteapotsbrokenspout]

Trying to solve a plumbing problem. I have one year old condensing boiler and an unvented indirect Megaflow cylinder (considerably older). Downstairs shower is an ordinary mixer shower, upstairs an electric shower.
Currently the electric shower goes into safety mode and stops hot water supply if the other shower is run, any toilet is flushed or kitchen appliances draw water. Not very pleasant as water turns to freezing cold.

I am hoping to upgrade both bathrooms this year, replacing the showers to both more modern mixer showers. I was assuming I could put a pump on the upstairs shower to increase the flow. I've now been told the set up here makes a pump not possible.

Our incoming water flow is approx 10 litres / minute and this is after it has run through the water softener.
Are there any solutions where both showers can run comfortably at once or am I doomed to sudden freezing showers upstairs?

"Our incoming water flow is approx 10 litres / minute and this is after it has run through the water softener."

you need to improve the incoming water flow. Are you on the top of a hill in a country area?

what size is the incoming supply pipe to your in-house stopcock?

is it iron, lead, copper, black plastic or blue plastic? Hhow old is the house?

The water softener itself will be reducing flow somewhat. Look at the size of the white hoses and the connectors and control valves. You can get larger ones that will make some improvement.

Is the pipe between softener and cylinder 15mm (finger sized) or 22mm (banana sized)?

Look at all the control valves and stopcocks. The worst type is like this it is nominally 15mm but the hole is less so it contricts flow. Flexible braided tap connectors often incorporate one, and the diameter of the hose inside the braid is also less than 15mm. Every one of these will constrict flow.

A really good valve is this It is "full bore" meaning it actually has a 15mm hole (22mm and larger are also available for bigger pipes) and is much higher quality so less prone to leak.

It's likely you need to use larger pipes. Having determined which the smallest ones are, those are the first to replace. It's possible you will need to replace all the way to the stopcock or water meter in the pavement. But 10lpm is quite poor so there is a fair chance you can make other improvements.

After having a look round for obvious constrictions, you (or a plumber) can disconnect the hoses from the softener and run each into a bucket or flow meter to see how much the softener itself reduces flow.

Thank you for answering @PigletJohn , i can only answer some of the questions:
The house is 1850's with additions / alterations 1960's and 80's. Not on the top of a hill but village area in the countryside.
I can't easily see the size of the incoming supply or what it is as the stopcock is behind the washing machine, when we moved in there were 2 stopcocks, one which fed the kitchen and one for elsewhere in the house. To install the softener the other stopcock was blanked off and everything is now fed through the kitchen one.
There is a very long run through the house to the megaflow, both are on the ground floor but I'm not sure where the pipes run. The plumbing (and electrics) here are a nightmare.
We have both types of those valves in various parts of the house, definitely got the more restricting ones on the supply to both showers.
I have included a picture of some of the water softener pipes, all of these have the non-restrictive valve on them.
Doesn't sound like an easy fix then.

if the braided hoses are for the softener, it looks like they are the larger size. I think the white one is the overflow or drain hose.

If you look under your sink, basin or WC cistern you may find braided hoses, and i think you will find them smaller than the ones on the softener.

You have an old house so the original pipe, if still in use, was probably lead in quite a small size, because when water supply was first run to English houses (mostly after about 1550) it was not pumped, and the system was to slowly fill a tank in the loft, and use that to deliver water at high flow, but low pressure, to the taps. In this case you may need a new, larger plastic pipe run out to the pavement. You might wait until you have a leak or burst. You will be astonished and delighted at the improvement.

Many other countries were piped up later and have a higher pressure system.

It's likely that you also have a hodgepodge of later modifications and extensions of the pipework, unless it has already been replaced. The incoming pipe may be visible inside the water meter pit, if you have one, and close to the first internal stopcock, if you can find a way to look at it.

Would it be impertinent to ask if you can afford to have a comprehensive replumb?

btw, if you have either a cellar, or old floorboards, it may be delightfully simple to draw a new plastic pipe under the floor. It is also easy to dig a trench in a flowerbed or gravel drive. The plastic pipe is quite stiff, but comes in a big reel and can be bent and curved.

if you suffer from concrete, the pipe can take a different route, such as round the side of the house.

We have a water meter so I should be able to look in the pit.

I’m pretty certain the hoses under the bathroom sinks are narrower, I’ll have a good look tomorrow.

Unfortunately I think a comprehensive replumb is going to be fairly low down on our list of improvements as the house has proved a money pit - extensive damp due to cracked cement render, which is being removed and replaced with lime, failed flat roof (x 2) been replaced with pitched, new boiler and oil tank, electrics overhaul.

I would be interested in replacing the pipe from the road to the house if necessary, we have a long gravel drive but there is also some main drainage across it. Unfortunately no cellar or wooden floors.

We also discovered a well in the garden when I was trying to plant a rose, and an old septic tank when digging a flower bed. It’s been an interesting house.