Water pressure - electric shower or water pump?

[JohnMalcolm]

Hi All,
I hope you are doing well.
My question is about the dilemma of installing an electric shower or a water pump instead?
The hot water pressure in upstairs bathroom is a bit weak.
I could get an electric shower installed but I also consider a water pump.
What would you suggest? A pump makes a noise which is the downside.
Best

 

[John.g]

A Pump, pumping both hot&cold water, the HW from the HW cylinder and the cold water from the CWST (cold water storage tank) will give you almost any flowrate you require up to say 15LPM. You can also buy a "electric" shower like the Triton Novel SR which has a internal pump, with hot&cold feeds like the above which will pump up to 14LPM, good enough for most needs. The pump noise from the Novel (SR stands for silent running) is quite low.
A all electric shower which has a cold feed only, either from the mains, or as you require, with the cold feed from the CWST, this shower also heats the water but will only give ~ 1/3rd of the flow of the above showers, a 9kw will give ~ 3.9LPM at 40C in the winter and 5.2LPM in the summer.

 

[Ric2013]

If it's only 'a bit' weak, would a Shower Power Booster work? I think they give a 0.6 bar boost, which is like lifting the cylinder feed cistern up another 6m.

 

[John.g]

it may but you would need two to boost both hot and cold.

 

[Knappers]

I like the mira digital showers (mode or platinum i think they're called), pricey but slick!

 

[JohnMalcolm]

I think in my case only hot needs boosting the pressure on cold is strong

 

[Ben-gee]

If all the cold is on the mains and all the hot is tank fed - consider a single impeller pump to boost all the hot. I’ve found this very satisfactory on a number of occasions. Use a Stuart Turner Monsoon pump, choose the ‘bar rating’ to match your cold main. ( if main is very high then put a pressure reducing valve on it down to 3bar)

 

[JohnMalcolm]

If all the cold is on the mains and all the hot is tank fed - consider a single impeller pump to boost all the hot. I’ve found this very satisfactory on a number of occasions. Use a Stuart Turner Monsoon pump, choose the ‘bar rating’ to match your cold main. ( if main is very high then put a pressure reducing valve on it down to 3bar)

Let me get the gauge and measure the pressure but I think it will be a booster pump, right?

 

[JohnMalcolm]

Let me get the gauge and measure the pressure but I think it will be a booster pump, right?

I just checked the water pressure and it's showing 3.75 bar so I reckon I should go for a 4 bar booster pump, right?

 

[JohnMalcolm]

I just checked the water pressure and it's showing 3.75 bar so I reckon I should go for a 4 bar booster pump, right?

The plumber came over and checked the pipework. It looks like installing that pump also involves some serious pipe work and ripping a lot of floor. I think the assumption was to install the pump for the shower only. Wondering if installing the pump for the whole system which is just additional tap downstairs is as complex as this booster pump for the shower.
The electric shower has been chosen but after the electrician has visited it looks like I need to run 20m cable.
The thing is because of that silly pull cord switch I have to run it in the floor then find a way to run it upstairs in the loft then down again for that switch. Do I really have to use that pull cord switch?
So my dilemma is between:
1. booster pump for the whole system provided it's simpler job than booster pump for the shower only.
2. electric shower provided I can use some wall switch instead

 

[Chuck]

Keep in mind that heating water by electricity is a lot more expensive (at least historically) per litre than using gas. Last time I estimated this for a 8.5kW 10 minute shower it was 73p vs 40p assuming the flow rates were equal. So, with two people each taking a daily 10 minute shower the electric option cost £241 / year more to run.

Please check my figures, the above are from memory and YMMV.

 

[JohnMalcolm]

Keep in mind that heating water by electricity is a lot more expensive (at least historically) per litre than using gas. Last time I estimated this for a 8.5kW 10 minute shower it was 73p vs 40p assuming the flow rates were equal. So, with two people each taking a daily 10 minute shower the electric option cost £241 / year more to run.

Please check my figures, the above are from memory and YMMV.

This is what I thought that these electric showers are not cheap to run.
In this case my question is installing a pump for the whole system less disruptive than dedicated shower booster pump?
If less then I go for a pump for the whole system.

 

[John.g]

Are you considering just boosting the hot water pressure?.

Electric/gas, a 9kw electric shower will give a average of ~ 4.2LPM at 40C, you might expect 3 times that with a pumped (gas) pumped shower, so the running costs of both per unit showering time is pretty similar based on energy costs here anyway. Of course you must be happy with the low electric flowrate.
Running cost of a 9kw electric shower is 0.15xcost/kwh pence (per minute), if you are paying say 45p/kwh then the running cost is, 0.15x45, 6.75p/minute or 34p for a 5 min shower.

 

[JohnMalcolm]

Are you considering just boosting the hot water pressure?.

Electric/gas, a 9kw electric shower will give a average of ~ 4.2LPM at 40C, you might expect 3 times that with a pumped (gas) pumped shower, so the running costs of both per unit showering time is pretty similar based on energy costs here anyway. Of course you must be happy with the low electric flowrate.
Running cost of a 9kw electric shower is 0.15xcost/kwh pence (per minute), if you are paying say 45p/kwh then the running cost is, 0.15x45, 6.75p/minute or 34p for a 5 min shower.

Yes just boosting the hot water, cold has very good pressure: 3.75

 

[Ric2013]

Re. the pull cord switch, this is usually because it is the only type of switch allowed near the shower. Realistically, you could probably put a 45A wall switch just outside the bathroom and it would serve the same purpose.

 

[JohnMalcolm]

So how do you reckon should I install the pump or the electric shower?

 

[JohnMalcolm]

I asked the plumber and booster pump for the shower only or a water pump for the whole system does not make much difference in terms of additional pipe work so electric shower still wins in terms of labor.

 

[John.g]

You said in your first post the the pressure in your upstairs bathroom is a bit weak, imo you need at least 2.5 to 3 bar static pressure downstairs to give you 5.5LPM or so in the summer at the 1Bar dy.namic minimum required by a 9.5kw shower in the summer, otherwise you may have to switch to 1/2 power which isnt much fun. You can buy a electric pumped shower where the pump is integral with the shower but this requires a gravity supply from a CWST in the attic.
You can install a PRV on the mains set to ~ 0.5bar to a pumped shower but I think it invalidates the warranty, I did it for a friend years ago and the shower is running away fine.

 

[JohnMalcolm]

You said in your first post the the pressure in your upstairs bathroom is a bit weak, imo you need at least 2.5 to 3 bar static pressure downstairs to give you 5.5LPM or so in the summer at the 1Bar dy.namic minimum required by a 9.5kw shower in the summer, otherwise you may have to switch to 1/2 power which isnt much fun. You can buy a electric pumped shower where the pump is integral with the shower but this requires a gravity supply from a CWST in the attic.
You can install a PRV on the mains set to ~ 0.5bar to a pumped shower but I think it invalidates the warranty, I did it for a friend years ago and the shower is running away fine.

right, the cold water pressure downstairs (ground floor) is 3.75

 

[John.g]

3.75 bar shoud be fine for a mains supplied electric shower installed upstairs.