Increasing flow rate from shower

[dishman]

This is a good guide:

Stuart Turner supposedly do good quality pumps. That is a name that cropped up when I was looking.

The only issue maybe the size of the exiting pipework. If you re-read my thread I think someone mentioned that the pipework needs to be 22mm to feed the pump. But, don't quote me on that.

 

[Madrab]

Before a pump is considered then check the type of shower it is. There are many different designs that have various sized internal waterways , the smaller they are the more they can restrict the flow especially if gravity fed. Pipework is also a factor, gravity fed should be 22mm to as close to the outlet as possible.

 

[Nick Allen]

Ok thanks.

Will we be ok for a pumped power shower if our hw cylinder is only about 100l?

And do any power showers look decent? They all look like electric showers.

 

[dishman]

You have three options.

1) As @Madrab states, and I mentioned. Look at the existing set-up and try to reduce resistance and restrictions at all points. Swap out 15mm pipework for 22mm where possible. Ensure there are no reduce bore isolation valves anywhere on the pipe run or just before the shower outlet. Ensure the mixer shower has a large bore and where possible a non-ceramic washer. Sometimes these are only available in a manual mixer rather than thermostatic ones.

2) Install a powershower, looks like an electric but basically contains a localised pump. Probably the easiest retrofit, but requires and electrician.

3) Install a remote pump, may require pipework modification. Unless you did not want it to, this would end up boosting the pressure to all the outlets.

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Regarding tanks size, 100litres is not huge but if you get your shower flow to 10l per min, that just means you could have a 10min shower before the tank ran cold. Your cold water tank would drain twice as fast as it is feeding hot and cold. But, as it is twice as big as the hot water tank, it should not be an issue.

 

[Madrab]

Also need to consider, you won't get 100L of hot water as the cold is fed in when the hot is used, effective amount of hot water will be less. Recovery may also be an issue.

If you want a good shower for a reasonable time then it may be time to consider upgrading your hot water cylinder/system.

 

[JohnD]

100litres is not huge but if you get your shower flow to 10l per min, that just means you could have a 10min shower before the tank ran cold. Your cold water tank would drain twice as fast as it is feeding hot and cold. But, as it is twice as big as the hot water tank, it should not be an issue.

10 mins if it was 100% hot

If you say the cold tank is delivering double that, the shower would last 20 mins.

 

[dishman]

Yes, sorry I should have clarified, I was assuming an equal drain rate of hot and cold till the hot ran out.....

I was more just giving an extreme example of what would happen to the tanks if both outlets were opened full till the hot ran out.

So in reality, if it was full hot and a tiny bit of cold added to give a desired temp, the cold tank would not drain at twice that of the hot.

 

[Nick Allen]

Thanks for this...

As we are on a budget. Would it make sense to try changing the pipework to 22mm and changing the shower to a newer Thermostatic mixer shower, was thinking Mira, to try and get the flow rate up to the same as the other bathroom. If that doesn’t work look at getting a pump and maybe a bigger cylinder?

 

[dishman]

The thing about thermostatic mixers is that they will probably all have ceramic washers. These have tiny holes which a low pressure system does not have enough force to push the water through without a huge reduction in flow.

I was looking online for ones with rubber washers and I could not find one. Usually the traditional styled ones are more likely to have them.

Personally I would consider something like this.

https://www.ebay.co.uk/itm/REMER-Lu...986947&hash=item283f8ea551:g:hjgAAOSw2AFZuk3R

It does not have the thermostatic component so you have to mix it manually. Which in reality is not that hard.

It does not look pretty, but something like that, with traditional multi-turn taps, will have rubber washers and a lot less restriction.
That and upgrading the pipework to 22mm where possible.

- You have to decide what is feasible.

 

[Nick Allen]

Yep ok. Thanks a lot for the advice it’s really appreciated.

 

[Madrab]

Target low pressure gravity fed thermostatic mixer showers, should give you the highest flow possible.

 

[Daveydub]

If both of your showers have 2m head, the reason for the difference in performance may be that 1 has more dirt in the filters than the other. Mira miniduo operates on minimum 1m head and I have used a few on low head applications and been pleased with performance. Not too dear either.