Flow straightener for bath filler?!?

[Adsibob]

I’m considering a Vado bath filler. It’s flow performance graph is pictured below. Despite the tap’s official rating at 3 bar being 17.6 litres per min, the graph shows a much steeper second curve that would appear to reach almost 40 litres per min way before 3 bar.

flow rate is important to me as the bath I’m filling is HUGE. Can someone explain what the

 “flow straightener” curve is please and how I can achieve the 40l/m rate?

 For background, I will have an UNvented cylinder and mains pressure is between 2.8 and 3.1 bar. Haven’t laid pipes yet, so could choose what diameter to optimise bath filler flow.

 

 

[Big Jimbo]

I cant help, but i want to know how big. Two people, Four people ?......Hope the floor is strong enough to take the weight. Sounds like fun.

[Adsibob]

28 minutes ago, Big Jimbo said:

I cant help, but i want to know how big. Two people, Four people ?......Hope the floor is strong enough to take the weight. Sounds like fun.

It’s a Large Picasso bath from Lusso Stone. @Bitpipe has one I think.

It is described on the website as: “Water Capacity to Overflow: 350 Litre” but I reckon I would take up at least 95 litres of that, so I need a filler that can do 250 litres. At 17.6 litres per minute it will take about 14 minutes. Not terrible I suppose, but if I could achieve something a tad quicker. 

[Temp]

Have you got a link to the filler you are looking at?

 

[SuperJohnG]

15 minutes seems OK. Defo pretty big at 300 litres but not huge. I think at standard Bath is around 200? 

[Temp]

The filler might allow 40L/min but what you actually get will depend on the supply to your house and the internal pipework. In short you can't do better than a pipe with nothing at all on the end. So perhaps test that first? 

[Adsibob]

18 minutes ago, Temp said:

Have you got a link to the filler you are looking at?

 

https://www.vado.com/product/6000/specifications-pdf

[Adsibob]

16 minutes ago, SuperJohnG said:

15 minutes seems OK. Defo pretty big at 300 litres but not huge. I think at standard Bath is around 200? 

It’s huge. It has a capacity of 350 and standard baths are anywhere between 130 and 175. It weighs 140kg... empty!

[Adsibob]

17 minutes ago, Temp said:

The filler might allow 40L/min but what you actually get will depend on the supply to your house and the internal pipework. In short you can't do better than a pipe with nothing at all on the end. So perhaps test that first? 

There is no internal pipe work at the mo. We ripped it out and are starting from scratch. Soo can spec whatever gets a good recommendation here. The (very) old connection to the mains supply gave us about 18 per minute max, sometimes less. We are widening the connection, but haven’t done that yet, so can’t test. I thought pressure was more relevant than flow as it’s an unvented hot water tank. Pressure is 2.8 to 3.1.

[Marvin]

What's more powerful being hit by a mouse fired from a cannon at close range or an elephant leaning on you?  

 

One is fast moving and small the other is slow and huge. Its all in the maths

49 minutes ago, Adsibob said:

I thought pressure was more relevant than flow as it’s an unvented hot water tank. Pressure is 2.8 to 3.1.

Both are important.

Edited May 16, 2021 by Marvin
Add info

[Adsibob]

5 minutes ago, Marvin said:

What's more powerful being hit by a mouse fired from a cannon at close range or an elephant leaning on you?  

 

One is fast moving and small the other is slow and huge. Its all in the maths

Both are important.

Well f=ma, so I agree mass is important. But presumably for that equation to balance, since the greater the pressure, the greater the force,  acceleration becomes a function of pressure.

[Marvin]

No matter what size the mains pipe is or how much pressure in it, if it gives you 18 litres a minute, that's what you got. 

 

I only know two ways that might increase this: more pressure or a bigger pipe. I say might because you do not know if the street main can supply more quicker. It was already indicated that the pressure fluctuates therefore so will the flow rate.

My bet is this system will not reliably work without being gravity fed from tanks in the building.

 

Anyway, a whole new subject is how you propose to supply the hot water quickly enough.

 

Good luck

 

Marvin

 

[Adsibob]

Forgive me, I'm a complete novice at this. I will have a large unvented tank in the loft (i.e. one floor above the bathroom in question). And the mains from the street was 18 litres a min previously, but I'm hoping it will increase slightly when we widen the size of the connection. Otherwise people wouldn't bother widening these pipes, surely.

[Temp]

You should get better flow rates by upgrading. 

4 hours ago, Adsibob said:

https://www.vado.com/product/6000/specifications-pdf

 

The installation manual say..

 

https://www.vado.com/origins-ind-ori140-brg

 

Maintenance The mixer is supplied with an aerator fitted as standard. To improve the flow rate in low pressure conditions this aerator can be changed for the plastic flow straightener provided. Carefully unscrew the mixer nozzle taking great care not to damage the plated finish. Remove the aerator and washer. Place the flow straighter into the nozzle followed by the Washer. Screw the nozzle back onto the spout.

 

To ensure max flow rate i'd be thinking about a 32 or 40mm incoming main and 22mm or 28mm copper to the tank and from tank to bathroom.

 

My builder was clueless about plumbing but knew a man that claimed to be an expert witness for all things plumbing. We wanted two quite high flow rate showers with rain heads and he recommended 28mm pipe from our thermal store to a manifold with isolating valves located between the two bathrooms. From the manifold we ran 22mm to the showers and 15mm to everything else (wash, basin WC etc). The latter could probably be smaller. 

[Marvin]

7 hours ago, Adsibob said:

Forgive me, I'm a complete novice at this. I will have a large unvented tank in the loft (i.e. one floor above the bathroom in question). And the mains from the street was 18 litres a min previously, but I'm hoping it will increase slightly when we widen the size of the connection. Otherwise people wouldn't bother widening these pipes, surely.

Ok. So now the question is about storage capacity and recovery rate.

If you need to fill 250 litres for the bath in say 15 minutes, not only do you need the correct, tap, water pressure and pipework, but also the right amount of water storage of both cold and hot water.

 

In simple terms you turn the hot tap on and hot water comes from the hot tank, but at the same time cold water enters you hot tank to replace the hot water filling your bath. Therefore 250 litres of hot water in 15 minutes equalls 250 litres of cold water in 15 minutes.

If the mains cannot supply it at this rate then you need to store it in a tank in the building. Whilst the cold water is draining from the cold storage tank the mains will be trying to fill it back up again, and the time taken to fill it is called the recovery rate. More maths, but don't forget you have to take into account any other use of water in the building whilst this is going on otherwise the recovery rate will be longer. 

 

M

 

 

[Marvin]

I still wonder how you are going to heat all this water...

[Temp]

54 minutes ago, Marvin said:

Therefore 250 litres of hot water in 15 minutes equalls 250 litres of cold water in 15 minutes.

If the mains cannot supply it at this rate then you need to store it in a tank in the building.

 

250/15 = 17 L/min

 

The existing pipe apparently does 18 so good odds the upgraded pipe should cope.

1 hour ago, Marvin said:

I still wonder how you are going to heat all this water...

 

+1 

 

Think I'd look at a bigger hit water storage tank. 

 

 

 

 

[Adsibob]

1 hour ago, Marvin said:

I still wonder how you are going to heat all this water...

It's a gas boiler, Vaillant ecoTEC plus 48kw, or possibly the Vaillant ecoTEC 637 which is 37kW. Not sure at the moment.

 

 

Edited May 17, 2021 by Adsibob

[Adsibob]

4 minutes ago, Temp said:

 

Think I'd look at a bigger hit water storage tank. 

 

 

 

 

The current idea is to go with a 300 litre unvented indirect hot water tank. Maybe that's too small? We won't be using this giant bath everyday. More like twice a week.

[Pocster]

13 hours ago, Big Jimbo said:

cant help, but i want to know how big. Two people, Four people ?......Hope the floor is strong enough to take the weight. Sounds like fun.

Rub a dub dub . Orgy in the tub