How can I reduce noise of header tank filling?

[Klaus_K]

Hi, I have two power showers which are fed from my header tank - all done in the correct way as far as I can see - each with their own direct feed. The only issue is that when the showers are running then the header tank has to fill up, naturally enough, to make good the water being fed to the shower(s). Unfortunately, this is really noisy - just gushing water, but a lot of it. My toilet cistern has a tube made out of polythene sheeting which acts as a noise reducer, since it effective directs the water beneath the surface, so you don't get the noise of splashing - I was just wondering if something similar is available for the main header tank. Obviously, I don't want to risk siphoning, but something similar to the cistern ought to work, surely? I could bodge my own solution, but it'd be neater if I could buy a proper product (if one exists).

 

[doitall]

If the tank had a by-law kit (lid and insulation jacket I doubt you'd hear it too much

 

[muggles]

http://www.fluidmasteruk.com/product/PRO75B.aspx

 

[Klaus_K]

Am I correct in thinking that the by-law kit is just the angled pipe that dips below the surface to provide overflow?

The tank is pretty modern (~15 y.o.) in a newish property, plastic and in good nick, so I'm confident that it's all within the law. May need to check out options for lagging and more soundproofing - it's already got a lid, but this may have moved out of place during my recent rummaging in the loft.

 

[JohnD]

a modern float valve such as the fluidmaster link above, or a torbeck, will be almost silent.

 

[Klaus_K]

http://www.fluidmasteruk.com/product/PRO75B.aspx

Sounds almost too good to be true, but it's cheap enough that I'll probably give it a try. Just need to see how much space I've got to work in the loft. If I combine this with the other suggestion then I ought to be on to a winner

 

[muggles]

They're the dog's kahunas, much better than an old-school ball valve

 

[Klaus_K]

They're the dog's kahunas, much better than an old-school ball valve

Not sure I want dog's kahunas dangling in my cold water supply - mind you, it's not drinking water I suppose

 

[JohnD]

a useful idea, if you find the power shower pump sucks water out of the tank faster than it refills, is to fit two float valves in parallel.

it requires a little basic plumbing on the incoming copper pipe.

 

[oldbuffer]

If you are going to fit two float valves, I'd fit another (making two) warning / overflow pipes. The area of the inside of a standard overflow pipe is fractionally less than the area of the inside of two 15mm copper pipes.

 

[Klaus_K]

If you are going to fit two float valves, I'd fit another (making two) warning / overflow pipes. The area of the inside of a standard overflow pipe is fractionally less than the area of the inside of two 15mm copper pipes.

Technically correct, I'd agree - but it does seem a touch pessimistic to prepare for the case of both valves failing totally at the same time!

If I do have a problem with the tank running empty then I think I'll go for the simpler option of just telling the kids not to be so bl**dy greedy with the showers!

Thanks all the same - it's not something that had occurred to me!

 

[Klaus_K]

If you are going to fit two float valves, I'd fit another (making two) warning / overflow pipes. The area of the inside of a standard overflow pipe is fractionally less than the area of the inside of two 15mm copper pipes.

Thinking further about this, the water coming into the tank via the valves would be at mains pressure, while the water going out would only be gravity fed. In order to allow the overflow to cope with water coming in at full mains pressure I'd guess that the pipe diameter would need to be much, much larger - prob. more like a soil pipe than a normal 15mm pipe (or even two of them).

I guess that the overflow is intended to cope with 'drip' type leaks rather than total failure.

 

[JohnD]

the overflow pipe is usually sized at twice the capacity (not twice the diameter) of the input pipe, to allow for that. For reasons due to geometry which I can't remember how to calculate, each common pipe size has a capacity of double the next one down (15mm, 22mm, 28mm, 32mm I think). How I wish I could remember pi.

Unless the valve falls off the pipe, it will not be unrestricted flow at mains pressure anyway.

 

[Klaus_K]

the overflow pipe is usually sized at twice the capacity (not twice the diameter) of the input pipe, to allow for that. For reasons due to geometry which I can't remember how to calculate, each common pipe size has a capacity of double the next one down (15mm, 22mm, 28mm, 32mm I think). How I wish I could remember pi.

Unless the valve falls off the pipe, it will not be unrestricted flow at mains pressure anyway.

Getting a *bit* off topic, but here we go...

I'd guess that the flow through a pipe is proportional to the cross-sectional area of the pipe, which is proportional to the square of the radius (pi * r-squared).

Taking the radius of 22mm and 15mm pipes, (11*11)/(7.5*7.5) is 2.1 wihich is close enough to 2, so your point stands.

I'd guess that it's also inversely proportional to the viscosity of the fluid, since 'thicker' liquids flow more slowly. However, since we are dealing with water in both cases, I'd guess this cancels out and so can be ignored.

However, common sense tells us that the rate of flow has got to vary with the difference of pressure along the pipe. So my point still stands - in the (unlikely) event of the valve falling off the end of the pipe.