Gravity fed shower.

[Mick Leek]

i have just fitted a new bathroom suite and installed a low pressure bar mixer shower. I originally thought my boiler was a combi (fitted about 2 years ago) but it is infact a conventional boiler with a hotwater tank.

I am now a little concerned with regards the pressure the shower will have. I have fitted all the pipes behind the plaster but haven't made the final connections yet. I went to the plumbers today and they said it would be advisable to fit a "surrey flang" or was it essex ?

They showed me 2 versions, one with what looks like a syphon tube and the other that you cut a hole in the tank.

What i want to know is , Do i really need one of these ? Because it is a gravity fed shower, I intend raising the header tank in the loft at least another couple of feet. The guy at the plumbers shop said that every 12" i rase the tank will greatly improve the pressure. Also he said i should feed the cold from the header tank.

I was thinking of taking a cold feed from the gravity supply to the hot tank but i then realised if i did that then the full gravity pressure would be split between hot and cold>

Do i make a new hole in the cold water tank and supply cold separately ?

Thanks in advance to any help.

 

[gas4you]

Use either of the flanges for the hot water supply and cut a new cold feed from the tank in the loft. You may find a speedfit tank connecter is the easiest to fit.

You will only get a 'poor' shower unless you can raise your tank by at least a metre, even then it will not help that much. Your real answer is to invest in a shower pump.

 

[Softus]

I went to the plumbers today and they said it would be advisable to fit a "surrey flang" or was it essex ?

Hm. The answer to that depends on whether they said "Surrey" or "Essex".

They showed me 2 versions, one with what looks like a syphon tube and the other that you cut a hole in the tank.

The first is a Surrey (or Warix), and the second is an Essex.

What i want to know is , Do i really need one of these ?

What does the shower valve manufacturer recommend?

Because it is a gravity fed shower, I intend raising the header tank in the loft at least another couple of feet.

That will add about 0.06 bar - you'd have to be quite desperate to think this is worth doing.

The guy at the plumbers shop said that every 12" i rase the tank will greatly improve the pressure.

This is true only if you had virtually head to start with.

Also he said i should feed the cold from the header tank.

He is right on the money with that advice.

I was thinking of taking a cold feed from the gravity supply to the hot tank but i then realised if i did that then the full gravity pressure would be split between hot and cold>

I think you mean flow, not pressure, and yes - you would be better off taking an independent feed.

Do i make a new hole in the cold water tank and supply cold separately ?

Yes.

 

[Mick Leek]

You will only get a 'poor' shower unless you can raise your tank by at least a metre, even then it will not help that much. Your real answer is to invest in a shower pump.

Cheers Gas, What do you mean by the above ?

Are you trying to say that what i am attempting is a waste of time ? The guy at the plumbers said that a pump was a waste of time because the hot water tank is only very small (stands around 24" tall) and the flow rate of the pump would mean that i could shower for a few mins before the tank would be emptied.

He said i could get a pump for the hot side only ? as in pumped hot but not cold. If i went that route, ould i still feed cold from loft tank ?

I'm not sure i understand why i need this flange thing ? does that improve the flow or something.

I have looked at the instructions supplied and all it says is suitable for gravity fed, pumped, and combi instulation. i cant see any tech info on delivery pressure, type and so on.

Cheers

 

[Mick Leek]

I had a thought, Isnt there some type of shower that has a small pump built into the unit that runs off 12V or something ?

I feel this may be the bast way to go considering all this technical stuff. Do these have a cold inlet as well as hot ?

 

[Softus]

The guy at the plumbers said that a pump was a waste of time because the hot water tank is only very small (stands around 24" tall) and the flow rate of the pump would mean that i could shower for a few mins before the tank would be emptied.

It isn't that simple, which is the problem of listening to merchants' staff.

If you have, say, a 20 gallon (about 90 litres) cistern, and the pump flow rate is, say, 20 l/m, and your incoming mains flows at 10 l/m, then for every minute showering you use 10 litres from the cistern. Therefore you could have a 9 minute shower. You can work out yourself how long a shower you can have according to these principles. If the time is too short, then get a lesser pump or a larger cistern.

He said i could get a pump for the hot side only ?

They do exist.

If i went that route, ould i still feed cold from loft tank ?

No - the supplies would be unbalanced and you risk the shower not working correctly.

I'm not sure i understand why i need this flange thing ? does that improve the flow or something.

It eliminates the possibility of air ingress, which can be very damaging to the pump.

 

[Softus]

I had a thought, Isnt there some type of shower that has a small pump built into the unit that runs off 12V or something ?

Mira Event (240VAC). Also Mira "Elite 2", and Triton "T80Si Pumped".

I feel this may be the bast way to go considering all this technical stuff. Do these have a cold inlet as well as hot ?

The Event does; the other two don't.

 

[Mick Leek]

Cheers softus,

I think i will connect it tomorrow and see just how bad or good it is.

I will then decide wether to fit a pump. Would you advise a twin impellar type then rather than a single ?

Are the pumped dhowers electricaly heated or do they just pump the hot water from the tank ?

 

[Softus]

Would you advise a twin impellar typethen rather than a single ?

Twin.

Are the pumped dhowers electricaly heated or do they just pump the hot water from the tank ?

I edited my previous post as it was incorrect - please see above.

 

[Mick Leek]

Just a quick update and a thankyou to softus for the info. I took the bar mixer back and got the mira power shower.

Plumbed it in today and all is working lovely.

Cheers softus, I owe you a beer.

 

[Softus]

In that case you should know that I prefer Greene King IPA and Gales HSB, depending on which part of the Lao People's Democratic Republic you frequent.