shower ? more like electric water pistol

[totty]

Hi All,

I've just fitted a 8.5Kw shower to replace an old one which I should have tried before scrapping it, at least then I'd know if the new shower is at fault or not. The pressure is really feeble. The shower also shuts off its heating element if you turn it above about 3 (the pressure drops as you turn it up as I'd expect). Its T'd into the cold water feed for the hot water tank in the loft which as far as I'm aware is at mains pressure. The baths cold water tap appears to have plenty of pressure.
Has anyone got any trouble shooting advice ?
Does the shower shutting off imply that its not getting enough pressure or an internal fault/blockage ?

I can't remember the make or model, I can look that up and add it tomorrow. Unfortunatly my laptops just died so I cn only get on here at work.

Thanks

Allan

 

[Kimba]

Could it not be T'ed into the Bath Tap's supply (suspect you would need a 22mm T and a reduced to 15mm for the shower).

With the temperature at it's lowest setting you SHOULD be getting near mains pressure from the shower (take the head off to judge the pressure and flow rate easier). If you are not, perhaps the pipe going to the hot water tank about isn't what you thought?

If the shower's element is cutting off as you turn the temperature up, it is almost certainly due to insufficent pressure.

Most installations require an absolute minimum of 1bar of pressure (14.5lb per squre inch)

 

[totty]

Hi Kimba, thanks for replying

The whole bathrooms being replaced so yes it could be T'd into the bath tap supply quite easily since I'm going to have to move it anyway

I'll trace the pipe its currently T'd off properly to double check exactly where it goes (its hidden a bit in the loft by excessive insulation about 2 foot deep) but it appears to come up from downstairs, a pipes T'd off it for the the sink and bath, then it goes into the loft and the shower is T'd off it then it goes to the tank.
If I remember correctly the hot supply to the bath is 22mm but the cold is only 15mm.
Its getting no where near mains pressure at its lowest setting.
I suppose after double checking the pipe I need to disconect the shower and see what the pressure's like at its feed ?
If thats ok then maybe back flush the shower ? (thats what I'd do with a car radiator anyway)
roughly what volume per min would be equal to 1 bar ? I dont have a pressure gauge but I have a bucket.

Thanks

Allan

 

[breezer]

bar is not volume its pressure, but you can measure you flow rate with a 1 litre jug

 

[totty]

Hi Breezer,

I know bar is pressure but if you have a given pressure and pipe diameter cant you calculate a flow rate which is just a volume per min ?

I was hoping someone would say some thing along the lines of "x gallons per min is roughly 1 bar"

I'm going to have another go at it tonight but I probably wont have time to lookup any formulas before then. I can at least compare the flow of the shower feed to the tap to try and norrow down where the restriction is.

Thanks

Allan

 

[ChrisR]

The flow is determined by the shower's ability to heat water. From a 8.5 kW shower you only get 3 and a bit litres per minute of water at showering temp. Tad more in the summer when the mains is warmer.

 

[totty]

Cheers ChrisR,

but I was thinking of the litres per min I should be getting at the feed to the shower so I could track the problem down to being either the supply or the shower itself.
3 doesnt sound allot, maybe I should have bought a 10.5kW the old one was a 6.5kW it must have been pathetic.
As a rough guess I'd say at the minute with the shower set to cold it's no more than 2 per min, its so bad you can point the head upover and the water only makes it to about 2 inches high. The one I'm used to if you drop it snakes about soaking the place till you can catch it.

 

[taydo]

unless your bath cold tap is mains fed you will probably not have the pressure to supply the shower. you may have a good flow rate from it because its 22mm pipe and carrying more water.

you need to confirm that your shower is plumbed into main cold water supply.

the old shower wasnt a pumped electric was it.

 

[totty]

Hi tatdo, Both the bath cold tap and the shower are mains fed, by 15mm pipe. The old shower wasnt pumped.

I had a good look at it last night, it seems to have improved slightly, it was warmer outside so maybe thats raised the mains pressure slightly ?
Its a Redring Active 320
The cold water tap (15mm) flows at 18L per min (can anyone give me an aproximate pressure from this ?)
I've found that the shower will turn down past 1 all the way back round to 9, in this position it has plenty of pressure. The flow from the outlet with the head removed is 7.5L per min.
The shower has 3 levels of heating, all but the highest wont do anything but take the edge off the coldness.
To get the element (light) to come on I have to turn the shower down to 1, I can then turn it back up to just under 4 (of 9) any higher and the light dims meaning that its dropped to a lower heating setting and the water goes cold, buy the time you get to 4 1/2 the light goes out altogether.
On 4 the shower is almost hot enough to use.
I haven't checked the feed to the shower to compare its flow with the tap but I've traced the pipework between them and I cant see any reason why there'd be a a difference apart from the shower being higher than the tap.

Anyone got any ideas ?
Is the shower faulty/not up to the job, is the mains pressure too low, what should I try next ?
If the mains pressures ok dos that imply a blockage in the shower ?

Thanks

Allan

 

[taydo]

in the user manual is there a help line give them a call

 

[totty]

I've just taken the shower back off the wall and tried the feed to it (with a hose duck taped on) and it has much less flow than the cold tap, but since I don't have a gauge and I havent found a way of aproximating the pressure from the flow I can't be certain that either has enough pressure. 0.7 bar is the minimum required, the tap seems to have plenty of pressure but I havent got a clue how much pressure 0.7 is.

The bath is due to arrive on Saterday so once I know where the taps are going I'll replace the pipe to the shower by T'ing off them and cut back the old one and blank it off.
Hopefully it'll all work then.
If not I'll have to resort to calling them.

Allan

 

[ChrisR]

O.7bar is nearly 7mhead, so if the folw is restricted enough you would be able to squirt a jet that high - theoretically. When the flow goes up you drop pressure in the supplies so the head is much lower. I'd look hard for dirt in the shower.

Pressure with no flow is easy to gauge by tryng to stop the flow with your finger - if you can do so on a normal tap, the pressure is less than about 2 bar.

If the pressure is there (wiht no flow) and the flow is there from the pipe(which it is as you have checked) then there must be TOO MUCH restriction in the shower- ie sh1t. Ask em how to get it out.

When yu fot an electric shower its impppportant that you use the ight head - if the holes are too big you get a very low water speed which feels dreadful;. The holes need to be quite small so you get all the water it can provide but at a decent jet speed.

 

[totty]

Hi CrisR,

I'd never considered this before now but suppose I could in theory run a hose out the window and see how high I can get it to spray to get a pressure aproximation. The neighbours would be very entertained.
When I took the shower off the wall last night I flushed it out in both directions and found no sign of any dirt in it.
I can stop the flow with my finger on the feed to the shower but I cant even get close to stopping it on the bath tap. Which makes me think that the pipework to the shower is at fault, it does go higher but I wouldnt expect that to make such a big difference, although I could be wrong.
I'm not quite sure what you mean by "If the pressure is there (wiht no flow) and the flow is there from the pipe" can you explain please.
I'm using the head that came with the shower so it should be ok, also without the head attached the shower still wont turn up above about 4 1/2 without shutting off the element.

I'm going to replace the feed to it when I install the new bath (hopefully this weekend but I havent had the call I've been expecting to tell me its arrived in stock) I'll post back to say how its gone and hopefuly it'll be working properly.

Thanks for the help.

Allan

 

[ChrisR]

YOu must have a low pressure supply to it (by mistake).

"If the pressure is there (wiht no flow) and the flow is there from the pipe"

You need a high pressure source and an unrestricted supply pipe. The max pressure is at zero flow. Test with finger over pipe.
Restriction is testable by removing the head as you have done. the flow should be high. If those were both right (which yours (p) isn't) then if it didn't work the shower unit would be responsible.