low water pressure - what to do

paulmapp8306

it appears my cold water pressure is quite low. My shower isnt particularly strong, and turning on a tap at the same time reduces it to a trickle.

Is there a way to increase the pressure of the whole system rather than just putting in a pump for the shower, because as I understand it i cant use suck a pump with a sealed system (which i dont have now but may well have in a couple of years).

twokcc

First thing to do is to get your water authority to check your water pressure, They will do this for free and if you get it checked at the meter and say the kitchen sink this will show if you need to replace the supply pipe to your house. Once you have determined this you can decide action to take, ie shower pump, combi or pressured hot water system with cylinder. If you have more than one shower would recommend the pressurized hot water cylinder these do however need a good water supply volume and its the most expensive option.

macman

What sort of shower is it? If not electric, what sort of boiler do you have?
Has this problem just started or has it always be there?

paulmapp8306

The shower is Electric. Its only 7 or 7.5Kw, as the breaker is only 32 Amp and we were just going to put in a higher power shower (when we do the bathroom) however, as the pressure drops so much when we turn on the bath tap - that may well not solve the issue as there doesnt seem to be the pressure to the system in the first place.

The boiler (at present) is a vented type with hot water tank in the loft. When the boiler gets replaced i have no idea which way to go. I was thinking about a combi as we hardly use any actually hot water (use shower mainly for washing, and dishwasher for kitchen, so its a little hot water to wipe down sides and the odd bath).

No idea how long this has been happening as we only moved into the hose this summer. Its an Ex 1960s council house (not that that will help I guess).

TBH, the pressure at the cold tap in the kitchen and at the bath seem fine (the hot water isnt strong but thats a seperate issue). Turning the taps on in the bath when the kitchen ones are running doesnt change the flow - it only seems to affect the shower pressure.

macman

The flow rate at the shower is almost certainly determined by the low rating (7.5kW is fairly low by today's standards).
Your bath's hot tap is fed from the hot tank, your bath's cold tap from the cold tank. Your shower heats the water internally and is fed from the rising main, so no connection here. The kitchen sink cold is the only tap that should be fed from the rising main, so turning that and the shower on simultaneously will of course affect the flow rate-and should be avoidable.
I'd be looking at uprating the shower to 9 or 9.5kWH, this will of course require you to uprate not just the breaker (which is already on the limit) but also probably the circuit cable as well-your electrician will advise. I'd always advise fitting proper RCD protection on a shower circuit, not just an MCB.
The problem will get worse in winter as the rising mains supply gets colder and the flow will consequently reduce.

ariba10

Have you checked to see if the Stopvalve is fully open?

macman

The OP reports that the cold tap sink pressure is fine, which would indicate that the issue is not low mains pressure. However, the stop valve should certainly be eliminated with a 2 minute check before investigating further.

paulmapp8306

Wheres the stop valve lol.

Seems odd - if the baths cold tap is turned on, the shower pressure goes down. No idea how thats happening. Im wondering if the shower has been plumbed so its gravity fed from the cold tank rather than a riser? As the tank is only a meter or so above the shower would that not explain the low pressure? and also why it goes down further when the bath colt tap is on?

I had intended to go to a 9Kw shower. Thats fine on a 6mm cable. in fact a 9.5Kw is as well, as the rating is for 240v not the 230 nominal voltage of the supply. a 6mm cable (directly clipped) is good for 41 Amps. a 9.5Kw actually takes around 39.6 Amps - though not all electricians will fit a 9.5 with 6mm cable. the breaker will need uprating to a 40 Amp though. (Just dont my 17th edition as part of my forces resettlement- and while Im no electrician as im electronics, I did get a lot of info from the instructor who is a practising electrician).

Theres no point in putting is a more powerful shower though if I have the same issue with the pressure.

macman

I think it unlikely, but it should be simple enough to trace the pipework back and investigate. But I'd locate and check the stop valve before you do anything else though.
I mentioned the cabling because posters regularly seem to be unaware of this factor when planning electric shower upgrades.

paulmapp8306

Ive found 3 "taps" behind the shower (in the airing cupboard) one is on a large diameter pipe coming from below and going into the loft. Its not connected to the shower and makes no difference when I alter it - its set fully open anyway. The second is below the tap for the shower on a small diameter pipe that also runs from below the airing cupboard up to the loft. This does effect the shower but is set fully open. The third is on a pipe that branches below the shower feed and then runs up to the loft. this makes no difference to the shower and again is set fully on.

Further investigation on the shower. When set to cold it makes no difference to the flow. When the temperature dial is set to cold, the flow does increase slightly (whether the power is set to med, high or cold). This is expected, and a higher power shower "should" get this higher flow rate with a higher temperature setting.

However, even on cold it only takes the cold tap of the bath to be on a little before the shower flow rate drops substantially - and when fully open only leaves a dribble. The bathroom sink tap has the same effect (though to a lesser extent as it doesnt have the flow of the bath taps).

So - I'm guessing either the shower is on a gravity feed, on the same supply as the bath/sink OR both bath and sink are plumbed to the same riser as the shower?

My "initial" thoughts on rectification, would be a higher power shower - probably 9Kw (not sure going to a 10.5 with associated wiring upgrade will make that much difference to flow than a 9?). At the same time (when the new bathroom suite goes in) make sure the bath and sink are not plumbed to the same riser - in fact should they be gravity fed direct from the tank?

southcoastrgi

one of two problems, either both your bath & shower are connected to the main (unlikely) or the electric shower is connected to the cold bath supply pipe from your roof tank, electric showers must be connected to the mains not a feed from the roof tank, turn off your incoming mains does the shower & bath feed stop ? if not then it's incorrectly connected to the roof tank, putting in a bigger output shower isn't going to make any difference to your problem