Is this a flow or pressure problem ?

[DiyNutJob]

Hi,

I have a serious problem with my ground floor flat. I have 3 cold taps: kitchen, bathroom sink, and bath. Whenever the bath tap is open, I get no water from the kitchen or the bathroom sink.

The pressure appears to be ok because when I try to cover an open tap, while the other taps are closed, with my palm and hold on tight with both hands, I couldn't prevent the water from bursting out into a fountain. I do however find the volume of water coming through the tap being on the low side.

I believe all these taps are connected to the mains directly given the pressure available. Can anyone tell me if this is flow problem, or that the noted pressure is still not high enough ?

If the water coming through the mains is somehow constricted. What options do I have. Is this something dealt with by a plumber or the water company ?

Thanks

 

[Armo74]

Check your stopcock is fully open.

Ask your neighbours if they are having the same problem.

 

[DiyNutJob]

Check your stopcock is fully open.

Ask your neighbours if they are having the same problem.

The mains stopcock inside the flat is definitely open in full. There is another mains stopcock outside of the flat. The outside stopcock is on a "junction" shared with other flats. Basically the flats share a bigger pipe. Then each of us is diverted off with a smaller pipe. Although the upstairs flats have 3/4" pipes while the ground floor has 1/2" pipes. My stopcock on the junction looks untouched and I couldn't turn it either way. I will use a wrench and see what happens. But I suspect it's probably open on full as the valve "turner" looks fully extended.

I think, although I am not completely sure, the problem occurred after I changed the kitchen taps. But I don't suppose an air lock can develop in pips connected to the mains ? It doesn't seem plausible an air lock can resist the mains pressure that is too strong for me to block with my hands at any of the three taps.

 

[Madrab]

this one sounds like it's down to insufficient pressure to feed the other taps when the bath tap is open, as Armo suggest, checking the stop cock is fully open. Get the water board to check your outside stopcock if you can't turn it. If that's ok then get a plumber in to check with a pressure gauge attached and see what pressure you're getting when taps are shut.
Tho it may be you have fitted high pressure taps and when the bath tap is on the pressure drops and there isn't enough pressure to feed the others as the problem only started when they were fitted.

 

[DiyNutJob]

The kitchen tap I installed is just a low end B&Q jobbie. I don't think it's a high pressure tap. Even if it is, when closed, it shouldn't affect my bathroom sink tap. This tap also has no flow when the bath tap is open. The arrangement of the taps is such that the kitchen tap is highest, the bath tap is lowest and the bathroom sink tap in between.

When opened full, the water flow coming out of the bath tap is low. It would probably take half an hour or longer to fill the bath.

I think there is enough water pressure, but just not enough water is coming through. I will buy a pressure gauge to see what kind of pressure I have.

One thing I have been looking for is some kind of a "universal" adaptor that allows me to connect things, such as a pressure gauge or a hose etc, to taps of various shapes and sized. Is there such an adaptor ? Any pro's care to share their trade secret ?

 

[Madrab]

Unless something new has been introduced into the mains feed that is restricting the flow - again this wld usually be a valve or stop cock issue - then it sounds like the mains pressure has been reduced. Do the other taps suffer from bad flow?
FYI, some of the cheapest B&Q monobloc single lever taps need at least 1 bar to operate, this wld be considered to be a high pressure tap - usually ceramic disk types. Low pressure taps run at >0.2 bar tho as you say this should not affect anything else when closed.
The easiest place to check mains pressure wld be at a washing machine valve if available, my gauge has a 3/4 bsp screw fitting. There are kits you can get that have different rubber connectors for different taps but they cost £££'s

 

[DiyNutJob]

All the taps are within 1 meter distance of each other. So I think they all share the same mains pipe inside the flat. The flow in all of the taps are similar, although more noticeably weak on the bath tap as that has a bigger spout.

Incidentally, the pressure was worst recently in that I could cover the taps with my palm and prevent the water from coming out. So I used a drill pump on the kitchen tap to draw water out. That increased the pressure at all of the taps to where they are currently - where I could no longer block the water with my palm.

Once I get the pressure gauge in, perhaps it will give me a better clue on what might be happening.

The reason I was asking about the tap adaptor was I wanted to use the pump on the bath and bathroom sink taps. I have no way to do that at the moment, and I can't tell from internet pictures which of the flimsy domestic plastic adaptor might work. So I am thinking something more "pro" would be better. What are these £££ adaptor kits called ? I will see if I can use my internet skills to find better deals on them.

 

[ianmcd]

Try asking your question again , you are mixing water PRESSURE with water FLOW RATE they are not the same thing water pressure is what your water supply will measure on a guage when no water is being drawn off, your water flow rate is the rate that your supply can achieve with outlets in demand, a high water pressure means nothing it is the flow rate you need to measure

 

[Madrab]

Checking the static pressure would rule out if there has been a drop in the mains from your supplier, if pressure is fine - >1bar - then it's looking for a restriction that's been introduced somewhere that is affecting the flow rate. That comes back to Armo's suggestion and getting the stop cock/isolators checked and asking the neighbours if they've also noticed anything

The kits for pressure/flow testing look like these from BES - http://www.bes.co.uk/products/118.asp

 

[DiyNutJob]

Try asking your question again , you are mixing water PRESSURE with water FLOW RATE they are not the same thing water pressure is what your water supply will measure on a guage when no water is being drawn off, your water flow rate is the rate that your supply can achieve with outlets in demand, a high water pressure means nothing it is the flow rate you need to measure

Yes, I know what you are saying. My flow rate can only be described as a joke. If I have to give it a more tangible estimate, I would say less than 1/4 asda's grey plastic bucket per minute. Joking ... but you roughly get the picture.

Nevertheless, I will measure the pressure to get a better handle on the situation. At the moment, I don't know who, what, when, and how, and this is not a good situation to be in.

But of interest is that my pumping one of the taps increased the pressure. That indicates something is happening in the pips. The same factors that is acting on the pressure could well be affecting the flow rate. My guess for now is there could be an air lock in the mains line inside the flat. Although this seems implausible, once I know the pressure that should rule in/out the possibility of the air lock.

Anyway, thanks for your comment. It is welcomed.

 

[DiyNutJob]

Checking the static pressure would rule out if there has been a drop in the mains from your supplier, if pressure is fine - >1bar - then it's looking for a restriction that's been introduced somewhere that is affecting the flow rate. That comes back to Armo's suggestion and getting the stop cock/isolators checked and asking the neighbours if they've also noticed anything

The kits for pressure/flow testing look like these from BES - http://www.bes.co.uk/products/118.asp[/QUOTE]

Thanks. Who should I get to check the stopcock/isolator. Plumber or water company ? What I have got is probably a bit complicated:

1. Mains stopcock inside the flat with a double check valve
2. Mains stopcock outside my door on a shared water junction that has a separate stopcock for each flat in a 3 storey building containing 6 flats
3. I guess but am probably right that another stopcock is outside of the building on some kind of large shared junction having a separate stopcock for each building

I haven't checked with my neighbours yet. If they have this problem, the upstairs people at least would be screaming blue murder because they would surely be getting drips of water instead of a trickle like mine.

Thanks for the kit suggestion. That's more than what I need. I am looking for a pro-edition of the following but with added bells and whistles and capable of handling any tap size and shape. I suspect there's no such thing.

 

[Madrab]

Thanks. Who should I get to check the stopcock/isolator. Plumber or water company?

Phone your water company and see what they are responsible for, usually they would be responsible up to the main stopcock outside. If no one else is affected then it wouldn't be a supplier pressure issue and it would be a plumber to check from your stopcock to your flat.
If you want to know your flow rate then fill a bucket for 60 secs get an empty ltre water bottle/measuring jug to measure how much water there is in ltrs/min

But of interest is that my pumping one of the taps increased the pressure

It's possibly opened a restriction in the pipe somewhere, e.g. a stop cock that is sticking. When you changed the taps, was the water isolated at main stop cock or valves under the sink?

 

[DiyNutJob]

When you changed the taps, was the water isolated at main stop cock or valves under the sink?

I closed the mains stopcock inside the flat when changing the tap.

I think I have reproduced the problem. I got the pressure gauge in, and measured the pressure at another property less than a mile away where I considered the pressure and flow rate to be excellent. The reading I got was 2.4bar/35psi. Then I went to the flat and took a reading at the kitchen tap. It turned out the pressure was actually higher at the flat which was 2.6bar.

I then left the kitchen tap running and went to close off the water mains stop cock immediate outside my flat. I wrenched it a bit and it turned off ok. I turned the stop cock up and down a few times to make sure nothing was sticking or blocking. Then I went back to the kitchen. To my horror, the water flow coming out of the tap had halved, back to the same flow before I pumped the tap. It seems to me turning off and on any of the mains stop cocks would reduce the flow rate afterwards. Anyway I measured the pressure again, and it remained good at 2.6bar.

The conclusion is I have a severe flow problem. A drill pump will get me some of the flow back. But I may need an industrial strength pump to get all of the available flow back.

What would a plumber do in this situation, any ideas ?

I haven't measured the flow rate yet. But I will, following your suggested technique. Whatever it is, the flow rate will likely to be abysmal.

 

[Madrab]

No need for the flowrate test , you've answered the question, pressure is fine, flow is being restricted by your stopcock(s). Even with you turning the stopcock on an off it may be sticking at half open. When you use your drill pump, it's drawing more flow through the stopcock and that is pushing open the valve more, ergo flowrate increases. Plumber would either replace the stopcocks required or service the ones in place. Personally I'd isolate stopcock, drain down as much water as possible, pull off the top of the valve body if easily accessed and check internals to look for excessive wear or if it just needs serviced/lubricated. If worn then a replacement would be installed. if access is very limited then it may be easier just to replace them

 

[DiyNutJob]

Thanks.

I had a good think and had to dismiss the possibility of an air lock given the available pressure, and the simple pipe-works I have. Also I am leaning against the idea of the stop cock failing because that would involve both the inside and out side stop cocks failing with exactly the same problem because turning on and off either has the same deleterious effect.

I do have a non-return (possibly a double check) valve immediately after the inside stop cock. As the check valve action is influenced by both the mains pressure as well as by negative pressure create by the pump on the tap side, I suspect that must be the culprit for my troubles.

It is within my capability to remove both the inside stop cock and the check valve for inspection. That's what I will do next.

Thanks for your continued help with your insights.