Changing water pressure

Hi

I have noticed that my shower is going hot then cold then hot then cold etc...although mainly cold. I tried using the sink taps and the water pressure is not constant it keeps going low and then coming back to full power.

The needle on the pressure gauge in the boiler in the combi boiler also keeps flicking up and down. I live in a 2nd floor flat from 5 storeys and am not sure if it is a problem from the mains or the boiler.

Has anyone had the same problem or know what the issue might be?

Many thanks in advance

Jon

The problem is with your apartment incoming mains/cold water supply pressure and not your combi boiler, Gary

The hot/cold thing sounds like limescale, I had a problem with this.

Thanks guys, what do you suggest, just get a plumber in?

For the limescale, I suggest you soak the shower head in vinegar over night every few weeks, works a treat for me. If you can access the filters, soak them too.

As for the pressure, hopefully someone else can help.

when I had the limescale problem, the pressure would drop in my shower, but my taps were uneffected. Since I use vinegar, no pressure or hot/cold problems.

I would get someone in to measure the flow rate and pressure of the mains water to confirm the water meets the boilers minimum water requirements(which can be found in the manufactures instructions),if it doesn't then the place to start is the incoming mains.

To get the best out of a combi you need the water pressure to stay constant giving a good flow rate, also there's another problem with combi's where if the boilers plate heat exchanger(part inside the boiler) on the heating side gets any dirt in it then it can cause the water at the hot tap to go hot/cold hot/cold, this would have no impact on the flow or pressure of the water, but it's possible you may have a mixture of the two, if the water has always had the flow problem but the loss of hot water is new, Gary.

Thanks for that, I am assuming if all the taps have the same problem then it must be the mains, but then wouldnt all the other flats be suffering the same problem?

Yes they would. are both hot and cold affected? What make/model boiler is it?

Both hot and cold affected, don't think its the boiler, have just been near where the main pipe enters the flat and there is a strange pulsing noise in the pipe as well, am assuming it is the water pressure or something blocking the pipe?

If the supply is fed from a break tank in the basement and there is a pump on it what could be happening is the pressure isn't stable and drops when the pump is off and increases when the pump is on.

I came accross this in an appartment block in Bond st in Dublin and no way you could have a shower as one minute it was cold and the next too hot. Just a good example for how not to plumb in a shower using a combi boiler.