Boiler pressure question

[britishboy7]

We had a new Worcester Bosch combi boiler fitted 3 months ago, it replaced the old open system with 2 tanks in the loft. Water pressure in all our taps improved massively as we expected. One thing I’ve noticed is with the shower on full, and running the downstairs toilet tap on full, the boiler loses pressure (on the gauge on the front of the boiler) after a few minutes. Is this normal?


I was under the impression that any loss in pressure is a leak, but I can’t find one?


If running the shower and taps on full was taking too much water from the boiler, could the drop in pressure be because the boilers not filling quick enough?

 

[terryplumb]

The pressure gauge is indicating the pressure in the sealed system ( boiler / radiators and their pipework ). The domestic hot water that comes from boiler to taps / shower is totally separate from the central heating sealed system and the pressure gauge does not show the pressure of the domestic hot water circuit. What pressure differences is it showing ??

 

[CWHEATING]

We had a new Worcester Bosch combi boiler fitted 3 months ago, it replaced the old open system with 2 tanks in the loft. Water pressure in all our taps improved massively as we expected. One thing I’ve noticed is with the shower on full, and running the downstairs toilet tap on full, the boiler loses pressure (on the gauge on the front of the boiler) after a few minutes. Is this normal?


I was under the impression that any loss in pressure is a leak, but I can’t find one?


If running the shower and taps on full was taking too much water from the boiler, could the drop in pressure be because the boilers not filling quick enough?

Ok first all you’ve got very confused but that is understandable.
Let me make this simple combi boilers are rubbish. The problem you are having when you run your shower and another tap whether it be hot or cold water is normal with combi boilers. Get used to it.

 

[ianmcd]

you are confusing pressure with flow rate, the rate that the water flows from the taps is flow rate not pressure, the guage on the boiler has absolutely nothing to do with the flow rate at the taps.

 

[CWHEATING]

you are confusing pressure with flow rate, the rate that the water flows from the taps is flow rate not pressure, the guage on the boiler has absolutely nothing to do with the flow rate at the taps.

Flow rate and pressure go hand in hand. You can’t have one without the other.

 

[CWHEATING]

Flow rate and pressure go hand in hand. You can’t have one without the other.

The

We had a new Worcester Bosch combi boiler fitted 3 months ago, it replaced the old open system with 2 tanks in the loft. Water pressure in all our taps improved massively as we expected. One thing I’ve noticed is with the shower on full, and running the downstairs toilet tap on full, the boiler loses pressure (on the gauge on the front of the boiler) after a few minutes. Is this normal?


I was under the impression that any loss in pressure is a leak, but I can’t find one?


If running the shower and taps on full was taking too much water from the boiler, could the drop in pressure be because the boilers not filling quick enough?

So the pressure gauge on the boiler indicates the pressure in your sealed central heating system and not the water pressure in your hotwater taps.
The pressure in your hot water taps comes from your mains cold water pressure which is fed in to your boiler.
The flow rate you have to your taps is dependent on the size of the pipework from your boiler to your hotwater outlets. Because combi boilers are not built for multiple hotwater outlets to be ran at the same time the pipe only needs to 15mm so technically flowrate is not the issue here. The issue is solely to do with you having a combination boiler.

 

[denso13]

so technically flowrate is not the issue here.

The OP isn't complaining about the flow rate. He/she only asked about the pressure gauge dropping when the taps were used (and I know the two aren't connected).

In fact he/she seems to suggest there was an improvement in flow rate once the combi was fitted.

 

[CWHEATING]

The OP isn't complaining about the flow rate. He/she only asked about the pressure gauge dropping when the taps were used (and I know the two aren't connected).

In fact he/she seems to suggest there was an improvement in flow rate once the combi was fitted.

Read the whole thread then come back to me.

 

[denso13]

Read the whole thread then come back to me

Ok, I've re-read it. Now what?

 

[CWHEATING]

Ok, I've re-read it. Now what?

I was replying to someone else. Aswell as the the original question at hand. If you read all of my comments then you wouldn’t have replied.

 

[denso13]

I was replying to someone else.

In post number 8 you quoted me and commented. But you were replying to someone else? Ok.

If you read all of my comments

I did.

 

[CWHEATING]

In post number 8 you quoted me and commented. But you were replying to someone else? Ok.



I did.

Ok. Iamncd said the thread starter is getting confused with boiler pressure and flow rate so I was responding to him.

 

[ianmcd]

Flow rate and pressure go hand in hand. You can’t have one without the other.

OH really, please explain, are you referring to working pressure or standing pressure, and please explain what the guage on the boiler has to do with anything that comes out of the HW tap ?

 

[Hot&Cold]

I’ve noticed is with the shower on full, and running the downstairs toilet tap on full, the boiler loses pressure (on the gauge on the front of the boiler) after a few minutes. Is this normal?

Does the pressure gauge pointer ping back to the set pressure when there is no hot water,no heating demand or any pump over run ?

Has the installer been asked to comment on your concern

 

[CWHEATING]

OH really, please explain, are you referring to working pressure or standing pressure, and please explain what the guage on the boiler has to do with anything that comes out of the HW tap ?

Didn’t mean it like that. All I meant was as far as flow rate to taps goes that’s dictated by the circumference of the pipe work. The bigger the pipework the better flow rate you get. But, good flow rate is useless without a good incoming coldwater mains pressure. And that also goes for having a good incoming mains pressure but not having big enough pipework to carry the amount of water needed, that’s your flow rate. That’s what I meant by it’s goes hand in hand. Sorry for the confusion
But as a combi boiler can only handle one hotwater tap to run at a time then the problem is to do solely with the boiler and not a flow rate problem as a 15mm connection is provided so 15mm to all taps will be perfectly fine. You see what I’m getting at?
As far as the pressure gauge moving slightly when the hotwater taps are run is a normal occurrence for combi boilers so I can see why he got confused. But like I said in my previous posts, the pressure gauge on the boiler itself is to indicate the pressure in the sealed central heating system and not pressure to hotwater taps.