How to find leak in pressurised CH system?is it possible?

[Dan Robinson]

I'm trying to work out what you think is happening.

 

[John D v2.0]

I think the water is in the system, being attracted to the earth by gravity, and being pushed around by the pump.
I also think you are making strange comments in the hopes that eventually I'll use some incorrect terminology so you can show how clever you are.

 

[Dan Robinson]

No, I'm wondering what you're trying to explain, as well as directing you to think... Mainly because I think you're taking Horlicks again.

Gravity has naff all to do with the system pressure at the top of a closed system, or why the pump will make a difference either.

 

[bernardgreen]

Gravity has naff all to do with the system pressure at the top of a closed system,

Doesn't pressure drop by 1 bar for every 10 metres of vertical distance along the pipe.

 

[Madrab]

Doesn't pressure drop by 1 bar for every 10 metres of vertical distance along the pipe.

I wouldn't necessarily say that pressure drops by 1 bar for every 10m, rather that it takes 1 bar of pressure to raise water vertically by 10M.

A sealed system that is pressurised to 1 bar will generally be 1 bar across the whole system, in a domestic setting, regardless of height.

 

[dilalio]

I wouldn't necessarily say that pressure drops by 1 bar for every 10m, rather that it takes 1 bar of pressure to raise water vertically by 10M.

A sealed system that is pressurised to 1 bar will generally be 1 bar across the whole system, in a domestic setting, regardless of height.

I think you’ll still have to do a drawing @Madrab

 

[John D v2.0]

Gravity has naff all to do with the system pressure at the top of a closed system

Correct. And the pressure at the bottom will be higher by an amount proportional to the height of the system. What's your point?

or why the pump will make a difference either.

Basic physics. Since water doesn't move by itself, the pump has to push it. Pushing it raises the pressure downstream relative to that upstream.

In case you prefer to think in terms of heating components instead of physics, consider if there was no pressure difference, why would you set the bypass valve to open at a set pressure difference? The bypass can only open when the pump is running so that must be where the pressure difference came from.

 

[John D v2.0]

A sealed system that is pressurised to 1 bar will generally be 1 bar across the whole system, in a domestic setting, regardless of height.

careful, Dan will be asking you how a pipe knows if it's in a domestic setting or not!

Agreed a standard semi 2 storey system that's on average 1bar will be in the general area of 1 bar at every point of the system.

 

[Madrab]

And the pressure at the bottom will be higher by an amount proportional to the height of the system

Not really, not to any real extent anyway, in a sealed domestic system. There is no real volume of stored water pushing down on it, as in the case of a gravity cold water system with a 50gal CWSC above it when an outlet is opened. There may be a small rise in an open vented system but again negligible as the volume in a F&E tank is minimal.

careful, Dan will be asking you how a pipe knows if it's in a domestic setting or not

A domestic setting would be when it would be normal domestic pipe runs and sizes up to 28mm, I'm sure Dan would make the same distinction though happy to be corrected.

When it gets up into larger commercial/industrial pipe sizes with much larger heights and water volumes, then water weight/height may become a factor and pressure could then vary depending on where on the system the reading was taken from.

 

[dilalio]

 

[Dan Robinson]

And the pump? How it drawing air in on a sealed system?

 

[bernardgreen]

There is no real volume of stored water pushing down on it

The volume of the water in a storage tank or cistern has no effect on the pressure at the outlet pipe, only the depth of liquid above the outlet affects the pressure.

 

[Madrab]

The volume of the water in a storage tank or cistern has no effect on the pressure at the outlet pipe, only the depth of liquid above the outlet affects the pressure.

OK, correct though in this scenario it's all semantics, I suppose I should have said weight.

In a sealed CH system though 'the weight' isn't enough to alter the pressure to any real extent and therefore the pressure would effectively be the same across the system.

 

[John D v2.0]

And the pump? How it drawing air in on a sealed system?

If it really were sealed id agree, but in practice most sealed systems lose water gradually. If it's air rather than water involved, it leaks quicker. That's why they always want to fill your tires with nitrogen, it leaks less throughMicroscopic holes.

 

[Wildcat1961]

What a load of twaddle.