New Radiators Not Working

[John.g]

There has been no mention of the make/model of boiler or if the pump is even inside it.

Both were/are system boilers so presume pump is internal?.

 

[Chuck]

Any air in the system is always going to be at atmospheric pressure i.e. 1 bar.

You are mistaken. It'll be at the same pressure as the water that surrounds it. In an unvented system, which is what I believe we are discussing, it'll be somewhere in the range 2–3bar (absolute). For for a vented system, the pressure is only 'atmospheric pressure i.e. 1 bar' at the top, i.e. the location of the free liquid surface in the expansion tank.

 

[Scott_D]

Both were/are system boilers so presume pump is internal?.

Lots of people confuse the boiler types. Some boilers allow you to adjust the pump settings in the installer menus.

 

[hometech]

There has been no mention of the make/model of boiler or if the pump is even inside it.

If the boiler is less than 5 years old

You are mistaken. It'll be at the same pressure as the water that surrounds it. In an unvented system, which is what I believe we are discussing, it'll be somewhere in the range 2–3bar (absolute). For for a vented system, the pressure is only 'atmospheric pressure i.e. 1 bar' at the top, i.e. the location of the free liquid surface in the expansion tank.

so as you increase the water pressure you increase the air pressure making air impossible to remove from any system ever. Thanks for that. Just out of interest, how does that work with boyle's law? I've added a BBC bitezie for reference Volume and pressure in gases – the gas laws - Temperature and gas calculations - GCSE Physics (Single Science) Revision - BBC Bitesize - https://www.bbc.co.uk/bitesize/guides/zc4xsbk/revision/3

 

[Chuck]

If the boiler is less than 5 years old

so as you increase the water pressure you increase the air pressure making air impossible to remove from any system ever. Thanks for that. Just out of interest, how does that work with boyle's law? I've added a BBC bitezie for reference

You don't seem to understand the difference between 'pressure', which does not affect the motion of bubbles, and 'pressure gradients', which do. In this context, Boyle's law tells you that as the pressure in the system water is increased the bubbles of trapped air shrink in volume.

 

[hometech]

You don't seem to understand the difference between 'pressure', which does not affect the motion of bubbles, and 'pressure gradients', which do. In this context, Boyle's law tells you that as the pressure in the system water is increased the bubbles of trapped air shrink in volume.

solubility of air in water...increase pressure..increase temperature...both increase solubility. So upping the pressure and temperature removes air locks as it dissolves the air in water. It's also known as Henry's law of solubility. You over think things bro

 

[Chuck]

I really shouldn't rise to the bait of a straw man argument but anyway. . .

solubility of air in water...increase pressure..increase temperature...both increase solubility.

Wrong again. In the temperature range relevant to heating systems, the solubility of air in water decreases with increasing temperature.

So upping the pressure and temperature removes air locks as it dissolves the air in water.

If a system is air-locked at its normal operating temperature and pressure then the scope for increasing the pressure or reducing the temperature is too limited for this to be a viable way to fix the problem.

 

[SimonG]

solubility of air in water...increase pressure..increase temperature...both increase solubility. So upping the pressure and temperature removes air locks as it dissolves the air in water. It's also known as Henry's law of solubility. You over think things bro

That must be the biggest load of crap I've heard on here.