Pressure on thermostat next to hot water cylinder dropping

[jakabi]

Hi Guys,

I have a problem with the pressure dropping on my system over a period of days/weeks.

I have bled all the rads a few times and the value at the top of the cylinder but the problem still occurs.

I use the filling loop to get the pressure back to 1 bar when its dropped really low. Then over a period of approx. 4-8 weeks it will drop to zero.

This morning the pressure on the 'cold' system was 0.5 bar, I've had the hot water on now for 1-2 hours and the pressure is approaching 2 bar. The heating has NOT been on at all for a day or so.

Is there anything I can check or do easily before finding someone to come and look at it ?

Thanks in advance!

 

[xr4x4]

2 bar is reaching the point of being to high, does it go any higher?

ESP with the heating on?

 

[twgas]

Expansion vessel needs checking.

 

[denso13]

//www.diynot.com/wiki/plumbing:faq:faq7

 

[jakabi]

2 bar is reaching the point of being to high, does it go any higher?

ESP with the heating on?

Apparently the expansion vessel was changed about 3 years ago before I owned the property ... maybe they had the same issue ?

In the past I've noticed it go very high, 3 bar ish. I'd need to check this again with the water on and heating on at the same time. What would this indicate if it goes up and up ?

Thanks for the responses, very helpful!

 

[kidgreen61]

As Denso said, read the FAQs, your exp vessel may just need re-charging.

 

[xr4x4]

2 bar is reaching the point of being to high, does it go any higher?

ESP with the heating on?

Apparently the expansion vessel was changed about 3 years ago before I owned the property ... maybe they had the same issue ?

In the past I've noticed it go very high, 3 bar ish. I'd need to check this again with the water on and heating on at the same time. What would this indicate if it goes up and up ?

Thanks for the responses, very helpful!

It's shouldnt go that high, chances are the pressure relief valve is opening at 3 bar and dumping the water/pressure, which would explain the low pressure.

The pressure vessel needs checking, it ethier needs recharging or replacing.

If you can get to it and the tyre valve, if you press it, air and no water should come out. If water comes out, it needs replacing.

 

[jakabi]

I've just had a look to see if I can press the value on the vessel but I have a problem ... the top of the tank (there is a black twist cap) is actually touching the ceiling and I'm assumming thats what I need to get to ...

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• jakabi
• 23 Sep 2013
• 1

edit - Just had the water AND heating on for approx 1 hour and it hit 2.6 bar, im guessing this would have just gone higher so knocked it off.

 

[xr4x4]

White are normally for domestic hot water cylinders, do you have mains pressure hot water?

Red ones are for central heating, or it could be in your boiler, what's your boiler model?

 

[jakabi]

White are normally for domestic hot water cylinders, do you have mains pressure hot water?

Red ones are for central heating, or it could be in your boiler, what's your boiler model?

Thanks Paul, boiler is a Baxi Solo 2 40 PF ... managed to get the bottom panel removed from underneath the cylinder which reveals this ...

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• jakabi
• 23 Sep 2013
• 1

cylinder and cylinder vessel above ...

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• jakabi
• 23 Sep 2013
• 1

I can get my hand in the top of the red one but still really tight.

 

[xr4x4]

That's the one..

I'm afraid you need a pro.