Greenstar Junior 28I Pressure Problem

[ChunkyD]

Hi Guys,

I have recently started to have problems with the above boiler.

When the heating is on the pressure slowly rises to the point where it expels water out of the saftey pipe outside, I got homeserve out and the engineer replaced a part and said that should be the problem solved. However, the problem is still there, I phoned homeserve again and they informed me that they will not send another guys out as the last one recomended that we had the system power flushed (i can not afford this at this present time)

I have checked the expassion vessel and that is reading 1 bar of pressure and there is no water comming out when the valve is pressed.

Does anyone have any suggestions?

Forgot to mention, the pressure does not drop once the heating is turned off

Thanks in advance

Shaun

 

[bryanpar]

i would get back on to home serve and tell them that you have paid for a repair and told it was fixed.yet you still have the same problem you have paid them to fix it and they have not!! homeserve are not good people to work with i have done some sub contrct work for them and in my oppinion they are cr*p.best sticking to your local plumber.as for the problem the pressure will rise when the boiler is on due to expansion in the hot water being pumped around and will fall again when off.if water spills out when pressure is high ,have you tried to remove some water from the system.there may be to much water in the system and when it expands it will come out of the expansion valve

 

[Andygasman2010]

How many rads do you have?

What parts have been fitted?

Was the expansion vessel pressure checked with the system open to atmosphere via the drain off?

Any boiler with a braided hose to connect the expansion vessel is prone to this. The hose can block up because it's not barriered and oxygen can diffuse through it. This DOES NOT mean your system needs Powerflushing.

 

[ChunkyD]

Thanks Guys,

bryanpar, I have to let water out of the system every 2 to 3 hours as the pressure does not drop when the system goes cold, I didnt directly pay for the repair its part of my Natwest insurance.

Andygasman2010, we have 3 double rads and 2 single rads, The part he took of is below (i would hope he put the same part back on!), vessel presure was checked by him when the system had no pressure in it but not sure if the system was open, is there an easy way to clean the braided hose?

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• ChunkyD
• 1 Dec 2011
• 1

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• ChunkyD
• 1 Dec 2011
• 1

Thanks again guys

Shaun

 

[Agile]

Thats an auto air vent.

I think you will find that the Natwest scheme is only an EMERGENCY service to do the amsolute minimum to get the system going.

It is not meant to replace normal servicing, maintenance and repairs!!!

Homeserve have a very bad reputation on this forum. Some engineers here have done or do some of their repair work and I can never understand why they dont improve the service they give. Telephoning in advance of the visit is a typical example rather that just turning up at any time on a particular day.

Tony

 

[Andygasman2010]

It sounds very much like the braided hose is blocked. Also, the PRV may need some attention if it's been passing.

Both are difficult to access, I can't quite remember how to do them but I have a feeling you need to remove the flue to get to get to the hose because the expansion vessel may need to come out.

Job for a pro, I doubt Homeserve will do this. They'll find some way to wriggle out of it!

 

[ChunkyD]

Andygasman2010 - "It sounds very much like the braided hose is blocked"

I have removed the braided hose (easy enough as we have a side flue) there was no blockage in it

When you say the PRV may need some attention what do you mean?

 

[Andygasman2010]

Hmm I think we're barking up the wrong tree here.

You say the pressure goes up when the heating is on ONLY? When you only use the hot water it's fine?

If the pipe isn't blocked and the expansion vessel is fully charged then you might have mains water passing into the heating circuit. Possible plate heat exchanger fault.

If the PRV has lifted off it's seat for whatever reason then it could pass slightly afterwards. Just check that it isn't dripping from the outlet.

 

[ChunkyD]

Andygasman2010 - Thanks,

Yes the pressure only rises when the heating is on, i can run hot water all day and the pressure stays fine, its funny that the pressure does not go down even after the system goes cold.

 

[Andygasman2010]

Very odd that it doesn't drop low once it cools, and odd that it only does it when the heating warms up.

Make sure the fill loop key or isolation cock is off.

Recheck the expansion vessel, set it to about 0.8bar when it's disconnected from the system.

 

[ChunkyD]

Thanks andy,

From further investigation today I have noticed that the pressure rises even when the boiler is off, I have also noticed that there is a very small amount of water continually comming out of the pressure release pipe outside, but would that also let water into the system, I have drained about 8 pints of water out of the system today and all the rads are still hot all over!

 

[Andygasman2010]

From further investigation today I have noticed that the pressure rises even when the boiler is off

You have probably got a faulty plate heat exchanger. But, like I said in my earlier post, you should double check the filling loop isn't partially open

I have also noticed that there is a very small amount of water continually comming out of the pressure release pipe outside

Water will not enter at this point, only exit. It'll be passing due to the excess pressure. This is what it's designed to do.