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Grant Vortex condensing oil boiler 15/26 Problems


 
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Helendav

from United Kingdom

Joined: 23 Apr 2012
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Location: Sussex,
United Kingdom

PostPosted: Wed Apr 25, 2012 1:55 pm Reply with quote

I have an external grant boiler which was installed in August 2007 along with a complete re plumb of the entire house. From the beginning the system was noisy but I was advised that this was because it was new and things would settle down once all the air was out of the system.

After 18 months I started to have real problems: boiler not firing, pressure dropping, some days no hot water. I have the boiler services regularly, have had the oil tank drained and cleaned and pipe work flushed through. At Christmas the boiler stopped and had a couple of valves including the PRV changed along with the jets and filter plus a lamp and switch. Since then my plumber and boiler engineer have been out 6 times, the most recent being last weekend. The pressure release valve is leaking again and once again needs replacing.

I really had hoped that by installing a new boiler i would have some hassle free years without huge bills and not be looking at replacing it in under 5 years of installation. Looking online it appears a number of other people have had issues with these external boilers losing pressure.

Can anyone one please give any advice as I really don't understand boilers and as a single recently unemployed mum of two could do without paying out hundreds of pounds in a regular basis just to keep this boiler firing?

Would appreciate any advice or knowledge that anyone could share.

Helen
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Burnerman

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PostPosted: Wed Apr 25, 2012 2:02 pm Reply with quote

Really the first thing to achieve is a stable water pressure inside the boiler, which is often between 1 and 1.5 bar.
This pressure should rise a little when the heating is on, but it should return down again when off.
If the pressure rises a lot, then its likely that the expansion vessel inside the boiler needs recharging with air.
Its true, PRV's can be notorious for not sealing once opened, but they should only open at 3 bar anyway so - is the filling loop shut off, or ideally disconnected? Whats the pressure on the gauge?
John icon_smile.gif
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dcawkwell

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PostPosted: Wed Apr 25, 2012 7:16 pm Reply with quote

Most likely expansion vessel is simply out of air.

Your plumber sounds hopeless.

I have installed gas and oil central heating systems
and they have years of trouble free running.

Get someone else in.
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Boilerman2

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PostPosted: Wed Apr 25, 2012 8:25 pm Reply with quote

On the Grant or any other boiler that uses a braided flexible pipe to connect the vessel to the system it is important to check that the flexi hose is not blocked - I have seen this numerous times !
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DeltaT2 (26 Apr 2012)
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holty

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PostPosted: Wed Apr 25, 2012 10:27 pm Reply with quote

boilerman 2 has the right idea. when grant boilers are serviced etc. to get to the baffles the pressure vessel. has to be out of the way. if the vessel isn't placed right then the braided hose can very easily be kinked. add that to a large system. hey presto. the prvs on grant external are around 2.5 bar release rather than the 3 bar norm . i keep a few in stock as it is a common problem they let by. but thats mostly due to incompetent installation. e.g no flushing as it seems people think an oil boiler can be installed on a dirty system. bad servicing e.g not checking the vessel. or just basic incompetence.
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Agile

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PostPosted: Wed Apr 25, 2012 10:50 pm Reply with quote

You do seem to have had a pretty poor installation which was compounded by an inability to sort out the problems.

Perhaps you are seen as a "soft touch" ?

Tony
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Helendav

from United Kingdom

Joined: 23 Apr 2012
Posts: 2
Location: Sussex,
United Kingdom

PostPosted: Thu Apr 26, 2012 6:38 am Reply with quote

John, the pressure is set to 1 bar currently but as the plumber located this along with the cylinder in a hard to access roof space I cannot keep an eye on it easily! The filling loop is turned off.

Thanks guys for your comments, nobody has mentioned the potential flexible hose issue before so will check that out.

Hotly, the pressure release valve that is on there is 2.5 bar, should it be 3? The expansion vessel is 12l and 3 bar.

Not sure if it's relevant but I am running 17 radiators off this system which are the AVOCA type that look like old fashioned school radiators.

As for being a soft touch, perhaps I was when I started this project 5 years ago but I've changed a lot and nobody gets one over on me any more!

Thank you for all your help and suggestions.

Helen icon_smile.gif
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DeltaT2

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PostPosted: Thu Apr 26, 2012 7:45 am Reply with quote

Boilerman2 wrote:
On the Grant or any other boiler that uses a braided flexible pipe to connect the vessel to the system it is important to check that the flexi hose is not blocked - I have seen this numerous times !


A very good point BM & as always you're right on the money.......... icon_wink.gif

The hard of thinking CC/CCC, would learn so much from simply reading your threads & posts BM, people like you are highly valued members here, you know your onions mate.
Thanks BM
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Burnerman

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PostPosted: Thu Apr 26, 2012 8:03 am Reply with quote

The braided flexy on these does have a very tight bend anyway, if I recall icon_exclaim.gif
Just for info Helen, the round red expansion vessel should be pre charged with air at 1 bar......thats with the flexy pipe disconnected.
John icon_smile.gif
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Boilerman2

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PostPosted: Thu Apr 26, 2012 7:33 pm Reply with quote

And with that number of Column Radiators fitted, the on-board expansion vessel (12 litre) may be too small for the water content, an additional expansion vessel may need to be fitted on the cool part of the system on the CH return pipe (Grant fit the largest vessel that will fit into the boiler case - it is not always big enough!) icon_wink.gif
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holty

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PostPosted: Thu Apr 26, 2012 8:13 pm Reply with quote

Quote:
And with that number of Column Radiators fitted, the on-board expansion vessel (12 litre) may be too small for the water content, an additional expansion vessel may need to be fitted on the cool part of the system on the CH return pipe (Grant fit the largest vessel that will fit into the boiler case - it is not always big enough!)


i think without looking. even grant literature will state that.
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snb

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PostPosted: Thu Apr 26, 2012 8:18 pm Reply with quote

same as others stated.

With 17 old style rads i would say the standard 12lt pressure vessel to be too small. Get them to fit an additional vessel on the loft and this should solve the problem
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Agile

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PostPosted: Sat Apr 28, 2012 1:35 pm Reply with quote

Better to see if its adequate by watching the pressure increase from 1.5 Bar colt to see what it is when hot. It should still be less than 2.0 Bar.

But it some rads have air at the top this will also absorb expansion so dont go round bleeding then just for the sake of it as that will compound the situation.

Tony
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