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gravity fed water system problem


 
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bash1978

from United Kingdom

Joined: 23 Jan 2008
Posts: 20
Location: Lancashire,
United Kingdom

PostPosted: Wed Jan 23, 2008 3:41 pm Reply with quote

Hi,

I hope someone can give me some advice on the following:

I have recently moved into a new home and have an ldeal classic boiler which pumps water for heating and has a gravity fed water system used to warm the water. The tank I have is a primatic tank and have a header tank in the loft.

The problem is this, if I switch on both my heating and water at the same time, I find I create some sort of air lock in the system so my water doesn't heat up as it should, the Gravity Flow pipe from the boiler is usually cold and the Gravity Return pipe is boiling hot. The heating works a treat no problems.

The only way of resolving this I have found is to drain the system from the cylinder and refill and all is well and it stays well aslong as I heat up the water for 5-10 mins before I switch on my heating. So I can't utlise the timer during these very cold morning to heat up the house!

I have checked the piping as much as I can (its diffcult to follow it to the tank) and there doesn't seem to be any sort of valve to help remove an airlock.

Any advice will be much appriaciated.

Thanks
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lopez11

from United Kingdom

Joined: 29 Dec 2007
Posts: 9
Location: United Kingdom

PostPosted: Wed Jan 23, 2008 4:03 pm Reply with quote

Rip out the primatic, have it converted to a fully pumped system and have it sealed as well icon_biggrin.gif
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bash1978

from United Kingdom

Joined: 23 Jan 2008
Posts: 20
Location: Lancashire,
United Kingdom

PostPosted: Wed Jan 23, 2008 4:09 pm Reply with quote

thanks lopez, I will be replacing the bulk of the system in a few years to a combi system, but was hoping to get a "quick fix" to this issue, any other suggestions ?
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izzy eckerslike

from United Kingdom

Joined: 26 Oct 2007
Posts: 79
Location: Worcestershire,
United Kingdom

PostPosted: Wed Jan 23, 2008 4:55 pm Reply with quote

It seems I have more or less the same problem as you Bash, altho I don't think my cylinder is primatic

see my thread http://www.diynot.com/forums/viewtopic.php?t=120935
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bash1978

from United Kingdom

Joined: 23 Jan 2008
Posts: 20
Location: Lancashire,
United Kingdom

PostPosted: Wed Jan 23, 2008 5:07 pm Reply with quote

hi izzy,

seems similar, but I think the solutions are probably very different. My boiler has 4 pipes coming out, 2 for water, Flow and Return and 2 for heating pumped flow and return. So heating is fine as its pumped, but the gravity fed bit is problematic. I am trying to understand why the water flow seems to be going back i.e.e return pipe gets hot and flow pipe doesn't ?
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izzy eckerslike

from United Kingdom

Joined: 26 Oct 2007
Posts: 79
Location: Worcestershire,
United Kingdom

PostPosted: Wed Jan 23, 2008 5:21 pm Reply with quote

My boiler has the same four pipes, the hot water pair are a bigger bore than the heating pair tho
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bash1978

from United Kingdom

Joined: 23 Jan 2008
Posts: 20
Location: Lancashire,
United Kingdom

PostPosted: Wed Jan 23, 2008 5:33 pm Reply with quote

I see, just re-read your thread, I think maybe what you should try is whats called "cracking" the nuts open a little on the coil inlet pipe at the top and the outpipe at the bottom of the cylinder. If there is any air it will soon be noticable. Other than that i'd re-try emptying the heating system and re-filling.
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izzy eckerslike

from United Kingdom

Joined: 26 Oct 2007
Posts: 79
Location: Worcestershire,
United Kingdom

PostPosted: Wed Jan 23, 2008 5:47 pm Reply with quote

I don't think I have a primatic cylinder, we do have two tanks, the pipework looks very old 1960's possibly so I am wary of loosening the nuts as they look gunged up somewhat, I just took off the lagging to see if there is any way to bleed the coil but no luck there.
My boiler is a Myson Marathon incidently
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