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Brand new radiator wont get hot

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diystupid

from United Kingdom

Joined: 06 Aug 2010
Posts: 25
Location: Kent,
United Kingdom

PostPosted: Fri Aug 06, 2010 10:50 pm Reply with quote

Hi, I have installed a new radiator tonight, complete with a TRV. This is set at 6 and the lockshield is open. But it gets luke warm across the top and stone cold at the bottom. Have felt the inlet pipe and this is boiling hot. Both radiators before and after this one are piping hot. What am I doing wrong. I have taken the TRV off and made sure the pin goes up and down. It does. Any advice.
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Hugh Jaleak

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PostPosted: Fri Aug 06, 2010 11:00 pm Reply with quote

Possibly air locked. Try shutting off all the other rads to force the flow through the new one, see if this solves the problem. You may then need to balance the system. (See FAQ's if you're unsure on how to balance.)
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JohnD

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PostPosted: Fri Aug 06, 2010 11:05 pm Reply with quote

which pipes did you attach it to?
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diystupid

from United Kingdom

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Location: Kent,
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PostPosted: Sat Aug 07, 2010 8:58 am Reply with quote

I attached it to the existing pipework. Sorry, should have said brand new radiator replaced an old one.

If I turn the rads off before and after this new one, would that force an airlock out or do I need to turn all the rads off in the house?
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JohnD

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PostPosted: Sat Aug 07, 2010 9:05 am Reply with quote

OK, so you took off an old radiator and connected the new one to the old pipe stubs that came through the floor? Did the old rad work OK?

was it connected to 15mm pipes, or 22mm, or 10mm?

is your system pressurised or does it have a feed and expansion tank in the loft? Is this rad upstairs or down?

if you have an airlock you need to turn off all the other rads

but if you take the rad off again, open each rad valve and let them squirt into a bucket. That will do it, and will also verify the flow.

how old is the system and how much dirt came out of the old rad? what colour? Did you do any cleaning or flushing?
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picasso

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PostPosted: Sat Aug 07, 2010 9:13 am Reply with quote

overdone the ptfe tape ?
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bengasman

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PostPosted: Sat Aug 07, 2010 9:59 am Reply with quote

Open vent by any chance?
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diystupid

from United Kingdom

Joined: 06 Aug 2010
Posts: 25
Location: Kent,
United Kingdom

PostPosted: Sat Aug 07, 2010 3:24 pm Reply with quote

Thanks for replies so far.

Ok, its 15mm pipework. No ptfe used.

Will try to explain this as best as I can. We have a ball joint on both the feed and return. We have disconnected the return pipe just before the ball joint just to make sure water was actually going through. Eventually the water coming out gets hot and the radiator heats up. But the pressure of water coming from the other side of the ball joint on the return is as high as the pressure of water going into the feed.

Once we connect the return pipe back into the ball joint, the rad starts cooling down. So its like we dont have a flow of water in and water out and two pressures of water are kicking against each other.

Any ideas.
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JohnD

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PostPosted: Sat Aug 07, 2010 3:37 pm Reply with quote

have you tried closing all the other rads yet?

it isn't a tower rad or towel rail, is it?
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diystupid

from United Kingdom

Joined: 06 Aug 2010
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Location: Kent,
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PostPosted: Sat Aug 07, 2010 3:53 pm Reply with quote

no its not a towel rad/rail. its the rad in our living room. i am assuming that i can just turn off all the trv's to 0 and the one doesnt have one, simply turn it off? will get back to you.
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doitall

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PostPosted: Sat Aug 07, 2010 3:55 pm Reply with quote

Is it a one pipe system. icon_rolleyes.gif

How many pipe do you have, do the two tails connect to the same pipe.
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diystupid

from United Kingdom

Joined: 06 Aug 2010
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Location: Kent,
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PostPosted: Sat Aug 07, 2010 3:59 pm Reply with quote

all rads are off, i appreciate they will take a long while to cool right down but if this was going to work, how long would it be before the new rad would get hot?
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diystupid

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Location: Kent,
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PostPosted: Sat Aug 07, 2010 4:00 pm Reply with quote

each radiator has one pipe in (feed) and one out. dont have a combi boiler and there is two tanks in the loft, one for water, one for central heating. also have an immersion with a self vent tap(?), where air can escape. dont have one of these on the boiler.
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picasso

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PostPosted: Sat Aug 07, 2010 4:12 pm Reply with quote

diystupid wrote:
Thanks for replies so far.

Ok, its 15mm pipework. No ptfe used.


what did you use to connect the rad valves where they go into the rad?
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diystupid

from United Kingdom

Joined: 06 Aug 2010
Posts: 25
Location: Kent,
United Kingdom

PostPosted: Sat Aug 07, 2010 4:15 pm Reply with quote

simply screwed them on, they're compression joints.
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