Rad not heating up


Postby xsarah55 » Mon Sep 29, 2008 11:00 am

Hi,

I moved in to my house this year and the bedroom rad has never worked.

I have bled it, checked if the valves are working and checked the pipe for bends.

When i have the rad off i turned the cold valve and it gushed out with water but when i turned the hot valve it trickled out. Once the heating is on the pipe below is boiling hot.

Is there a chance that the plumber who installed the system got the pressure wrong with the hot and cold pipe as it seams the rad is not heating up because the hot flow is not strong enough to compete with the cold. Also all my other rad work fine?

Thanks for your help
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Postby TheDoctor4 » Mon Sep 29, 2008 3:33 pm

Hi

Have you had a look at the DIY Projects area: http://www.diydoctor.org.uk/projects.htm There are several projects related to Central Heating that may be of some use to you.

Regards
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Postby jim the plumb » Mon Sep 29, 2008 8:32 pm

If the pipe to the rad is hot but the rad isn't, the fault lies after the first valve to the rad. Make sense?

You've clearly got a flow problem. Close all other rads and see if it heats up.

Yes? - balance the heating system.

No? - Change both valves, by doing this you eliminate both valves from sticking/ blocking. The only other thing to do is flush the rad.

HTH, jim.
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Postby htg engineer » Tue Sep 30, 2008 9:19 am

Hot and Cold ???? you mean flow and return. Many DIYers think radiators are plumbed in the same as bath's etc with hot and cold pipes. And many seem to think the water in the radiators is the same water that comes out when you open the hot tap :? if this is you're thinking - then you need a plumber, you need to understand how systems work before you can start fault finding and trying to repair faults.

Check both valves are open - Isolate all other radiators and see if it heats up, If you're sure the valves are ok - then there may be a blockage, especially if 8 or 10mm pipe, there could be a blockage at the manifold.


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Postby xsarah55 » Tue Sep 30, 2008 10:49 am

Hi,

The rad in the bedroom is connected to the rad in the bathroom as the bedroom rad pipe does not heat up without the bathroom rad on.

Its not the valves they work fine, tested by taking them off and blowing through and they do not block or stick.

There is no blockage in the pipes as the pipe feeding into the rad is boiling hot, also when draining the rad and checking the valves there was not sign of a blockage just poor pressure.

I cannot see how it can be a blockage as the pipe below got hot very quickly.

Is it possible that the flow and return has got mixed up? as the pressure from the hot pipe is little and the pressure from the cold pipe is strong?

Please help, i have already consulted a plumber and he could not find a solution.
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Postby htg engineer » Tue Sep 30, 2008 5:08 pm

"Is it possible that the flow and return has got mixed up? as the pressure from the hot pipe is little and the pressure from the cold pipe is strong ?"

It doesn't matter which way you connect the flow and return to a radiator.

Explain what you mean by hot and cold pipes ??

Poor pressure when radiator valve open ???? = airlock, blockage, or faulty radiator valve.

If the plumber couldn't find the fault, then he's not much of a plumber. More likely to be a kitchen/bathroom fitter. Get a different plumber or a heating engineer to take a look for you.


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Postby Steve the gas » Wed Oct 01, 2008 5:04 am

IMO it's the valve(s)
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