Central heating may need new pipework


Postby Tinman » Mon Feb 09, 2009 10:25 pm

My heating system has been driving me crazy for a few years. It's a fully pumped vented system with HW priority. After we'd been here for a couple of years I had to replace the pump and during the drain-down noticed the water was black, like ink......so I flushed it all out until it ran clear, replaced pump, refilled, added inhibitor etc and all seemed well.......I say 'seemed' cos after I while I noticed the downstairs rads (only 2) wern't getting very hot. Anyway, (I'm cutting a long story short, believe me!) if I turn off the upstairs rads, the downstairs ones get hot, but as soon as I crack open the upstairs ones, downstairs go tepid. I lifted some floorboards and found that all the upstairs rads feed directly off 22mm pipes, but the feed to the downstairs rads is tee'd off one of the bedroom rads 15mm pipes!.......to me this doesn't feel right, as there are 3 rads all trying to be supplied through a pair of 15mm pipes. I also tested for magnetite using a strong magnet and it 'pulls' in a few places, noticably on the branch going downstairs. I put some sentinel x400 in over two weeks ago but the water is still clean in the system. Is it possible for the magnetite to go hard and resist the cleaning sloution?
I intend (when the weather gets warm) to redo the pipework and extend the 22mm feed so that the downstairs rads get fed off that, and replace the pipes that are 'magnetic'..........and also to run 22mm pipes into antoher bedroom so I can drop down to the living room and fit a rad there. Does this sound ok, or have I missed anything out.......your comments and/or suggestions would be very welcome....thankyou :wink:
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Postby Steve the gas » Tue Feb 10, 2009 6:09 am

Hi Timan,

That sounds like a plan - go for it.
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Postby htg engineer » Tue Feb 10, 2009 11:45 am

That's the best way, feeding 3 rads of one 15mm branch is asking for trouble. You really need 22mm flow and return with 15/10mm branches to each radiator - as you are suggesting doing.

Remember to flush and add inhibitor.

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Postby Tinman » Sat Feb 14, 2009 8:00 pm

Thanks for replying guys......sorry I have taken so long to thankyou, got a few things on the go. I have a few questions to ask but will post asap.......thanks again...... :D
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Postby Tinman » Sun Mar 01, 2009 3:35 pm

Ok.......I have bought a honeywell mid position valve to replace my defunct one.....it's a 22mm version...(V4073A)....but, although my pipework is 22m, I have noticed that the actual fittings on my existing valve are around 24-25mm....there are step-up tails soldered onto the 22mm feed and outlets. My question is, can I just replace the valve mechanism ie. motor and valve assembly, or am I going to have to replace the whole tee-piece?
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Postby Steve the gas » Mon Mar 02, 2009 3:26 am

Yes, just replace the head if compatible.
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