Microbore return pipe blockage

[Bilabong007]

Firsty thanks to the many members of this board for giving me the insight and knowledge to tackle what my dad and I did today.

We removed radiators, replaced trvs, soldered pipe and tons more.

My question is about a single rad in my soon to be nursery for my sprig due Xmas day. It has never worked since we bought the house.

It seems the return pipe is blocked as rad/trv and lockshield have all been replaced, but it will not get hot. the flow pipe eventually gets hot, but never the return.

Is there any trick to get a small amount of flow in this pipe to let the fernox 5 cleaner do the rest? I did fit drain tailpieces on all rads so maybe I could use this and mains pressure?

Also when balancing with microbore do I need to go up in q turns? They are danfoss lockshield valves and I must be at 2.5 turns from shut on a big double rad that has a cold return still. Can I just go a bit heavier handed with opening it or will this mess with the balancing?

Many thanks

Graeme

 

[HERTS P&D]

Various fittings from micro bore to 15mm with hose pipe attached, then main water flush.

Andy

 

[Bilabong007]

Can I do that by shutting the Flow end, opening the return end and using a fitting on the drain tailpiece you think?

Cheers

Graeme

 

[jackthom]

That's worth a try but of course the mains water will have to flush out somewhere. Is there another drain point, preferably somewhere around the far end of this dodgy piece of microbore.

You can't assume it's only the return which is partially blocked, have you tried the bucket test on each valve, ie to see how fast water flows out from each end?

 

[Agile]

Assuming you have feeds to the rad at each end then its best to do the bucket test on each valve.

With rads which have a 1/2" tapping for the bleed point it is possible to fit a 15mm iso valve into the tapping and attach a hose pipe onto the other end of the iso valve.

Then close each rad valve in turn and see what will flow from the iso valve!

Microbore can be very difficult to clear and usually needs aggressive acidic chemicals.

Tony

 

[Bilabong007]

Tony,

Just did the bucket test using the fernox f5 express adaptor thingy into the bleed valve (the black adaptor meant for injection into the filling loop)

The flow pipe spluttered a bit then erupted with black gunk. The return was similarly shunky, but much faster. I took about 1.5 litres out each pipe

Rad now toasty

The amount of junk in there got me thinking I should clean the tf1 now as it may have collected lots of stuff since yesterday.

Is it worth doing this to all the rads to blow any stuff through the pipe work?

Cheers

Graeme

 

[HERTS P&D]

Fit a magnetic filter on the return to the boiler and clean out weekly until clear.

Andy

 

[ianmcd]

+1 for a magnetic filter and clean it every week till it is almost clear then add inhibitor

 

[Bilabong007]

Thanks for that advice on cleaning my filter. I fitted a tf1 when the boiler was replaced before we moved in.

Cleaned it tonight and it was pretty sludgy. (it was cleaned yesterday when I replaced the rads and trvs)

Going to flush out the fernox f5 at the weekend, would you leave out the inhibitor until it runs clear?

Cheers

Graeme

 

[Terry lambert]

Let the chemicals run for a couple of weeks and then drain, refill and drain and then refill with some inhibitor.

It won't hurt to give the rads a whack with the palm of your hand all over every now and again over the period