Power flush and 8mm microbore

My brother has been told by a plumber he cannot have a power flush on his central heating system as it uses 8mm microbore.

Is that true?

Adam

Reply to
ARWadsworth
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On Mon, 29 May 2006 16:35:44 +0100, ARWadsworth wrote (in article ):

Power flushing machines that I've seen connect in place of the pump and work by circulating a chemical solution through the radiators one at a time - i.e. the operator is supposed to go round and close all radiator valves and then open at one radiator at a time. This is meant to flush through crud in the radiators and it gets filtered at the power flushing machine or to the drain

One can figure out that if the radiators are badly silted up, that this could be difficult through 8mm tube even though the lengths from the manifold are typically only a few mm.

I suspect that the plumber is saving himself some grief in case the job is unsuccessful or that it takes him longer than he'd like to do it.

I have an 8mm system which has been well looked after from the outset.

The approach that I took when exchanging boilers and switching to a sealed system was to do the sealed system conversion first - this provided a means to fill and flush the system from the mains rather than the roof tank.

I drained the system and then starting closest to the boiler, I visited each radiator in turn and removed it. Care is needed because sludge is an indellible dye. I covered the floor with plastic sheet and old towels and used a cat litter tray under each valve. The radiator valve unions can be undone. Fit a small plastic bag on each tail with a rubber band and take radiator outside. Flush through with a pressure washer. At the radiator turn off the valves and turn on the mains water at the filling loop. You can then flush any crud in the pipes out. `Since the pipes are only

8mm, there is not going to be a lot to come out and it is not being pushed around the pipes either.

I repeated this for each radiator and then refitted everything and added a chemical flushing agent. The system was run hot for a few days and then flushed to drain with fresh water. Finally, corrosion inhibitor was added.

The whole job can be done easily in a morning.

Reply to
Andy Hall

If a system with micro-bore pipe ever gets to be in need of a power flush it is truly beyond any hope of redemption.

Frankly the idea of disturbing what little dirt there may be in such a system out of the rads into the pipes looks like madness. besides which the power flush flow rate in each radiator will be fairly small due to the resistance of the 8mm pipe.

A flushing out of individual removed radiators (with a pressure washer if you must) is all that should be done.

Reply to
Ed Sirett

return coaxial at one end). I always remove radiators for decorating and have never found much sludge. My main worry is sediment settling in horizontal (or sagging) lengths of pipe. I am surprised that Ed feels that flushing would not help. I wouldn't mind trying it - I imagine a pump that sends shock waves through the water would be effective. Incidentally - I have not found any faults with the twin valve arrangement and can't understand why it became obsolete. It can be a very neat installation and much easier to remove radiators. Mine have a nylon tube to send the flow to the far end. I understand some people used metal and suffered from corrosion. Was the problem a lack of understanding? I think my house was the last in the road to use this system (1988) as an identical house completed a few weeks later by the same plumber had conventional valves on each end. Does anyone know when my type of valve fell from favour?

Reply to
John

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Reply to
John

====================== Twin entry valves had a reputation for being difficult to get the circulation going. I don't think it was a serious problem but it certainly could be difficult at times. There was some debate about long the internal pipe should be and whether it should be plastic or copper. I used copper about 2/3rds the length of the radiator (as recommended) and always got a good circulation going eventually.

As far as flushing is concerned I can only guess that it's less necessary with 8mm because the normal pumped flow has a more powerful scouring action than is the case with 15mm or greater. I've never had any blocked pipes, possibly because I don't have a Summer shutdown. I think our weather is too unpredictable to have a fixed Summer period when heating isn't necessary.

Cic.

Reply to
Cicero

Mainly because the older units had copper internals which corroded and broke as they were in contact with the iron. This caused only the corner to get hot.

They are not as widely available and whilst a thermostatic version is probably available the requirement to add TRVs to most radiators make their replacement nigh on inevitable.

Reply to
Ed Sirett

thermostatic valves - but how a sensor only inches from the heat source can work properly is beyond me.

Reply to
John

I hope not, he wants me to rewire his house!

Unfortunatley, this system is 15 years old and has been neglected before my brother bought the house

Can I do that without changing the hot water cylinder?

- this provided a means

I removed all the rads and flushed them last year when he moved in. I also changed the pump which was noisy and added inhibitor. The main problem is now of overpumping which as I understand will reduce the effectiveness of the inhibitior and the sound of water falling down the vent pipe when the pump shuts off. I removed a rad over the weekend and although there was plenty of black water there was not the sludge that was present a year ago.

I think I may reflush the rads and this time use a cleanser.

Adam

Reply to
ARWadsworth

All of it or just the rads? I am prepared to swap them if needs be.

Cheers Ed, see my reply to Andy

Adam

Reply to
ARWadsworth

Little heat is trasnferred by radiation especially from the lower part of the rad. The convection draughts keep the TRV more in tune with the room that the radiator. The TRV does not have to be at the same temp as the room but merely has to sense and react to changes in the room temp.

Reply to
Ed Sirett

15mm can and do block on very badly sludged systems. It won't take so much to block an 8mm pipe. I have no idea wether an 8mm pipe is unblockable by pressure and chemicals alone - but I'd reckon against it. >
Reply to
Ed Sirett

S**t. Any more chance of being successfull in a soft water area. I am now only hoping for miracles.

Adam

Reply to
ARWadsworth

Soft or hard water probably won't affect scale in CH systems... if you flush the radiators through, then I should think that the reduction in total sludge in the system, combined with the fact that small bore pipes have a high flow rate, and radiators are nice "settlement tanks", might help.

Reply to
Chris Bacon

On Tue, 30 May 2006 18:28:13 +0100, ARWadsworth wrote (in article ):

It should be possible in principle. However, if it's a hard water area the coil might be scaled up. You would need to take out the immersion heater and look inside to check that. If it is, then you could descale with chemicals and replace the immersion heater. However, this may not be the best way to invest in the system. It might be better to write off the cylinder and start with a new one,...

That's reasonably easy to do and would give an idea of the general state of the system as well.

Reply to
Andy Hall

" a few mm" ?????

Reply to
Stuart

On Sat, 3 Jun 2006 15:06:03 +0100, Stuart wrote (in article ):

Well, yes. Maybe a couple of thousand for example.....

What's that between friends.?

Reply to
Andy Hall

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Power flushing is not very effective on microbore because the drop in flow is big with small pipes. Try a powder flush as it has been developed especially for microbore systems and use much stronger machines.

Reply to
powerflushingpro

Well I will bear that advice with a pinch of salt. After all you are replying to a post I made in 2006. We swapped the pipework to 15mm a few years later.

Any ideas of how to clear a turd from the uk.d-i-y newsgroup in the year

2012?
Reply to
ARWadsworth

fit an enema fitting to the end of the power flush hose...

Reply to
Gazz

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