Brown rust blockage in copper pipe? (see pics)

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ChrisNason

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This is so similar to mine. Hot upstairs and cold downstairs (although I do have thermostat and valve on hot cylinder.

I've been losing my radiators gradually. Early last week I had all cold downstairs. After reading advice on this forum I spent Thursday evening working my way round all radiators one by one just concentrating all the flow through each. By the end of the evening every one had had a period getting up to temperature. I left 4 turned on but Friday morning when the timer called for action I had nothing. Everyone was cold. The pump still turned, the boiler and flow pipe were scalding but nothing in the radiators.

I've had a plumber in today and he drained one radiator down and pronounced the water all most clear enough to drink. He's added chemicals and now I have some heat (2 radiators scalding, 2 radiators very warm, 2 radiators luke warm and 1 radiator stone cold) while the Hot Cylinder is turned off.

The pump is mostly making a grinding noise although a bleed of the screw above the pump (off the tee that goes to the cylinder) produced a hiss of air, some gurgling and then a 5 minute quiet period.

Do I need a power flush?

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keep bleeding them

what was the chemical?.
 
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Plumber back this morning. Sentinel X300 drained out with very little discolouration.
He thinks there may be a blockage in the return pipe. It's an up side down U shape in the first floor airing cupboard. The radaitors return in the floor and then enter up in to this upside down U where it collects the bypass exit and then the Hot Water Cylinder exit before going back down to the boiler.
He's taken out a section of the return pipe further down in the kitchen and it is not blocked but it's walls have a gritty grey paste on them.
 
A inverted "U" sounds to me more likely to collect air than sediment, but I am just a householder, not a plumber.

I wonder what the gritty grey stuff is? Do you suppose it is limescale collected over a long period? Put a bit in vinegar and see if it fizzes.

the more common sediment is deep black iron oxide, caused by corrosion of steel radiators, very fine, but can settle and harden. Sentinel X400 is good at loosening this, it is a very mild cleaner that can be left in for up to a month before draining. You know it's starting to work when the water goes inky black as the sediment starts to be washed away in the circulating water.

But I expect your plumber is familiar with local conditions, unless he is inexperienced.

OOI. a blockage or restriction due to black sediment can be detected by holding a magnet close to the suspected blockage. Magnets are not attracted to copper pipe, but they are attracted to black iron oxide.

ChrisNason said:
The pump still turned, the boiler and flow pipe were scalding but nothing in the radiators.
Click to expand...
make sure the hot flow is not all going round the cylinder and bypass instead of being forced round the (more resistant) radiator circuit
 
Finished and sorted (mostly). When he got to the upside down U of the return it was very clogged. If I can work it out I'll post pictures.
He's cut out the whole U together with the Cylinder return. Then he's cut out the last 12 inches of the bypass, removed the rest of the down pipe (return) to the boiler. He didn't power flush as it was already mid afternoon and he said he would need 4 hours for the flush.
I now have gloriously hot radiators in every room and a very hot cylinder.

The only down side is that on pump speeds 2 & 3 it's pumping over from the expansion in to the tank. But even on speed 1 it's got a rapid heat up. The pump is a Grunfoss 15/60

The pipes have gone back to the museum and I'm a lot poorer (£90 + VAT per hour)
 
I still like the idea of giving it a clean with X400 (it's easy DIY job) which will reduce the sediment load a lot and only cost you £15.

If you can afford an extra £100 and can do simple pipe cutting and compression joints, a Magnaclean will do a lot of additional good (provided your sediment is mostly black iron oxide).

Of course, the best time to do it is before you get a blockage as it can save a lot of work and money later.

You need a litre of X100 on final fill after flushing.

p.s. turn down the pump to avoid pumping-over. This aerates the circulating water and speeds up corrosion (thus making more sediment)
 
Oh. And by the way. I did try a magnet on them and did not notice any pull. The other pump had black/grey gritty coating. These pipes looked very brown but also gritty. They are all 3/4 inch.
 
Yuk brown rust!!

that is not attracted to a magnet

It is encouraged by aerated water so the pumping-over will have made it worse.

Hang around a bit (or start a new thread) and you will hear from some of the pros who've dealt with it before.
 
JohnD said:
Yuk brown rust!!

that is not attracted to a magnet

It is encouraged by aerated water so the pumping-over will have made it worse.

Hang around a bit (or start a new thread) and you will hear from some of the pros who've dealt with it before.
Click to expand...

I'm confident it wasn't pumping over before and I've been in the house for 20 years.
The layout looks right and I can't work out why the pipe that is 6 inches below the sucking side of the pump has enough positive pressure in it to send water up 10 feet in to the tank. You would think that it went in the other direction in to the pump!
 
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