Brown rust blockage in copper pipe? (see pics)

[ChrisNason]

The pumping over problem is not there on pump speed 1.
On speeds 2 & 3 it starts to happen again.

The circuit (up from the boiler) first passes the expansion (overflow?) and then, after 12 inches, it passes the cold feed and then 3 inches further it enters the pump. This pipe is a straight vertical all the way from the boiler (after the first 18 inches of horizontal pipe out of the back of the boiler).

This flow (to the pump) has not been replaced.
If it were slightly blocked would it cause pumping over and how does this happen?

 

[Slugbabydotcom]

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,

The pump could be the source of the air ingress. You know if this is the case because the inlet will be black from normal sludge and the outlet will be brown from the rust.
I have seen pipes like that before. Powerflushing was useless. Only way to clear it was to remove the pipes that were worst affected with a recommendation that when funds allow the crudded pipes could be chased back further or better still renew the lot.

Isn't there something about pumping over in the faqs? Whatever! If you have the pump in between the feed and the vent pipes you will get a problem. Easiest way round it is to fit a de-aerator as this will put the feed and vent pipes together on one side of the pump. Watch out for a blocked feed pipe, indicated by slow filling or sometimes not filling at all. I've seen that cause some real 'loft geysers'.

Any leak or other loss of water will cause suspended air to be released from any new water entering the system. New water also contains the finest traces of chemicals that will react with a system over time to build up various forms of crud.

 

[ChrisNason]

Isn't there something about pumping over in the faqs? Whatever! If you have the pump in between the feed and the vent pipes you will get a problem. Easiest way round it is to fit a de-aerator as this will put the feed and vent pipes together on one side of the pump. Watch out for a blocked feed pipe, indicated by slow filling or sometimes not filling at all. I've seen that cause some real 'loft geysers'.

The pump is not between the Vent and Feed pipes. It's arranged like this...
Boiler -------6 Feet-------Vent----12 Inches---Feed----3 Inches---Pump
I just cant work out where the pressure is when the Vent is 15 Inches below the suction side of the Pump.
Also, the pump looked clean and the filling was very quick (indicating a good flow down the feed)
With the state of the pipes cut out I suppose there could be the same problem elsewhere. Except that now, on pump speed 1, the heat to the radiators is within 60 seconds which I thought was pretty stunning. But then I have lived with this problem for some time!

 

[JohnD]

In terms of cleaning out the rust, I know nothing, bit it could be worth phoning Sentinel and Fernox to see what they suggest.

 

[ChrisNason]

Just read the Potterton Install book and it shows the S-plan Open Vented with the Feed joining the Vent before meeting the Flow with just a single pipe on to the Flow side before the pump.

So their layout is...

Boiler....3 Feet....Vent (with a tee just above for Feed)....6Inches...Pump

 

[Slugbabydotcom]

The pump is not between the Vent and Feed pipes. It's arranged like this...
Boiler -------6 Feet-------Vent----12 Inches---Feed----3 Inches---Pump
I just cant work out where the pressure is when the Vent is 15 Inches below the suction side of the Pump.

Because the feed is only 3 inches away it is sucking on the feed and blowing on the vent. Theres less resistance that way than pulling round the whole system.

Fit a de-aerator and/or keep a bit of distance between pump and feed / vent.

I still think there could be a ferret loose with your pump. Its noisy and that is a sign of wear. At best its simply not long for this world.

Surely you can get a plumber for less than £90 an hour. If not where do you live? I'll turn into a gypsy plumber

 

[ChrisR]

Very Simple!
It's pumping over because there's a (partial) blockage in the circuit between the vent and the feed. It usually starts off at the bottom of the feed pipe and grows. Often you can clear it by removing the pump, and poking a drain spring back up the pipe. Won't go round an elbow though. You can also cut the feed pipe and poke a drain spring down there.

I did a pic, some time ago...

If the blockage is soft, red rust (magnet won't stick) you stand a chance of shifting it with the method I put in one of the faqs - Blocked Feed Pipe - I think it was..

 

[fine tune]

chris r has got it bang on and with a nice picture to boot , also i would add the distance between the vent and the feed should be a maximum of 6 inch . not 12 inch .. cheers

 

[ChrisNason]

Ah. Now I understand.
I suppose it's quite likely that the 'Flow' could be blocked on the evidence of the 'Return'.
As it's pumping over only on speeds 2 & 3 (and there was a fast refill) I think it can't be quite as bad. Should I try chemicals first (with a slight drain down) or just cut out the 12 inch section below the pump (with a full drain down).

 

[ChrisNason]

When it's warmer I think I'll cut out the 12 inches up to the pump. This will allow me to also change the arrangement of the Fill and Vent pipes. Should be a picture below.
How close should the Fill and Vent pipes be arranged to each other?
Then How close should they be to the pump?

 

[ChrisNason]

I linked to the thumbnail! Try this...

 

[twgas]

I linked to the thumbnail! Try this...

is this a real picture or have the pipes been air-brushed, or something???

 

[WDIK]

is this a real picture or have the pipes been air-brushed, or something???

all the background has been blacked out
theres a pipe running across below the pump
and the peculiar tee has been drawn in note the lack of fittings

 

[twgas]

well sus me thinks

 

[WDIK]

well sus me thinks

Hmmmmmmm seems like a lot of effort to go to