Stubborn blockage not cleared after two powerflushes, what next?

[mhnp]

Assistance would be much appreciated as I have lost faith with the company I engaged to deal with this. They have come on 3 separate occasions, first to powerflush, second to lift floorboards to see what they could see and third to powerflush again from 'the other end'.
The problem: This Spring 6 upstairs radiators in my open vented CH system failed to heat. I drained down a few litres poured Sentinel sludge disperser into the header let it run several weeks, tried closing down all working radiators and eventually called in the professionals for a power flush.
They attached their pump to a downstairs radiator pumped for several hours, I am fairly sure with all radiators open, packed away and seemed surprised the blockage was still there. In response to my query they said they had fully flushed the system notwithstanding the blockage because of 'agitation' and reverse flow - sounded dubious to me. Their theory was that there was a stuck valve so the next full day was spent lifting floorboards deciding there was no stuck valve but then taking an upstairs (non functioning) rad off and discovering to their surprise the water was all black. So they decided to repeat the powerflush this time from an upstairs radiator. They seemed very confident when they heard water circulating in one of the affected upstairs rads but of course were simply pushing water through a rad back to their pump. Again they did not close down any radiators and again they seemed surprised when they packed up, turned the heating on and no change. I asked them about pressure and they said their machine delivered 2 to 3 bar and they were not altogether clear but I think their machine pulsates back and forth. When I asked if they could locate the blockage they talked about pipes underneath a bath and fitted cupboards making that difficult. I wait to hear what they propose to do next.
I am wondering whether I should close down all radiators, drain the system, connect one of the affected rads to main pressure and open the valve attached to the line which is blocked and give it a quick blast of mains pressure being careful that if the blockage does clear I do not flood the header tank. Is this worth a go? If so what is the simplest means of attaching my water hose? Any other ideas or recommendation as to who near Ascot, Berks can sort this out?
Thanks

 

[Roger Welton]

Is it microbore pipework or 15mm? did all of the upstairs rads stop working at the same time of over a period of time?

 

[mhnp]

Is it microbore pipework or 15mm? did all of the upstairs rads stop working at the same time of over a period of time?

It's 15mm and they all stopped together.

 

[nysk2008]

You may have got a better result if they flushed from the pump rather than from a rad.

 

[Roger Welton]

Almost certainly a blockage in the return after they all T back together, cut out and replace section and bob's your uncle.

 

[mountainman]

What age is the system and was it installed during building or refurbishment of the property?

 

[mhnp]

deleted

 

[mhnp]

deleted

 

[mhnp]

What age is the system and was it installed during building or refurbishment of the property?

At least 20 years old and probably installed after an extension built on.

 

[mhnp]

You may have got a better result if they flushed from the pump rather than from a rad.

I thought that, certainly the first time since the water was simply taking the path of least resistance through the boiler. On neither occasion did they think about directing the pressure specifically to the blocked line.

 

[mhnp]

Almost certainly a blockage in the return after they all T back together, cut out and replace section and bob's your uncle.

They do not T back together they are on the same line which T s into a line that comes up from the boiler. They say they cannot locate the blockage.

 

[jtsplumbing]

Hello mhnp I used to live in Bracknell a while ago so understand what problems you can get , sound's like the people who did the flushing don't understand how to do it the correct way, if you have micro-bore pipe (10mm) its not recommended to power flush, if you have the time and some one to help you , drain system remove the problem radiators take them outside turn upside down and connect a hose pipe to flush through at the same time bang along radiator with rubber mallet, check radiator valves, replace if necessary, refill system and add Fernox F5 heavy duty cleaner try to add this into a radiator or towel rail (direct into system) run system for 1 week drain, Refill using Fernox F1 inhibitor. worst case you may need to replace some pipe. Any problems I am sending you someone's number in Wokingham.

 

[mountainman]

Blockage could be a plug of mortar etc that gradually wore away until it became just the right size to move and block the 15mm.

These six rads, do they represent all of the rads on the level in question?

Have you tried disconnecting both ends of an affected rad and, in turn,turning on the valves fully to see if one has a much lower flow than the other?

 

[jtsplumbing]

Hello mhnp I used to live in Bracknell a while ago so understand what problems you can get , sound's like the people who did the flushing don't understand how to do it the correct way, if you have micro-bore pipe (10mm) its not recommended to power flush, if you have the time and some one to help you , drain system remove the problem radiators take them outside turn upside down and connect a hose pipe to flush through at the same time bang along radiator with rubber mallet, check radiator valves, replace if necessary, refill system and add Fernox F5 heavy duty cleaner try to add this into a radiator or towel rail (direct into system) run system for 1 week drain, Refill using Fernox F1 inhibitor. worst case you may need to replace some pipe. Any problems I am sending you someone's number in Wokingham.

 

[Ermintrude]

Is it a one pipe system? I.e there is one pipe under the floor and both sides of rad are connected to the same tube?

Yeh abounds like your contractor was a power rusher! Probably elbow or tee obstructed. You could also if one pipe cut the pipe at a convenient location and with two bits of hose measure (by eye) the discharge rates, if one is significantly lower......

If its a one pipe I would trace by hand how far along the pipe it gets hot...... And bobs your mothers brother.

You haven't had an additions or rads moved on the system have you. If its a one pipe the power rushing contractor may have dropped a massive steaming turd!

 

[heliotrope]

Would be helpful to know if yours is a pumped heating with gravity hot water system.

 

[tackleburger]

A powerful magnet use this on the pipework around tees in particular if it sticks hard to the pipework assuming its copper then that will tell you where your problem is. I use a magnet out of a Fernox TF 1 filter for this purpose.

 

[AWheating]

a power flush normally would struggle to move a large/total blockage, it would have been better to find and remove the blockage then power flush the system adding a filter to help ensure it wont happen again.

 

[mhnp]

Blockage could be a plug of mortar etc that gradually wore away until it became just the right size to move and block the 15mm.

These six rads, do they represent all of the rads on the level in question?

Have you tried disconnecting both ends of an affected rad and, in turn,turning on the valves fully to see if one has a much lower flow than the other?

No another 7 upstairs rads work just fine.
The plumber took an affected radiator off to do the 2nd powerflush. One had a MUCH lower flow but I would have to repeat to determine whether it was supply or return.

 

[mhnp]

Would be helpful to know if yours is a pumped heating with gravity hot water system.

Pumped heating and hot water

 

[mhnp]

Is it a one pipe system? I.e there is one pipe under the floor and both sides of rad are connected to the same tube?

No there are separate supply and return pipes running parallel

 

[mhnp]

Hello mhnp I used to live in Bracknell a while ago so understand what problems you can get , sound's like the people who did the flushing don't understand how to do it the correct way, if you have micro-bore pipe (10mm) its not recommended to power flush, if you have the time and some one to help you , drain system remove the problem radiators take them outside turn upside down and connect a hose pipe to flush through at the same time bang along radiator with rubber mallet, check radiator valves, replace if necessary, refill system and add Fernox F5 heavy duty cleaner try to add this into a radiator or towel rail (direct into system) run system for 1 week drain, Refill using Fernox F1 inhibitor. worst case you may need to replace some pipe. Any problems I am sending you someone's number in Wokingham.

Thanks for the contact. One thing established with some certainty is that there is not a coincidental blockage in each radiator so I am not clear what manually flushing each rad would achieve.

 

[gassafe]

Powerflushing is not designed to clear a blockage! If the pipe is blocked then the powerflush won't get any circulation through it. They don't operate at 2 or 3 bar either!

Disconnect a rad and get a foot pump on the f & r tails. That will show up a blockage!

 

[Ermintrude]

Just read above post again..... Nothing like duplicating !

Ok may or may not help, cut flow and return after last working rad, attach either a test gauge so u can use a compressor or just attach hose (2 jubilee clips) other end secure a full bore ISo valve and then hose to outside. Close ISo and blow system up to 3 Bar or as high as u dare. Once full crack ISo fully open and hopefully obstruction is removed. Doubt it's going to be a 10mm stop end or cement plug probably large bits of rust dislodged by your power rusher!

 

[mhnp]

Powerflushing is not designed to clear a blockage! If the pipe is blocked then the powerflush won't get any circulation through it. They don't operate at 2 or 3 bar either!

Disconnect a rad and get a foot pump on the f & r tails. That will show up a blockage!

Was wondering about pumping with air and how to get an airtight connection. is this the sort of kit I would need?

https://www.NoLinkingToThis/p/monument-dry-pressure-test-kit/72940

 

[heliotrope]

Pumped heating and hot water

Not very likely to have a check valve in the system then.
Can cross that one off as a blockage point.

 

[mhnp]

Just read above post again..... Nothing like duplicating !

Ok may or may not help, cut flow and return after last working rad, attach either a test gauge so u can use a compressor or just attach hose (2 jubilee clips) other end secure a full bore ISo valve and then hose to outside. Close ISo and blow system up to 3 Bar or as high as u dare. Once full crack ISo fully open and hopefully obstruction is removed. Doubt it's going to be a 10mm stop end or cement plug probably large bits of rust dislodged by your power rusher!

Similar idea. Any reason to cut pipes rather than remove a rad valve? Also would it not be better to go from a non working radiator as the blocked section would be much easier to pressurise.

For an air compression approach, should I drain system first?

 

[Ermintrude]

Yes drain down. Close off rads as blockage isn't in rads, leave furthest rad fully open when blasting out system. Close furthest rad when draining down, and then open once pressurising set up is connected so that water from rad will go through pipes hopefully moving debris with the compressed air.

Make sure drain down pipe is secured with jubilee clips on to other side of ISo valve.

To pressurise i use a monument dry pressure test kit.

Cut F&R as that's where blockage is and if you just blast it down rad tee, the poop will go into rest of system.

When u cut pipes put towels and paint roller tray on ceiling between floor joists as there will be water in pipes.