Potty Suprima problem.

[stulew]

I have to go back on a job tomorrow that has got me stumped, but hopefully the regulars may give me some pointers before I go.
I powerflushed a Potterton Suprima powered conventional system today and everything was fine, the symptons were a really sluggish C/H system system that would take an age for all 10 Rads to heat up, the boiler was also kettling slightly. The rad water was an awful colour that took all day to flush successfully, anyway the problem is still the same now even after the flush.
The flow pipe from the top of the boiler gets really hot quickly,the system has 2 X 2 ports that both open when the H/W, C/H is selected or shut off but the return pipe stays cold. The boiler shuts off after a couple of mins and then cools, before firing up again.This continues and eventually the rad temperature creeps up.
1... I have tested the 2 ports, they open and close OK.
2... I have closed the rads (all but one) to try for air lock.
3... I have reversed the pump and the return pipe gets hot but the flow pipe stays cold.
4... I have even tried blocking the vent to try to force the pump to work harder.
I keep getting drawn back to the boilers heat exchanger, could the kettling (which is not really bad) mean the H/Exchanger is blocked. I am considering draining down again and using my Kamco to descale the H/Ex.
I would really appreciate any help with possible fixes for this problem before I go down this route.
Thank You
Stuart

 

[stulew]

Sorry gents (Long day)... It was a profile not a suprima.

 

[Agile]

Why is our company not listed on the "recommended installers" list ?

Tony

 

[stulew]

Tony.. that part isn't done yet, email me your link and I will of course be happy to oblige. You are definately recommended.
Stuart

 

[stulew]

Tony.. Dare I ask what you are doing at 4:03am. Surely not a call out.

 

[corgiman]

this is probably a silly question but does it circulate ok with the machine on the go?

 

[ChrisR]

Dud pump?

Kamco is only about 1.4 bar so if you half shut one of its valves you can get about the same (dynamic) pressure as a normal heating pump. If everything heated up nicely then it should with the normal one.
Easier now thought to try a replacement pump - you can always take it out again!
Try a 6m one in case, well, in case...

 

[stulew]

Ok.. a quick update after spending most of the day trying to sort this out.
When I got to the house this morning the rads were lovely and warm, but after a chat with the householder and the amount of time it took to get to this stage I think it was just by heat transfer from the hot water to the cold water in the pipe, then the boiler fires up and reheats and so this continues until the heating has crept round.
I started by reconnecting the Kamco to the first rad in the system, shutting all the other rads and flushing this backwards and forwards for about 1/2 hour using the heat from the flow and return pipes to try to speed up the process, tried firing the boiler but got the same result,(Boiler fires, heat exchanger kettles, flow pipe gets scalding hot, return stays cold, boiler switches off.
I drained down again into the pump chamber and cut into the flow and return pipes above the boiler adapting them so my pump can just flush the H/E, I bought some descaler and again flushed for a good hour, to be honest the flow in both directions was good so I have partially discounted the blocked H/E option. I then attached the pump to the flow and return pipes shut off all the rads and tried a flush on just that circuit, it was not a good result, with the flow being restricted quite badly so I am starting to think that maybe there is some sort of anti-gravity valve(If this is the right name for it) left on one of the pipes after the system was converted a few years ago and it is stuck.I went into the loft and as a last resort tried allowing header tank water down each pipe in turn to see if it is getting to the boiler, the flow pipe was fine but the return pipe didn't let any water through it. The last thing I tried before burying my head in my hands was I pumped up the return pipe to 2 bar with my compressor and then released it to hopefully clear any s--t stuck in there, I reconnected the pipework up, filled the system and turned the boiler on all to no avail the system is in the same state (boiling flow pipe and cold return) I am at my wits end has anybody got any other ideas. I am thinking that I should run a 22mm polypipe return just as a test to see if that allows water to flow through it would this be a good idea ?
The trouble with this property is most of the pipework in this heavily extended property is run in boxing in sections and under concrete floors so a straight replacement is not possible.
Thanks again
Stuart

 

[stulew]

Chris...
The pump is a reasonably new Grunfoss 6 metre.
Stuart

 

[corgiman]

Stu, does the system have an air sep? these are gits for sludging up.

other than that I cannot see any other way than start hacking and slashing the pipework out

powerflushing just does not cut it in extremely bad situations, had a few myself

 

[stulew]

Corgiman..
No there is no air sep in this system. I have tried everything to get this sorted, I think I mentioned it before but the flow and return pipes are buried in concrete and boxing in sections. I will let you know how I solve this eventually.
Stuart