Central heating problem

[charlie frederi]

charlie many combi's can be run tank fed on ch side - some can also manage it on the cold.

Oh right never seen that myself and been plumber heating/engineer for 25 years

 

[charlie frederi]

charlie many combi's can be run tank fed on ch side - some can also manage it on the cold.

yes but they are still sealed systems not vented as there is no open vent
to the header and cold feed has a non return valve fitted with a stopcock so it still relies on the safety valve
the term is low pressure sealed system that is why i said i have never seen a vented system on a combi

 

[benny_headland]

hi guys im only a secound year apprentice but im quite sure your not supose to conect a power flush to the boiler and only the flow and returns as it can couse problems with the boiler! as it has obviously

 

[JD24HOURS]

go back to valiant and tell them it is there problem because if everything has been done properly then may be the plate heat exchanger is just to fine and causeing the problem we had the same prob with vokera and after 2 years they just replaced the boiler and we never had the problem again

 

[charitynjw]

"One said fit a Magnaclean. So we fitted a Magnaclean. But still the boiler had same trouble of heat exchanger getting blocked."

Is it fitted on the return pipe?

 

[rickphysicist]

I am not a plumber but have been called in by my son whose plumbers have failed to solve a problem which sounds much like this. The boiler effectively shuts down through water starvation.

I notice two irregularities on the installation - Vaillant vented ecotech plus (inst. guide). One, the pump is in the return pipe before the boiler and drives through a raised loop with no bleed, Two, the feed and vent are within 150mm in the flow circuit but the wrong way round.

Number one exacerbates the problem but I am sure when we swap them round two will be the real cause.

When air/water mix flows down the flow circuit, the first opportunity the air gets to escape is the water feed pipe (15mm). It takes it, the bubbles expand rapidly as they move up the pipe, so reducing the system head throughout the system but especially at the junction with the flow pipe. This means more of the air will follow the initial bubble and none will move on to the vent pipe. The water head in the vent will be lowered and could even allow more air in that way. Water will certainly be expelled from the circuit and it's recharging will be obstructed by the counter flow of air - this is a 15mm pipe. Add to that the potential for further air input through bleed valves - depending on position - and one can see an escalating problem. That is what I think we are seeing and I hope to fix it soon.

 

[mrclemo]

you still have sludge in the system from a proper powerflush not being done. The magnaclean will clean the system but over a period of time. What you need to thoroughly clean the system you want a powerflush with the magnaclean filters on it, also the engineer needs to go round each rad with an agitator on a cordless drill and bang the rads to get every bit of sludge out.

 

[FD Powerflow]

You could try fitting a TF1 or Magnaclean twintech as these combine magnetic and non magnetic particle removal so you get magnetite and any other debris out of the system. I would also recommend getting a System Health Check from a plumbing merchants such as Plumb Center or PTS, these are made by Fernox and are also what Vaillant use to indentify potential faults with system water, this will identify if there is enough inhibitor present, what type, if there are high levels of flux/calcium carbonate/iron/copper etc and also recommend a course of action.

It might help to post the results of the system health check on here too.

Happy hunting

 

[thomas donovan]

we get a bit of wood wrapped in a rag and batter the sludge out of the rads with a hammer, sounds iffy but works a treat