No hot water or heating

Try taking the heads off the TRVs and manipulating the pins. You might have got some crud down from the f&e that's now in the bottlenecks. You could also try draining down again, and if the f&e is now clean, let it continue to fill whilst the drain cock is open... This is a manual flush and should help get any more detritus out... Open and close rads one at a time so each gets a flush individually.
 
I still think you have air in system sometimes I had to leave pump on for hours to clear air .
Have you any bleed valves on heating system apart from rads
 
Ok, update.

So the rads in the upstairs are warm. The trv pipe on each rad is hot whilst the lockshield pipe is cold...in all upstairs rads.

The downstairs rads are completely cold.

Drained, Added x800, drained added x400

No other bleed points. All rads spout water when they are bled as well as cylinder and pump.

The pump seems to be running smoother before it was chugging along.

Slowly but surely.

Flushing out downstairs rads.
 
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So, bleeding each rad downstairs the trv pipe instantly gets hot and warms up the rad.

I don't understand why this is working?
 
I've left it running over night, perhaps it needs another treatment of x800 or x400?

What would be the best way to clear up the pump?
 
Ok, update.

Flushed downstairs rads. All clear.

Opened pump, no sludge. Spinning fine.

Discovered the boiler pipe is missing one of these screws on the far pipe. When I opened this one in the pic air came out. Maybe this is what is letting the air in?

Any idea what to ask for at the plumber merchant for this?

Screenshot_2019-09-22-11-30-25-910.jpeg
 
It's an automatic air vent (AAV) and is designed to allow air out when required. A small float within prevents water coming out... Which it hasn't, as you can see. You'll need to drain down to change it.
 
Do you think this will cause the rads not to heat up?

Do you think this is what is causing the knocking sound from the boiler?

I don't see any water dripping at the moment but obviously will need to change it at some point.
 
tmf786 said:
Do you think this will cause the rads not to heat up?

Do you think this is what is causing the knocking sound from the boiler?

I don't see any water dripping at the moment but obviously will need to change it at some point.
Click to expand...

They have been installed there probably because your boiler is at the top of an inverted loop on the pipework and catches air when refilling the system.
If one or both are not working it could well be the cause (or part thereof) of you problems. If the boiler has air trapped it will overheat and start kettling. It will also impede circulation.
 
Update.

I've changed the two bottle vents on the boiler with new auto vents.

However, it seems that the return pipes are the issue. I've drained down and filled again.

It's a bit random whether the rads get hot or not. I think either airlocks or obstruction.

If it's an obstruction, can I put a pressure washer on one of the return pipes and drain out?

How else to get rid of the airlock?
 
It's really hard to give you a step by step guide to sorting the issue.
Every installation is different and has its own quirks and nuances.
If all components have been tested for working order and replaced where necessary then it's all down to circulation performance and this could be hindered by airlocks, blockages and original installation design defects (or a combination thereof).

The usual method involves a combination of isolating various parts of the system (rads etc) and concentrating the power of the pump on the remaing circuit to open up pathways, getting air out and encouraging "clots" of detritus to break up into suspension. Chemicals can help with this.
Your are, in effect, trying to short circuit the system.

You can also try linking rad valves with a length of plastic pipe, to bypass them and give the secondary circuit less resistance to encourage flow, this also helps clear blockages in radiator feed pipes.

Also note that your circulation pump is not in an ideal orientation.

Screenshot_20190928_092018.jpg


Yours is in the bottom right orientation above.
Your pump may also be tired and not giving the oomph needed to get things moving.
 
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