No hot water after radiator change

[Johntheo5]

I said where the top pipe joins the cylinder coil which is the compression nut.
You can initially vent with the HW off but do the final venting with it on.

 

[mcprinter]

I said where the top pipe joins the cylinder coil which is the compression nut.
You can initially vent with the HW off but do the final venting with it on.

Cheers John

I guess what I read elsewhere was suggesting undoing that joint has a risk of disturbing the tank connection.
I just need to go slow and grip the tank connection if needed.

 

[Madrab]

I think they were suggesting that the tank connection could be disturbed.

.... and that's exactly what we want to happen, we want the cylinder connection to loosen up until any trapped air is released and only water drips out. Then nip it back up. I presume they are talking about the tapping itself so just support that when loosening and take it easy.

The AAV is supposed to release the air yes, but if enough air becomes trapped in the coil then given it's a gravity feed sometimes there isn't enough pressure to push the air out and down the return, hence why cracking open the connection can be enough to allow it to release enough air to allow it to flow.

Yes, have the pump running when you do it to help with the bleed

 

[mcprinter]

.... and that's exactly what we want to happen, we want the cylinder connection to loosen up until any trapped air is released and only water drips out. Then nip it back up. I presume they are talking about the tapping itself so just support that when loosening and take it easy.

The AAV is supposed to release the air yes, but if enough air becomes trapped in the coil then given it's a gravity feed sometimes there isn't enough pressure to push the air out and down the return, hence why cracking open the connection can be enough to allow it to release enough air to allow it to flow.

Yes, have the pump running when you do it to help with the bleed

Yes. Will be taking it very easy!

Thanks again.

 

[Madrab]

If it looks like the tapping is starting to twist and the nut isn't moving then of course stop.

 

[mcprinter]

Loosened the nut to the coil inlet. Very large. Had to remove the stop from my biggest adjustable.
Bit of hissing and gurgling and the outlet is now warm.

Problem appears solved thanks to the advice.
Thanks all.

 

[1SJC]

Hi @Madrab,

I hope you don't mind me piggybacking off this thread, as I think I'm experiencing the same issue.

I made a post a while ago about not having any hot water after changing a radiator. I followed the advice there, and before the plumber could come back to take a look at fixing it, the hot water sorted itself out.

However, shortly after, we had to remove a radiator again to allow for some plastering, and I think we had a faulty TRV valve as we ended up draining the entire system. So once again, we now have loot-warm water in our taps and shower that we have to boost using the immersion heater. The central heating & radiators are working perfectly and getting nice and hot.

Many people in the thread I created suggested that I might have a system full of airlocks, particularly in the cylinder coil.

I've tried repeating several suggested steps that I did last time, including:
- Opening the hot water zone valve and releasing air out of the manual air vent.
- Unscrewing the two silver caps at the pipes attached to the hot water pump and ensuring all air is removed / until water starts to spray out.
- Carefully opening and closing the HW zone valve a few times to ensure that it's not stuck.

This time, I'm left thinking I've got a blockage in the cylinder coil, much like @mcprinter had, and so I just wanted to check that the nut I've highlighted is blue in the picture is that one I can carefully release until a few small drips appear?

Thanks

 

[Madrab]

That would be the one to crack yes, does that pipe that the nut is on, after the 2 port valve, get hot at all?

 

[1SJC]

That would be the one to crack yes, does that pipe that the nut is on, after the 2 port valve, get hot at all?

Right after the port valve seems to be warm, but as you get to the bend where the nut starts is basically cold.

 

[Madrab]

OK, certainly sounds like a air locked coil.

 

[1SJC]

OK, certainly sounds like a air locked coil.

I tried loosening the top nut highlighted in the picture, and water started dripping immediately. Would this suggest that there isn't a lock?

 

[Madrab]

I tried loosening the top nut highlighted in the picture, and water started dripping immediately. Would this suggest that there isn't a lock?

Not necessarily, there as there will be water in the pipework from the valve direction too, have the system running too as the pump may help move things along. You may also have to crack the bottom one open as it may be airlocked further down and not in the coil specifically.

 

[1SJC]

Not necessarily, there as there will be water in the pipework from the valve direction too, have the system running too as the pump may help move things along. You may also have to crack the bottom one open as it may be airlocked further down and not in the coil specifically.

Thanks Rob, I'll give that a try this evening.

Re-checking after boosting the hot water for 30 minutes, I noticed that the part of the pipe that was previously cold is now getting warm, but the tank itself is stone cold.

As you suggest, it could also be an airlock further down. I will try that before coming back for more suggestions.

Thanks for all your help so far.