System won't fill

[Steve698]

Hi,
I drained our vented system yesterday to fit new valves to bathroom radiator. When draining I noticed the F&E tank did not empty, I had the supply off and all rad bleeds open, the rest of system emptied. When I try to fill back up I can't. I tried bleeding the rads but although 3 of 8 hissed for a minute or 2 no water ever appears. Am bouncing between an airlock and a blockage, fact that the tank doesn't empty suggests the latter but I don't know where to look for the blockage. Some have suggested the magnet thing but I don't pick anything up with that. Our cold from the F&E tank comes down and joins next to the pump but also next to some bell type thing that I have no idea what it is.

 

[Last Plumber]

Sounds like a blockage. Try around the first bend or tee on cold feed. Failing that, the lowest point.
Not always easy !
Good luck

 

[Steve698]

Sounds like a blockage. Try around the first bend or tee on cold feed. Failing that, the lowest point.
Not always easy !
Good luck

Is there anything I can try to clear this ?

 

[Masood]

Our cold from the F&E tank comes down and joins next to the pump but also next to some bell type thing that I have no idea what it is.

Possibly an air separator. Good place to look for your blockage! A picture would help...

 

[Last Plumber]

Is there anything I can try to clear this ?[/QUOTE

I've always found it easier to drain and start cutting tbh. Siphon water out of tank to empty it otherwise if you cut above blockage you'll wish you had !

 

[Steve698]

Possibly an air separator. Good place to look for your blockage! A picture would help...

Your wish is my command here are some pics.

First pic is bottom valve is mains into F&E tank (that's fine) above that red lever valve is out going that is fine. Then it bends down at right angle and another to the left. It gets to pump it's the vertical pipe on the right. From the pump it goes to T junction bottom (right) goes to immersion and top (left) goes to motorised valve and off to rads.

 

[Steve698]

A quick update - we have made some progress but still not working. Decided to backfill from mains which all went nicely. Then bleed each rad untill we got water at the nipple - fantastic. Switched on boiler, fired up no problem then run for 3/4 mins and started gurgling and shut off. I went into loft and motorised valve was whirring away so I shut down again. Any ideas from here ?

 

[Best]

A quick update - we have made some progress but still not working. Decided to backfill from mains which all went nicely. Then bleed each rad untill we got water at the nipple - fantastic. Switched on boiler, fired up no problem then run for 3/4 mins and started gurgling and shut off. I went into loft and motorised valve was whirring away so I shut down again. Any ideas from here ?

Carefully backfill again and bleed air from everywhere - especially highest points. Then try system again. But you really need to get the blockage problem solved, or this will keep reoccurring

 

[Steve698]

Carefully backfill again and bleed air from everywhere - especially highest points. Then try system again. But you really need to get the blockage problem solved, or this will keep reoccurring

Latest update - we decided to vent the pump and whilst at it bleed the highest vent again next to the motorised valve, then run the pump at different speeds and everything gurgled and started up again. It has been working now for a couple of hours so our fingers are crossed. You still think there's a blockage problem Best ? is that because the tank didn't drain at the start ?

 

[snowhead]

Our cold from the F&E tank comes down and joins next to the pump but also next to some bell type thing that I have no idea what it is.

Has the F& E tank got a valve on the outlet or in the pipe down to the separator, if so it may be sheared in the off position.?

Tower air separator, next place to look for a blockage;

https://www.heatingcontrolsonline.c...IBib--sKje3Ba5ZhV5UxwJaieGY5kn9rz8aAgBI8P8HAQ

 

[bright spark]

I'd say blocked cold feed or if there's a fill valve on the cold feed it's broken shut.
Sometimes the blockage in the cold feed can be near tee where cold feed joins the heating system. You could cut out and check but I'd say just replace cold feed

 

[Alex Knight]

I've unblocked a cold feed quickly a few times with a few well placed hits with a big spanner where the cold feed joins the heating pipework, obviously this does come with a risk of damaging the pipework

 

[GQuigley67]

I've cleared a blockage before with electricians cable rods, really flexible one down the cold feed worked a treat!! Lucky spark was on job though, set of those will set you back around £150!

 

[Steve698]

I've cleared a blockage before with electricians cable rods, really flexible one down the cold feed worked a treat!! Lucky spark was on job though, set of those will set you back around £150!

I have a set of of cable rods - not sure they flexible enough to get around a couple of right angled bends I have in the pipework though, may be worth a try tomorrow.

 

[GQuigley67]

I was lucky to have a 22mm cold feed with formed bends, but still worth a try!

 

[cdodds2004]

best bet is to get it cut out properly, I would advise having it re piped with a combined cold feed and expansion but some plumbers wouldn't recommend this. It personal preference between engineers but I personally would always combine as it causes less problems in the future.

sometimes people cut the cold feed and just pipe it into the existing expansion but as you have circulation problems I would cut the tee out as this will be the negative point and almost guarantee the blockage to be there.

job for a decent plumber im afraid to get it piped up correctly and hopefully stop any future issues

 

[Steve698]

OK lets not say it's sorted, said that yesterday and it came back and bit me on the ****. Lets say it's working fine at the moment, it's been switched on and off 3 times, it's been on with both heating and water going at same time and worked fine. It's worked on the programmer and in over-ride mode. I'll give it a few days before breathing a sigh of relief. There was a blockage we moved it in the end with mains pressure into the vent pipe, after a short wait loads of black crud exited into the F&E tank, a bit gurgling within the system and as I say fingers are crossed.
Thank you all who replied to this thread.

 

[Best]

I've cleared a blockage before with electricians cable rods, really flexible one down the cold feed worked a treat!! Lucky spark was on job though, set of those will set you back around £150!

An old speedometer cable salvaged from a scrap car will be both very flexible and very strong.
Save you spending money or borrowing from a Spark.

 

[bright spark]

If ye can't clear the blockage. Don't bother replacing cold feed. Just blank cold feed and expansion.
Make the system a sealed 1.