F & E Back filling

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Hi All,
Thanks for all the help so far from this site.

Following on from this thread //www.diynot.com/forums/plumbing/gurgling-boiler.292682/

I have changed my pipe arrangement so that the feed T's in to the vent about 6 inches above the 'H' section. I done this as I wanted to try and keep the vent as an added safety measure.

Now when the pump is turned off I get hot water coming in to the F&E tank from the feed pipe, but it doesn't pump over through the vent or overflow to outside. I get about a cup of water come in, and the feed pipe gets red hot all the way up to the tank from the 'H' section, about 3 foot.

Then when the pump starts up again I still get the trickling noise in to the boiler. I have been around the accessible pipes with a magnet and the only part where it slightly sticks to is where the return from the rads and hot water cylinder T in to the return to the boiler. Could there be a restriction here causing my issues?

I'm guessing hot water shouldn't come in to the F&E tank from the feed like this. I am also worried that the F&E tank cannot take hot water and will split.
I have put some X800 in to see if that will give it a good clean out. But still seems the same.
Any help greatfully recieved.

 

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Anyone got any ideas please? I'm pulling my hair out now.

 

[45yearsagasman]

I wonder why people come on here and ask for advice and then not do as is suggested. If you had done as suggested in the previous thread, you wouldn't be posting again. Your symptoms still indicate a restriction. What you did with the cold feed tee into the vent just above the H section is totally useless.

 

[Boilerman2]

Have you actually cleaned out the 22mm pipe between the feed & the vent?? on what you insist on calling an "H" pipece!! (is this a technical term?) it is the flow pipe between the vent and the feed that is likely to be partly blocked!!

 

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I wonder why people come on here and ask for advice and then not do as is suggested. If you had done as suggested in the previous thread, you wouldn't be posting again. Your symptoms still indicate a restriction. What you did with the cold feed tee into the vent just above the H section is totally useless.

I do appreciate everyones help. I wanted to try and keep the vent as an extra safety measure.
If I combined the vent and feed, like you suggest, wouldn't the hot water just back fill the tank up the 22mm pipe? Or would this not happen?

Obviously I am not a pro, so just trying to work out the best course of action.

 

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Have you actually cleaned out the 22mm pipe between the feed & the vent?? on what you insist on calling an "H" pipece!! (is this a technical term?) it is the flow pipe between the vent and the feed that is likely to be partly blocked!!

I called it an 'H' piece as I didn't know what else to call it! At least you understood what I ment.
I have checked all around this section with a magnet and looked in to the pipe whilst T-ing the feed in to the vent and all looked clear.

Could there be a partial blockage that the magnet would not pick up?

 

[spraggo]

If the blockage is caused by fragments of fibre glass roof insulation or remains of dead birds, mice etc then the magnet will not detect it. Have you checked that the valve nut connected to the inlet side of the pump is screwed up tight?.

 

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If the blockage is caused by fragments of fibre glass roof insulation or remains of dead birds, mice etc then the magnet will not detect it. Have you checked that the valve nut connected to the inlet side of the pump is screwed up tight?.

I have not checked this, I will check the connections tonight, suspect they probably are as they are not weeping etc, but something else to check. Thanks
I guess any partial blockage could cause this, so maybe worth cutting the pipe and checking I suppose.

 

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Checked the connections tonight. all tight and no air seems to be coming in there.
I also checked the magnaclean in case air was getting in there. but all seems fine.

Do you think a combined vent and feed would stop the F&E tank from back filling on pump switch off?

Thanks for everyones help.

 

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I converted to a combined vent and feed as suggested by 45yearsagasman. However I still get hot water rising up this pipe in to the F&E tank when the pump switches off. When the pump starts up again it pulls water in through the combined vent and feed as it pulls in cold water again and the pipe goes cold.

Anymore suggestions?

 

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update.
I still have a problem where when the pump switches off the 22mm combined vent and feed gets red hot right up to the tank and water flows in to the tank. Although the trickiling noise I originally had has quietened down quite a bit it is still there slightly.

Does anyone have anymore suggestions on what to try? I'm pulling my hair out and just want to get this fixed now.

Any help appreciated.