Gravity hot water not circulating please help

[gasmannn]

I had a problem with no hot water on a gravity circulation system, I thought the coil was blocked as it was getting hot to one side, so I changed the cylinder, still didn't work, I then found a two port valve boxed in and the head was gone so I replaced, started to fire but still hot to only one side of the coil, tried back filling through the boiler drain off got some heat round the return while filling with boiler running but once I stopped and tried running it again still won't circulate????

 

[gasmannn]

On the flow there is some type of fitting that is compression that has a cap on and feels like there is a spring in it,but the pipe gets hot above and below this??I don't know wat it is someone said it is an old pressure relief is this true?

 

[gasmannn]

On the flow there is some type of fitting that is compression that has a cap on and feels like there is a spring in it,but the pipe gets hot above and below this??I don't know wat it is someone said it is an old pressure relief is this true?

 

[vern]

Valve is 28 mm and I turned the spindle with grips it was ok

Sounds like a really bad airlock, or cylinder coil is too high a resistance?

 

[gasmannn]

I've boiled it through to clear air and cylinder is no higher than previous and I assume it's work s for years

 

[vern]

I've boiled it through to clear air and cylinder is no higher than previous and I assume it's work s for years

No I meant coil resistance not cylinder height, did you order cylinder specially as they are not generally available since part L came in, deffo a full bore 28mm gravity spec coil?

 

[gasmannn]

Just a normal cylinder I'm afraid I'm 23 and have not worked on these before really I naively thought this would be ok, I the only option a different cylinder? I've lost all profit in the job already I've been so long trying to fix it

 

[Best]

Some cylinder coils are not for gravity. I remember Range cylinders said on their books that you had to specify a cylinder for gravity. I think ordinary cyl had too level a coil. Ask manufacturer.
Do check the primaries are gradually rising & falling without the least wee dip. A droop in a flow pipe of an inch will stop flow.
I take it you didn't drop the flow or return a bit below the floor when you fitted cylinder?

 

[vern]

Just a normal cylinder I'm afraid I'm 23 and have not worked on these before really I naively thought this would be ok, I the only option a different cylinder? I've lost all profit in the job already I've been so long trying to fix it

That your problem then pal, you will have to have one made, unless you can find one at a suppliers gathering dust, failing that convert to fully pumped, or talk them into a combi
don't worry we all f£ck up from time to time, valve you mention earlier is a spring loaded pressure relief valve should the expansion block up and boiler stat fail
good luck sorting...

 

[gasmannn]

Some cylinder coils are not for gravity. I remember Range cylinders said on their books that you had to specify a cylinder for gravity. I think ordinary cyl had too level a coil. Ask manufacturer.
Do check the primaries are gradually rising & falling without the least wee dip. A droop in a flow pipe of an inch will stop flow.
I take it you didn't drop the flow or return a bit below the floor when you fitted cylinder?

The return fitted ok but the flow was a bit higher so I just dropped it with a straight connector no elbows or bends

 

[AWheating]

you can still buy cylinder with gravity coils from most merchants, its what they use on solid fuel installs. grade 1" gravity coil cylinders, prob cost abit tho.

 

[Best]

The return fitted ok but the flow was a bit higher so I just dropped it with a straight connector no elbows or bends

As long as the pipes weren't able to drop down, then you did nothing wrong there. I would have had the flow above the coil & dropped down as someone has said, but it should still work. If you are sure no airlock in pipes then looks like you have an unsuitable cylinder.

 

[gasmannn]

Trouble is I spent 300 on the other cylinder it's a 1600x 450 looks like I'll have to bite the bullet

 

[Best]

you can still buy cylinder with gravity coils from most merchants, its what they use on solid fuel installs. grade 1" gravity coil cylinders, prob cost abit tho.

I think they just use a 28mm coil that is pulled out a bit more. Hopefully not dear.

 

[gasmannn]

As long as the pipes weren't able to drop down, then you did nothing wrong there. I would have had the flow above the coil & dropped down as someone has said, but it should still work. If you are sure no airlock in pipes then looks like you have an unsuitable cylinder.

Do you think I should try and raise the flow? Is this to give it more gravity to push round and how high do I need to raise it? It is level at the minute

 

[nicro3]

Is there cytrol valve on return.

 

[gasmannn]

No just a compression elbow of the cylinder

 

[Best]

Do you think I should try and raise the flow? Is this to give it more gravity to push round and how high do I need to raise it? It is level at the minute

No, don't bother, - it should still have worked if straight in.
The extra vertical height on a flow helps it to gravitate & also makes it easy to connect to a coil & easy to change to new cylinder with different height of coil & easy to solder the tee as it is above the side of cyl.

 

[Best]

Just had a thought about how to confirm if the coil is the problem, or not.
This may not be easy, but if you could have disconnected the flow & return from cyl coil & joined them together & tried the boiler to see if the gravity pipes circulate.

 

[snowhead]

Just to remind everyone, he had no flow thro' the old cylinder before he changed to the new one.

It's got to be a problem in the flow or return.

You need to drain and check the 2 port valve is definitely clear and this in the flow is not restricting the flow.
It may be hot both sides but you may not have a good flow;

On the flow there is some type of fitting that is compression that has a cap on and feels like there is a spring in it,but the pipe gets hot above and below this??I don't know wat it is someone said it is an old pressure relief is this true?

 

[gasmannn]

Just to remind everyone, he had no flow thro' the old cylinder before he changed to the new one.

It's got to be a problem in the flow or return.

I had no flow through the return but i didn't find out till after I had changed everything there was a two port valve that had been boxed in a rediculous place and the head was faulty so I think this was the problem all along a not a blockage as I was advised so i now realise that I fitted the new cylinder for no reason and have now made more problems by changing it

 

[tamz]

Gasmann your either a retard or a wind up merchant. Either way better than the rubbish on the telly :wink:

 

[gasmannn]

Gasmann your either a retard or a wind up merchant. Either way better than the rubbish on the telly :wink:

Come up with a solution then clever clogs if not take your smart comments somewhere else! If asking for help makes me a retard then I am you cocky

 

[tamz]

A wean wi a biscuit bum could figure that one out lol

 

[sweet]

Gasmann your either a retard or a wind up merchant. Either way better than the rubbish on the telly :wink:

Tamz you wouldn't say that to his face so don't say it on here. Gasmann is only trying to get a heads up to a problem that he hasn't encountered before & being a youngster he's may never have had a problem with a semi-gravity system but he's going to learn a lot with this one and surely that's what is all about...

 

[tamz]

Tamz you wouldn't say that to his face so don't say it on here.

Would you like a bet on that?