Help please with my central heating

[stuart_adair]

I really need some advice please.
My old central heating system consisted of a Baxi Bermuda backboiler, circa 1970, 2 manifolds one upstairs which I assumed to be flow and one down stairs which I assumed to be return. From the manifolds I have microbore to old radiators which have the pipes entering on the same side. Apart from the boiler making a hell of a noise it all worked well. The rad valves had broken years ago and are fixed open.

I've taken the old boiler out and replaced with a Ravenheat combi. The flow pipe comes out of the boiler, to the manifold upstairs. The return from the manifold downstairs back to the boiler. Between them both I fitted a bypass valve in readiness for me fitting new rads with thermostatic valves.

I fired up the boiler today for the first time. The flow got nice and hot but the bypass valve kept opening and returning the water back to the return side of the boiler. No water was going round the system. Its been bled and the boiler is maintaining a pressure of 1.5 bar.

I've removed the bypass valve and blocked the pipes off, meaning that water has to flow around but it makes no difference, all that happens is that the boiler trips out.

Am I correct in my assumption that the flow manifold would be upstairs and the return down, other than the water flowing the wrong way through the rads would this make a difference.

Can anyone suggest ideas why the water just wont flow through the heating system at all ?

Stu

 

[JohnD]

What method did you use to clean out the old sediment?

 

[stuart_adair]

I kept flushing water through the system and its now fairly clear water coming out. I could understand if one or two rads remained cold but its as if there is a 1 way valve fitted to the manifolds ?

 

[doitall]

Both manifolds should have a flow and return.

or

did I read it wrong.

again

 

[stuart_adair]

Ah, thaqt might be the problem then. I've got the flow pipe going to the flow manifold, then after the microbore pipes filter off I've put a blanking piece. The same with the return manifold. On the old system I took out one end of the flow manifold connected to the end of the return manifold, basically water could flow from the boiler, through the flow manifold, through the return and back.

Sounds like thats where I've cocked up.

Stu

 

[doitall]

Perhaps I didn't explain that very well

you should have two pipes for each radiator a flow and return, from seperate manifolds.
e.g. all the flows from one or two manifolds depending on size and layout. then a mirror image for the returns.

Will try and knock up a drawing over the weekend

 

[stuart_adair]

Just to let you know that although I've got a flue problem to solve, the heating now works fine and the water is flowing well.

Appreciate the help.

Stu