Gravity system to combi

[johnad]

im in the middle of taking out my old gravity system and need some advice on converting the current pipe work at the hot water tank ?
I have taken out the loft tanks etc disconnected the hot water cylinder and cut and caped off the two pipes that go down to the old back boiler so what I have remaining to deal with is 3, 22mm pipes,
one came from the bottom of the old cylinder (I'm assuming this is the return ?)
One came up into the pump then a zone valve then to the top of the cylinder (flow ?)
The 3rd pipe came Up from the floor to the zone valve, I'm assuming this is the heating flow ?
My bathroom rad was hot when the hot water was on so I'm assuming this was connected to the boiler flow and return
So my question is should I connect the two "flow" pipes together then feed them back to my new combi ?
And the return to the one that came from the bottom of the tank?

I have been trying to find a diagram but nothing like the setup I have
What was also confusing me was that the little header tank in the loft was connected to what I'm assuming is the return (bottom of the tank) all the diagrams online are showing this connected to the flow (same run as the pump)

Your help/advice will be appreciated

 

[stardanny]

Your installer who is fitting a combined should be able to do the pipe work, converting to fully combi system without pump and zone valves.

Pipe that go to towel rail should be connected to flow pipe that go to radiators. Remove pump and zone valves, cap off return pipe that went to cylinder, and the flow pipe that was connected to pump should connected to pipe that go straight to radiators.

Do that make sense?

Daniel.

 

[johnad]

Hi
Sorry I'm still a little confused ?
Today I have connected up as I explained in my first post linking the two that I assumed was the flow from the old back boiler and the flow to the rads and the return (from the bottom of the old hwc ) to the new combi
I think my bathroom rad along with my hall rad was on the flow pipe work from the old back boiler ?
All I have is 3 X 22 MM. pipes in the airing cupboard and I am unable to lift the floors to see exactly where they go ?
Everything worked ok but the bathroom rad and hall rad was red hot and the two downstairs rads was cold so I closed the valves on the two hot rads to restrict the flow this did I prove matters but the return pipe to the new combi was considerably cold compared with the flow ?
Is it just a case of trying to balance the original rads for the new boiler or have I got something wrong ?

Just to recap, I started with a back boiler with a hot water cylinder after removing the cold drop from the loft tank etc I was left with 3 X 22 MM. pipes coming up from the floor (I can't gain any access under the floor)
I cut the flow and return from the old back boiler and caped them off
I have removed the 3way zone valve that went to the top of the cylinder
And linked the two pipes and connected to the new boiler flow
The remaining pipe that came from the bottom of the old cylinder I have connected to the new boiler return
Is this correct ?

Everything runs but I have two rads on the ground floor that take an age to get any heat and the boiler return feels quite cold in relation to the flow

Any help appreciated please

 

[stardanny]

Wrong pipework layout.

You still need to lift floorboard to find radiators return pipe and connect that to combi heating return.

The flow that go to radiators, that goes to combi heating pipe.

Cylinder return is to be capped.
The flow pipe from old boiler is to be removed.

Who installed the combi?

Daniel.

 

[johnad]

surely the flow for the rads came directly from the old 3 way valve ?
and I was thinking that the return would be also linked to the old return pipe from the bottom of the old tank ?
it was the remaining pipe I was confused about as this was the flow from the old back boiler and my bathroom and hall rad was on this side of the system so I have just teed them together all the rads get hot now after I shut the bathroom rad down a little as this was getting all the heat but the others in the house are slow to warm up
lifting the boards is almost impossible the bathroom is done and tiled (not by me) and the remainder of the flooring has been over boarded and covered with a vinyl flooring that is well stuck down
am I missing something as my way of thinking was if the heating was coming from the back boiler to the pump at the hot water cyilinder I should be able to feed my new flow from there ???
I will try to take a pic tonight

 

[Agile]

For safety reasons, you are not meant to cap off the pipes coming from the old back boiler!

Tony

 

[johnad]

Hi
Maybe my explanation is not very good I cut the flow and return under the upstairs floor just before they go down to the old back boiler and capped the two open ends that are still connected to the heating (the ends running to the airing cupboard to the pump etc) ?
The two that are still running down to the back boiler are still open and drained of water as the old boiler will be coming out.
I was mistaken in my first description the bathroom rad is not on the old boiler flow and return.
I have now disconnected the pipe that was the flow from the boiler to the pump so now just have the flow and return and everything works ok now I have shut down some of the rad valves a little
I found a pic online that is the same setup I had (now removed)
My combi flow is connected to the central heating flow and the return to the return that was from the bottom of the cylinder the pipe with the pump connected is now obsolete.
as I said it all looks like it's working but is this the correct way ?
(Please ignore the drawing over the pic )