Combi conversion nightmare

[Scott_D]

can anyone help before I start ripping up floor boards

Converting to a combi but I can’t get the heating to circulate to the rads
New boiler in the same place as old so piped up to the flow and return dropping from the ceiling

I removed the cylinder and piped the flow from the boiler to the flow out to the rads
I capped the cylinder return and stuck an air vent on but it wont circulate

I linked the primary flow and return in the airing cupboard and it circulated back to the boiler
It’s as though the rads are not connected to the return

 

[ShaunCorbs]

You sure the main return is linked to the rads return now?

Could of been gravity hot water before

I would link the cylinder ret to boiler ret

Was the old sys working ?

 

[Scott_D]

I have only got 3 pipes in the airing cupboard
Flow and return from the boiler
Flow to the rads

The house isn’t old enough to be gravity

It seems like the rad return isn’t teed into the primary return

 

[ShaunCorbs]

the main return has to be connected to the rads return else it would of never been connected

What does the boiler do ?

 

[Welder]

Deleted as my eyesight is sh1te!

 

[Scott_D]

Boiler works fine if I link the primary’s in the airing cupboard

The heat doesn’t go anywhere when I remove the link

 

[Harvest Fields]

Doesn’t this pipe and this pipe go together to make the link and effectively the cylinder flow and return are then redundant? Don’t forget the bypass.

 

[Harvest Fields]

If needed that is.

 

[Scott_D]

Looking at the image, the RH pipe looks like the rad feed from the 3 port. Where is the flow from the boiler to the pump?

from left to right
Cold
Hot
Primary flow
Primary return
Rads flow

 

[Scott_D]

Doesn’t this pipe and this pipe go together to make the link and effectively the cylinder flow and return are then redundant? Don’t forget the bypass.

View attachment 38035

That’s what I have done
Linked the flows so the heat goes to the rads
Capped the return with a vent
Assuming the rad return must be teed in under the floorboards

 

[ShaunCorbs]

from left to right
Cold
Hot
Primary flow
Primary return
Rads flow

thought the primary return wasnt in the airing cupboard?

 

[Harvest Fields]

If you have joined the ones I said mate it should work. Blockage?

 

[Scott_D]

Defiantly got a primary flow and return
When I link them it circulates around the boiler

And what was flow to the rad from the old 3 port
Those are my three pipes I’m left with once everything was removed

 

[Harvest Fields]

Boiler hot but not rads? What boiler?

 

[Scott_D]

Ideal independant
Cheap landlord job that was supposed to be easy

The boiler works fine when I link the primary’s in the airing cupboard

 

[Harvest Fields]

Ideal independant
Cheap landlord job that was supposed to be easy

The boiler works fine when I link the primary’s in the airing cupboard

Has it got an integral bypass?

 

[Harvest Fields]

Ideal independant
Cheap landlord job that was supposed to be easy

The boiler works fine when I link the primary’s in the airing cupboard

But you say the rads are cold?

 

[Scott_D]

But you say the rads are cold?

I think there is a bypass but it’s not adjustable
Boiler works but no heat going out to rads

 

[Harvest Fields]

Possible faulty bypass if the boiler flow and return are hot

 

[Scott_D]

Possible faulty bypass if the boiler flow and return are hot

It’s only working if I link the primary’s in the airing cupboard
Did that to test the boiler was ok

 

[Scott_D]

I have given up
Will try again tomorrow

 

[Millsy 82]

Have you got the new flow going up the old flow?

A lot of people struggle with y and s plans so if they messed it up they may have put a non return valve in which if you have the flow and return the opposite way round won't work.

 

[Scott_D]

Yeah the flow and return are correct at the boiler

I’m baffled

 

[Last Plumber]

I removed the cylinder and piped the flow from the boiler to the flow out to the rads
I capped the cylinder return and stuck an air vent on but it wont circulate

It might be a numb question so excuse me (haven't seen it) but there's no high point to air lock in the connection from primary flow to CH flow to rads is there?

 

[Scott_D]

It might be a numb question so excuse me (haven't seen it) but there's no high point to air lock in the connection from primary flow to CH flow to rads is there?

I put a vent in the airing cupboard
The only thing I can think of is the tenants went round with a spanner and shut off all the rads

 

[Last Plumber]

I put a vent in the airing cupboard

I read it like you'd put it on the return!
My apologies, it is on the highest point of the flow connection is it?

As long as it can't trap air, it should work. Sounds strange.

 

[Scott_D]

I left it like this in the airing cupboard
Then linked the primary flow and return on the stumps for vents and the heating circulates to to the airing cupboard and back to the boiler
The rads dont heat

 

[Scott_D]

I took up some boards under where the cylinder was sat but couldn’t see the rad return anywhere

 

[Scott_D]

It can’t have ever worked properly

 

[ShaunCorbs]

Return not linked?

 

[Scott_D]

Return not linked?

No

 

[Harvest Fields]