New heat exchanger left me with no hot water

[Howard123]

Hi DP, everything was working ok until I switched the HE so that would lead me to think air in the system then. Any suggestions how to clear it?

 

[ianmcd]

it wont be air, you have a blockage somewhere somewhere

 

[ianmcd]

Are you sure the pump definately runs when only HW is selected and you run a hot tap ?

 

[Howard123]

Ok, thanks Ian. Yes the pump definitely runs when HW only is selected and I open a tap.
Is there another way I could clear the blockage?

 

[ianmcd]

when you run a hot tap does one of the CH pipes get hot ?

 

[Howard123]

Do you mean in the boiler or at a radiator?

 

[Deleted member 267285]

Boiler - either of the 2 larger outer pipes.

 

[Howard123]

Let me check...

 

[ianmcd]

when you reply to posters put @ and then their user name and they get a notification that you have replied, otherwise they have to look up the post and find if you have replied as in @Howard123 you will have a notification now

 

[Howard123]

Thanks @ianmcd
Can I check - when you said 'when you run a hot tap does one of the CH pipes get hot ?' did you mean overiding the flow switch so I get hot water or just open up the tap and let it run cold?

 

[ianmcd]

switch the CH off and run a hot tap, does one of the CH pipes below the boiler get hot, (you are testing the diverter valve by doing this, which I suspect was your origional problem and not the plate heat exchanger )

 

[ianmcd]

sorry if the boiler is not firing that wont work, remove the diverter valve actuator, it is a black motor on top of the diverter valve, it has a clip that you pull out to remove, leave the motor off and run a hot tap, what happens now ?

 

[Howard123]

@ianmcd
Ok so with CH off and hot tap open, nothing gets hot. The boiler doesn't fire up at all like this.
If I turn the CH off, hot top open and override the flow switch then I get hot water no problem.

 

[Howard123]

@ianmcd

sorry if the boiler is not firing that wont work, remove the diverter valve actuator, it is a black motor on top of the diverter valve, it has a clip that you pull out to remove, leave the motor off and run a hot tap, what happens now ?

Same issue. I open the hot tap and nothing happens - the boiler doesn't fire up and it's just a stream of cold from the tap

 

[ianmcd]

ok when you removed the motor ther is a pin in there , run a tap and push that pin in with something, you wont be able to do it with your finger it has a strong resistance, does the boiler fire when you manually push that pin in ?