Ideal Logic Heat 12 boiler fault

[snb1]

is this a new install? if yes what was there before?

 

[Stadan20]

I would certainly agree it sounds like a flow issue . Turn on heating does the flow pipe get really hot after a short period ?

 

[dilalio]

Mag filter on system?
Check isolation valves for it.

 

[Madrab]

Something isn't right even though it seems to have all tested properly. If everything is equal then the boiler shouldn't cut out and we're definitely back to lack of flow again and the flow switch shutting it down, it's the only thing that's left.

 

[dilalio]

Mag filter on system?
Check isolation valves for it.

Scrap that!
DHW wouldn't work either.
Has to be pump or 3 port not opening to CH.

 

[Stadan20]

Ahhh my bad i had it in my head it was a combi looool

 

[flexyboy]

existing system, new build from 12 years ago. As per original installation.
There is no mag filter
madrab - I totally agree something not right. I cannot get my head around there being a call ( c ) on boiler display whether on HW only or CH, and the boiler somehow differentiating c for CH only or c for DHW/DHW+CH
I agree that flow is sensible cause to investigate, which i have, in as much the live output to pump is correct and the pump is circulating when CH only is selected (assuming room stat is NOT satisfied), and SL at boiler is at 240V when c at display panel
However, the flow sensor must be working, otherwise burner light indicator would not stay on when CH + DHW is selected

 

[Madrab]

However, the flow sensor must be working, otherwise burner light indicator would not stay on when CH + DHW is selected

Yes it would, if there is flow to the HW, which we know there is. The flow sensor isn't a suspect, lack of flow on CH only is.

When both are calling and the HW stat is satisfied does the system shut down like in CH only mode (call both and turn the cylinder stat down)

Are all the rads on TRV's and is at least one open?

 

[flexyboy]

Madrab
As in my or post, all rads get hot when CH and DHW selected
sytem DOES shut down when cylinder stat satisfied

 

[flexyboy]

removed cyl stat which is a basic mechanical 3 contact type. common, norm closed and norm open, this all fine when tested

 

[dilalio]

Yes it would, if there is flow to the HW, which we know there is. The flow sensor isn't a suspect, lack of flow on CH only is.

Exactly!

@flexyboy just because there is power to the pump and you believe it is circulating, doesn't mean it is!

How old is the pump?

As I mentioned above, a lazy pump may be able to overcome the (relatively low) resistance through the DHW circuit, but not that of the CH circuit.

So, flow rate through boiler not enough to activate flow switch and boiler shuts down due to quick rise in temperature.

Have you tried spinning the pump?

Edit: just read your recent post after I had typed the above! So... RADS ALL get hot when both CH and DHW selected?

 

[flexyboy]

But all rads are getting hot, suggesting that circ pump is ok, and spindle spins freely. Not sure on pump age
the boiler is shutting down within couple of secs. Not even ideal can get a boiler to raise temp that quickly !

 

[dilalio]

all rads get hot when CH and DHW selected

Then suspect 3 port if pump is pushing round CH.

 

[dilalio]

Possibly voltage on switched live at boiler is fluctuating when CH is selected. Induced voltage maybe.

Can you test it with MM?

 

[flexyboy]

yes, tested with DMM, constant 240