Trend Heating System Problem

[Newbie90]

Hi all.

Been looking at a heating system fault where the heating boiler will not fire.

There is a trend control panel which is set on "hand" and showing that the heating is enabled with a green light. However, the boiler is not starting. This is the same when set on "auto"

I opened the panel and the relay is energising when the dial is set to hand, then de-energising when set to off (as expected) However, I am getting 240v on the coil (a1 + a2) but only 7v on the common and normally open terminals. Surely if the coil is 240v then the other side should be 240v?

I swapped the relay with an identical known working one and its the same.

The shunt pump for the boiler is running and according to the panel + the trend computer system, it should be running.

Any ideas why the boiler is not running?

Would a faulty temperature sensor cause this? Or maybe the boiler is faulty? Just don't understand the low voltage coming from the relay.

Any help would be much appreciated.

Thanks

 

[snowhead]

The low voltage on the C ans N.o contacts are the control voltage from the boiler.

If it's gas boiler you need a Gas Safe registered engineer to fault the boiler.

 

[Newbie90]

Ok thanks.

Any ideas why the boiler is not firing?

According to the panel it should be running and the relay is energising. There are no other components for the boiler in the panel.

Would you assume the boiler is faulty?

Yeah a gas safe engineer is also working on the boiler.

 

[Kamikaze]

Have you checked if there is a voltage at the boiler?

 

[Newbie90]

Yeah the boiler is on and displaying the temperature as 22 degrees.

It's just not firing up, as if its not being called.

 

[Kamikaze]

Does sparking take place? (Listen for a spark discharge)

 

[Newbie90]

No it doesn't.

Would thermostats be wired between the boiler and the control panel?

What would the connections be labelled as in the boiler from the control panel?

 

[grantr37]

what about the Gas cut off valve, this will cut off the gas supply to the input of the burner assembly.....with BMS systems this likes to shut off the gas when there is a stuck on signal coming from the fire alarm panel......or a dead relay....it will be on the big panel diagram and labelled up inside the door....that puts the boiler out of action....if there is no ignition action happening inside the boiler as well, most boilers will have a flow switch on the gas line for safety which cuts the power for that... Fire Alarm sounding= Gas cut off, needs manually reset. Fire Alarm Fault= Gas cut off to Boiler. some Fire Alarm panels with a fault/error that has been put to silent(ignore zone) will cause a gas cut-off. In the event of a fire alarm, the gas for the boilers and the kitchens gets shut off, also there is a gas leak sensor( stuck open sensor) behind or above the boiler which does the same thing, it shuts off the gas supply....