Central heating system Boilin, Banging

[stubbyrama]

Well I have a suprima 60 and I have had problems with no temp control and banging...etc...I have changed the PCB to the new modern one as suggested in my last post......and the system has worked fine for the last three weeks...but then at 0630 in the morning....the system vents to the expantion tank and the boiler starts banging...like it did before...and it has dont it again this morning at 0730.......with the hot water and heating on...

Its like there is no temp control again...........but I get the feeling its not the boiler now....

Is there any reason that the water on the system can boil with out the boiler going into lock out?.....or reaching its selected temp?

Or is the New PCB U/S......

The pump seems to be working ok.....is was on setting three..but now I am trying it on setting two....

I could do a test to see if the system behaves its self on just selecting the hot water or heating seperatly.......

But I suppose my question is.....What things cause system boiling....

erm what other info.........the water in the system when this does happen is very..hot...........

 

[ollski]

sticking / not working pump or no water / blocked cold feed in the f&e tank usually.

 

[stubbyrama]

sticking / not working pump or no water / blocked cold feed in the f&e tank usually.

well the tank is fine and full.....

And I suppose the only way of finding out if the pump is sticking is to change it and see if it fixes the problem.....

one thing i have noticed is that the feed to the system is also the vent.......ie pipe coming out of tank....t piece one side going to supply the system..and the other coming back round to the top of the tank.....ie the vent...is that correct.....?

DO these new PCB's have reliability issues like the old PCB's???

 

[billington]

Sounds like the pump to me. Could check the boiler thermostat and see if the boiler turns off when you lower the temp

 

[corgigazza]

1 make sure also flow & returns are fitted round correct way on boiler and pump is fitted correct way also, feel flow pipe when boiler is on this should get hot first.
2 also have all trvs been fitted.
4i s it wired up for pump over run. Auto bypass may be required

 

[stubbyrama]

Sounds like the pump to me. Could check the boiler thermostat and see if the boiler turns off when you lower the temp

Well I decided to do a bit of investigation.....I turned off the heating last night and had just the hot water on . Fine for the last 12 hrs.....5 showers and a bath......Yeah I am clean....

Now I have turned off all the rads....bar two and turned on the CH.and turned off the HW it is running ok.....when I turned on two more of the rad...i noticed that the return valves where not open fully....and these two rads are bathroom rad so they are between the boiler and HW tank...so come on when you are using hot water....

So will those valves make a difference?

The thermostat was replaced when the PCB was done....and I have checked it is seated properly yestaday.

The boiler was cycling ok ok when the HW was selected on and too early to say about the CH. I have subsequently lowered the temp of the boiler as when the CH was selected the rads were TOO hot.....

 

[stubbyrama]

1 make sure also flow & returns are fitted round correct way on boiler and pump is fitted correct way also, feel flow pipe when boiler is on this should get hot first.
2 also have all trvs been fitted.
4i s it wired up for pump over run. Auto bypass may be required

Cant answer all your questions yet as I have just turned off the system for it to go cold so I can check the flows.

But I can tell you there are drayton TRV4's fitted to the rads..i put them on as I decorated...the only ones that don't have em are the bathroom ones...(2 rads).

The pump is wired for over run.........clever little thing that is isn't it.....

Well will get back to you laters about the flows....

thanks so far......

 

[billington]

It sounds like your bathroom rads are teed off the heating primerys, which means they will heat up every time the hot water calls for heat,that is why the radiator valves were balanced down.