Boiler Not Firing Up

[Chrismac]

Hi, I went round to my brother in laws house because he had a very slight leak from one of his living room rad valves. The plumbing has recently been converted to a sealed system with the F&E tank taken away and replaced with an expansion vessel.
Back to the rad, I closed the valves either side of the rad and opened the air vent. I then opened the nut and drained rad into bucket. I put PTFE tape round the valve thread and tightened back up.
Here is where I think I might have messed up a bit. On refilling the rad I opened the control valve (I think its called) first and heard the water rushing into the rad and pushing the air out the vent. Once the water started comming out the vent I closed the vent and opened the lockshield valve. I never opened the filler (washing machine type valve at exp vessel) at this stage and the pressure guage dropped from 1.5 bar to just below 1. I thought 1 bar was usually ok for a sealed system so I fired up the boiler to see if everything was working OK. After about 15mins of waiting there was no heat coming from any rads but the flow pipe from boiler was hot and the return was slightly warm. At this point my brother in law said that the pressure should be up at 1.5 bar and proceeded to open the filler while the CH was still on which might have been the wrong thing to do. He closed it again when the guage had moved up a bit and we waited about another 10 mins for the rads to heat up before realizing that the boiler was actually off even though the timer was set to all day. We switched the timer to off and I checked to rads which were still cold. I went all of them and bled them and all bar one was full of air, we then topped up the system with fresh water . Now the situation is that all the rads are bled and full of water but the boiler is completely dead. When I switch it on at timer nothing at all happens, I also turned up the boiler stat to see if that would fire up the boiler but to no avail. I dont know if it is just a coincidence that the boiler stopped working at this time of if it was something we done (more that likely). The CH has only been on a couple of times since the plumber changed the system and my bro in law isnt sure if there was heat coming out of all the rads anyway before we started so we are unsure if it was something we done that caused there to be so much air in the system.
It is quite an old looking oil fired boiler btw, not a combi or anything like that.
Sorry for the long post

 

[gas4you]

Sounds like you somehow got a massive air lock in the system and therefore the pump could not produce a proper flow through the boiler.

Have you got power to the boiler? Have you checked if any motorised valves are working correctly? Have you checked that the pump has not stuck?

I suspect that if the boiler is now totally dead that the overheat stat has tripped when the boiler was very hot. There should be a button of some sort to reset it. I hope there is as all boilers that are on a sealed system must have one. I hope the plumber checked this before changing to a sealed system.

Why was the system changed over? Did you remember to add fresh inhibitor to the system when filling it up?

1 bar with rads cold is fine and it should rise to around 1.5-2.0 bar when all rads are hot.

 

[Chrismac]

How do you check if there is power to the boiler? (I hope this isnt a stupid question). When the timer is switched to all day absolutely nothing happens. Its not like it goes to fire up and then switches off a few seconds later, its just dead full stop.

I was told once that the way to check if the pump is stuck is to tap it with a hammer? . I cant bleed the pump as the said plumber has fitted it so that the air vent is sitting almost flush against the side of boiler if that makes any sence. I would have to turn the pump round a bit to get at the vent which I suppose I could do if I have to.

There is a red button on what looks to be to be the motor part of the boiler, dont think that would be anything to do with an overheat stat?
My brother in law has ended up having a bit of a fall out with the plumber because the overall standard of work wasnt as high as it could have been, a bathroom was fitted too which wasnt of the highest quality so god knows if he checked if there was an overheat stat.

The system was changed over because they just bought the house and it is being totally done up. The plumber fitted an unvented cylinder and the whole house was converted to mains fed.

 

[Chrismac]

forgot to add, the pump is fitted to the return, and on the sucking side of the pump there was a very slight leak at the nut. Could this be sucking air in when the heating was on?

 

[gas4you]

I'm not an oil boiler engineer, just gas, but the red button is probably what you press when the boiler goes to lock out and a light comes on.

Is there an 'on' or mains light on the boiler? Can you here if the pump is going? Yes that could be sucking in slightly, but not enough to fill the system with air that quick.

If you can't hear any noise etc check the fuse in the main fused switch for the heating system. Are there any lights on the timer?

if it is possible for you to turn pump for access why didn't plumber You need to access this screw to see if you can turn pump internally.

If after all of the above you still cannot tell if anything is 'live' then you will have to check wire terminals for power with a multimeter as long as you are comfortable working with 230V live electrics.

Definitley need to check if boiler has overheat stat fitted!

 

[Chrismac]

What would happen if an overheat stat was not fitted? I take it the boiler would fry?

I still dont know exactly what I done that could have caused there to be so much air in the system? Like I said the heating was only on a couple of times previous to me fixing the rad and my brother in law said he never went round and checked them to see if they were hot so maybe the air was already in the rads since the new system was fitted. I am not trying to pass the buck.....honest but from my description of what happend, what did I do wrong that could have caused there to be air in all those rads?

 

[gas4you]

Overheat is for safety on a sealed system as when under pressure water can reach higher temperatures.

I don't think taking a rad off could cause so much of a problem as you describe. It makes you wonder if the plumber left the heating system in a safe working condition. Trouble is you will never know now, especially if your brother cannot remember if it has ever worked properly since the work was done!

Was the plumber registered to fit un-vented cylinders? Did your brother see is card? Although by the sounds of it he didn't touch the oil side or boiler was he oftec registered? These qualifications all point to a general quality of installer.

have you checked electrics yet?