PLEASE PLEASE HELP... ANY ADVICE APPRECIATED...RAVENHEAT 820

[Amy Carter]

The diverter valve was changed on Thursday along with the PCB, the system filled and initilally everyhting was ok, the radiatores were bled of air and the system (rads) got hot, however a problem has developed. This problem occurred after the hot water tap in the upstairs bathroom was turned on. The system began to get cold downstairs. It now heats rads upstairs but not down. I took the cover off the boiler to see if
a. the pump was running, it was. I flicked the pump from both the second to the third speed and back again leaving it set on position 3, first problem encountered is this, Turn on the kitchen hot tap which is situated right next to the boiler 1. the boiler fires straight away, the pump is running the water slowly it gets hot and then when it is piping hot the boiler stat turns off the boiler so you are yo yo'ing between hot and cold water, everything points to a the pump not getting the hot water away from the heat exchanger fast enough, that is the problem with the hot water side of things 2. I have systematically gone around the radiators turning them all off bar one, the one's nearest the boiler appear to get hot, but those farthest away get luke warm, and when they are all turned on and calling for heat the downstairs one's remain cold, again everything points to the pump, it is pumping to the nearest rads but the one's and the end of the food chain so to speak are not getting hot , i have put a screwdriver against the body of the pump and my ear to the screwdriver the pump is clearly running, but how good it is running is another issue. When the plumber changed the diverter valve, we had cause to removed the micro switch at the back of the body of the valve for ease of fitting, is it possible in any way that this could have been re assembled ''the wrong way around '' it is not possible to get the outlets pipes the wrong way around as they had to line up to the existing fittings with the boiler.
My daughter now has put in a new pcb and three way valve and still we are struggling to get this right, any help or suggestions would be greatly appreciated.

 

[Slugbabydotcom]

Did you check that the cap on the AAV in the boiler was loose to enable the air to clear from it?

The pump should be on the fastest setting [3]

At any one time it will provide either heating or hot water so if a tap runs it is obvious that radiators will cool down.

Is your system sludged up?

Why did you change the PCB?

Possible things to look at next are the CH stat, the pump, an airlock or a powerflush.

From what you said I still feel a little suspect about that new DV.
With the system cold [summer setting, water only] Run the hot tap. If the flow pipe gets hot then the DV is not functioning correctly and could be sticking either due to a fault in manufacture or more likely debris in your system.

 

[ChrisR]

Old pumps do get tired. The capacitor dries up and they lose power.
Sludge could also be a factor. It blocks pump impellers, hot water heat exchangers, and downstairs rads.

 

[Amy Carter]

My father drained down the entire system last nite as we were suspecting an air lock in the pipes and not necessarily the rads. He filled the system from bottom to top ensuring no air could get caught in the pipes.

As before the rads downstairs remained cold (lukewarm at very best, then cold) but surprisingly, only 2 rads upstairs got hot, (warm-hot at best) Everything seems to point towards the pump?? When I returned last night about 10pm, the pilot was out, i re-lit, but it went out again, i re-lit and went to bed. This morning the pilot was out again, and this time wouldn't stay alight.

Any advice would be greatly appreciated.

Amy

 

[Slugbabydotcom]

Did you check that the cap on the AAV in the boiler was loose to enable the air to clear from it?

You didnt give any feedback on the above point

 

[Amy Carter]

Could you let me know where the AAV is on the Ravenheat RSF 820/20.

What are your thoughts on this problem?

 

[Slugbabydotcom]

It is within the combustion chamber. Thirteen screws may have to be removed to gain access to it. The Auto Air Vent is on the left hand side if I remember right. Cant remember specifically but sometimes they do it so that the top of the air vent peeks through the top of the casing so have a look over the top of the boiler to see if you can see what looks like a tyre valve cap and loosen it off by about a turn before you start on the 13 screws.

This cap should be left loose but sometimes they leak. If it does then tighten it back up once all the air is out and that should leave it working until you can replace it.

I have already expressed some of my thoughts on your problem and this is simply the first step.

Few on here will advocate non Corgi's removing the combustion chamber cover but its difficult not to get a good seal on this particular boiler. Please be conscious of the importance of the seal if you need to go in there.

 

[Agile]

AAV is on the left and pokes out of the top.

I always wonder at the odd logic some people seem to use. If they suspect air in a system then the last thing anyone should be doing is to drain it again as that just fills everything with air again.

My chief suspect would still be the pump.

Tony Glazier