Got a Ravenheat RSF 820/20. Its had a new pump and a new diverter valve this year. I have a problem that shortly after the heating fires up it starts to make a weird whining noise. After about twenty seconds of this noise starting the heating system switches off. I have tried to diagnose this problem and have started back from scratch. The diverter valve has been out and checked (seems ok) the system has been drained and flushed. The system has been refilled and the radiators brought back into the system one by one. But heres when the fun starts. There are four mid size rads upstairs and three larger rads downstairs. I can get the system to work fine on all the upstairs rads and can get the system to work fine on all the downstairs rads, but try and run more than five rads at a time and this noise starts and the system shuts down. I have reduced the flow rates to a minimum, increased bar pressure a little, bled and bled and bled the system, but now I am completely bemused. Any of you guys out there got any ideas? (Please don't just say get a new boiler as although this may well be the ultimate solution, its getting to the bottom of the problem which is my challenge). One last thing, This noise stops every time I put the hot tap on, and I can even make the noise go away completely if I quickly turn the hot tap on and off a few times, but the noise does always return. Please note the system has no trouble at all running ANY combination of four rads, but the fifth is when the fun starts.
Heres a weird one for you guys to ponder
- Thread starter Tony123
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Tony when did it work O.K or has it never worked O.K
Sounds like there is either a restriction or a short circuit somewhere. Does the return get as hot as the flow straight away or just the flow and then off.
Sounds like there is either a restriction or a short circuit somewhere. Does the return get as hot as the flow straight away or just the flow and then off.
I'd be interested to know why the new pump was fitted, and if it worked afterwards. At what point did this problem start? Did it evolve gradually or did it one day just stop working?
The noise sounds to me as though it is the pump air-locking, so I think you need to establish WHY the system shuts down. Is the boiler up to temperature? Does the pilot light stay alight when the system shuts down? What do you mean, exactly, by 'system shuts down'?
This sounds to me like one of those situations where being there to look touch and feel is more likely to find the answer than chatting about it on a discussion board.
Cheers, Mike
The noise sounds to me as though it is the pump air-locking, so I think you need to establish WHY the system shuts down. Is the boiler up to temperature? Does the pilot light stay alight when the system shuts down? What do you mean, exactly, by 'system shuts down'?
This sounds to me like one of those situations where being there to look touch and feel is more likely to find the answer than chatting about it on a discussion board.
Cheers, Mike
Hi, when I have less than five rads on it works perfectly, the return gets v-hot and the system works like a dream, its increasing the rads past four that makes the problem arise. I would agree about there maybe being a blockage if it wasn't for the fact that I can get any four rads working, either upstairs or downstairs or a combination of both.
If I put the system on now with four rads it will work perfectly, but if I then open the last rad in the system about a minute later the noise starts and then it shuts down. Its a real head scratcher.
If I put the system on now with four rads it will work perfectly, but if I then open the last rad in the system about a minute later the noise starts and then it shuts down. Its a real head scratcher.
Hi Mike
The pump was fitted as this was an initial diagnosis of the problem. So I now have two perfectly good pumps (hehe). The pilot stays lit, its just the heating that decides its not happy and stops. The only way to get the heating back on it to let the system cool down, then restart about an hour later. If I restart with only four rads, it works fine. Hot water not a problem at any time, its only the heating that cuts. It can be fully up to temp and working fine on four rads and at any poit if I introduce the fifth rad it takes a minute of to for the noise to start and then another twenty seconds to cut the heating. I agree its one of those difficult ones where being there helps, but your help is still appreciated.
The pump was fitted as this was an initial diagnosis of the problem. So I now have two perfectly good pumps (hehe). The pilot stays lit, its just the heating that decides its not happy and stops. The only way to get the heating back on it to let the system cool down, then restart about an hour later. If I restart with only four rads, it works fine. Hot water not a problem at any time, its only the heating that cuts. It can be fully up to temp and working fine on four rads and at any poit if I introduce the fifth rad it takes a minute of to for the noise to start and then another twenty seconds to cut the heating. I agree its one of those difficult ones where being there helps, but your help is still appreciated.
It sounds like the flow is being stalled somehow, then the boiler starts to overheat/kettle and then the overheat stat cuts it off.
Have you tried balancing the system by turning the lockshields on the downstairs rads to almost shut. I suspect there is a blockage or at least a severe point of resistance in the system. Is it a system with nice neat pipe bends or is it a mass of elbow fittings instead. With a system close to its limits this can make a difference to resistance in a system
I might even suspect a piping error, though this seems far fetched somehow...no rads piped flow to flow by accident I suppose.
I went to a two year old system on Friday in a flat..Combi & 6 rads..nothing on the return at all, but HW OK....Turned out it was blocked up with scale on the return (we have filters, but this would not clean up and kept reblocking), having not been flushed properly on install. It was one of our own installers, and he is being talked to on monday I gather as we've got to powerflush it now
Alfredo
Have you tried balancing the system by turning the lockshields on the downstairs rads to almost shut. I suspect there is a blockage or at least a severe point of resistance in the system. Is it a system with nice neat pipe bends or is it a mass of elbow fittings instead. With a system close to its limits this can make a difference to resistance in a system
I might even suspect a piping error, though this seems far fetched somehow...no rads piped flow to flow by accident I suppose.
I went to a two year old system on Friday in a flat..Combi & 6 rads..nothing on the return at all, but HW OK....Turned out it was blocked up with scale on the return (we have filters, but this would not clean up and kept reblocking), having not been flushed properly on install. It was one of our own installers, and he is being talked to on monday I gather as we've got to powerflush it now
Alfredo
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Have u tried leaving different rads off at a time? Or is it just the one certain rad when u switch on it shuts the boiler off etc?
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I reckon it's the age old problem of magnetite.
When the sytem just powers 3 or 4 rads it can just about cope. Add the fifth rad and (as Alfredo says) it puts the final straw into the equation and the pump can't cope and the boiler kettles.
Poweflushing may do the trick.
When the sytem just powers 3 or 4 rads it can just about cope. Add the fifth rad and (as Alfredo says) it puts the final straw into the equation and the pump can't cope and the boiler kettles.
Poweflushing may do the trick.
Boiler is on longer to heat the extra rad and is overheating the safety thermostat (not the same as the hi limit stat - there's another one).
Check the gas rate, check the boiler thermostat is working at the right temps. Should be better if you turn the boiler stat right down.
Check the gas rate, check the boiler thermostat is working at the right temps. Should be better if you turn the boiler stat right down.
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