daft one try locking the three port valve open with the lever 
Replaced Pump - boiler still slapping and banging
- Thread starter buckmoy
- Start date
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Kev
Tried that last night - had no discernable effect. The 3 way valve is only about 3 months old - I think its ok.
So the boiler is still firing up every minute or so for about 20 seconds and kettling before switching off. The rads aren't getting that warm.
I tried moving the pump to a faster setting and putting the boiler to "high" - it was doing the same thing and in fact sounded like it was going to bang again after about 20 mins of regular on/off, on/off, so I put it back to low.
When I switched the HW+CH off at the timer, the pump kept running for a while (about 5 mins) - so the I guess that means the overrun stat is doing that bit of its job properly.
Bled the rads with the pump off - no air. Bled the pump - no air.
At my wits end on this one! One of the plumbers I talked to said I should rip the whole lot out. I'm sure this would solve the problem (and also make my summer holiday decision more easy - ie. none. ) but is there anything else I can try first?
Cheers
Tried that last night - had no discernable effect. The 3 way valve is only about 3 months old - I think its ok.
So the boiler is still firing up every minute or so for about 20 seconds and kettling before switching off. The rads aren't getting that warm.
I tried moving the pump to a faster setting and putting the boiler to "high" - it was doing the same thing and in fact sounded like it was going to bang again after about 20 mins of regular on/off, on/off, so I put it back to low.
When I switched the HW+CH off at the timer, the pump kept running for a while (about 5 mins) - so the I guess that means the overrun stat is doing that bit of its job properly.
Bled the rads with the pump off - no air. Bled the pump - no air.
At my wits end on this one! One of the plumbers I talked to said I should rip the whole lot out. I'm sure this would solve the problem (and also make my summer holiday decision more easy - ie. none.
) but is there anything else I can try first?Cheers
the water aint moving (at risk of stating the bl**by obvious)
are you sure the pump is the right way round
are you sure the three port valve is working not just making a noise
you could try taking the head off and operate the valve manually
your at your wits end i've got no hair left
are you sure the pump is the right way round
are you sure the three port valve is working not just making a noise
you could try taking the head off and operate the valve manually
your at your wits end i've got no hair left
Ha
yes this is dragging on a bit isn't it??
At least your hair isn't frozen to your forehead though (mind you - you are from oop naarth aren't you. Nothing wrong with that.. )
OK
pump is right way round - an expert fitted it.
3 way valve - the pipes on each side are getting hot water when they should.
the water ain't moving - right - so could there be an airlock between the boiler and the pump? I'm talking to myself now really - I can't expect you to be able to see my setup.
The pipes run vertcially from the boiler in the kitchen to a loft space, where they run horizotally under some floorboards to the room with the pump in, before running vertically again.
Could be a problem in there? One guy (who replaced the first pump but left a leak running above it) had lifted the boards and given the pipes a good old shake.
Thing is - this setup ran fine for years. So its not as though some hidden pipes could have suddenly subsided and caused probs..
I wonder if shelling out for a power flush before I spend 1000s on new system might be an idea?
yes this is dragging on a bit isn't it??
At least your hair isn't frozen to your forehead though (mind you - you are from oop naarth aren't you. Nothing wrong with that..
)OK
pump is right way round - an expert fitted it.
3 way valve - the pipes on each side are getting hot water when they should.
the water ain't moving - right - so could there be an airlock between the boiler and the pump? I'm talking to myself now really - I can't expect you to be able to see my setup.
The pipes run vertcially from the boiler in the kitchen to a loft space, where they run horizotally under some floorboards to the room with the pump in, before running vertically again.
Could be a problem in there? One guy (who replaced the first pump but left a leak running above it) had lifted the boards and given the pipes a good old shake.
Thing is - this setup ran fine for years. So its not as though some hidden pipes could have suddenly subsided and caused probs..
I wonder if shelling out for a power flush before I spend 1000s on new system might be an idea?
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You DEFINITELY have a circulation problem. PROBABLY the boiler is working correctly and is being forced into cycling and / or overheat by bad / no circulation in the rest of the system.
You have a fixed bypass (with a gate valve) linking flow and return near the pump and motorised valve? With rads AND hot water loops both blocked or valved off (by some mistake!), if you open the bypass valve FULLY there should be enough circulation to heat up the pump and nearby pipes and keep the boiler from tripping. Is there? (In this state, the boiler SHOULD cycle on and off at (say) five minute intervals after an initial burn from cold of about (say) 3 - 5 minutes.)
If with the bypass open the boiler is still distressed and / or the pipes near the pump are NOT getting quite / very hot, you have a blockage or major airlock in the primary Flow and Return pipes between pump and boiler. Can you hear whining, rattling or rustling noises from the pump? If so, it may be running dry or full mostly with air. In this state it CAN'T pump (and the bearing is suffering from lack of water lubrication!). If the pump is dry or 'cavitating' due to air, the next step is to get the air out of it. If the pump is mounted high up relative to the 3-port valve and the return pipe to the boiler, it may not be able to develop enough pressure (due to cavitation) to push the air out. Also, there's nowhere for air in this location to go except into the rads (which ain't happening!) or back through the boiler via the bypass or HW cylinder coil. From your description, it sounds like there's a large height difference between boiler and pump.
If you turn OFF the pump momentarily but leave the rest of the system ON (you can do this by shifting the speed control to 'in between' settings - not recommended but it works!) do you hear water rush / air bubbling noises? This would confirm the airlock theory. If I'm right so far, seems to me that the next step is to fit an air bleed as close as possible to the 'high point' on the output side of the pump.
OTOH, if the pump DOES produce circulation through the bypass pipe, the block / airlock is further on, towards the HW cylinder and / or the rads.
Alternatively, with the system on and bypass open, can you hear trickling water noises coming from the (horizontal?) pipes leading from boiler to pump? If so, there's probably a lot of air stuck in the primary Return. Given the history of your system, this is not going to disperse without a LOT of circulation of hot water through the boiler and past the bottom of the open vent. Again, an air bleed (preferably automatic) on the OUTPUT side of the pump SHOULD help after a time. It's still a bit of a mystery why the air is not dispersing by itself up the open vent, however.
As Kevin suggested, what happens when you lock the 3-port valve in the mid position? Does it move automatically to release the lever as soon as you start the system? With the valve centred, you SHOULD get flow through both rads and cylinder primary.
You have a fixed bypass (with a gate valve) linking flow and return near the pump and motorised valve? With rads AND hot water loops both blocked or valved off (by some mistake!), if you open the bypass valve FULLY there should be enough circulation to heat up the pump and nearby pipes and keep the boiler from tripping. Is there? (In this state, the boiler SHOULD cycle on and off at (say) five minute intervals after an initial burn from cold of about (say) 3 - 5 minutes.)
If with the bypass open the boiler is still distressed and / or the pipes near the pump are NOT getting quite / very hot, you have a blockage or major airlock in the primary Flow and Return pipes between pump and boiler. Can you hear whining, rattling or rustling noises from the pump? If so, it may be running dry or full mostly with air. In this state it CAN'T pump (and the bearing is suffering from lack of water lubrication!). If the pump is dry or 'cavitating' due to air, the next step is to get the air out of it. If the pump is mounted high up relative to the 3-port valve and the return pipe to the boiler, it may not be able to develop enough pressure (due to cavitation) to push the air out. Also, there's nowhere for air in this location to go except into the rads (which ain't happening!) or back through the boiler via the bypass or HW cylinder coil. From your description, it sounds like there's a large height difference between boiler and pump.
If you turn OFF the pump momentarily but leave the rest of the system ON (you can do this by shifting the speed control to 'in between' settings - not recommended but it works!) do you hear water rush / air bubbling noises? This would confirm the airlock theory. If I'm right so far, seems to me that the next step is to fit an air bleed as close as possible to the 'high point' on the output side of the pump.
OTOH, if the pump DOES produce circulation through the bypass pipe, the block / airlock is further on, towards the HW cylinder and / or the rads.
Alternatively, with the system on and bypass open, can you hear trickling water noises coming from the (horizontal?) pipes leading from boiler to pump? If so, there's probably a lot of air stuck in the primary Return. Given the history of your system, this is not going to disperse without a LOT of circulation of hot water through the boiler and past the bottom of the open vent. Again, an air bleed (preferably automatic) on the OUTPUT side of the pump SHOULD help after a time. It's still a bit of a mystery why the air is not dispersing by itself up the open vent, however.
As Kevin suggested, what happens when you lock the 3-port valve in the mid position? Does it move automatically to release the lever as soon as you start the system? With the valve centred, you SHOULD get flow through both rads and cylinder primary.
I've just managed to catch up with this thread and it is beginning to sound like one or more airlocks. To shift them you will need full pump pressure around the circuit and you don't have this while that bypass is open. In any case half open sounds like too much. You want just enough flow to move water through the boiler while the overrun thermostat does its stuff. A fraction of a turn is all it takes on mine.
Try this:
Turn the boiler to pilot only so it doesn't fire up then close that bypass right down. Now run HW and CH together. If you're lucky, a bubble of air will escape up the vent pipe.
Whether it does or not, switch to HW only and bleed the heating coil pipework then go to CH only and start bleeding radiators. I find it best to have only one radiator open at a time, starting with the lowest and most distant ones.
Hopefully, and if the airlock theory is correct, the system will start to work properly. Finish off by setting up the bypass as I suggested in a much earlier reply.
If closing the bypass doesn't work then I'm afraid I've run out of ideas. It might help us all help you if we could actually see the pipe layout around the pump and three port valve, including the connection points for feed and vent.
Try this:
Turn the boiler to pilot only so it doesn't fire up then close that bypass right down. Now run HW and CH together. If you're lucky, a bubble of air will escape up the vent pipe.
Whether it does or not, switch to HW only and bleed the heating coil pipework then go to CH only and start bleeding radiators. I find it best to have only one radiator open at a time, starting with the lowest and most distant ones.
Hopefully, and if the airlock theory is correct, the system will start to work properly. Finish off by setting up the bypass as I suggested in a much earlier reply.
If closing the bypass doesn't work then I'm afraid I've run out of ideas. It might help us all help you if we could actually see the pipe layout around the pump and three port valve, including the connection points for feed and vent.
Disagree. Oh dear - this is my night for being disagreable, it seems.
If there's an airlock in the primary Flow between boiler and pump or primary Return, between pump / valve area and boiler, you need to REDUCE the RESISTANCE of the system to minimum to give best chance of clearing it. Since the bypass is between pump outlet and primary Return (or should be!), it must be OPEN to achieve this!
If, alternatively, airlocks are in the cylinder coil and /or the flow pipes leading to the rads, proving that the boiler will run in a controlled fashion just using the primary Flow, bypass and primary Return should help confirm where the problem(s) actually is / are.
Wo hoo!
Experts in disagreement is always excellent to behold.
Guys - thanks very much for your help. I will be printing the entire thread and settling myself in for some serious head scratching over the w/end.
Well - an update. I left the system on its boiler-low, pump-medium setting, CH+HW, bypass a fraction open settings and went to work yesterday. Came home last night and the house was cold, boiler pilot light out.
So it must have got unhappy and tripped itself.
Pump was still spinning (sounded quiet = no air? maybe no water??!) so I re-lit the pilot and sparked the boiler onto "low". It complained and re-tripped itself almost straight away.
I switched the pump off upstairs and tried to bleed it - no water came out at first, then only a drop. Re-lit boiler, tripped straight away.
Croydon - did some looking at your post: (Thurs 11:06pm)
The 3 way valve manual lever offers no resistance when the timer is set to CH (it stays down). When its set to HW, the lever offers resistance to being pushed down, makes a winding noise, then slowly pushes the lever back up - at this point if I push it to the right it catches itself in the provided slot.
You are correct - the pump is one floor above the boiler.
Didn't get a chance to try the in-between settings pump trick as the boiler had cacked itself, however I seem to rememver bubbling in the F&E tank when I tried this before.
Anyway - so my next steps are to follow what Croydon and Felix have agreed - CH+HW, open bypass fully, then close bypass fully. Although having said that, the system seems so unhapy now that getting it to go for more than a few seconds may be a challenge.
felix - can you clarify how I would bleed the cylinder coil? Is this where I run HW only with the bypass fully closed?
If I don't blow myself up over the weekend, I'll post some digi pics of the setup if its not solved by then.
Once again , thanks for your help.
Experts in disagreement is always excellent to behold.
Guys - thanks very much for your help. I will be printing the entire thread and settling myself in for some serious head scratching over the w/end.
Well - an update. I left the system on its boiler-low, pump-medium setting, CH+HW, bypass a fraction open settings and went to work yesterday. Came home last night and the house was cold, boiler pilot light out.
So it must have got unhappy and tripped itself.
Pump was still spinning (sounded quiet = no air? maybe no water??!) so I re-lit the pilot and sparked the boiler onto "low". It complained and re-tripped itself almost straight away.
I switched the pump off upstairs and tried to bleed it - no water came out at first, then only a drop. Re-lit boiler, tripped straight away.
Croydon - did some looking at your post: (Thurs 11:06pm)
The 3 way valve manual lever offers no resistance when the timer is set to CH (it stays down). When its set to HW, the lever offers resistance to being pushed down, makes a winding noise, then slowly pushes the lever back up - at this point if I push it to the right it catches itself in the provided slot.
You are correct - the pump is one floor above the boiler.
Didn't get a chance to try the in-between settings pump trick as the boiler had cacked itself, however I seem to rememver bubbling in the F&E tank when I tried this before.
Anyway - so my next steps are to follow what Croydon and Felix have agreed - CH+HW, open bypass fully, then close bypass fully. Although having said that, the system seems so unhapy now that getting it to go for more than a few seconds may be a challenge.
felix - can you clarify how I would bleed the cylinder coil? Is this where I run HW only with the bypass fully closed?
If I don't blow myself up over the weekend, I'll post some digi pics of the setup if its not solved by then.
Once again , thanks for your help.
Follow the pipe from the top of the cylinder coil upwards. Ignore any pipes or branches going down because you cannot bleed air downwards. At some point you will find either a bleed valve or the open end of the vent above the feed/expansion tank or, just possibly, the feed/expansion pipe from the same tank. In the last two cases the coil will vent itself and does not need bleeding.
If you find no upward path for air to escape then you have a problem. Your only hope is that the pump has enough force to push the air downwards and out by some other route. This is not a solution because the problem will keep coming back. You'll have to fit a bleed valve.
If you find no upward path for air to escape then you have a problem. Your only hope is that the pump has enough force to push the air downwards and out by some other route. This is not a solution because the problem will keep coming back. You'll have to fit a bleed valve.
Hello again.
Its been "working" for about a week on timed CH+HW, but when the heating comes on in the morning the rads all make a kettling type noise (maybe transmitted from boiler?).
Pump on 3 (fastest), Boiler (Thorn Apollo) on high
The boiler itself is cycling quite rapidly - on for about 20 secs, off for a minute or so.
Felix - there doesn't seem to be a hot water bleed, (unless its somewhere under carpeted floor? Surely not..) so it must lead to the vent. The inflow HW pipe to the immersion coil is too hot to touch.
Anyway - as promised here are some pics: The pump room:
The F&E tank is top right off shot. I assume that copper chamber thing top left lets air bubble to the F&E vent if locks reach it?
Here is the tank room:
One small concern here is iff the thermostat on the front is functioning correctly to presumably divert HW coil to CH if temp reached.
Anyway if you can help, my goal is to stop the cycling and kettling! At the moment theres some x400 rattling round the system, to be drained in a week or so.
Thanks again for your help.
Its been "working" for about a week on timed CH+HW, but when the heating comes on in the morning the rads all make a kettling type noise (maybe transmitted from boiler?).
Pump on 3 (fastest), Boiler (Thorn Apollo) on high
The boiler itself is cycling quite rapidly - on for about 20 secs, off for a minute or so.
Felix - there doesn't seem to be a hot water bleed, (unless its somewhere under carpeted floor? Surely not..) so it must lead to the vent. The inflow HW pipe to the immersion coil is too hot to touch.
Anyway - as promised here are some pics: The pump room:
The F&E tank is top right off shot. I assume that copper chamber thing top left lets air bubble to the F&E vent if locks reach it?
Here is the tank room:
One small concern here is iff the thermostat on the front is functioning correctly to presumably divert HW coil to CH if temp reached.
Anyway if you can help, my goal is to stop the cycling and kettling! At the moment theres some x400 rattling round the system, to be drained in a week or so.
Thanks again for your help.
OK - simple question.
I had to drain the system to get out some x400 that had been in there for a few weeks.
Refilled and added some x200 + x100 via F&E tank.
Valve in mid position for refill, bled rads downstairs, then upstairs, then pumps.
Boiler fired for about 1 minute, then off, then on, then started banging and tripped.
I left the pump running for a while with the boiler off - now when I switch the pump off, water seems to gush into the F&E tank. There are also some bubbling noises - origin unknown.
What does this mean?
I had to drain the system to get out some x400 that had been in there for a few weeks.
Refilled and added some x200 + x100 via F&E tank.
Valve in mid position for refill, bled rads downstairs, then upstairs, then pumps.
Boiler fired for about 1 minute, then off, then on, then started banging and tripped.
I left the pump running for a while with the boiler off - now when I switch the pump off, water seems to gush into the F&E tank. There are also some bubbling noises - origin unknown.
What does this mean?
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