Any ideas? Unreliable heating.

[garyevans]

Thanks John. I have bled the rads but not emptied them per se - when you say 'no circulation or corc pump defective' what else could cause the 'no circulation'? The weird thing is that on Sunday after I changed to CP2 all rads were hot, same Monday but then Monday night the downstairs rads went cold. So that must be an airlock? But there is no air in rads! Given that we have had heat i would guess the pump valves are fully open.

last one - the screw in the pump to deblock - manual says to turn screwdriver anticlockwise, but youtube vids say ant and then clockwise? Is that a possible issue?

 

[John.g]

That makes sense, an airlock is a distinct possibility, the only way ("new fresh") air can get into the system is through the air vent, the pipe that bends over the F&E (small) tank. Try and tape a container of water (say a few litres) under this vent with the open end immersed in the water and watch it while starting/running the pump or as I suggested earlier on, just get someone to do as I suggested in post #15, do this first mybe.

 

[John.g]

last one - the screw in the pump to deblock - manual says to turn screwdriver anticlockwise, but youtube vids say ant and then clockwise? Is that a possible issue?

Don't think so, if it needed deblocking anyway you should get a LED alarm.

 

[EvilDrPorkChop]

Turn all the rads off downstairs bar one, get that one red hot. Turn it off. Turn next one on and repeat for rest. It's just airlocking that's all by the sounds of it. If valves are red hot to radiators, then sounds like air. You've not balanced up downstairs have you?

 

[garyevans]

Turn all the rads off downstairs bar one, get that one red hot. Turn it off. Turn next one on and repeat for rest. It's just airlocking that's all by the sounds of it. If valves are red hot to radiators, then sounds like air. You've not balanced up downstairs have you?

Yes, balanced all rads up and down a few times.

Had a plumber come round. He has checked the pump, the valves, drained the system, rebled the system, checked the feeder tank in loft and it is still the same. He is convinced there is a blockage in the 'return' feed pipe (I am not going to pretend I know what that is) and we need to do a powerflush.

 

[John.g]

Was the pump renewed without any drain down?

 

[garyevans]

Was the pump renewed without any drain down?

No idea sorry as I was not here. I reckon so as it was a British Gas engineer as we have the home care.

 

[John.g]

I don't see why anyone would drain down a system just to change out a pump, however we can talk till the cows come home but
I would go way and buy one of those cheap plug in energy monitors on amazon or where ever, remove the pump cable from the terminal box, Connect a 3 pin trailing socket into the terminal box where the pump was, put a 3 pin plug on the end of the pump cable, plug the energy monitor into the socket and plug the pump into the energy monitor and monitor the pump power, that will eliminate or not a pump problem to start with as these pumps have a very high failure rate or inconsistent performance even out of the box, the monitor is only £15 or £20 and very accurate.

 

[EvilDrPorkChop]

Yes, balanced all rads up and down a few times.

Had a plumber come round. He has checked the pump, the valves, drained the system, rebled the system, checked the feeder tank in loft and it is still the same. He is convinced there is a blockage in the 'return' feed pipe (I am not going to pretend I know what that is) and we need to do a powerflush.

Unbalance the downstairs ones, so they're open fully. Leave upstairs balanced.

 

[EvilDrPorkChop]

I'm guessing everything worked before new Pump OK?

 

[garyevans]

I don't see why anyone would drain down a system just to change out a pump, however we can talk till the cows come home but
I would go way and buy one of those cheap plug in energy monitors on amazon or where ever, remove the pump cable from the terminal box, Connect a 3 pin trailing socket into the terminal box where the pump was, put a 3 pin plug on the end of the pump cable, plug the energy monitor into the socket and plug the pump into the energy monitor and monitor the pump power, that will eliminate or not a pump problem to start with as these pumps have a very high failure rate or inconsistent performance even out of the box, the monitor is only £15 or £20.

The plumber took the pump off and checked it and said it is fine. The pipe that feeds downstairs is overhot as is the feed to boiler so the boiler is cutting out intermittently thinking it is overheating.

I'm guessing everything worked before new Pump OK?

No it was hit and miss since the heating went on at start of November. BG decided it was the pump but looking back I reckon there was a blackage then too.

 

[John.g]

HW & CH worked a treat for 2 weeks after renewing pump?,
Have you checked the F&E tank as suggested or at least look into its condition?
Is there a magnetic filter, usually installed on the boiler return and just before the boiler?

 

[garyevans]

HW & CH worked a treat for 2 weeks after renewing pump?,
Have you checked the F&E tank as suggested or at least look into its condition?
Is there a magnetic filter, usually installed on the boiler return and just before the boiler?

HW & CH worked fine once I balanced the system after new pump installed. PLumber checked the F&E tank yesterday and said there was no issue. No filter on the boiler return.

 

[John.g]

Maybe I'm overthinking it but if a system works fine for a few weeks and then stops working then the easiest common denominator to check out is the pump, your plumber obviously checked the pump ports, impeller, etc for sludge but he couldnt check it electrically/output etc but you can do that yourself by spending a few quid, that monitor can also be useful for balancing the system.

 

[garyevans]

Maybe I'm overthinking it but if a system works fine for a few weeks and then stops working then the easiest common denominator to check out is the pump, your plumber obviously checked the pump ports, impeller, etc for sludge but he couldnt check it electrically/output etc but you can do that yourself by spending a few quid, that monitor can also be useful for balancing the system.

If you could send me a link to one I will take a look - does it plug into the cable socket on the actual pump?
For info, I have just been into attic to look at F&E tank - no spurt of anything anywhere when the pump stopped. I am home alone so can't look now at what happens when the boiler comes on.

 

[John.g]

Something like this, I wouldn't spend more than £15 or £20, all you want to monitor is the pump power in watts, nothing fancy required.

Don't know where you live but you can get one of these in Maplins? or the like, or Amazon.
For initial pump test, (boiler off) just note and remove the terminal numbers where the pump cable is connected, then remove it and fit a 3 pin plug to this cable, then plug the energy monitor into a extension lead powerd from anywhere and plug the pump lead (with now 3 pin plug) into the power meter and you can carry out cold pump tests with boiler switched as the 3 way valve will allways be open to either the CH or the HW. Depending on results, to do a longer/hot test, get a 3 pin socket and connect it with a bit of cable, connect the other end into the terminals where you removed the pump cable, then connect energy monitor and pump cable as above and fire up your boiler, you can then monitor the power indefinitely.

 

[Ric2013]

View attachment 79999
This is the old pump and if it appears you will see what I mean by upside down. I don't have any other image so can only presume the British gas engineer who put the new one in ensured it is pumping on same direction. No chemical cleaning I am aware of.

Can't see the arrow, but by the shape of the casting of the cast iron section, this certainly looks to be pumping downwards.

 

[garyevans]

Something like this, I wouldn't spend more than £15 or £20, all you want to monitor is the pump power in watts, nothing fancy required.

View attachment 80077


Don't know where you live but you can get one of these in Maplins? or the like, or Amazon.
For initial pump test, (boiler off) just note and remove the terminal numbers where the pump cable is connected, then remove it and fit a 3 pin plug to this cable, then plug the energy monitor into a extension lead powerd from anywhere and plug the pump lead (with now 3 pin plug) into the power meter and you can carry out cold pump tests with boiler switched as the 3 way valve will allways be open to either the CH or the HW. Depending on results, to do a longer/hot test, get a 3 pin socket and connect it with a bit of cable, connect the other end into the terminals where you removed the pump cable, then connect energy monitor and pump cable as above and fire up your boiler, you can then monitor the power indefinite

Hi John, apologies but that is like reading Greek to me! No idea which cable you are referring to. I wlll attach a picture of the setup - electrically, everything seems fine.

 

[garyevans]

Hi John, apologies but that is like reading Greek to me! No idea which cable you are referring to. I wlll attach a picture of the setup - electrically, everything seems fine.

 

[John.g]

Can you see where the end of the pump cable is connected?, it is electrically connected correctly but want to monitor the pump power which will show if the pump is performing electronically correctly by removing this cable and putting a 3 pin plug on the end to enable it to be plugged into the power meter.