- Thread starter Wozzaaah
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brightspark
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even condensing boilers arent that reliable. y plan megaflow are the best with conventional boilers but the boilers arent verry eficient but bomb proof
Tigman
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yeah put my potterton in 15 years ago ,it was 2/3 years old when i took it out of a house and fitted a combi ! paid for a new flue and changed gas valve and presto been working a treat ever since ! Fan stopped once took it out oiled the thing put it back and still truckin on , cant beat it
Firstly not actually an ideal boiler, its a Biasi in diguise! Anyway wont be diaphragm if your heating works ok because they only have a pump proving diaphragm and use an electronic flow switch. If you take the front panel off, the manifold on the right were the pump is you will find the HW flow switch, when you run the HW tap there is an led that will light on the flow switch.
I suspect if it is running hot,cold,hot cold,etc the flow switch will stay lit, and your problem could be the HW temp sensor or maybe a partial blockage in your HW heat exchanger. Just before the water goes cool have a listen to the boiler and see if it sounds like a kettle boiling and then the burner goes off???
Let me know and i'll try and find a fault finding chart for you if it will help
Mike
To try and test your HW temp sensor, run the HW with the stat set to max then turn it slowly to min and watch the flame to see if it modulates down
I suspect if it is running hot,cold,hot cold,etc the flow switch will stay lit, and your problem could be the HW temp sensor or maybe a partial blockage in your HW heat exchanger. Just before the water goes cool have a listen to the boiler and see if it sounds like a kettle boiling and then the burner goes off???
Let me know and i'll try and find a fault finding chart for you if it will help
Mike
To try and test your HW temp sensor, run the HW with the stat set to max then turn it slowly to min and watch the flame to see if it modulates down
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Yes, it does modulate down. It will run continuously at about 2/3 max but any higher than that and it runs for a bit then the burner cuts out then fires back up etc.
The flow switch stays lit and the boiler is running very quietly, no unusual noises at all.
One thing I've just spotted, the temp gauge isn't working at all, not in CH or DHW mode.
Temp gauges quite often dont work! Sounds like your HW sensor could be working ok if it modulates down and it could be a partial blockage.
When the HW is running watch the 3 leds on the front panel, I think the end ones should flash alternately when the tap is running, When the flame goes out because you have the stat set high does the right hand led start flashing??? This is saying excessive temp in primary circuit(usually partial blockage in plate heat exchanger) Whats the water temp like if you keep it below 2/3.
You could also double check with the heating on does the burner modulate down when you reduce the CH stat on the boiler.
If you have a multi meter you could check the primary and HW temp sensors, just unplug the wires and check if you have between 12 an 1.5 Kohms accross the pins.
Mike
When the HW is running watch the 3 leds on the front panel, I think the end ones should flash alternately when the tap is running, When the flame goes out because you have the stat set high does the right hand led start flashing??? This is saying excessive temp in primary circuit(usually partial blockage in plate heat exchanger) Whats the water temp like if you keep it below 2/3.
You could also double check with the heating on does the burner modulate down when you reduce the CH stat on the boiler.
If you have a multi meter you could check the primary and HW temp sensors, just unplug the wires and check if you have between 12 an 1.5 Kohms accross the pins.
Mike
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Hehe, great timing Mike, I was just about to reply with some more info! 
Now that I've worked out how to activate the boiler diagnostic LEDs
yes, the left and right ones flash with a tap running and as soon as the burner cuts out it goes to right one flashing which indeed indicates 'excessive temperature on primary circuit'.
With the control set to below 2/3 the water is just warm, certainly nowhere near hot enough to use.
Yes the burner does modulate down when I turn the CH stat down.
I've just ordered a new sensor anyway, it was only 6 quid and even if it's not needed now I'm sure it will be someday.
I'll stick a multimeter across it later and see what it reads.
Thanks again Mike, appreciate your help.
Now that I've worked out how to activate the boiler diagnostic LEDs
yes, the left and right ones flash with a tap running and as soon as the burner cuts out it goes to right one flashing which indeed indicates 'excessive temperature on primary circuit'.With the control set to below 2/3 the water is just warm, certainly nowhere near hot enough to use.
Yes the burner does modulate down when I turn the CH stat down.
I've just ordered a new sensor anyway, it was only 6 quid and even if it's not needed now I'm sure it will be someday.
I'll stick a multimeter across it later and see what it reads.
Thanks again Mike, appreciate your help.
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DHW thermistor reads about 16.1KΩ, the DHW one reads about 15.1, could be my meter isn't accurate but with them both being that close would it indicate they're both probably ok?
Just checked the magnaclean and there wasn't a massive amount of crud in there but it does show that the system is still dirty.
As I said, the plate heat exchanger was replaced not that long ago.
Just checked the magnaclean and there wasn't a massive amount of crud in there but it does show that the system is still dirty.
As I said, the plate heat exchanger was replaced not that long ago.
I'd say with them both seeming to modulate your HW and CH down and the readings being close together that they're probably ok and its the multi meter, but could be worth a try for the cost of sensors. Without seeing or hearing the boiler its getting tricky and proabably gone a be a partial blockage. Plate heat exchanger would be the usual place to start, but if only replaced 18months ago they're must be a lot of muck in the system. Why was it replaced last time??? With it being so new it would probably clean up with a Sonic clean or similar but it would mean finding somewhere to do it. The only other thing I can think of could be a blockage in the diverter valve not letting the full flow to the plate heat exchanger, but i'd think it would be moving over fully to HW or it would just pass down into your CH and stay on anyway but have poor HW.
P.S your a brave man cleaning your magna clean! I take it, it has the black valves and not the red ones. They do seem to catch a lot of muck though, just a nightmare for leaking from everywhere!
P.S your a brave man cleaning your magna clean! I take it, it has the black valves and not the red ones. They do seem to catch a lot of muck though, just a nightmare for leaking from everywhere!
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I'm starting to accept that it probably is a partial blockage Mike.
The PHE was replaced due to the last problem we had where the boiler would only produce DHW when the CH was on. The old one did have a fair amount of magnetite in it as was demonstrated by running it under the tap.
As far as I'm aware he didn't clean anything else so there could well be a blockage anywhere tbh. I'll be a little annoyed if it is the PHE and it needs replacing yet again but the rads are a fair few years old and quite obviously contain a lot of muck.
Would it be worth cleaning what is accessible/removable as best as I can and run a system cleaner through it with all the rads turned off purely to try and shift anything else? I gather there are cleaning solutions available that will dissolve magnetite?
Another thought, is there anywhere who might rent out power flush machines or are they normally trade only?
The system was power flushed when the new boiler was fitted but could probably benefit from another.
Regarding the magnaclean, red valves and you aren't kidding!!!!
It's the second one we've had, the first leaked from the lid straight away and was replaced FOC. The new one leaked from the lid but eventually sealed ok...until today when I cleaned it. I finally managed to shut the valves off with water peeing from both then after cleaning it and opening the valves it's now leaking from the lid again.....oh, and the plastic ring spanner doesn't fit either!
The PHE was replaced due to the last problem we had where the boiler would only produce DHW when the CH was on. The old one did have a fair amount of magnetite in it as was demonstrated by running it under the tap.
As far as I'm aware he didn't clean anything else so there could well be a blockage anywhere tbh. I'll be a little annoyed if it is the PHE and it needs replacing yet again but the rads are a fair few years old and quite obviously contain a lot of muck.
Would it be worth cleaning what is accessible/removable as best as I can and run a system cleaner through it with all the rads turned off purely to try and shift anything else? I gather there are cleaning solutions available that will dissolve magnetite?
Another thought, is there anywhere who might rent out power flush machines or are they normally trade only?
The system was power flushed when the new boiler was fitted but could probably benefit from another.
Regarding the magnaclean, red valves and you aren't kidding!!!!
It's the second one we've had, the first leaked from the lid straight away and was replaced FOC. The new one leaked from the lid but eventually sealed ok...until today when I cleaned it. I finally managed to shut the valves off with water peeing from both then after cleaning it and opening the valves it's now leaking from the lid again.....oh, and the plastic ring spanner doesn't fit either!
Ive no idea how replacing the plate heat exchanger helped your HW work independantly from CH last time??? Its probably worth putting in some sentinel x400 or I think the quicker more aggressive one is x800 and just run it all as normal for a week then drain the lot, got to be worth a try. There have been occasions were doing this has made problems worse though as its dislodged more muck and blocked things worse
If you contact magna clean they'll probably send you a new O ring pack because they know how bad they are for leaking, but the valves were changed to a different design to stop them leaking as much which are black.
If you contact magna clean they'll probably send you a new O ring pack because they know how bad they are for leaking, but the valves were changed to a different design to stop them leaking as much which are black.
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The pin that activates the primary flow switch wasn't extending far enough and it was put down to crud in the HE impeding the flow. It worked ok after the HE was replaced and has done so for some time. Thinking about it a while back it did the same, the pin was coming out but not quite far enough so I bent the metal bit on the switch slightly to compensate and it's run fine like that ever since.....until now.
I wonder if it's dirt in the diverter, not the HE or is there not really anywhere it could collect?
I can sense a bit of a stripdown and clean coming on.
I'll try the Sentinel stuff though as you say, it may do more harm than good if the system is that dirty.
I'll also give magnaclean a shout, it's pretty poor to be honest, great idea but shoddy design.
and it's run fine like that ever since.....until now. I wonder if it's dirt in the diverter, not the HE or is there not really anywhere it could collect?
I can sense a bit of a stripdown and clean coming on.
I'll try the Sentinel stuff though as you say, it may do more harm than good if the system is that dirty.
I'll also give magnaclean a shout, it's pretty poor to be honest, great idea but shoddy design.
The rstricted heat ex not allowing it to make the flow switch makes sense but wouldn't have thought the HW would have worked very well when the CH was on because the flow switch would still have been telling the diverter to move over to a restricted heat ex??? Anyway doesn't matter it obviously fixed it last time!
Ive had blocked/restricted diverters before but from the description I'd probably still look plate heat exchanger first. Try the chemicals first and see how you get on, after that you might have to dig the tool box out!
Ive had blocked/restricted diverters before but from the description I'd probably still look plate heat exchanger first. Try the chemicals first and see how you get on, after that you might have to dig the tool box out!
