Hi guys
I've been a regular reader of these forums over the years and always found the advice sound - it's extended the life of my boiler, for sure! So, I think I might have one to test you here:
Thorn Apollo 30/50B, open vented system. Bolier in kitchen, upstairs in airing cupboard is hot water tank, 3 way valve and pump. Pump replaced about 2 years ago with a Grundfos - like for like. Hi and lo stats and thermocouple have all been replaced in the last 3 years at various times. Expansion tank in loft - works OK as I've had to lock it off and use it to fill the system when fernoxing. Basic working is fine - all rads heat up OK, no apparent airlocks, 3 way seems to work fine as it will heat up just hot water when I switch it over. System has been fernoxed twice in the last 3 years (once as a maintenance thing, then last year when the boiler kettled after the hi stat went) - boiler is probably about 17 years old. Basically working OK apart from an issue which has been happening for about 4 months. Started off being a once in a blue moon thing, has gradually got worse. Now, there are 2 separate issues but they may be related as they seemed to start happening at the same time, and there is a certain amount of crossover as well.
1) On the lo stat setting, when on central heating, intermittently the pump will stop running whilst still heating the water. This will kettle the boiler and then the pump seems to spring back into life again, normally in about a minute or so. Carries on working OK and then it may happen a few times more in the 5 hours I normally have it on in the evening at the mo. This issue seems to be getting worse just recently.
2) On the hi stat setting, everything heats up well and then randomly at some point, the system trips the house mains supply, the boiler switches off, punp stops etc, but the boiler pilot seems to stay lit as once I reset the trip, the boiler comes back on (I'm assuming this is the thermocouple doing it's job but I thought that by tripping the mains it should kill the boiler too? Mayne I'm getting confused!) however you can pretty much guarantee that a few minutes later it will trip the supply again. Switching to lo stat seems to reduce this problem drastically.
If I leave the house with the heating switched off for a while (i.e. when I was away for 2 weeks recently) then problem 2) will occur on the lo stat setting too. Once I've reset the mains a few times and the boiler has been on for a while then this stops on lo stat but it is very consistent on hi stat. It has popped the mains on the lo stat once in the last 3 weeks, but I tested the hi stat today and within half an hour everything went off again.
PLUS I have heard the pump stop running as in problem 1) when on the hi stat setting as well. Luckily, the boiler wasn't heating at the time, it was inbetween heats, so all was OK - again the pump started again after about a minute. Very strange!
I have noticed that when 1) is occurring, I get a lot of interference on the TV screen, so I'm wondering if there's a possible issue with something switching inside the boiler, hence the spiking on the mains on the TV which might also be a symptom of problem 2) which results in a sufficient spike to trip the mains (mind you, my RCD is VERY sensitive - it has been known to trip the house when I switch on my PC at the mains!)
I know there's a pump overrun stat on this unit, but I though that it's only purpose is to keep the pump running for 5-15 mins to cool the water down a bit after the timer switches off. Does this get involved in the normal running of the unit, and more importantly could it be a possible cause of the issue?
I appreciate the boiler is knocking on a bit and that you may recommend a replacement condenser boiler, however there seems to be a major difference of opinion on this forum as to what's a good one! To me that says there isn't one out there that stands out as a quality unit - let me know if I've got the wrong end of the stick there! I'd rather not replace the Apollo if I can fix it myself, as to be honest apart from standard wear and tear things going wrong with it (up to this point!) it's been a solid and reliable unit, and having done a lot of maintenance on it myself, I've got to know the unit quite well, so I'm happy to try anything you guys suggest and, within reason, quite happy to replace parts. Plus I am a great believer in keeping things simple - Apollo is simple, condenser boiler sounds complicated
I hope I've covered everything there - if not please ask. Any help will be, as ever from this forum, greatly appreciated.
Cheers
Mark
I've been a regular reader of these forums over the years and always found the advice sound - it's extended the life of my boiler, for sure! So, I think I might have one to test you here:
Thorn Apollo 30/50B, open vented system. Bolier in kitchen, upstairs in airing cupboard is hot water tank, 3 way valve and pump. Pump replaced about 2 years ago with a Grundfos - like for like. Hi and lo stats and thermocouple have all been replaced in the last 3 years at various times. Expansion tank in loft - works OK as I've had to lock it off and use it to fill the system when fernoxing. Basic working is fine - all rads heat up OK, no apparent airlocks, 3 way seems to work fine as it will heat up just hot water when I switch it over. System has been fernoxed twice in the last 3 years (once as a maintenance thing, then last year when the boiler kettled after the hi stat went) - boiler is probably about 17 years old. Basically working OK apart from an issue which has been happening for about 4 months. Started off being a once in a blue moon thing, has gradually got worse. Now, there are 2 separate issues but they may be related as they seemed to start happening at the same time, and there is a certain amount of crossover as well.
1) On the lo stat setting, when on central heating, intermittently the pump will stop running whilst still heating the water. This will kettle the boiler and then the pump seems to spring back into life again, normally in about a minute or so. Carries on working OK and then it may happen a few times more in the 5 hours I normally have it on in the evening at the mo. This issue seems to be getting worse just recently.
2) On the hi stat setting, everything heats up well and then randomly at some point, the system trips the house mains supply, the boiler switches off, punp stops etc, but the boiler pilot seems to stay lit as once I reset the trip, the boiler comes back on (I'm assuming this is the thermocouple doing it's job but I thought that by tripping the mains it should kill the boiler too? Mayne I'm getting confused!) however you can pretty much guarantee that a few minutes later it will trip the supply again. Switching to lo stat seems to reduce this problem drastically.
If I leave the house with the heating switched off for a while (i.e. when I was away for 2 weeks recently) then problem 2) will occur on the lo stat setting too. Once I've reset the mains a few times and the boiler has been on for a while then this stops on lo stat but it is very consistent on hi stat. It has popped the mains on the lo stat once in the last 3 weeks, but I tested the hi stat today and within half an hour everything went off again.
PLUS I have heard the pump stop running as in problem 1) when on the hi stat setting as well. Luckily, the boiler wasn't heating at the time, it was inbetween heats, so all was OK - again the pump started again after about a minute. Very strange!
I have noticed that when 1) is occurring, I get a lot of interference on the TV screen, so I'm wondering if there's a possible issue with something switching inside the boiler, hence the spiking on the mains on the TV which might also be a symptom of problem 2) which results in a sufficient spike to trip the mains (mind you, my RCD is VERY sensitive - it has been known to trip the house when I switch on my PC at the mains!)
I know there's a pump overrun stat on this unit, but I though that it's only purpose is to keep the pump running for 5-15 mins to cool the water down a bit after the timer switches off. Does this get involved in the normal running of the unit, and more importantly could it be a possible cause of the issue?
I appreciate the boiler is knocking on a bit and that you may recommend a replacement condenser boiler, however there seems to be a major difference of opinion on this forum as to what's a good one! To me that says there isn't one out there that stands out as a quality unit - let me know if I've got the wrong end of the stick there! I'd rather not replace the Apollo if I can fix it myself, as to be honest apart from standard wear and tear things going wrong with it (up to this point!) it's been a solid and reliable unit, and having done a lot of maintenance on it myself, I've got to know the unit quite well, so I'm happy to try anything you guys suggest and, within reason, quite happy to replace parts. Plus I am a great believer in keeping things simple - Apollo is simple, condenser boiler sounds complicated
I hope I've covered everything there - if not please ask. Any help will be, as ever from this forum, greatly appreciated.
Cheers
Mark