Radiator banging / clicking - possible reaction to F1 protector?

[TheGiantHogweed]

Hi.

We’ve had rather a lot of noise issues with our radiators since we had a new boiler installed. Our radiators other than 2 more recent ones are all over 30 years old.

When the boiler got installed in the middle of 2020, after the first few days, we had several loud airlocks each day. Probably up to 10 times in total until we got the plumbers round to sort it out. I can’t remember exactly what they did, but the air locks stopped occurring then. But what then was the case was that whenever the heating was on, the main radiator that must remain on all the time seemed to have a sound similar to a cold tap permanently running. That sound was amplified to the room above, unless the TRV on this radiator was either on 5 or totally off.

We got the plumbers back, and they then drained the system (not a blast out though) and added some Fernox F1 Protector.

This seemed to remove the issue I described with the sound like a tap was running, but introduced a whole load more.

The system clicks and bangs occur very regularly when the heating is on. It however is much more noticeable in my bedroom, but the noise is very similar in many other places in the house. It is not coming from the radiators, but they are what makes it more audible as upstairs all the pipes are under the floorboards. The F1 Protector I’m guessing caused some sort of chemical reaction. Every single day, loads of air / gas was generated and the radiators could be bled very frequently with more build up of whatever this was. The water was also very dark grey and smelt strong. We kept dealing with this throughout the winter ourselves and although the noise remained, the issue with the gas does seem to have gone now, probably because the radiators hadn’t been used this last summer.


Now, the clicking decreases when the heating is off at the boiler, but it still clicks or bangs randomly usually at least once an hour through the night. Sometimes it can be incredibly loud.



From what I’ve read, this now could be many things:


Boiler kettling – It seemed that F1 protector it supposed to help with this, but it seemed putting that in caused trapped air and other nasty reactions.

Expanding / shrinking pipes – This sounds like it could indeed be the case. As I can lift and move my radiator slightly and feel it rubbing in the hole in the floorboards, and I can almost create the identical sounds myself by doing this. However, the radiators and pipes have not changed since our boiler got replaced, so as that is the case, I can’t understand why this should be related. Our heating with our old boiler just bade a very quiet and consistent tinkling while on, and no noise when off.

Dirty pipes – While we had the F1 protector put in supposedly to clean the system, given the reaction it caused, it probably has made it worse. We don’t have air / gas in the system now and the water seems clean, but I obviously can’t tell what the pipes are like. I don’t believe it is related to the radiators now, as I can turn them off at both the TRV and other valve and the noise still occurs from the pipes.


As it is a new boiler with very old pipes and radiators, it is hard to know if a full system flush will solve this issue. I know that these radiators and pipes can be quiet, and nothing physically should have changed about them. Just likely to be something in them.



This clicking / banging has been irritating me so much that I’ve done rather a lot of recordings of it. So I can explain what it is better.



This first link below is actually from last year. This was during the day when I was at my desk. The microphone easily picks up me pressing a few buttons on my keyboard, but then it just sounds like a hard metal object hits the radiator hard. The radiator is nowhere close to my microphone, which just shows how loud it can be. This is a good example of what can occur in the night.

http://www.wetherby.me/wiki/pub/Sandbox/RandomImages/1_Radiator_Sound.mp3

This next clip is close up to the pipe when there was an obvious reaction of some sort. You can hear what sound like fragments rolling around in the pipes, spitting, gurgling and then this clicking and banging begins. The gurgling has long since stopped, but the banging and clicking remains.

http://www.wetherby.me/wiki/pub/Sandbox/RandomImages/11_Radiator_Sound_Close_Up.mp3

Number 6 was only from a few days ago when the boiler was on, but my radiator off. I’ve edited the recording and joined many of the sounds closer together. They sound similar, but can vary a lot regarding how far apart they are.

http://www.wetherby.me/wiki/pub/Sandbox/RandomImages/06-Left_Pipe_-_Morning_Noise.mp3

This is an awful lot of information, but I’m really stuck with what this is most likely to be, and what sort of people would know most about it and be able to sort it.







Many thanks.

 

[Ric2013]

F1 is not designed to free off dirt or clean the system. If the water quality is poor then the system should have had a full powerflush when the boiler was changed IMO. Most likely the disturbance of the works has shifted crud that was hitherto deposited and not in circulation. I cannot see how F1 would caused the problem, however.

 

[TheGiantHogweed]

Thanks for the info.

Before our old boiler failed, we were not having these issues. So it has been quite difficult to work out what it is related to. The water system was totally drained when we got the new one installed, and that was when we for the first few days got a lot of airlocks occurring. After all this and a few other issues (the banging and clicking hadn't started yet) , they drained the system again and added the F1 protector and filled it back up. It only seemed to be a few days after this that all this banging, gurgling and clicking started to occur so frequently with rather dirty water. This was when there also seemed to be gas or whatever it was being generated daily as there were no leaks anywhere. After 2 summers of no heating being on, the radiators now full of just water again when on, but most of the noise is still there, but it seems to be in the pipes.

If it is related to dirty water or the reaction after the system was last drained with F1 added, then as the water was dirty at the time, it is entirely possible that the pipes will have a lot of that still in them. It hasn't been treated since this was added, but each attempt of anything at the time seems to have made it worse, so that is partly why it has been put off.

We considered new radiators, but then thought that if it was related to the pipes which are likely older than are 30+ year old radiators, it may make no difference at all.

The power flush seems to look like the best option, but we had one plumber round who would have been able to do that able to do that (though he was too busy then), but he admitted that he didn't have any idea what the issue could be, which surprised me a little. As the sound effects fit the description of several things I mentioned.



Any more advice would be much appreciated.



Many thanks.

 

[Chuck]

I've only skim-read your essay (sorry, but a bit pressed for time today) but my suspicion is that your installers have left the pump on its highest setting rather than the lowest – preferably constant pressure or proportional pressure – one that achieves proper circulation. This will cause the whooshing noises in your pipework. The creaking and banging is probably due to the new boiler having a much lower heat capacity heat exchanger than your older one, which means the flow temperature will rise and fall more rapidly. Also, if the system is probably cycling on and off more than your previous boiler did. The creaking and banging (arising from so-called slip-stick friction) will occur when the pipework is heating or cooling.

You can probably mitigate the problems by carefully balancing the system (so the TRVs are normally open) and matching the pump setting to the emitter system properly. A full cure may need you to have a look at points where the pipework and radiators are attached to the fabric of the house and insert some hemp or felt to allow smooth sliding.

Use the search box on the top right of this page. These issues have been asked and answered many times on this forum.

 

[TheGiantHogweed]

I've only skim-read your essay (sorry, but a bit pressed for time today) but my suspicion is that your installers have left the pump on its highest setting rather than the lowest – preferably constant pressure or proportional pressure – one that achieves proper circulation. This will cause the whooshing noises in your pipework. The creaking and banging is probably due to the new boiler having a much lower heat capacity heat exchanger than your older one, which means the flow temperature will rise and fall more rapidly. Also, if the system is probably cycling on and off more than your previous boiler did. The creaking and banging (arising from so-called slip-stick friction) will occur when the pipework is heating or cooling.

You can probably mitigate the problems by carefully balancing the system (so the TRVs are normally open) and matching the pump setting to the emitter system properly. A full cure may need you to have a look at points where the pipework and radiators are attached to the fabric of the house and insert some hemp or felt to allow smooth sliding.

Use the search box on the top right of this page. These issues have been asked and answered many times on this forum.

Sorry for the long post! I'm not good at explaining things in brief, maybe because I think it isn't enough for me to understand though! But this has been happening for such a long time that i thought I would go into more depth.

They did replace the old pump with a new one. Our old one was on speed 2 and this one was put on Speed 3. We didn't know this until we checked it and changed it back to 2. But this was after the first lot of problems. We have had it on 2 for well over a year with this issue still happening.

The most confusing thing is that I've tried avoiding using my radiator in my room for nearly a week now, but that seems to make no difference to the noise at all. The only time the system goes totally quiet (and remains consistently quiet with no bangs or ticks at any point) is when the boiler hasn't been heating up the radiators and pipes for several days, which will be why summer was fine.

I could tolerate some quiet noise while our heating came on and turned off, which is pretty normal, but the fact that it continues to bang and clunk a few times an hour over night is why I myself am really struggling to tolerate it.

Now I have looked and tried to listen in more areas of the house, this very similar noise seems to be happening in many other pipes too. As the pipes never used to make these noises, and the fact that they haven't moved, it suggests to me that using foam / checking the hole size in the floorboards and other movement related things are less likely to be related.

Our heating used to come on and off a bit more regularly actually. We used to have a brief 30 minutes in the middle of the day as well as the longer in the mornings and evenings. Now we just have morning and evening. It does the same in the day between the times it is on as it does in the night. Less clicks, but often there will be one or two very loud bangs. It is odd as it shouldn't be related to the temperature changing if the radiators have been off for so long.

Just need to think very carefully before spending money on anything that we are not sure will fix the issue.

 

[Chuck]

Our heating used to come on and off a bit more regularly actually. We used to have a brief 30 minutes in the middle of the day as well as the longer in the mornings and evenings. Now we just have morning and evening. It does the same in the day between the times it is on as it does in the night. Less clicks, but often there will be one or two very loud bangs. It is odd as it shouldn't be related to the temperature changing if the radiators have been off for so long.

The cycling I was referring to occurs every few hundred seconds within the longer periods the programmer is on.

I'm assuming the 'loud bangs' are coming from the pipework. If they are coming from inside the boiler, i.e. explosive ignition, it needs to be shutdown and investigated by a registered gas engineer as a matter of urgency.

 

[TheGiantHogweed]

The cycling I was referring to occurs every few hundred seconds within the longer periods the programmer is on.

I'm assuming the 'loud bangs' are coming from the pipework. If they are coming from inside the boiler, i.e. explosive ignition, it needs to be shutdown and investigated by a registered gas engineer as a matter of urgency.

The occasional loud bangs and more frequent quieter clicks all sound like they are only in the pipes. You can hear them through the radiators, but when listening closely, it is clear that the louder points is in the pipe work. So I don't think this is a serious problem, other than in my case being extremely annoying as the loud bangs can sometimes wake me up at night. I keep changing my mind on weather it is the pipes moving, as that according to what I read does make sense, but then as they never used to do this and the pipes haven't been touched, this shouldn't have changed. The loudest bangs do sound like metal buckling as if it is shrinking or expanding, but I'm unsure why it would do this in the middle of the night with over 4 hours between the heating going off and coming back on. If it isn't the pipes shifting, then can dirty water and a very small amount of air maybe stuck in them cause this?

 

[Chuck]

If it isn't the pipes shifting, then can dirty water and a very small amount of air maybe stuck in them cause this?

No. Air tends to cause a 'trickling' sound. Occasionally a 'glugging' noise as a large bubble makes its way around the system.

Changing the boiler will have changed the operating temperatures of the pipes, the rate of change of those temperatures with time and the installer may have moved the ones near the boiler and/or anchored them more firmly at various points than they were previously cause the far ends to have to move more than previously to accommodate expansion / contraction.

Google 'central heating slip stick noise' or use the search box at the top right of the page. This is a common problem and the fix is a bit tedious but not difficult.

 

[John.g]

The occasional loud bangs and more frequent quieter clicks all sound like they are only in the pipes. You can hear them through the radiators, but when listening closely, it is clear that the louder points is in the pipe work. So I don't think this is a serious problem, other than in my case being extremely annoying as the loud bangs can sometimes wake me up at night. I keep changing my mind on weather it is the pipes moving, as that according to what I read does make sense, but then as they never used to do this and the pipes haven't been touched, this shouldn't have changed. The loudest bangs do sound like metal buckling as if it is shrinking or expanding, but I'm unsure why it would do this in the middle of the night with over 4 hours between the heating going off and coming back on. If it isn't the pipes shifting, then can dirty water and a very small amount of air maybe stuck in them cause this?

What make/output were/are the old/new boilers.

make/model of old/new circ pumps

Check that pump is pumping in the correct direction. (Towards either a mid position valve or towards two port valves)

 

[John.g]

Might seem a bit simplistic but also check that the boiler pipework is installed correctly, ie that the flow pipe is hotter than the return pipe.

Is it a open vented system or sealed with a expansion vessel?.

 

[TheGiantHogweed]

What make/output were/are the old/new boilers.

make/model of old/new circ pumps

Check that pump is pumping in the correct direction. (Towards either a mid position valve or towards two port valves)

Unfortunately, I know very little about our old boiler or pump, as I never really thought about it. I just know it was a Glow-worm. Don't know anything about our old pump.

Our new pump is the grundfos ups3. It first got installed at an angle, then when we first complained of a heating noise issue, plumbers said that was wrong and put it on its side.

Regarding the pumping in the right direction, I don't have much knowledge about this, so I will share a picture to show the set up here - if it helps. One from as close to the side as i can get, and one from above.

I rarely notice much noise coming from here though.


Our new boiler is the ideal LOGIC HEAT R18. I didn't realize that small sticker got put on it with the date that the F1 protector got added. This was on the 19th of October last year. I think I remembered wrong. So we will have just had this summer with no heating, which seemed to have settled all this generation of whatever gas it was, but the clicks and bangs are still just as bad.

Let me know any other information I can provide.


Thanks.

 

[TheGiantHogweed]

No. Air tends to cause a 'trickling' sound. Occasionally a 'glugging' noise as a large bubble makes its way around the system.

Changing the boiler will have changed the operating temperatures of the pipes, the rate of change of those temperatures with time and the installer may have moved the ones near the boiler and/or anchored them more firmly at various points than they were previously cause the far ends to have to move more than previously to accommodate expansion / contraction.

Google 'central heating slip stick noise' or use the search box at the top right of the page. This is a common problem and the fix is a bit tedious but not difficult.

Our old heating system (same radiators and pipes, but old boiler) made what I would can a tinkling noise. Loads of really quiet ticks almost the entire time it was on. Could be heard in almost every radiator, but was extremely quiet and not annoying. Always stopped when it was off.

When there was a load of air / generated gas in the system, it sounded similar to the middle of the 3 links i posted. Bit of glugging and rattling like there were loose bits rolling around in the pipe. Although whatever the air was seems to have gone now, the other stuff likely will still be there I feel, as the system has not been drained since.

I will try and do more research. I did try to do a lot before posting here, but I'm bad at finding appropriate questions to find the results, and haven't yet found anything that seems to totally match the issue, and what can be done to solve it. Each time plumbers came round since the boiler installation, the sound seemed to change or get worse in this case.

 

[John.g]

Unfortunately, I know very little about our old boiler or pump, as I never really thought about it. I just know it was a Glow-worm. Don't know anything about our old pump.

Our new pump is the grundfos ups3. It first got installed at an angle, then when we first complained of a heating noise issue, plumbers said that was wrong and put it on its side.

Regarding the pumping in the right direction, I don't have much knowledge about this, so I will share a picture to show the set up here - if it helps. One from as close to the side as i can get, and one from above.

View attachment 65309

I rarely notice much noise coming from here though.


Our new boiler is the ideal LOGIC HEAT R18. I didn't realize that small sticker got put on it with the date that the F1 protector got added. This was on the 19th of October last year. I think I remembered wrong. So we will have just had this summer with no heating, which seemed to have settled all this generation of whatever gas it was, but the clicks and bangs are still just as bad.

Let me know any other information I can provide.


Thanks.

Can you feel the pipes under the boiler and feel with your hand which is the hotter of the two (flow/return) and either count them from the left or photo them to rule out any mess up there on installation.

If there is a small header tank in your attic (together with a bigger one) then you have a open vented system, these systems are prone to pulling in air and causing all sorts of problems especially if the pump setting is too high.
The UPS3 is a very powerful pump and even setting 2 constant curve can cause problems (even though you say that the air has gone).
Your are on constant curve II (one solid green+one solid yellow) suggest (especially if you have this open vented system) changing to either constant curve I (one solid green) or preferably CP1 which is one flashing green + one flashing yellow, second last right diagram and see how it goes.

 

[TheGiantHogweed]

Can you feel the pipes under the boiler and feel with your hand which is the hotter of the two (flow/return) and either count them from the left or photo them to rule out any mess up there on installation.

If there is a small header tank in your attic (together with a bigger one) then you have a open vented system, these systems are prone to pulling in air and causing all sorts of problems especially if the pump setting is too high.
The UPS3 is a very powerful pump and even setting 2 constant curve can cause problems (even though you say that the air has gone).
Your are on constant curve II (one solid green+one solid yellow) suggest (especially if you have this open vented system) changing to either constant curve I (one solid green) or preferably CP1 which is one flashing green + one flashing yellow, second last right diagram and see how it goes.
View attachment 65313

Thanks for this. When I first tried to take the image of the pump, a shadow was over the instructions. I pressed the button without knowing it had to be held for 3 seconds. I will try the other things you mention.

A lot of the things you mention are just things that I have to guess what they are. I have attached more pictures of related stuff that hopefully with give you some of the answers to the things you are asking.

This is above our boiler in the kitchen. Directly above is the pump under the bathroom, that I showed in my previous post.

This is under our boiler. Presumably the one on the left will be the main input for the water. The one on the right goes directly outside.

This is out airing cupboard tank. This got replaced at the same stage as our boiler. We used to get a lot more noise here, but it has been a lot quieter (and much more well insulated) than the old one.

This is above the water tank in our loft. I know very little about this. Have attached a picture of the label if it helps. We also have a large cold water tank near by it.

One time when we had the plumbers round after the install when we reported the airlocks and air trapped in the radiators (before the F1 protector went in) they believed that a valve near this tank was possibly a bit loose. Can't remember exactly, but they said they tightened it up, but it didn't seem to change anything.




When the heating is next on, I will try out changing the pump settings again.

 

[John.g]

Should have told you about pressing the pump setting button for 3secs to change modes.

That's great info there.

1. Just feel the two copper pipes on the boiler top and identify (left or right) the hotter of the two) best felt when boiler fires up after being off for awhile but doesn't really matter as long as you can differentiate.

1a. After identifying the above immediately feel the piping at the pump and see if its the same temperature as the hotter or the cooler boiler pipes.

2. What pressure is the pressure gauge showing.

3. Try and see where the pipe (after the red expansion vessel) connects into the system, you maybe able to feel the pipe into which it connects and determine if on the flow or return or if it connects into the boiler heating coil, whether its connected into the top or bottom coil piping.

 

[TheGiantHogweed]

Should have told you about pressing the pump setting button for 3secs to change modes.

That's great info there.

1. Just feel the two copper pipes on the boiler top and identify (left or right) the hotter of the two) best felt when boiler fires up after being off for awhile but doesn't really matter as long as you can differentiate.

1a. After identifying the above immediately feel the piping at the pump and see if its the same temperature as the hotter or the cooler boiler pipes.

2. What pressure is the pressure gauge showing.

3. Try and see where the pipe (after the red expansion vessel) connects into the system, you maybe able to feel the pipe into which it connects and determine if on the flow or return or if it connects into the boiler heating coil, whether its connected into the top or bottom coil piping.

As I should be at home when the heating comes on in the evening tomorrow, I will try to check the 2 pipes then. I have tried them now, some time after the heating has been on, and I really can't tell any difference. Both were just a bit too hot to touch or hold for more than a second.

I am not great at taking instructions or understanding things. If you could just confirm what the pressure gauge is, and if it is in any of my pictures. Is it in the picture by the water tank?

The pipe that the red expansion vessel (if that is what it is) seems to go down to the airing cupboard and into the tank. Then the pipe that comes out of there and splits, and goes back into the loft, and under the floorboards upstairs. I don't know enough about this stuff, but I did think this was more related to heating hot water for the tap water and shower, rather than the radiators.

 

[Deleted member 123817]

The pressure gauge is in the third photo, it is probably scaled 0 to 4 bar and the needle is indicating either close to 1 or close to 2 bar.

 

[Deleted member 123817]

Did you change the pump mode to CP1

 

[TheGiantHogweed]

I haven't changed anything just yet. The pump is hard to access as it it under a cork tile in the bathroom with several screws. When I next get a chance, I will try changing the mode.

The strange thing that makes me wonder how it can be related to the pump is that these clicking / banging sounds usually happen several times a night many hours after the heating goes off and well before it comes back on. Can it really still be pump related when the pump isn't active at this stage?

There are far more clicks when the heating is on, and while they sometimes emit the louder bangs, they tend to more often be the quieter ones, but still very annoying. I just don't know what can be causing the ones in the night as surly the pipes won't be having water shifted around in them so many hours after the heating is off. Unless it is related to the pump speed allowing being fast, so that is cools down faster, and then the pipes not contracting at the same speed they used to. But this seems strange to me. Very confusing!

The pressure gauge is in a bedroom that isn't mine, so will need to also check that another time.

 

[John.g]

Banging can be caused by piping heating/cooling, if circ pump head is very high the return temp will be very high and just may cause some of these problems so rule out the easy items first.

Also check boiler flow temperature and ensure not > 65C, some systems can get very noisy if flow temp approaches 70C.

The system pressure is also important and should be 1 to 1.5 when cold.

Anyway check what is available to you especially the boiler flow/return, this evening.

(Attached, picture of pressure gauge, to avoid any confusion.)

 

[TheGiantHogweed]

I'll check the pipes above the boiler tonight right when the heating first comes on, if I get the chance.

When our new boiler got installed, they set it to 69 degrees claiming that was the most efficient. But we had read that this can cause noisier heating and possibly the reaction we had with the build up of gas (hydrogen?). However, since then, we turned it back to 62 or 63. Can't remember at the moment, but it was one of these two, and this was what we had our old boiler at too.

This is the pressure gauge. It looks to be just under 1.0. When I took this picture, it was the middle of the day, over 3 hours after the heating had gone off. Just like the night, there are still occasional clicks or louder bangs, but usually only a few an hour or even less. But that is a real issue at night as it is louder than anything else by a huge margin. And as I said, this does just seem to be in the pipes rather than the radiators, but the radiators are where you hear the noise more as upstairs, all the pipes are in the floorboards.

After I have checked the pipes above the boiler this evening, I will let you know and then see if I can try the alternative pump options. Though I myself still struggle to see how the pump that doesn't operate when the heating is off can be related to the bangs when the heating is off. Will see though.

 

[John.g]

If the E.vessel is effectively connected into the discharge side of the pump rather than the suction side then when running at the 6M head originally or even the 5M head now then there was/is a very good chance that the system is running under negative pressure in some parts so at least until the E.vessel piping position can be established I would recommend increasing that cold pressure (via the flexible top up hose) from just less than the present 1bar to say 1.3ish max 1.5 as you don't want to exceed ~ 2.3/2.5 bar with a hot system, then regularly vent the system with boiler off and maintain this pressure.
Flow temp anywhere < 65C should be fine IMO.

Banging is strange alright as it apparently only appeared on boiler changeout so difficult to understand why this is, also as it happens hours after normal cool down with pump off, also just ensure that the pump does in fact shut down and isn't running continuously.

All you can do is to address the obvious and the answer to the riddle might manifest itself.

 

[TheGiantHogweed]

If the E.vessel is effectively connected into the discharge side of the pump rather than the suction side then when running at the 6M head originally or even the 5M head now then there was/is a very good chance that the system is running under negative pressure in some parts so at least until the E.vessel piping position can be established I would recommend increasing that cold pressure (via the flexible top up hose) from just less than the present 1bar to say 1.3ish max 1.5 as you don't want to exceed ~ 2.3/2.5 bar with a hot system, then regularly vent the system with boiler off and maintain this pressure.
Flow temp anywhere < 65C should be fine IMO.

Banging is strange alright as it apparently only appeared on boiler changeout so difficult to understand why this is, also as it happens hours after normal cool down with pump off, also just ensure that the pump does in fact shut down and isn't running continuously.

All you can do is to address the obvious and the answer to the riddle might manifest itself.

The first part I have put in bold, I may just need describing what the two heads are.

It is true that we didn't have this banging or clicking at this volume with the old boiler. It used to just be a very quiet and consistent tinkling sound. However, this banging didn't start until after the 2nd time the radiators had been drained and refilled. And on the 2nd refill was when we had f1 protector added, which was when we had this reaction that triggered the build up of gas or air almost every day for most of last winter.

The clicking and banging is much more frequent when the heating is on - sometimes can do it many times per minute for quite some time. But usually, when it does it in the night, it is generally predictable that the clicks or bangs that you hear will be the louder sort. Almost as if something has been building up and it then releases. Hard to describe. It is a loud enough bang to cause vibration, as I was irritated enough that I tried to guess when it would happen, and I held the pipe under my TRV one time as it did it, and you can certainly feel the vibration from the bang.

As none of the pipework under the floorboards has been modified or moved in the slightest, it is hard to understand how the cause of this banging would be related to the pipes moving well after the heating has gone off. Unless it is something to do with the fact the pump makes it cool down so much quicker, that the pipes possibly done contract at the same speed, and end up taking much longer. But I really don't know here.

 

[John.g]

The pump should stop after a few minutes at most after boiler shut down.

Full speed CCIII on the UPS3 is well over 6M and CCII is over 5M, the proposed CPI is a 3M constant head which should do the job pretty well IMO.

 

[TheGiantHogweed]

I appreciate your help, I just am limited as to what I can understand as the graph doesn't mean much to me unfortunately. It is the meaning of the 6m, 5m and 3m that I don't know about.

I'm a slow learner so I may take a while to understand!