Potterton Kingfisher Mf CFL 70

[spraggo]

[quote="stevecaner3546";p="1851972"

All joking apart - I asked if a faulty aps (air pressure switch?) could cause this and was laughed down at the suggestion.

Steve[/quote]


All joking apart if it were a faulty APS the pilot would not ignite.
I have told you the possible problems which can be checked out by a competent electrician.

 

[stevecaner3546]

Simple? That's what I thought then it got too cold so I called in an "expert(?)" but You also seem to think that you are also an expert - Tony

I am not an expert in as much as a heating engineer but I am also not stupid either.

I had another so called "heating engineer" look at my system yesterday and again he said that there was nothing wrong that her could see. Ok! But without shouting me down or telling me to xxxxoff please answer this......

This is a fully pumped system with 2 x electric valves. As I understand it each of these valves when opened has a feed to the pump to circulate the water in the 2 systems?

When the water in the tank is at the correct temperature the tank stat closes the HW valve and the pump should stop (providing the CH valve is not open) and likewise, if the CH is at correct temperature that valve should close and the pump should stop (providing the HW is also at the correct temperature).

Now, please bear with me on this, if the CH valve is faulty in as much as there is no feed to the pump when OPEN - and - the HW is at the correct temperature thus closing the HW valve and (theoretically) switching off the pump feed there will be no water flowing in the CH system because the pump will be off.

The boiler, on the other hand, is OFF because the temperature of the water INSIDE it (remember no pump running therefore no circulation) is at the boiler stat setting. As the water in the boiler cools slightly the boiler stat will ignite the burners and heat the boiler water again - 3 mins??? - and then switch off.

If you can follow this - is it possible that a faulty CH valve pump feed could cause this "no heating" problem after the system has been running for a couple of hours and no HW is being used like during the evening (this is when it happens) when watching TV or when we are out etc?

Taking a chance I know but if this is going to be fixed I feel the only way is to become a dammed expert or have my theory confirmed or thrown out by one.

I know the system is about 20 years old except for the new controller, pump and boiler but could my theory cause this weird occurance?

System seems normal now - wife cooking dinner and washing up etc. I know it will play up about 21:00 when the HW isn't being used.

Steve

 

[spraggo]

[I am not an expert in as much as a heating engineer but I am also not stupid either.

Steve

Hi Steve
You seem to have over looked the fact that the pump gets it`s feed from a permanent live feed going into the boiler through a pump overrun switch. Thus when ever the boiler is running the pump is also running, when the boiler reaches temperature the boiler will cut out but the pump will continue to run to get rid of the heat from the boiler through a bypass fitted before the flow to the motorized valves. Once the boiler cools down then and only then will the pump stop. You say that the system is 20 years old, is it possible when the present boiler was installed that it was converted to a fully pumped system but the pump feed was not connected to the boiler?. Also as I have already stated if the pilot is lit but there is an intermittent main flame the fault has to be either the gas valve or PCB. Do you have the installation manual for the boiler?

spraggo

 

[twgas]

You're not quite right with how you think your system works. The usual operation is, when either valve opens, it closes the end switch which sends power to the boiler for it to fire, some boilers control the pump and some have the pump and boiler wired to start and stop together.
If the boiler gets to is set temperature the burner will stop but the pump will continue to run. Only when both valves are closed will the supply to the boiler be cut, as will the pump supply if there is no overrun on the boiler, if there is the pump will continue for a preset (by the boiler maker) time OR until the boiler has cooled to a certain temp.

 

[stevecaner3546]

[I am not an expert in as much as a heating engineer but I am also not stupid either.

Steve

Hi Steve
You seem to have over looked the fact that the pump gets it`s feed from a permanent live feed going into the boiler through a pump overrun switch. Thus when ever the boiler is running the pump is also running, when the boiler reaches temperature the boiler will cut out but the pump will continue to run to get rid of the heat from the boiler through a bypass fitted before the flow to the motorized valves. Once the boiler cools down then and only then will the pump stop. You say that the system is 20 years old, is it possible when the present boiler was installed that it was converted to a fully pumped system but the pump feed was not connected to the boiler?. Also as I have already stated if the pilot is lit but there is an intermittent main flame the fault has to be either the gas valve or PCB. Do you have the installation manual for the boiler?

spraggo

I have this sneaky feeling that the guy who installed the original system was a half wit as opposed to a complete fool.

The original boiler was a potterton with a manual constantly lit pilot and no electronics whatsoever. The guy that installed this one was Ok because it worked but I don't think the pump is wired to the boiler. The reason for this is that as a fully pumped system I should be anle to run CH & HW separately or together and times independently but the boiler will ONLY light when the HW is on and NOT when the CH is selected,

So it appears that it is wired as a gravity system and has been converted by this DIY owner before the guy before us to what resembles a fully pumped syste,

This was possibly done because, I believe, gravity tanks with the long internal heat exchanger running from bottom to the top were becomming increasingly difficult to find as replacement tanks about 25/30 years ago - well this is what I found out when mine went kaput when I lived in London. This guy could have bodged the system into a fully pumped system without swapping the electrics over as you described.

The worrying bit is the boiler not lighting in mode16 CH only but only with the HW on at the same time. Setting the controller to mode 10 cures this problem but not the spasmodic non ignition after abot 2 hours during the evening.

Steve

 

[misterdubya]

5 pages

Mr. W.

 

[twgas]

Don't know if this has been asked of you, but do you have the means to test for electricity at the junction box(s)?
You're assuming the wiring is wrong, while in fact, there could be a broken component. Which will need some tests to diagnose.

 

[spraggo]

5 pages

Mr. W.

Good fun, why don`t you join in

 

[spraggo]

[I have this sneaky feeling that the guy who installed the original system was a half wit as opposed to a complete fool.

Steve

I am beginning to think that the guy who installed the original system was you.

 

[twgas]

68 posts and not once have you answered a question without prattling on. What is wrong with YES or NO.

 

[stevecaner3546]

5 pages

Mr. W.

I need help and advice not amature comedians.

 

[stevecaner3546]

[I have this sneaky feeling that the guy who installed the original system was a half wit as opposed to a complete fool.

Steve

I am beginning to think that the guy who installed the original system was you.

The system was installed about 1980 ish. I was living in South London at that time and only moved down here in 1998. I inherited an old potterton, clock type controller and a pump with a built in bypass.

When th eboiler was changed and new pump fitted (6 years and 2 years respectively) I was working so had spare cash and employed somebody to do the job. I would NOT attempt to fit a boiler or pump as I am not corgi registered and the latter means draing the system and refilling and big spanners etc.

 

[Nige F]

5 pages

Mr. W.

I need help and advice not amateur comedians.

Typical Londoner`s answer - our family moved to Sussex in 1900. Just about accepted now . Plenty of Croydon reject plumbers around to call @ your house - But you have to pay them - This is Free Good Comedy Club in Brighton

 

[misterdubya]

I need help and advice not amature comedians.

You need to act on the advice your given and not:

1, keep veering off on a tangent.
2, suggest idea's to qualified trademen that you've read in the readers digest.

PCB comes in as a last resort on the Potterton fault finding list

It did for the Potterton Suprima aswell.

Mr. W.

 

[stevecaner3546]

I need help and advice not amature comedians.

You need to act on the advice your given and not:

1, keep veering off on a tangent.
2, suggest idea's to qualified tradesmen that you've read in the readers digest.

PCB comes in as a last resort on the Potterton fault finding list

It did for the Potterton Suprima as well.

Mr. W.

Obviously you mistake the question of asking here if the DIY book's suggestion is a valid one with the idea that I am actually suggesting this to a tradesman standing in front of me.

I wouldn't suggest anything to a "tradesman" but I dammed well want to know if I am being ripped off.

I feel I now know a lot more about central heating than the guy that put my boiler in 6 years ago and the "tradesman" that told me it was working OK when it clearly isn't.

In answer to the other question - I can and I am able to test things electrically and electronically and if need be mechanically.

And, as you well know, often the YES/NO is not a correct answer as 90% of the time a BUT comes into the equation. Not everything is black and white. As I say the system is working OK most of the time and then it throws a wobbly so is the answer to the question "does it work" cannot be YES or NO more likely SOMETIMES.

At this moment in time (or now) I am looking at a wiring diagram for a fully pumped system mode 16 based on the system I have. Later today I intend to check for power from the two 2 port valves to the boiler/pump circuit as has been suggested.