Netaheat 16/22 Potterton boiler problem & pump overrun?

MTK

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I have two issues which I think are quite separate:

1. I have a Netaheat 16/22 Potterton boiler which is heating the system but has a firing-up anomaly. When the system requires the boiler to start / fire-up the following happens;
(i) the boiler fan comes on OK
(ii) in one click the ‘pilot’ fires-up OK
(iii) in a big click the burner fires-up, then sometimes there is an immediate click again and the burner flames rapidly rise and fall (oscillate) with repeating clicks, the burner flame never quite goes out and after a few clicks everything seems to run normally.

2. I have a Grundfos Type 15-50 130 circulator pump. When the system is just heating the stored water it seems the pump continues to run for ages after the boiler has stopped (I haven’t measured the time, but could easily be 30mins – maybe more), and continues even if I manually turn the hot-water heating off at the control panel by the boiler. However, if I manually get the radiator heating to come one, even if just very briefly, and then turn off the radiator heating – the circulator pump stops as expected.

Immediately after the pump there is a Honeywell valve at a T junction to switch between (a) the radiator system and (b) the stored hot water. Then on the pipe branch (b) there is another Honeywell valve, this time simply in-line, immediately before the mains-pressure hot water tank.

I would be most grateful for any questions, prognosis or suggestions please.

Many thanks in anticipation.
 
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We do not give DIY advice on gas/combustion issues here.

The advice would be to get a competent engineer familiar with that model.

The two port valve on your unvented cylinder is part of the safety equipment and again should only be touched by someone qualified for unventeds.

Tony
 

MTK

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Thanks for your reply Tony.

I'm sorry, I was unaware of any restriction on advice of likely causes of any problem for the burner firing. I don't want to get a technician in who struggles to remedy the problem and instead gets distracted with trying to repair other items (which has happened to me before). I don't intend to do the work myself either, but I would like to know some expert opinion from here about what I'm facing please.

Secondly, are you saying that I do have a problem with the running of my circulator pump and that there is a restriction on advice for the hot water valves (if that's where you think a problem is likely to arise)? I am unaware that I have mentioned any safety equipment valves on my hot water tank. My reference to the Honeywell valves was to explain the hot water plumbing configuration directly from the circulator pump, I thought they were just part of any usual hot water system.
 
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The boiler is very old and the non Electronic ones were quite complicated. There's an enthusiast's (?) website which is quite interesting but do note what he says and that these things are quite old and will require someone of experience to diagnose them properly.

Regarding the water, are you sure it's not just the boiler cycling on-off? You could have a separate issue of a broken programmer giving you a mis-diagnosis that the pump's overrunning. You need to make sure the tank's got up to temperature when this overrun is taking place and that the programmer output is clicking on/off when required. If you turn the thermostat down on the cylinder during a heating cycle, what happens? Be sure you don't put it back any higher than it was before (should be around 60 or less).
 
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Thanks for your reply Tony.

I'm sorry, I was unaware of any restriction on advice of likely causes of any problem for the burner firing. I don't want to get a technician in who struggles to remedy the problem and instead gets distracted with trying to repair other items (which has happened to me before). I don't intend to do the work myself either, but I would like to know some expert opinion from here about what I'm facing please.

My reference to the Honeywell valves was to explain the hot water plumbing configuration directly from the circulator pump, I thought they were just part of any usual hot water system.

You may not be aware but the site rules are shown in RED at the top of the plumbing topic list. They cannot make them much cleared than that!

There is also a sticky topic headed DIY gas work.

By using the site, you have agreed to abide by the rules and are deemed to have read them!

You may well think that the valve on your cylinder is just part of "any usual hot water system" and indeed they are standard valves but when used as part of the safety equipment for an unvented they are covered under Building Regulations and only qualified people are meant to work on them.

I don't know how your pump is connected so am unable to comment on how its running.

Tony
 
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Thanks for your reply Tony.

I don't want to get a technician in who struggles to remedy the problem and instead gets distracted with trying to repair other items (which has happened to me before).

That's why we recommend that you only call someone who specialises in boiler repairs and is familiar with that model.

Mike, on that link, likes Netaheats and thermal stores. But he has developed a rather unique way of charging for visits according to the distance/time taken which few of us do.

Although in East Reading he is reluctant to go to West Reading! Thas because its close in miles but can take quite a while due to traffic.

Tony
 

MTK

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The boiler is very old and the non Electronic ones were quite complicated. There's an enthusiast's (?) website which is quite interesting but do note what he says and that these things are quite old and will require someone of experience to diagnose them properly.

Regarding the water, are you sure it's not just the boiler cycling on-off? You could have a separate issue of a broken programmer giving you a mis-diagnosis that the pump's overrunning. You need to make sure the tank's got up to temperature when this overrun is taking place and that the programmer output is clicking on/off when required. If you turn the thermostat down on the cylinder during a heating cycle, what happens? Be sure you don't put it back any higher than it was before (should be around 60 or less).

Mike, many thanks for your reply and the link.

I'm not sure whether it's the boiler cycling but I thought it was just the pump running without the boiler running (the pump continues when I turn the water heating off). Also, if I switch the central heating on and then immediately off it causes the (previously running) pump to subsequently stop. Is that usual/normal.

I will need to check what happens if I adjust the tank thermostat.
 

MTK

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You may not be aware but the site rules are shown in RED at the top of the plumbing topic list. They cannot make them much cleared than that!

There is also a sticky topic headed DIY gas work.

By using the site, you have agreed to abide by the rules and are deemed to have read them!

You may well think that the valve on your cylinder is just part of "any usual hot water system" and indeed they are standard valves but when used as part of the safety equipment for an unvented they are covered under Building Regulations and only qualified people are meant to work on them.

I don't know how your pump is connected so am unable to comment on how its running.

Tony

Tony, please accept my apologies. I had read the rules before my original post. I thought the restriction would include not giving guidance on how to fix a problem. I didn't realise it also included discussion on how the problem would develop if left alone, or discussion of likely causes. As I said above, I was not planning DIY work in that area myself. I was not, and am not, challenging the rules of the forum. When I said I was unaware it was just that - nothing more.
 
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That's OK.

Whilst you might not be intending work yourself there are many others who do.

They think that by saying "they have an engineer", their father is gas reg etc. then we will be giving them all the information they need.

Obviously anyone who is gas reg should already know what to do.

In any case the replies are there for anyone else to read and not just whoever started the thread.

The forum rules are quite simple that we don't give ANY advice on gas/combustion matters.

Even if we did then it would just be deleted.
 
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It's usual for the boiler and pump to stop when the heating and hot water are both turned off.

If the pump is still running when both are off or satisfied by room/tank thermostats then you have a problem somewhere.

The boiler will cycle quite a bit when heating the water as the return temperature will be quite high.
 

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