Glow-worm Flexicom problem

J

jimmir

If the flow and return when you run your Central heating are much more than 20*c difference (which I suspect they will be if you know theres no hot bypass water getting back up there) ie a temp difference of 30+ degrees C would be clear that there is circulation issues.
I've run all the hot water out of the cyl but the boiler behaves the same - it reaches 72C and then burner goes off even though cold water is returning.
I understand that slow circulation would cause this and yes that is what Dan first said.

Dan - when you ask "What do you know?" - a helluva lot more than me! I'm a diy guy trying to understand the problem.

I just don't understand where the restriction could be. I've tried a new pump but no difference.

Agile - thanks but I've watched a Glow-worm Ultracom working yesterday which Is also set at 72C and the burner stays lit as it approaches the max temp so continues to put heat into water.
 
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As the boiler is doing the same thing on hot water I would be looking for a blockage in the main heat exchanger.
 
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The burner only stays lit when its providing heat at or above its minimum power output.

So the operation is dependent on the load it can deliver heat to.

If your cylinder is old then its absorbtion will be quite low and probably less than the minimum boiler output thus causing short cycling.

But as I said above the max power setting affects this too.

Whilst you don't seem keen to adjust that, if you want to progress you will need to measure the flow and return temps during the firing cycle.

Tony
 
J

jimmir

Picasso - I understand your suggestion although there has always been a Magnaclean on return to boiler.

Agile - the cylinder is older than I thought so 10 years old. There has always been Sentinel inhibitor in system.

With a cold hot water cyl, the temp quickly climbs to 72°C but he return temp still feels cold to the touch.

I don't understand what you mean by adjust max power setting?
 
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Is that the flow and return at the cylinder?

Have you seen the d40 and d41 readings?

What is the outside of the cylinder made of?

In theory if the two pipes to the cylinder are not within 5-10 C of each other then that can indicate a lack of flow.

Finding a system blockage which is not in the pump is serious DIY work and few succeed.

Tony
 
J

jimmir

Agile - I was referring to the 72°C being displayed on the boiler panel and the return pipe to the boiler being cold near the boiler. I understand that this could indicate lack of flow in that the boiler reaches max temp but can't put the heat into the water because it isn't moving fast enough.

The hot water does reach the cyl coil very quickly (which is a distance of about 10m) so there is flow.

I must read the book again but wasn't sure how to get the d40 & d41 readings.

The cylinder is copper clad with foam which I believe I bought from Wickes when I installed it about 10 years ago.

I am a serious DIY guy and do want to understand this so thanks to everyone for the help.

Paul - Thanks but I have experienced a blocked cold feed on another system but this one definitely isn't.
 
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Paul - Thanks but I have experienced a blocked cold feed on another system but this one definitely isn't.

How do you know?



Like has already been said you can heat things up and down till the cows come home but until you get some accurate readings theres nothing that will help on here. And when you do get the readins and they (likley) are quite far apart then you only will have confirmed a circulation issue. You would still have to find out where the restriction is.
 
J

jimmir

Paul - Thanks but I have experienced a blocked cold feed on another system but this one definitely isn't.

How do you know?
I've just drained the system and the feed/exp tank empties quickly.

Dan - I don't know why you think that? I genuinely have a problem with this new boiler not liking my system. The old boiler was a 35 year old floor-mounted Glow-worm Spacesaver and it looks like it was more tolerant of system definciencies.
Surely that is not an unusual situation?

Thanks for your other comments and it does look like other guys are agreeing with you that there is a circulation problem.

ScottishGasMan - point taken about finding where restriction is, thanks.
 
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Wow, you drain the system which no one has asked you to do.

But you don't want to push a few buttons to read d1, d40 and d41 !!!

We need this information to help you any further.

But don't do anything which we have not asked for.

Tony
 
J

jimmir

Wow, you drain the system which no one has asked you to do.
Tony

Going back a bit, I first became aware of the problem when I switched on the central heating for the first time since last winter and the mid-position valve was stuck. I could move it by removing cover and pushing it across but it would not spring return so I decided to replace it which is why I drained the system.

The new valve operated correctly but it was at that point I realised I had a problem because with the ch cold I expected the boiler to stay firing instead of cycling up to 72°C then down to 44°C

Dan - I've read the notes about reading d40 and d41 but it says I have to put in a code which it does give. I can do plumbing but I'm not a heating engineer and was concerned that I may get locked out if I get it wrong, that's all.

It's honestly not a wind-up but we can leave it here if that's what you think. I do appreciate all the replies including yours and now think you are right that I have a circulation problem so thanks to you and everyone else for your time.
 
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The password is 96, if you give the details of the flow(d40) and Return (d41) temperatures then your questions would be easily answered. I would put money on the Heat exchanger or pump being blocked though.
 

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