Glow Worm Ultimate overheating/cutting out

[canetoad]

Hi, I just joined this forum and have searched for other posts that may help but I'm still not sure what exactly is the problem.

Firstly I noticed the boiler wasn't on (no hot water). I got an engineer to come out and take a look at it. He serviced it (I service it once a year) and found that the pilot starter was shorting out on the chassis. He wrapped the wire it in some insulating tape and the boiler started OK.

I called him back a few days later because the radiators weren't getting hot. He diagnosed a dodgy pump, which I had him replace. It took ages to get heat at the radiators as there was an air lock in the system after fitting the new pump. Job done and sorted. Anyway, now I am having a problem with the overheat tripping out. I had them back to test and the guy said it was probably air in the system and that boilers that don't have cast iron tanks can do this a lot. That's fine but when I checked my boiler has a cast iron tank. Anyway, to cut a long story short, I bled all the radiators but I still have the problem that it overheats intermittently. I also notice there is some gurgling coming from the boiler occasionally.

Anyway, should I replace the pilot starter because it was shorting through the insulation? If so, can somebody tell me what part to order?

Would air still trapped in the system be causing the intermittent overheating/shutdown problem? Should I just keep bleeding the system regularly to get out all the air? If so, what is the best way to isolate and remove any air, other than just bleeding all the radiators?

One other item I wanted advice on. The little plastic fan broke off and the engineer told me it's not really needed. Is this the case or should I replace it?

Sorry to be long-winded but the system has been trouble free to this point and I have my doubts about the competence of the engineers involved. Any help would be greatly appreciated.

 

[gas4you]

I wouldn't worry about the ignition lead.

You could still have air in the system, or perhaps a lack of water.

Check the f&e tank in the loft is full (the small one). If it is try draining some water from the system and see if the f&e fills at the same time. If it doesn't you have a blockage.

Only you can judge the competence of the engineers you have had out.

 

[Agile]

Can a G-W Ultimate really have a cast iron heat exchanger?

Or is it the model where the cover squeezes the HT lead until it sparks to the case?

Tony

 

[ChrisR]

Can a G-W Ultimate really have a cast iron heat exchanger?

Yes!

Trapped air and overheating are problems in many old (sludgy) systems. Pipework layout is often partially to blame. It can take a couple of weeks for air to work its way out of aerated water.
It's likely to be worse where the pump's on the return to the boiler, rather than the flow from it.

No evidence to condemn your plumber from what you've said!

 

[canetoad]

The tank in the loft is full. Engineer left cover and insulation off though. I'll take advice and drain some water from the system and see if it refills correctly.

I have since re-bled all radiators and some still had a bit of air in them. I'll continue to do this and see if it helps. The system currently cuts out about once every 5 or 6 days. It was originally doing it almost every day so it is improving.

Thanks for the replies.

 

[canetoad]

Further to the problems I was having:

I've checked and the system isn't losing any water.

The boiler is still shutting itself off every day while I'm at work. It was fine all summer without the heating being used.

On investigation when the pump starts up the slave radiator in the lounge would start to gurgle and fill up with air almost immediately. It seems to be the first radiator in the system after the pump. I could bleed off a heap of air every 10-20 minutes. I went upstairs to the airing cupboard and waited for the pump to start and could hear air being taken into the pipework through the one-way air bleed valve next to the tank. I closed the screw lid on it and this seemed to help.

There is still air getting into the system. I've treated it with Sentinel 100 just to be sure it isn't from corrosion but the problem still exists.

It's only been a problem since the pump was replaced. Can a pump have faulty seals and suck air into the system somehow? Could it be a build-up of sludge in the system causing a pressure problem?

It works fine as far as flow goes compared to the old one. I'm a bit dubious that it was new when it was put in the more I think about it. Would putting in a new pump be worth trying? The tosser at the company who installed it has told me he's not interested in my business even though the pump has been in for less than 12 months. I have a day off tomorrow. I might go and speak to him in person and see if he changes his mind with my boot jammed up his arse!

Can anybody shed any light on the problem?

I'm going to turn the pump down tonight to 1 (currently on 2, max is 3) and see if this helps.

 

[Agile]

If the system is properly configured then it should run fine on setting "2".

Putting it on "1" will slow down any expulsion of air.

I dotn go back either to any customers who want to kick my ass! But then I try to ensure they are completely happy.

Tony

 

[canetoad]

He didn't refuse because I was going to kick his arse, he refused which made me want to kick his arse! He basically wasn't interested at all in helping me sort the problem.

I switched the pump back to 1 and it has been running fine all weekend. I'll see if it shuts down today while I'm at work.

Next spring I'll give the system a good flush as sludge buildup may be causing back pressure problems when the pump is set to 2.

I'm from the tropics so central heating is pretty new to me. Sooner or later I'll sort it out without the help of incompetant/apathetic professionals.

Thanks for the help just the same.

 

[canetoad]

He didn't refuse because I was going to kick his arse, he refused which made me want to kick his arse! He basically wasn't interested at all in helping me sort the problem.

I switched the pump back to 1 and it has been running fine all weekend. I'll see if it shuts down today while I'm at work.

Next spring I'll give the system a good flush as sludge buildup may be causing back pressure problems when the pump is set to 2.

I'm from the tropics so central heating is pretty new to me. Sooner or later I'll sort it out without the help of incompetant/apathetic professionals.

Thanks for the help just the same.

 

[Agile]

"""Australia’s most notorious and resilient pest, the cane toad, has been known to poison snakes, birds and even kangaroos — but a chilly day will stop it in its tracks, a new study by the University of Melbourne suggests.

The toads, introduced into Australia in the 1930s for pest control, have steadily advanced across Australia, conquering Brisbane and Darwin in the north, and hopping south towards Melbourne.

Michael Kearny’s study, published in the journal Ecography, centred around a two-metre sprint event for toads collected from four populations across the invasion front, conducted at a range of different temperatures. “We found that cane toads can barely hop once the get below about 15 degrees Celsius,” Dr Kearny said. In wet and warm Darwin, toads can hop more than 50km (30 miles) a year. But in cooler, drier Sydney and Perth, toads can barely manage 1km, and in Adelaide, Melbourne and Hobart they fail to get off the starting blocks at all. """

So you will not be doing much arse kicking if the heating is not working!

Tony

 

[canetoad]

So you understand my dilemma...

 

[Agile]

Pump connections can suck air in and particularly if they are on the return side of the circuit.

Shaving creme will usually show up any air being sucked in through a dodgey joint.

Tony