Boiler kettling - Glowworm Fuelsaver F

[Docbill]

Boiler: Glowworm fuelsaver F45

Symptom: Once up to heat, boiler runs for 30sec -minute then turns off as is overheating.

Actions: 1 Have drained the system several times and each time added stronger cleaner, Fernox, sentinal , Wickes own, the final was Fernox Ds40 - citric acid. No improvement.

2 Have just spent several hundred pounds having the system powerflushed with water and magnet cleaner. The engineering added Fernox f2 the week before to pre-treat - when compared to the videos on line not much really came out - the magnets were ringed rather than fully coated. So happy system is as clean as it can be. Also changed the 3 way valve and added a Fernox omega filter.

However, the problem persists. The engineer now says it is the heat exchanger but he will not investigate it further and is recommending a new boiler.

I live near the South Downs in Hampshire so water is very hard, so probably the heat exchanger is full of calcium deposits?

The boiler is 30 years old (has not been run hard - I am comfortable at 16'-18') and the part is obsolete so replacing it is probably not an option. So can it be cleaned - whilst in situ or remove it and clean with descaling acid outside? Are there any filters which may be blocked?

Can anyone suggest another solution or better still is there any one in south Hampshire, woth experience of this who can come and provide a solution.

Here's hoping!

 

[Mottie]

I'm no heating expert but I t does sound like you are chucking good money after bad. 30 years old? If parts are obsolete, it may be time to cut your losses and fit a new boiler?

 

[ianmcd]

new boiler time and fit a scale reducer at the same time if you are in a hard water area, and dont expect your replacement boiler to last 30 years

 

[Docbill]

Thanks for taking the time to reply.

I was however looking for help with finding some experts in my area. I have contacted Glowworm and asked them to confirm the part numbers and suggest an expert but sadly have had no reply.

Changing boiler is not possible at his stage without significant rework of the system - apparently my existing boiler exhaust comes straight out of the side of the boiler and unfortunately the new ones only come out of the back or the top. So this would result in a complete re-do of the kitchen which I do not have time or funds to do.

 

[fixitflav]

Symptom: Once up to heat, boiler runs for 30sec -minute then turns off as is overheating.

Does it re-start after cooling a while? Or does it need a manual reset? If the latter, it could be the control-stat faulty. It's a "filled system" and sometimes the working fluid leaks. Not hard to replace, if you can find the part I guess your plumber would be happy to fit it.

 

[ollski]

What happens if you turn the boiler stat down to number one?,they do go out of calibration and the scale in the hi can prevent accurate temperature sensing especially after 30 plus years

 

[Docbill]

Thanks. Boiler relights once it is a bit cooler. Last engineer will not touch it as the heater unit has asbestos. As for the stat knob I will try it and see what happens. I generally have it between 3 and 4, 5 is highest. Can it be recalibrate? The last engineer said to try a new pump, old one is grunfos USB, and will be over 20 years old, but appears to be working, but will a newer one push the water around better?

 

[fixitflav]

Thanks. Boiler relights once it is a bit cooler. Last engineer will not touch it as the heater unit has asbestos. As for the stat knob I will try it and see what happens. I generally have it between 3 and 4, 5 is highest. Can it be recalibrate? The last engineer said to try a new pump, old one is grunfos USB, and will be over 20 years old, but appears to be working, but will a newer one push the water around better?

If when the boiler's firing you turn the control-stat down till it clicks , does it go out? And then fire again when you turn it up again? (with a fair bit of hysteresis). If so it's basically OK. If the fluid has leaked out boiler only stops when turned right down, which opens the contacts with no help from the diaphragm.

 

[Docbill]

Thanks very much. I will try this later this weekend and let you know.

 

[fixitflav]

Thanks very much. I will try this later this weekend and let you know.

And does it need manual reset?

 

[Docbill]

No manual reset. It just keeps cycling-- turn on , “overheat”, switch off, cool down a bit and switch on etc. When I say cool down I guess that the pump has pumped some cooler water into the boiler? I have never done a manual reset, how is this achieved?

 

[fixitflav]

No manual reset. It just keeps cycling-- turn on , “overheat”, switch off, cool down a bit and switch on etc. When I say cool down I guess that the pump has pumped some cooler water into the boiler? I have never done a manual reset, how is this achieved?

OK so it doesn't sound like failure of the control-stat.
Manual reset needed if the boiler trips out on the lmit (overheat) stat. Usually a button pops out, and you click it back in.

 

[Docbill]

Thanks.

Have fitted a new Grundfos Alpha pump. No real change. However, the old pump was original so the same age as boiler. The pipes were approx 1/3 blocked with baked on limescale/ other. I believe therefore that it is likely that heat exchanger could be the same.



To summarise, have changed pump and three way valve and powerflushed. Used a whole pack of DS40, X400 and numerous other cleaners none of which appear to have touched the baked on limescale. So only option left is to find a properly experience heating engineer in south Hampshire to come out and remove heat exchanger and apply spirit of salts to the heat exchanger. If anyone can recommend a person please let me know.

 

[JohnD]

It may be worth adding Sentinel X200

This is not an acid, it contains a chemical that limescale will dissolve in. You add it to the circulating water and don't drain it out.

I had great doubts before I tried it but it does seem to work. It may take a couple of weeks, and you may need more than one litre.