Glow Worm Boiler - British Gas 330 Fault Code Issue (long)

[b1ffb0ff]

Hi

I have the above boiler, i recently installed a Honeywell Evo system on all rads. So i now have control over all rads and hot water.
We recently moved in so have no benchmark of operation before i made the change.

I am not a Proff plumber but have done plenty of plumbing on past houses, including soldering etc, got my own kit have had for over 10years. I am a sparks, not Part P and likewise when we have done building work i have done my own electrical and notified Building Control and presented test reports of the related work, so am not a complete numpty

When i first swapped to Evo (great system by the way!) the overheat stat would operate and i would have to take the cover off and reset it, as the Bypas is only a few feet in length, next to the boiler and was wound quite tight. So in the summer if i only had one rad calling for heat, i guess the boiler could not shift enough heat in time, i guess if evo shut down when it was just powering up, it had no place to go. I slackened this so as it would bypas but not prevent far rads form getting hot. Problem has not reoccurred and rads are still getting nice and hot. I do intend on extending the bypas to the recommended 5m in eth manual. The HW and CH zone valves are right next to the boiler, hence why the bypas is so close i guess.

Anyway, the above is a bit of background. Now winter is setting in, the boiler has tripped of twice in the last week with a new f26 fault. maximum Delta temperature.

What are the possible causes here please?

I did balance the rads, by touch alone some time ago over the period of a week. I even took note of turns for each lock shield. Eventually i got it so the farthest rads would get hot at the same time as all the others. Balanced.

Could the problem be related to all the returns being wound to tight? In other words all open enough to work, and to be balanced, but not quite enough for a good flow? If i moved all lockshield open another half a turn, might this help?

I have flushed (not power) the pipes, before I fitted the Evo. All rads have been removed, and flushed out - i had to fit new TRVs and loickshields so should not be sludge related.

It is a new cylinder too.

Also have a magclean 28mm on the return, that gets thin films of magnetite on but not big gobbets of the stuff.

I have an inhibitor in also and it is a pressurized system, sitting at just under a bar (2 story house)
The boiler did have a new heat exchanger and a new modulating pump. The pump is not set to modulate though, it is on setting 3. When we moved in i took out a policy with the manufacture, they came out and did the exchanger and pump, and also upped it to 30KW as it was on lowest setting (4 bed largeish house).

If you stayed the course and read all that lot, i thank you for your time.

Cheers

John

 

[Agile]

Is the heat loss of the house REALLY as high as 30 kW ?

Who calculated it?

Tony

 

[petit_pablo]

Id say your boiler is over powered at 30kw for a start. Most 330s get put in at 18kw as standard.

The heats not leaving the boiler quick enough so you either have a lack of circulation or too much heat.

 

[b1ffb0ff]

Thanks for the replies so far. It sized according to the number and size of rads it is feeding, if they were all turned on together.

What are the thoughts about lock shields. They are standard Honeywell lockshileds, all new. Closest rad is shut down to 1/4 turn from closed, while furthers rad is set to 4.5turns form closed. If i moved them all on about half a turn, might that make a difference to circulation?

As i said, i have a drawing which shows the house plan, location of rads and number of turns on the lock shield.

Thanks in advance

John

 

[The831Bunny]

A quick rule of thumb is to allow an average of 1.5Kw per radiator. Not seeing your property and circuit design makes it slightly difficult, but experience says that even a large 4 bed detached is usually 16-20 KW max. Modernish build with double glazing and insulation up to spec could even be as low as 10-14kw.

 

[b1ffb0ff]

Hi, there are about 15 rads in the property. Early 80s build.

I am going to phone the manufacturer today to check how the boiler determines this type of fault. May help me understand what the issue is better.

I am pretty sure it is related to EVO in some way, i just need a better understanding of what conditions the boiler must see to trigger this fault code. Saying it is a restriction is not enough, otherwise the thermistor would be tripping out as well, as heat cannot get away from teh boiler.

Re the KW rating, i guess today it is not so important, as the boiler modulates to demand / setting on panel and return temp? It will only burn what it's sensor tell it it needs?

Cheers

John