- Joined
- Nov 28, 2009
- Messages
- 14,762
- Reaction score
- 951
Grant Vortex outside combination oil fired boiler.
Called to fix it after the plumber tried and failed.
Burner not firing at all.
Now back in the day, on these boilers the burner was fired via a thermostat with a capillary bulb. It was also overridden by the hot water flow switch to fire the burner all the time hot water was drawn.
Fast forward to 10 years ago when this one was built.
Now there's a printed circuit board. It takes an input from a thermistor (replacing the capillary bulb) and compares that to a set point from a potentiometer and turns a relay on or off.
The board looks simple, so lets do some fault finding. I find a 5V regulator is U/S so I replace it. 5V power now okay, but still not working. The heart of this little board is a PIC chip, i.e a programmable device, so without the program and the tools to program it, I can't fix it.
[rant #1] Why design something with a programmable device when a simple off the shelf comparator would do [/rant #1]
So I start looking for a replacement.
FFS £72 plus VAT plus a rip off £25 postage because i'm up near the Arctic circle (or so they must think)
[rant #2] why can't they post it via royal mail for under £5 [/rant #2]
So a bit more searching. I find a newer version of the same board. It has all the same connections, and is the same size, but uses different components, but this time £50 with free postage (from flea bay)
Looking at it, this new one is even more complex. It looks to have a switched mode power supply with a tiny little transformer now, and a more complex surface mount controller.
[rant #3] When your first design was already overkill for the task, why design an even more complex, even less serviceable replacement? [/rant #3]
If this was my own boiler, I would be fitting a capillary thermostat in the thing, but as it's a customers I don't want to be seem modifying it, so I I'll go for the £50 board.
I see a business opportunity here for someone so inclined. Reverse engineer a compatible replacement and churn them out for £30 a go, which should still give you a healthy return on the less than £10 worth of components used.
Called to fix it after the plumber tried and failed.
Burner not firing at all.
Now back in the day, on these boilers the burner was fired via a thermostat with a capillary bulb. It was also overridden by the hot water flow switch to fire the burner all the time hot water was drawn.
Fast forward to 10 years ago when this one was built.
Now there's a printed circuit board. It takes an input from a thermistor (replacing the capillary bulb) and compares that to a set point from a potentiometer and turns a relay on or off.
The board looks simple, so lets do some fault finding. I find a 5V regulator is U/S so I replace it. 5V power now okay, but still not working. The heart of this little board is a PIC chip, i.e a programmable device, so without the program and the tools to program it, I can't fix it.
[rant #1] Why design something with a programmable device when a simple off the shelf comparator would do [/rant #1]
So I start looking for a replacement.
FFS £72 plus VAT plus a rip off £25 postage because i'm up near the Arctic circle (or so they must think)
[rant #2] why can't they post it via royal mail for under £5 [/rant #2]
So a bit more searching. I find a newer version of the same board. It has all the same connections, and is the same size, but uses different components, but this time £50 with free postage (from flea bay)
Looking at it, this new one is even more complex. It looks to have a switched mode power supply with a tiny little transformer now, and a more complex surface mount controller.
[rant #3] When your first design was already overkill for the task, why design an even more complex, even less serviceable replacement? [/rant #3]
If this was my own boiler, I would be fitting a capillary thermostat in the thing, but as it's a customers I don't want to be seem modifying it, so I I'll go for the £50 board.
I see a business opportunity here for someone so inclined. Reverse engineer a compatible replacement and churn them out for £30 a go, which should still give you a healthy return on the less than £10 worth of components used.
