Sam's Many Projects
Sunday, 14 January 2018
Ssangyong Rexton Electrochromatic Mirror Install
Sunday, 4 September 2016
HRM Wallstar - capacitor replacement
So let's get inside the boiler and have a look. First things first, turn off the power supply to the boilerat the switch. We then need to go outside and remove the front cover by slackening off the four screws on the sides of the cover and lifting it up and off
It's best to check if there is any stored energy in the capacitor, so set your multimeter to volts AC and put it across the terminals, you are expecting a reading close to zero. You can discharge it with a resistor, or by shorting it out with a screwdriver as long as there's not too much voltage in there.
With your multimeter set to capacitance, put the two probes on the capacitor terminals.
Any sort of 3uF 400v motor run capacitor should be OK, most newer ones seem to be plastic cased rather than aluminium though. This shouldn't be an issue as the operating temperature ratings are the same, I was however worried about using a Chinese eBay special so opted for an AEG branded one which matches the motor. The ones from oil boiler parts sites seem to be stupidly expensive, upwards of £20, whereas mine cost £11. Plastic chinese ones can be had for around £3-4. I decided to test it before fitting, and it measured 2.99uF which is within the parameters.
Removing the old one is far more difficult than it should be in my opinion, for what nowadays is considered a service item. The motor has to be removed, and to remove the motor, the high pressure fuel line has to be removed. I believe technically this means you should be OFTEC registered, as I'm working on my own system and feel fairly competent having spent many years maintaining diesel engines, I decided to have a go anyway.
The top union came undone with a 15mm spanner, and the smaller union on the side of the oil pump needed an 11mm spanner. I suspect they are probably imperial size, but these were a close enough fit. With this removed, keep this safe and make sure it definitely won't get any dirt in it, wrapping it in a lint free cloth would be a good idea.
You can now access the two bolts securing the motor to the burner casing, they are located at 2 o'clock and 8 o'clock, and require a 4mm allen socket/key.
Pull the motor away from the burner casing and lay it down, be careful of the flexi oil pipe. The capacitor is secured to the motor lug with a 13mm bolt. I hadn't realised this, and mullered my old one trying to get it off, so here's a picture of the new one fitted instead.
The motor can now be fitted back into place and the two allen bolts tightened back up. The high pressure oil pipe can be refitted, taking care to nip it up tight but not too tight so you strip the threads.
I believe only the early style units used small width terminals on the capacitor, rather than the more common 6.3mm spade terminals (commonly known as 'red' spade crimps). As I had an early unit, I had to swap the terminals, fortunately I had the kit in the garage to do this.
I cut off the old terminals, stripped back some of the insulation, and crimped the new terminals on. As the cable is so thin, I had to fold it back over on itself so it fitted snugly in the crimp. It's always best to give them a little tug test to make sure they have crimped down properly
That's it, all finished. Stick the cover back on the burner, and the test mode switch can be operated to force the boiler to run. Turn the power on and make sure it runs up. Don't forget to push the switch back over again before putting the outer cover back on.
Fingers crossed this will cure the problem of the boiler locking out first thing in the morning, but only time will tell....
PS - you may have noticed the air box has been removed in some of the pictures, this is from when I was still trying to figure out how to remove the capacitor! There is no need to take it off though if you follow the steps above.
HRM Wallstar - control box swap and spark generator transformer inspection
So let's get inside the boiler and have a look. First things first, turn off the power supply to the boiler at the switch. We then need to go outside and remove the front cover by slackening off the four screws on the sides of the cover and lifting it up and off
The control box will be obvious on the front of the burner, it has a small screw holding it in place, and then just pulls out.
The spark generator transformer is located behind the wiring base located behind the control box, which can be removed by undoing the two allen bolts.
Once these are removed you can push the wiring base out of the way and pull the spark transformer out to check for deformities or the tell tale bump, fortunately my unit was fine.
A visual inspection of the Satronic TF 830B indicated that it's likely this is the original unit, which would have been installed in 1997, so it has had a pretty good innings. As far as I know there's no real way to test these units, and most people (including engineers) just try swapping them and seeing if the problem goes away.
It turns out there is a later control box, the Satronic DKO 970 which is pin compatible with the TF 830B. Apparently the issue of destroying the Danfoss EBI doesn't happen with this later version, so I started hunting round for one, and managed to pick one up for a sensible price on eBay.
On checking the wiring diagrams for both units, it appears the DKO 970 also has an extra pin which gives the ability to wire in an external reset button for the lockout function, which would be incredibly handy considering how inaccessible the current one is. It also has a feature to give flash codes to give the cause of the lockout. You can see from the pictures, the DKO unit uses plastic cased relays whereas the older unit uses open relays which I imagine are more prone to dirt ingress and failure.
To swap the spark transformer, follow the above procedure to gain access to it, then disconnect the existing one from the wiring base, and wire the new one up, then refit is the reverse of removal. To swap the control box, it's just a case of following the disassembly procedure to inspect and remove the old control box, push the new one into place, and tighten the screw.
Once done, we need to fire up the boiler and check everything still works. I decided to prove the lockout function by removing the photocell so the control box would not see a flame.
Once this was done, I turned the power back on and operated the override switch at the very bottom of the unit which forces the boiler to start. As expected, the unit went into lockout quickly. With the photocell back in place, I pressed the reset button the control box, and it fired up fine. Last thing to do is to turn the power back off, put the override switch back into its normal position, and put the covers back on before turning the power back on.
I will write a future guide on how to add a remote lockout indicator/reset to the front panel of the boiler on the inside, which is much easier to get to. I've got big plans for the winter to rig up a Raspberry Pi to alert me when the boiler goes into lockout, which will hopefully stop the big surprise of cold water in the morning when you expect hot!
Parts required to do this:-
Honeywell Satronic DKO 970 control box
Danfoss EBI4 spark generator transformer - cheapest I found was on eBay so have a look there
Friday, 2 September 2016
Nest thermostat installation and review
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| Danfoss Y plan wiring diagram |
| First wiring attempt |
| Second attempt, with ferrules, much better |
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| Nest app overview |
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| Hot water schedule |
Wednesday, 31 August 2016
Replacing toilet flush and fill valves
Close coupling kit
Cistern blanking plug
300mm flexible tap connector with isolator
PTFE tape
15mm pipe slice
Installing a wall mounted TV with hidden cables
1x 2 gang dryline box
1x 1 gang 2 module faceplate
1x 2 gang 4 module faceplate
2x flex module
1x aerial module
Monday, 29 August 2016
Welcome...
I've set up this blog to keep track of the various bits and pieces I get up to. I've got a few things on the go, a Land Rover Defender, a Sinclair C5, and a house in rural Lincolnshire that I've just moved in to.
I've got big plans for all of the above, and haven't had time to do the things I enjoy doing (i.e. my many projects) until recently, thanks to a busy job and having to totally renovate my previous house. Both brought considerable experience, but now it's time for something a bit different.
The intention is that posting this in a blog format will allow people searching for information on how to do similar things to come across it, and hopefully it'll help someone out.
I've done a few bits to the house already, so there will be some retrospective posts with not many pictures of the before/during.
I hope some of this will be of use to someone out there!
Cheers,
Sam









