HRM Wallstar - capacitor replacement

Another possible cause of my early morning lockouts is the motor run capacitor. This is used to keep the motor running, and if it's faulty it can result in the motor running too slowly, which consequently results in lower oil pressure, which can cause a lockout.  With a digital multimeter it's very easy to test.

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

Next step is to unscrew the red burner cover which has a single plastic screw holding it in place

With the cover off, you can see the capacitor to the side of the motor, with a plastic cap on it.

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.

You will then need to remove the connectors on the terminals, I believe you only need to do one, but removing both theoretically will give a more accurate reading.

With your multimeter set to capacitance, put the two probes on the capacitor terminals.

My capacitor is rated at 3uF +/-5% as indicated in the casing, and I measured it at 2.52uF, which is outside these parameters. It looks like the original from 1997 so it has had a good run.

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

With the proper terminals now in place, they just push on to the capacitor, followed by the plastic cover.  The cover didn't fit as well as before, owing to the longer terminals, but it does the job of protecting the terminals against fingers or other conductive things touching them and shorting it out.

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

I have been having issues with my HRM Wallstar oil boiler locking out, usually first thing in the morning.  One of the common issues that was mentioned is the control box.  This sits inside the burner unit under the outside cover of the unit, and has the lockout reset button on it. I had also read that the TF series control boxes had a tendency to destroy the Danfoss EBI spark generator/transformers on these units.  This is indicated by the transformer casing being deformed and having a 'bump' at the top.

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

Next step is to unscrew the red burner cover which has a single plastic screw holding it in place

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

Nest thermostat installation and review

Out here in the sticks we haven't got mains gas, so the heating and hot water is supplied by an oil boiler. As this is a finite resource in the sense you have to keep some oil in the tank, I wanted to keep it as efficient as possible.  I researched a number of smart thermostats, and eventually settled with Nest. I liked the Honeywell Evo setup with smart TRVs but the cost was prohibitive in my opinion.  The original setup was a programmer and room thermostat and I was struggling to get it to work properly.

My system is a Y-plan, with a wiring junction box in the airing cupboard. It was wired pretty much exactly the same as the below diagram. Although I have a lot of electrical experience I'd never worked on heating systems and always had a combi boiler so it took a bit of head scratching!

Danfoss Y plan wiring diagram

First things first, I turned off the supply to the heating system. As the room thermostat in the nest system connects wirelessly to the heat link, rather than being hard wired in as before, I needed to modify the wiring to bypass the room stat. This meant removing the feed to the thermostat from pins 2, 4 and 5 and then moving the feed to the mid position valve from pin 5 to pin 4.  Unfortunately I didn't have enough spare cores (only 1) between the heat link and junction box, so couldn't make use of the facility to supply the nest thermostats power from the heat link. This wasn't a problem as it comes with a USB Power supply.

Once this was done, I connected the heat link up. I originally intended to fit it in the same place as the previous programmer, but as it was on a tiled kitchen splash back, I instead joined the cables through and fitted it next to the boiler. I found the terminals quite small and fiddly in the heat link, and struggled to get them in, probably because I was using the existing 1mm solid cables. As I had the kit, I used ferrules on the ends to make things easier as I struggled to get a proper connection on the ones with 2 cables in.  Pictures below show my first attempt followed by the second attempt which was much neater.

First wiring attempt

Second attempt, with ferrules, much better

With all the wiring completed, I turned the power on and plugged the Nest display in.  There were a few simple settings to sort out on the display, and it asked for the WiFi password, and that was it, all up and running.  I got the app downloaded as it was easier to set up the schedules this way, it defaults to having hot water on for 0600-0800 and 1700-2000, I thought this was a bit excessive so we've got it set for 0600-0700 and 1900-2000, with a view to using the 30 minute boost function if required.  This seems to work well for us.  At the moment we have the heating side of things turned off, as it's not cold enough yet.

Nest app overview

Hot water schedule

I did have a small problem with the Nest system, as I noticed my boiler randomly starting up in the middle of the day, when there was no call for heating or hot water.  My initial thoughts were the frost stat in the boiler itself, but that checked out OK.  After much head scratching and testing, it turned out to be a faulty relay on the hot water side of the heat link.  It was leaking around 30v to the normally open contact, and creeping up to around 50v which was enough to start the boiler.  This was a major concern as it could have caused the hot water cylinder to explode!

A quick call to Nest support sorted everything out, I explained the symptoms and they agreed it sounded like a relay fault, and sent me a replacement unit which was dispatched the same day (from Germany!) and arrived at my door the day after.  It was a simple case of swapping the heat link over and then the display, and registering to my Nest account again.  I was very impressed with how easy it was to get this problem sorted and get back up and running again.

Even with the minor issue, I am very impressed with the Nest thermostat.  It's incredibly easy to control and adjust, and of course there are lots of other products that work alongside Nest.  The aftersales support was excellent, and the returns process was very fast. 

One thing this did highlight though, was that my old thermostat was not entirely to blame.  My boiler (a HRM Wallstar) has a tendency to lock out first thing in the morning, which seems to be a common problem with this model.  It always fires up straight away on pressing the reset, which is inconveniently located behind the cover outside.  I've been reading up on troubleshooting the boiler, and there will be further posts on this.

Replacing toilet flush and fill valves

The toilet in the en suite was suffering with terrible water hammer when it had been flushed. This manifested itself as a loud hum that rattled through most of the upstairs, which was quite an embuggerance.

I did a bit of research and found the culprit was most likely the fill valve, and saw that Fluidmaster appeared to be the best replacement. I then found a kit that also included a replacement flush valve, with a half flush function, so decided to go with that while I had it all apart, we're on a water meter after all.

I isolated the water feed to the cistern, and immediately noticed it was weeping a small amount of water. I got the two screws securing the cistern out, which were considerably rusted, disconnected the overflow and feed, then wound off the two wing nuts holding the cistern to the pan and lifted it off. At this point I noticed the existing doughnut and clamp were in poor condition.

The cistern was then taken outside and all the old gubbins removed, and it got a good hosing and scrubbing down as it was full of mould. I suspect this is due to the cold air from the external overflow disagreeing with the warmer air inside.

Once clean, I assembled the new flush mechanism. I had to use the insert as the hole was 2.25" rather than 2", but a standard 2" close coupling kit worked fine.   The backing plate goes on first, then the large plastic nut over the top, and then the doughnut with the rounded end to the bottom.

At this point I realised I didn't need the external overflow as there was now an internal one, so had to source a blanking plug which was then fitted. I couldn't install the fill valve just yet as it blocked access to the right hand mounting screw so left this out for now. The flush button was attached and the nut wound up tight, and the flush cable attached.

Next, the cistern was brought back up stairs and offered up to the pan with the new bolts in place. The wing nuts were tightened, which brought the previous rail plugs back into view through the mounting holes, and two new screws and penny washers secured that.

I then went to fit the fill valve into place, and noticed it was a longer length than the previous one. As the isolator valve was leaking I thought it best to replace with a flexible connector with isolator built in, so another trip out to screwfix.

I turned the water off, and cut off the 15mm copper feed pipe at a sensible length to allow for the new flexible pipe. As the pipe had been painted I filed it down and wire brushed it to get back to the copper to ensure a proper connection.  When assembling the fitting, I remembered a guy in the pub told me when using compression fittings, a wrap of PTFE round the olive will mean it will never leak, and so far it's been a success. The fill valve was then fitted and tightened, and a few wraps of PTFE on the screw threaded end and fitted the flexible pipe.

I turned the water back on, no leaks on the new isolator, so I turned the isolator on and allowed a bit of water into the cistern and shut it off again and checked for leaks - all good again. I turned the isolator back on and allowed it to fill up and checked the levels which were all correct at their standard settings. I held the fill float down and proved the overflow, which worked fine. Last test was to flush and check the doughnut didn't leak, again success.

I was very impressed with the new setup, so much so that I fitted the same to the two other toilets in the house! The only job left to do is to fill in the holes from the now removed external overflows.

Here's a list of all the parts I ended up needing...1 of each per toilet...once again all from Screwfix

Fluidmaster fill and flush valve
Close coupling kit
Cistern blanking plug
300mm flexible tap connector with isolator
PTFE tape
15mm pipe slice

And here's some pictures of the finished article...

Installing a wall mounted TV with hidden cables

One of the very first jobs I did in the house was sticking the bedroom TV to the wall. I mounted the same TV to the wall using the same bracket I used in the old house, the only difference was that I needed different fixings. I used two types of plasterboard fixings as a form of redundancy , and also managed to find one of the wooden studs so fired in a 2.5 inch no. 8 wood screw as well.

The stud wall made it much easier to retrofit the hidden cabling that I really wanted. I was lucky in that directly below where the TV is now mounted, there is a double socket and an aerial point. I also have a PVR/Bluray player so needed to have a HDMI cable between the TV and this.

I set to and removed the aerial faceplate and back box, and fished up and found the noggin in the stud wall, verified by shoving the phone in on video mode with the flash on. I decided to cut out a new double box above the existing double socket, as the existing single one was tight up against a stud, and also the existing hole in the noggin was central so it'd all line up better.

I then cut 3 holes in the wall, using my Makita multi tool which made it easy and neat. The first hole was a double box above the double socket, then cut out a square to expose the noggin, and then cut out a single box behind the TV position. Once these were done, I slotted out the existing hole in the noggin with the multi tool as there will be a lot more cables running through now.

With the hard work done, all that was left was to clip in the plastic dry line boxes, pull in the cables (1x power, 1x hdmi, 1x aerial coax), screw in the modular faceplates, and terminate the existing aerial cable in its new module. I pushed a Cat5 module in the spare way in the bottom box, as I will run a load of ethernet cables in at some point, and I had one laying around.

Parts used were as follows (from Screwfix as they were local)

1x 1 gang dryline box
1x 2 gang dryline box
1x 1 gang 2 module faceplate
1x 2 gang 4 module faceplate
2x flex module
1x aerial module

Here's some pictures of the finished result. The hole in the middle still needs patching and plastering, but I am having a plasterer in for some other work anyway. If it wasn't for this, it would just be a case of screwing a piece of plasterboard into place, taping, skim with easi fill and sanding down until a smooth finish is achieved.

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