Glowworm Compact 100e: DHW lockout

[oscarsdad]

Hi,
I have a Glowworm Compact 100e and am having an intermittent problem with the hot water. Every now and then (actually most of the time) the boiler locks out and the red LED comes on. This happens when I turn on a hot water tap while set to the Summer setting (i.e. CH is switched off).
It seems to makes all the right noises as if it's about to come on, apart from the final electrode click and gas firing.

If I turn the CH on (either manually or with the timer), the DHW will fire, 100% of the time.

The problem seems worse when the hot water hasn't been used for a while, around an hour or so. If the hot water has been used recently, then it doesn't seem so bad and will usually work.

This has been going on for a while but my Mrs is getting pretty fed up with it (and me) so any suggestions would be greatly appreciated.

 

[mickyg]

Could be any number of things. I would suspect the pump flow switch not making but this in itself could be caused by a few different things. Hows your technical skills? (without trying to sound patronising). I can try and help if you wanna have a go but it could get tricky

 

[oscarsdad]

(Not trying to sound cocky) A few years ago I was able to diagnose and fix a problem with a split diagram and faulty dhw microswitch (on separate occaisons but before this problem).

Sometime ago (when this problem started) I thought it was an issue with either one of the thermistors around the diverter but I think I've ruled them out. Either by measuring their resistance while out-of-circuit, while they were disconnected and boiler heating or measuring output voltage with boiler heating (was a while ago).

I guess what I'm trying to say that I'm willing to play around with the non-gas side of things.

 

[Deleted member 105431]

call glow worm for a fixed price repair-£215. 01773 828100

 

[mickyg]

(Not trying to sound cocky) A few years ago I was able to diagnose and fix a problem with a split diagram and faulty dhw microswitch (on separate occaisons but before this problem).

Sometime ago (when this problem started) I thought it was an issue with either one of the thermistors around the diverter but I think I've ruled them out. Either by measuring their resistance while out-of-circuit, while they were disconnected and boiler heating or measuring output voltage with boiler heating (was a while ago).

I guess what I'm trying to say that I'm willing to play around with the non-gas side of things.

This is good news This is the kind of fault which could well be causing your problem. This boiler has a pump flow switch, which if not operated in a short time after the pump kicks in will cause lockout. If you remove the case and drop down the control panel, you will see it with a black microswitch box which has a red, white and black wire. A black clip holds the microswitch housing on, remove this and you will see the pin that operates the switch. Now try the boiler in a situation which would normally cause it to lock out and observe the pin. As soon as the pump comes on the pin should come straight out. let us know the result, and we'll go from there.

 

[oscarsdad]

When I first took the microswitch off the pin was retracted.
When I turned the hot water on, the the pin came out.
When I turned the hot water off, the pin went back in.
I did this a few times and without the switch mounted, the boiler locked out (after turning the water off for the first time).

I put the switch box back on, reset the bioler (to turn the red LED off) and sure enough the boiler locked out when I first used the hot water.

Then without the switch mounted, I thought I'd try the CH. The pin came out and stayed out even after turning the CH off. Even a little nudge and it popped back out. Now that the pin is out, the hot water is not locking out...
I think you might be onto something here

BTW, there is no red wire, just black and white.

 

[oscarsdad]

It's been a little while (about 1/2 hour) since I last did the previous test and the pin has gone back in.

I just repeated the hot water test and now when I turn the hot water on and off, the pin seems to be going in and out quicker that before (not sure if I was imaging it) and the hot water is still OK.

I'll wait until it locks out again and check it out.

 

[mickyg]

Well basically, as you've worked out, if that microswitch doesn't make, you have lockout. So........If this is the case, you could have a faulty diaphragm, microswitch or underneath the diaphragm there's a small hole which can block up, sometimes partially which could be your problem. Also blockages in plate he, or in the CH return filter(fitted in the isolation cock) can also sometimes cause this problem. If it turns out its not to do with this valve, then its likely to be ignition lockout in which case the only advice I can give for that would be to call an RGI or Glowworm on a fixed price repair.
Good Luck

 

[oscarsdad]

I think I've been able to establish that it's not the switch (pity, would have been an easy fix). I guess I'll have to drain down the system to check the rest, so I'll have to leave that until at least the weekend.
Thanks for your help so far. Fingers crossed.

 

[Gasguru]

The gauze filter is located in the lower pump connection...you need to remove the plastic elbow to access it.

 

[Deleted member 105431]

remove the plastic elbow to access it.

these elbows are easily damaged and prone to warping/distortion (best left alone)

 

[oscarsdad]

We went away on holiday during September and since we've been back the heating has been on for most of the time so the Mrs hasn't complained much about the boiler.... until today.

The problem has become repeatble, but instead of locking out, we get HOT/COLD/HOT water in approx 5 second cycles.

I checked the diaphragm under the microswitch and looked for blockages. Both seemed OK but there was a bit of black gunk (same as in the bottom of the rads) underneath the diaphragm.

Anyway, that appeared OK so I noticed that when the boiler was powered there was a strange noise (not very loud) coming from the diverter switch\motor. I took it off, while powered and noticed that the solenoid was going in and out, with approx 5 second cycles.

I checked the voltages on the 3 pins with DHW and CH demands and they behaved as described in the Glow-worm manual.

So I think I'm pretty sure it's the diverter switch\motor but the Glow-worm manual has a mis-print and doesn't give the part number.

Does anyone know what the part number is (Compact 100E)?