Glowworm 80e - hot water, no central heating

[ljp126]

Hello all you helpful people.

I've read though the FAQ's, and ended up a bit confused. I'm starting a thread to collect some opinions. I hope someone will have a little insight into my problem.

- Hot water works fine
- Boiler fires up on CH demand from thermostat, does not lock out
- Pump appears to be running. Switching the pump between I II and III does produce an audible difference.
- Some 'gurgling' apparent at pump/return feed when pumping CH
- Opening the screw in centre of pump: water does flows out. I haven't opened fully or investigated this too deeply, I will do so if I am told exactly what to look for
- Return feed pipe remains cold
- Pressure vessel seems to be properly pressurised, pressure does drop a little bit on CH demand but not to zero
- I can't find any sign of a blockage at the return feed end with a magnet
- System does not appear to be losing pressure over time

Do combi boilers use the same pump to supply hot water? As I'm getting hot water, I'm concerned it may be a blockage. If this is the case, what is my best course of action?

Thanks everyone, help much appreciated. The other half is looking very chilly now the cold weather has set in and I really don't want to let her down

 

[Boilerman2]

The Glow-worm 80e has a 4 pipe heat exchanger, which means that the pump does not operate in Hot water mode, (it works like a multipoint) the pump only runs for a few seconds at the end of a hot water demand to dissapate heat and of course to supply heat to the radiators in heating mode
I suspect that the pump has failed if you can hear it running it may be that the impellor has broken away from the drive shaft

the good news is that a standard UPS15/50 head will fit!!

 

[ljp126]

Thanks for the advice. Since the pump ran when I switched off CH, I came to the wrong conclusion. Your advice is definitely in line with what I'm seeing.

the good news is that a standard UPS15/50 head will fit!!

I might be being thick, but what does that mean exactly? Cheaper off the shelf replacement? Would be great if so, will get one and fit tomorrow

Edit: sorry, should have spent more time with Google before posting... will pick up a Grundfos 15-50 tomorrow and report back. Thanks again

 

[ljp126]

Fitted a new pump, no joy -same symptoms. What do I look at next?

The old pump seemed fine, clean on the inside with the impeller intact and fixed fast to the spindle.

Getting cold!!

Edit: I'm looking at the system diagram in the service manual. The only other relevant parts I can see are the three way divert valve and a "bypass valve" that I'm struggling to locate. I've taken the actuator off the three-way valve and operated the pin with my finger. It moves, it does take a strong push but I assume this is normal? I also confirmed that the actuator solenoid does move with CH demand. If I push the valve in with my finger while running hot water, it does get colder -perhaps not as cold as I'd imagined, but I assume this could be residual heat. Should it get very cold or perhaps stop altogether? If so, I'll look at replacing the valve (seems like an quite involved job)

 

[ljp126]

GOOD NEWS: I've got it up and running now.

Drained system again and removed the needle spring assembly as this was quite easily accessed for removal. I cleaned it all over with a toothbrush (long and painful job), carefully recording the disassembly process to be sure I put things back in the right order.

Refill system to 1.0bar, run again -boiler now going to lock-out for both CH and hot water. Argghhh! It being now 11pm, I retired to bed and resolved to look at it in the morning.

Ran again first thing this morning, some sloshing as the pump ran but no lockout, pressure had dropped to ~0.5bar. However, CH now heats correctly! I'm on the right path here. System 'sloshing' gradually subsides as air works it's way through the system. Once it has I top up pressure in small stages little by little, bleeding rads each time. System 'sloshing' has completely subsided. I've now completely topped up to 1.0 bar and everything, has been fine for a few hours now.

I'll will monitor the system closely over the next couple of days, I do need to add an inhibitor to the system ASAP but I don't want to waste money if I just need to drain again in a day or two. I'm considering putting a system cleaner in briefly, but on reflection this may may be asking for trouble. Nothing I have disassembled has been excessively dirty and the water initially drained from system was surprisingly clean.

I am now pretty sure that the 3-way divert valve was likely to have been sticky. The new pump (Wilo, £60 at ScrewFix) is certainly more quiet than the old one, so I'm not upset to have spent money on it. I will keep the old one as an emergency spare, as I really don't think there is anything wrong with it.

The house is much warmer now and my other half is thrilled. I've learned a lot about this boiler in the process and although I know GW don't have the best reputation for reliability, I will say that the service manual is pretty decent, the diagrams being clear enough for a novice like me to identify everything. Information on the forum FAQ's have been very helpful as well.