Can you not ring the plumbers and say its come back on and working fine see if they can suggest something? Not saying this been cocky its just they have seen the boiler/pipes/job? Maybe its a warning something is about to break completely and could repair earlier?

Oh absolutely. Been over 24 hours now and still fine... so fingers crossed we can get a few more months out of it!

If heating working but not hot water will more than likely be an electrical fault, could be knackered 2 channel timeclock, 3 port valve or cylinder stat, all of which are relatively inexpensive compared to new boiler.

But it sounds like you've done the right thing and got a few quotes, doubt all 5 will be quoting for a new boiler without it actually needing it!

[Edited on 04-04-2014 by ash_corsa]

This is getting weirder.

My watch stopped and I was going to drop it off for a replacement battery tomorrow. Picked it up a couple of minutes ago and it's working again.

I'm going with 3CorsaMeal's suggestion atm...

Poltergeist imo

Mines the same but the other way around. Hot water is great but no heating. Not a combi. Thing it's time for replacement as it's 16 years old. Just thinking of all the ££££'s I'm saving with the mrs not being able to leave the heating on all day. Even when we're at work. Been like this a week. Think I can wait another before getting it fixed

diveter valve probably got stuck

If it sticks on the CH side it will cause the boiler to run all time as the diverter valve signal overrides boiler control and thermostat

No it's not a combi, don't think they were even around 40 years ago lol. It hasn't even got an immersion... the plumbers love it.

What type of boiler? if you're getting heating but not hot water; I assume its a combi in which case it sounds like a faulty diverter valve.

So the hot water went last week... radiators still fine. We've had 5 separate quotes now and was just about to pull the trigger on one guy to come and do the job. Every single plumber noted we needed a new boiler. We also had someone mention a knackered pump, another saying the pipes were blocked and another saying he could fix it, but it wouldn't be worth it, as it's 40 years old and just so inefficient.

Today, the hot water came back on :o all that mum was doing was running the tap as per usual. She went up and felt the pipes (that had been stone cold for over a week) and they were all hotting up!

We know the job needs doing eventually, but money is tight, so we're trying to hold out. If we can just postpone it a few months that would be great... just wondering if anyone knows what could cause this? To me, it is sounding like a pipe blockage and perhaps that's simply cleared itself?