Jaguar Combi-Boiler problem (Gloworm/Plumbcentre)

7 May 2007
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United Kingdom
Hi all,

My combi boiler has two problems.

1/ The hot water won't come on unless the heating is on. Sometime with no heating on if I leave it long enough, like 15 minutes, I finally get hot water.

2/ The heating has started playing up. First I got F1 which is overheating. The saftey switch needed reseting after I bleed the system.

It then repeated this error 10 days later. I reset it again it ran for about an hour then again F1 error. Reset again run for about 4 or 5 hours then stopped.

When I went into the loft there was no F1 error and pump was working but no flame.

It then started working again an hour or so later.

Then stopped again, no error, just stopped. I checked all electrical connections connected sound, checked visually all looked ok.

In frustration I gave the side a whack, it sprung into life.

It then stops again a few hours later.

The heating temperature was 23c so frost protection isn't kicking in.

Any ideas?

As the boiler was replaced on the cheap and the system was never descaled or flushed, I'm thinking use a chemical descaler and then refill the system with inhibiter.
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1. the dhw diaphragm is burst or a slim chance that something is wrong with the venturi.

2.what is the water pressure like when all of this is happening. from memory f1 isnt exclusively overheating. a lot more could be happening for this to be showing all the time.

giving it a whack to get it started normally indicates a dodgy air pressure switch.

sounds like the boiler needs the service from hell.
Thanks Nickso, the water pressue is fine.

At the moment F1 overheating isn't being triggered.

The heating runs for about an hour, then the flame goes out and the fan stops. The display doesn't show any errors. The reset panel switch doesn't do anything, and overheat saftey switch isn't triggered. Turning it on and off doesn't have any effect either.

But give it a whack and the heating comes back on and stops again.

As the heating was drained and refilled with just water several weeks ago, I'm going do a chemical descale and flush, then refill with inhibitar.

I'm just hoping that I've got scale jamming things up causing it to fail.

How can I check the APS, do I need to check signals with a meter or is there something physical I can check? The manual says if the pump AND fan are running, but no flame then the APS should be checked. My fan isn't running.
it may still be the aps though.

the boiler will most likely check for no air pressure first. if the aps is stuck closed it wont start. having to bang it to get it started is a pretty godd sign its the aps. i would check it with my multimeter for continuity when the fan is off/on, or do it manually. if you cant do that then i would suggest you may want to take a punt on the aps anyway. they are not really pricey.
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APS is about £25, really easy to replace. I'll probably sort that out anyway.

Whats you opion on scale in the system, is descaling and flushing worth the effort.

The pipes and rads have been in place for decades, the system was just flushed with cold water and the Jaguar plumbed in. Its been running for 5 years with inhibitor added. But the drained in refilled with just mains water for the past seven weeks.
im not the man to speak to about scale as i live in a soft water region....never even seen scale in the flesh :LOL:

if its there then it needs removing, thats obvious enough. if the system was previously open vented it usually ends in tears if its not flushed out somehow. at least you have used inhibitor.
I have the reverse of the problem I have central heating but not water, and no manual. Someone has mentioned it could be the diverter valve, can anyone help !!!

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