Unhappy Ravenheat LS80T Combi Boiler.

[Lawwey]

Hi all,

I am seeking an explanation for these symptoms with a Ravenheat LS80T Combi Boiler.

When I first turn the system on the central heating is turned off at the in-built timer and CH temp is turned down fully, the summer/winter push button switch is at the summer only setting. also no HW or cold water taps are open, however the fan and pump both operate immediately even though there is no call for hot water or CH. After 5-10 seconds the red overheat light comes on and stays on, the fan and pump continue to run, at no time does the boiler ignite or as far as I can tell even tries to.

If I turn on a HW tap nothing happens, no firing up, fan and pump continue to run, red light stays on.

If I turn on the CH via the summer /winter switch, temp control and timer, nothing happens, no firing up, fan and pump continue to run, red light stays on.

(All inlet valves under boiler are turned on and water pressure is at 1.5 bar)

The boiler is in my flat which I am in the process of selling, the buyer wants the system operational. I had an engineer in to look at it and he said the boiler was obsolete and he could not get the parts and he would not even look at it, he only wanted to sell me a new installation at £2,500. I have checked online for parts and they appear readily available, so I believe boiler is still serviceable.

I don't mind paying an Engineer to fix it, but having an idea of what is wrong before I ask would be useful.

I would very much appreciate any and all advice.

Thanks in advance.

 

[muggles]

After 5-10 seconds the red overheat light comes on and stays on

You've very nearly diagnosed the problem yourself here, apart from it being a Ravenheap of course...
I'd take a wild punt and say that the boiler has overheated, and the overheat stat needs resetting. Just a thought

 

[Lawwey]

Thanks Andrew,

Any idea how I do that? can I do it myself or do I need an Engineer to come out and reset it?
I'll look through the manual in the meantime.

From what I've read Ravenheap appears to be correct! still if I can fire it up then the new owner will have the pleasure in the future!

 

[muggles]

Open the control panel cover, there should be a protection cap for it (but there might not be if someone's lost it) just to the left of where the timer is if you have one. Unscrew cap, press red pin

 

[Lawwey]

Thanks Andrew,

I'll give it a go.

 

[muggles]

If you drop the cover down and get stuck, post a picture. Let us know how you get on

 

[Lawwey]

Hi Andrew,

I have looked for an overheat reset, but can't find one, I read in another post that there are two versions of this boiler, the mark one has a manual reset and the mark 2 has an automatic reset????

I took a picture of the front panel, and a picture of where the manual says the thermostat should be.

 

[muggles]

You've identified correctly - you have a Mk2 with an auto-resetting OH stat and the newer style control panel. IIRC the red light would flash on this version for overheat, and is solid for flame failure, so it sounds like your problem may lie elsewhere although it'd be worth getting a multimeter out and checking the continuity of the OH stat just in case I'm wrong

 

[Lawwey]

Thanks Andrew,

I'll put a multimeter on it just to see, I appreciate your time and advice.

 

[oilhead]

When you turn on, does the pump run? I suspect not, which is why the boiler goes to overheat. Check the pump and replace if faulty.

 

[Lawwey]

Hi Oilhead,

The pump and fan both come on immediately when the power is turned on to the boiler, even though there is no call for HW or CH. I have not had a chance to check the OH stat as previously suggested.

 

[Lawwey]

Recent developments to the original post.

I called and engineer out to look at the boiler, he found that the air pressure switch was faulty, by blowing into the tube he got the boiler to fire up when the hot water tap is open, so the pressure switch needs to be replaced. However the boiler will not fire for CH. The pump and fan both come on when the power is turned on even with the timer turned off and summer/winter switch set to summer, so something is calling for the boiler to fire up even though everything but power is off, logic suggests to me that it must be DHW calling for the boiler to fire given that CH is all off, could this happen even if the hot water tap is off? DHW flow switch fault? Diverter valve?

Does anyone one have an idea what I could check.

 

[Agile]

You have already listed things to check.

Quicker to check them than to list them here

Ton