What F5 mean on a Glow Worm Boiler model 18hxi?

ryan you are best you save my monry and my headech , guys just need to pen the white cover and still cover and on the top left side beetween black soucket you got red botton just press that and that set

milad
December 2019

You're all missing the point, by removing the combustion cover as an unqualified engineer you are committing an offence. There is a good reason for this. You need to be able to test combustion performance after any "work" on a boiler and you also need to be experienced in fault finding and identifying and potentially dangerous faults which may be the route cause of the overheat fault.

Qualified Gas Engineer
June 2017

Read this forum on Monday evening the 14th October 2013. After reading the advice I pressed the overheat stat back in on my Gloworm 38 CXI

After a day of working the boiler failed again. My first thought was to press the stat again but I noticed that the Gloworm sticker on the silver cover had gone black in the top corner and there was also blue discolouring on the burner chamber. This was not there a day or so before.

I decided to get an engineer out and it turned out to be the best £40 I have ever spent. The burner chamber had warped due to the excessive heat and had left a 2mm gap in the seal that would have been spewing CO2 and gas into my 10 year old son's bedroom.

If I had been daft enough to try and get the boiler running again, without qualified advice I may have killed my eldest. Think long and hard before you trust the ill though out advice of others. I now have a new boiler as the old one was destroyed within 48 hours as I did not get professional help.

I have photographs of the damage and the boiler was a write off. 7 years old and needing a complete new burner and heat exchanger assembly meant I had to shell out for a replacement boiler or spend £400 on a boiler that I originally picked up for £600.

Now got a new unit with a 5 year guarantee and I will ensure it is regularly serviced etc.

Paul
October 2013

I have now found red button but not sure how hard to press

RP
March 2013

Where can I find red reset button for 30hxi model? thanks

RP
March 2013

What's f5 mean on ya combay boiler myn is.a 15hxi how can I mend this matter

chantelle
March 2013

THanks. FIxed my problem.

Tim
March 2013

F5 keeps appearing and boiler stops when temp reaches 72 degrees, I've renewed part with red trip button on but still trips off

Steve
March 2013

Thanks a lot Jo and Ryan. I think I caused this cut-out by cranking the heat control almost to max!! I'll leave it at about 2/3 round from now on!

Oliver
March 2013

Followed your advice. It worked Thanks

John B
July 2012

This was great advice!! I'm a single mum with 2 kids and I fixed this in no time. I'm actually thinking I might become a plumber, lol! Thanks so much.

Sumayya
November 2011

On glow-worm 18hxi
Isolate power
Take off front white cover (2 screws underneath)
Take off silver cover (2 screws one on each side)
Look at the top left corner you will see 2 black prong like things there is a small red button in the center of them press this in.
"You're system is now reset"
Re-attach all covers securely and fire her up all done!!
Ryan

Ryan Davenport
October 2011

T hank u Jo ur info helped me get my boiler working again it has warmed my house up thanx .xxx

shubs
March 2011

f5 has come on all of a sudden on my glow worm boiler 18hxi - what can i do to resolve this please?

Neil Page
February 2011

red flashing light!? turned the whole thing off and then turned it back on green light comes on and then flashes back to red? help.. any ideas? x

stacey
December 2010

The Reset button worked for me guys! thanks for your help with this

JJR
November 2010

Thanks Jo, very handy tip.

Worked like a treat

The only thing that concerns me is that the thermostat safety switch tripped for a reason, and by ignoring a potential problem by resetting the safety switch may cause a more severe problem No?

Luke
September 2010

Jo you are a legend.....

Russell
July 2010

Changed a bathroom rad, got F5, messed around for a few hours trying to bleed the boiler then thought I'd check the web. 10 minutes later everything works!!! Why doesn't the fault page from Gloworm tell you this fix?

Trevor P
July 2010

i tried the reset thing and boiler start up gets to the point where light comes on then goes off. fan runs continuously but does not light. if i turn temp control up till green light comes on, the temp reading jumps around and trips out with an f14 fault after a few seconds. do i need to change the overheat sensor or the flow temp sensor? i have tried the standard power off resets. any help would be greatly appreciated. i have added a rad and despite asking someone to repressure the system before turning it on they still managed to start boiler with no water in it!

mr t
May 2010

Power cut today and boiler gave F5 on start up. This did the trick on a 6yr old 18hxi. Excellent advice. Thanks.

Greg
May 2010

Thanks a million, fixed in five minutes! Now I can have a lovely HOT bath!!!

Fiona
April 2010

Hey thanks Rob - a fantastically easy fix for F5 - thanks for saving me a fortune and getting my heating back proto. I knew the internet was wonderful but not this wonderful!

Philip
March 2010

I found this really helpful. Thank you!

David
February 2010

WOW!!! I am a stay at home mum who spends alot of time on my own due to my husband working away. Last night my boiler stopped working for the second time since December. Because I cant afford the £100 it cost me last time to be fixed, I searched the net for some help.
THANK YOU so much for these easy to follow instructions which resolved my problem in seconds. My baby and I are now warm and VERY VERY grateful.
My boiler is a Gloworm 18HXI about 3 years old.

Niki
February 2010

Boiler Failed to startup after changing radiator some air still in system even after bleeding rads - about to go on holiday and couldn't get hold of plumber. Desperate!
you saved out bacon red button did the job. Thanks for a great web site

Phil - Suffolk
February 2010

Thanks, Great fix which worked a treat and saved shed loads of dosh!

Dave
February 2010

Jo Bourne, you're a marvel. We've woken up to 6" of snow and F5 message on the boiler. Goggled Glowworm F5 and the first of the message boards included your succinct solution. Thank you!

Jude
January 2010

I had the same problem, same fix worked, shame plumbers don't use Google, would of saved us all a lot of time !!

Martin
November 2009

Excellent information. Saved a cold weekend waiting for the repair man to come.

Thanks

Trevor
October 2009

Wow, this like the others really saved my bacon. I too had been removing a rad. I had left the boiler on, think next time, turn all off and check the water pressure before switching on again. The little button you refer, is not visible (certainly on mine) so you have to just put your best finger forward (ensure the power is off) and press between the main terminals as described in this trail. Thanks guys!!! Hooray foor the internet!

Silu
October 2009

instructions found at http://www.high-efficiency.info/images/hxi%20install.pdf

codes at the back

Julian Bell
September 2009

thanks for that was quoted like £370.00 to fix and took me 2 mins big money saver !

allan clark
July 2009

Thanks for your answer, Red reset is only small but does give a positive click when reset 30hxi. Had to use it after new radiator fitted and air had been left in system by plumber.

pmrpete
May 2009

jo your a genius thank you. for me it was very well hidden up in top right hand corner clipped to a pipe may be different for others. great hekp thank you kids and wife now happy...er

dave
April 2009

My Granny could have done it too!!!!!,, Thanks guys for the infomation about the F5 fault signal. It is amazing how much I would have paid some idiot just to reset that switch. Amazing.

Dr Thabani
March 2009

The switch is really small. Found it and followed the steps. Working fine.

Thanks very much

S Jeanes
January 2009

Thanks it happened again & once again this advice got us sorted quickly.

Pete
January 2009

Fantabulous! I was really not looking forward to spending the night without the boiler on. A million thanks from me and my family!

Jack A.
January 2009

Thanks very much what simple thing to do. Thanks Thanks and Thanks again

Nick H
October 2008

Mate you saved my life, and the cost of a Plumber. Did exactly as you said and back up and running. Many many thanks.

Mark
October 2008

Guys - you've saved my life! Just followed the instructions and managed to get my 38hxi boiler running again. What winds me up is that Glow.worm would not tell me how to do this over the phone as I'm not a Corgi registered. I'm not also not registered to have a freezing cold house with a poorly baby in either, but I know what my priorities are! I just hate the way all these companies assume you either are a total muppet and know nothing, or they know they can make a very quick buck from your lack of knowledge. Well thank God for the internet and forums like this! (Thanks also to my neighbour & local landlord also - top boys!)

Miko
October 2008

Guys - you've saved my life! Just followed the instructions and managed to get my 38hxi boiler running again. What winds me up is that Glow.worm would not tell me how to do this over the phone as I'm not a Corgi registered. I'm not also not registered to have a freezing cold house with a poorly baby in either, but I know what my priorities are! I just hate the way all these companies assume you either are a total muppet and know nothing, or they know they can make a very quick buck from your lack of knowledge. Well thank God for the internet and forums like this! (Thanks also to my neighbour & local landlord also - top boys!)

Miko
October 2008

Guys - you've saved my life! Just followed the instructions and managed to get my 38hxi boiler running again. What winds me up is that Glow.worm would not tell me how to do this over the phone as I'm not a Corgi registered. I'm not also not registered to have a freezing cold house with a poorly baby in either, but I know what my priorities are! I just hate the way all these companies assume you either are a total muppet and know nothing, or they know they can make a very quick buck from your lack of knowledge. Well thank God for the internet and forums like this! (Thanks also to my neighbour & local landlord also - top boys!)

Miko
October 2008

I had this problem with 18hxi and after reading through these messages i was able to fix the problem myself so thanks guys really it was very helpfull and i am glad this site exists.

Louise
October 2008

Thank you!! Worked a treat straight away, I'm so happy! No more bills from plumbers!!!

Pete
August 2008

just reset my 15hxi in the same way thanks everyone. It happened when changing a rad.

Dave Purdy
August 2008

i have had the same problem, sorted it in minutes thanks to your advice, the red button is hard to find i was expecting bigger, many thanks saved me shed loads £££££

steve
July 2008

Jo Bournes explanation is perfect. Thanks Jo

Bruce Moult
May 2008

Rob

I've had exactly the same F5 fault code ... if you've been adding rads to system or similar, then chances are you have introduced air into the boiler, which causes the thermistor to click off.

You need to take off the front panel (2 retaining screws underneath) and lift off. Then take off silver panel (remove retaining screws again). Top left hand side of innner workings of boiler is the overheat thermostat/reset switch. Two black plastic prongs sticking up with red button inbetween. Press down on red button - it should click. You have reset system.

Now restart boiler - turn central heating water temperature control dial (on LHS) to 0. Turn mains reset switch (RHS) to ON (1) position. Green light should come on and then go off. SYstem pressure should show on digital display. SHould read at least 0.7 bar.

Turn central heating dial (LHS) ON. The lighting sequence will begin, lamp will go green to show boiler has lit and you should be able to see the flame through the peep hole. Display should show system temp now rather than pressure.

Put the silver plate back on and then the front cover!

The manual can be found for 12/15/18/24/30/38hxi on the following web site: http://www.high-efficiency.info/images/hxi%20install.pdf

hope this helps

Jo Bourne
November 2007

the waste water from the Boiler can't come out......
your Kitchen sink pipes blocked..

khalid
November 2007

We have the same problem ewith model 30hxi.
Can anyone please help as it's getting cold and her indoors in mouning with the kids.

Help Please!!!!!!!!!!!!!!!!!!!!!!!!

Tim
November 2007