Trouble lighting balanced flue Baxi wall heaters

[coldvince]

Can anyone help please. I have 2 baxi F5S balanced flue wall heaters and one F8ST heater. Since new, lighting all 3 of them has been really difficult. The main issue is that after the spark causes the fire to light you can hold the gas control knob in for far longer than 20secs and when you let go the flame goes out. This has happened on all 3 fires since new. The installing Corgi guy couldnt get one to light very easily at all and it was replaced by baxi after they changed lots of bits but was only slightly better. Once alight the fires are all fine and have never gone out. I have had Baxi fires for many years and my old ones (same as current models but without the flame failure device) work fine. Its now driving my wife nuts as about half the time they behave as above. I notice that when that happens its no good trying again for a couple of minutes; the spark ignites the gas and goes out instantly. I am guessing the correct air/gas mixtures hasnt been reached. Has anyone come across this problem as the corgi guy has given up and stupidly I havent chased baxi and 2 years has passed. I remember the corgi guy talking about the flame failure device not getting hot enough or being in the correct position but despite him adjusting the tip of the device to be in the flame as shown in the manual the fault persisted. I am wondering if this is a well known design fault or have I got a bad batch or something else wrong. Oh and just in case its relevant my Robinson Willey WARMPLAN balanced flue wall heater is fine too and on the same 15mm supply. Final thing: It doesnt matter whether I am trying to light a fire when no other house appliances are drawing gas or whether all the other fires are on so not the gas pressure?? Help! and Thanks for reading this rather long question

 

[gas4you]

Personally I've never come across this problem with any of the Baxi's I've fitted.

I would start with the very basics and want to check WP at the meter and inlet at each appliance.

Working out gas pipe sizing would also be beneficial to check if there is enough in theory to let them work.

Also check there are no blockages on the flue terminals that could be restricting the amount of air being drawn in.

All of the above should have been checked and double checked by your gas engineer, who no doubt is registered and competent to fit fires/wall heaters

 

[Homesafe]

i had a similar prob to one i fitted not long back (f8s) ,
it wouldn't light and when it did it went out after a short while,

BP, WP, pipe size everything ok,

customer eventually called baxi and they didn't do much and said it was ok

i suspect a bad batch with problem valves,

i think it started working for longer periods before shutting off.

 

[baxpoti]

Check the electrode lead is correctly routed, on firmly and the plastic cap is securely covering it (after checking).

I also double insulate the lead.