Baxi WM 522 RS Problem

[stevcolx]

Ok guys! Here's my problem. The Baxi Central Heating boiler was working fine until this morning. Never noticed till tonight of course. The Baxi boiler I have is old and not listed in the Baxi webpage. Ok, to light the pilot light you depress the button then press the pilot light button. Leave depressed for a while then let out slowly. The pilot light stays on. But as soon as you switch the heating on at the wall and let the burner go on after 20 seconds or so the burner and pilot light go out. Course the button you keep down while lighting the pilot makes a noise then pops out.

What's the problem? If it's replacing a part I just need the instructions to do it. Unfortunately the Baxi website as I said doesn't have it listed. Anyone help? House is getting cold. Especially up here in Scotland!!

 

[croydoncorgi]

Boiler's probably fine - but getting all hot and bothered because of NO CIRCULATION.

Turn of CH AND HW, then try and bleed rad upstairs. if nothing comes out (no air, no water) the feed tank is probably empty or the cold feed pipe to the boiler blocked. If water (or air, then water) comes out, all well and good.

Next possibility is pump not turning. Find it (may be well -hidden!), turn on CH (without lighting boiler) then put stick of some sort against pump casing and your ear to the other end. If you can't hear mechanical noise, it ain't turning!

 

[stevcolx]

Ok. The radiators are bleeding water. I'll have a go at the pump right now!

 

[stevcolx]

When pump is on Auto you feel a small vibration. I turned the pump to manual and the pump started whirring. I tried the pilot light and burner again while the pump was on manual. Same thing happened. The button popped out after 20 seconds and the pilot and burer went off!


??????????

 

[croydoncorgi]

Describe the pump. makers name? model?

 

[stevcolx]

Ok: Grundfos Not sure about model Number. But I did find it stamped 500A15.

 

[croydoncorgi]

When you mentioned Auto & Manual, I thought you'd found a motorised valve, not a pump. Grundfos pumps usually have 3 speeds, marked I, II and III. Probably should be on II in a Backboiler setup.
If its whirring loudly (louder than usual) it's probably full of air - and so not pumping anything. Don't leave it running like that - you'll knacker the water-lubed bearing.

 

[stevcolx]

Ok. I have checked. And your right there are 3 settings. Usually it's been on setting 1. I have just switched it to setting 2

 

[stevcolx]

Does the same on that setting too!

 

[namsag]

What you have is a dirty pilot with just enough gas passing through it to heat the themocouple and allow the pilot to stay. When main gas is coming on it is robbing the gas from the restricted pilot and allowing the thermo-couple to cool down and drop pilot out this is the click you are hearing. What you need is a sevice and possibly a thermo-couple

 

[stevcolx]

Could be just blocked then. Easy to remove and clean? Don't have a drawing of the breakdown of the boiler. Sorry to sound thick but I don't even know what to take apart to clean or replace and since I'm in between jobs I can't afford to call an engineer out!

 

[croydoncorgi]

You need to be VERY specific about HOW LONG the burner stays on, and what it sounds like.

If it only lasted (say) a maximim of 10 seconds it could indeed be an internal gas problem, so that the main burner is starving the pilot burner and cooling the thermocouple too much, so it goes out. BUT you said '20 seconds'. That would usually be too long for a thermocouple problem.

To clinch it: can you hear the main burner light up and run, making normal noises? As time passes, towards 20 seconds, can you also hear 'kettling', popping or banging noises from the boiler (ie. the noises from overheating)? Or does it sound completely normal and then suddenly click off?

And did this problem suddenly happen? or has the pilot been going out increasingly frequently but the boiler working OK once re-lit?

 

[namsag]

Croydon know what your thinking but that model of baxi does not have any form of overheat stat , so nothing there to interupt the thermocouple and trip the pilot. And sorry stevc these pilots are prone to gas leaks at the best of times and quite easily broke so not telling you how to take apart. Engineers job as oppossed to diy

 

[tech]

Blocked pilot assembly ?

 

[tech]

DONT DIY