Worcester 24I/28I Junior Flashing 4 Times A Second

[Flashard]

carried test E and all checked out ok, but still locking out,

Fault finding chart says investigate

1 sense tubes ? Where are they

2 pressure switch, How?

 

[Rob_the_rich]

hi Flashard, welcome to the forum.

As you have posted in the "introduce yourself" section, perhaps you might like to do so?

What exact model do you have? gc number might also help.

 

[Doc Hudson]

Welcome to the forum, Thread moved.

Doc H.

 

[Flashard]

Hi Sock

It's a 28i junior

GC 4731170

I have carried out all the tests, boiler fires up then locks out and flash 4 times every second

I am new and don't know my way round this site yet

 

[Rob_the_rich]

disconnect one at a time the pink and white tubes from the air pressure switch only, and blow hard through them, reconnect to air pressure switch and see if that works.

 

[Andy™]

pressure switch is usually at the top near the fan. also note that you will normally need to be gas safe to do this unless its DIY on your own boiler

or is it the heating pressure switch, which is usually on a pipe near the bottom. or it might simply need the pressure topped up

 

[Flashard]

Hi guy and thank you for you advice

I removed the pipes and blew through them they were clear?

Replaced

Turned hot water on boiler fired up, water ran hot, turned hot water tap off, boiler shut down correctly.

I then I switched the heater on and the following happened.

1. Fan ran at full speed

2. Boiler fired up

3. Fan stopped running

4. Boiler locked out and flashes 4 times in a second

Does that help you guys to help me

Please it's cold In the house

I thank you in advance

Flash⚡

 

[Andy™]

if its the fan pressure switch thats faulty, it wont go any further than fan coming on

 

[Flashard]

Hi Andy

So would you advise me to replace Air Pressure Switch.

 

[Flashard]

I would like to thank you guys for your help,

but I am still not sure what the fault is, are you saying it's the air pressure switch? Because I don't understand why the fan is running at full speed and didn't lock out when I only used hot water.

The boiler only locks out when I put the heating on ? Which happens after the fan kicks in reaches full speed boiler fired up, fan stops and the boiler locks out, which is part of the fail safe system I would imagine?

Sorry to being stupid

 

[Rob_the_rich]

I would like to thank you guys for your help,

but I am still not sure what the fault is, are you saying it's the air pressure switch? Because I don't understand why the fan is running at full speed and didn't lock out when I only used hot water.

The boiler only locks out when I put the heating on ? Which happens after the fan kicks in reaches full speed boiler fired up, fan stops and the boiler locks out, which is part of the fail safe system I would imagine?

Sorry to being stupid

I've changed my mind now, I think it is your pump. Apparently, page 33 says that on hot water demand the pump switches off (over-runs 4 secs if hot), so you don't need the pump for hw. When the heating turns on, the pump doesn't work, it overheats and shuts down.

The pump might just be stuck, put a towel under it and undo the big screw on the front with a big screwdriver (boiler off), then put a smaller screwdriver in and try and turn the spindle. If a lot of water comes out when undoing the big screw, stop and re-think how you catch the water (plastic bags, trays etc) you do not want water dripping onto any electrics or control board.

 

[Andy™]

i did think pump myself, but most boilers use the pump to move CH water to the DHW heat exchanger. not looked at the manual for this one though

 

[Rob_the_rich]

i did think pump myself, but most boilers use the pump to move CH water to the DHW heat exchanger. not looked at the manual for this one though

yes the water goes straight through the primary heat exchanger for hot water, not pumped, no 2y heat exchanger.

Was the hot water working before you blew through the tubes?

 

[Andy™]

yes the water goes straight through the primary heat exchanger for hot water, not pumped, no 2y heat exchanger.

Was the hot water working before you blew through the tubes?

in which case then it could be a faulty pump and boiler shutting down on overheat. when you switch the heating on and it fires up, do the CH pipes under the boiler get hot as though water is flowing or stay fairly cold?

 

[Flashard]

Hi guys thanks

Yes the ha worked before I checked the pipes.

I will check the pipes on the pump, and get back

 

[steptoe]

Not sure about this particular boiler, but some have separate diaphragms in the Diverter valve for DHW and CH. 

Could be a split diaphragm,,,,  

 

[Flashard]

This started on Saturday, the heating and hot water was working fine

Then the fault light came on, I reset it thinking the high winds had caused the problem

This happen again on Sunday,

Every time it locked out I Isolated the supply for about 30 mins, and the system fired up with no problem

Then yesterday Monday it locked When we were using the heating not running the hot water,

After repeating the resetting process I switched of the heating and carried out test "E" which indecated the air pressure switch could be at fault.

I then used the hot water to have a shower and wash my hair, during this extended use of the hot water it locked out. I then contacted you guys, I reset the system again and didn't use it until morning only using hot water not the heating.

During the day I switched the heating on it locked out, then I then followed your advise with the tubes.

That didn't make any difference

The last test I did was run the hot water only, then switched the heating on the fan cut out and the system locked out?

I hope this helps confirm your thoughts

 

[Flashard]

Again thank you for all you advice I am very grateful

But I am not sure what to do

I agree that the air pressure switch may not be the problem and regards the pump I understand what you are saying about the DHW working normal because the water does not pass through it

I have tried to check the condition of the pipes on the CH but it is locking out before the burner has chance to get anything warm

Because if it is locking out on the CH is that not a the safety system doing what it should do?

So would before I strip down the pump is there any other safety devices I can check to rule them out of the fault

So could I please ask what would you do now

Thank you again so much

Flash⚡️

 

[Rob_the_rich]

When you did test E and checked all those resistances, you pretty much checked out all the safety devices I think.

You could take of st15 with boiler off, and check the resistances between the leads, and post here. This should tell us whether the pump should work.

But it is most likely that the pump is stuck, and I have described above how to unstick it with a couple of screwdrivers.

The other thing to check is whether there is power to the pump during heating demand.

 

[Flashard]

Thanks Rob the Rich

Will do

How do I check the power to the pump during heat demand

Thanks for that update this seams to make sense

Flash⚡️