Turboxmax 242

[newcomers]

My aunts boiler has been playing up recently so went round today too see if I could fix it

The problem is is that when they open hot tap, boiler fires up, goes upto about 85 deg c, water comes through hot, gas shuts off, water goes warmish, gas back on, water hot, so on and so on.

Central Heating works fine

I had a pcb on the van for this boiler (even though I was convinced it would be thermistors). Changed the board and still the same problem

Looking at the boiler, I could see 2 ntc's (one on the flow and one on the dhw flow or return), is this correct. Anyway, I thought that by unplugging either ntc would produce an error code on the boiler. I unplugged the ntc on the dhw side, and the boiler still functioned. I then plugged the ntc back in and unplugged the ntc on the flow, which then brought up the error code on the boiler.

Going on what Ive said, do you think the problem lies with either ntc? Why didnt I get an error code when unplugging the ntc on the dhw side?

Thanks

 

[Rob]

Can you visually see the flame modulate down depending on flow rate of HW. Common cause is sludge in plate HE causing to overheat.

 

[Agile]

Was there really a 242 with a fault indication?

Are you sure its not an 824 ?

 

[newcomers]

Pretty sure it was the 242, was VUW 242 / 2E or something similair

No sign of modulation, apart from when its about to shuty off, it drops quite a lot, the goes out

 

[newcomers]

Also, is it normal for temp to go up to 85? Thought they shut off at 70 max?

 

[Rob]

is this model similar to the sine18, big black HE on the left?
242 vcw i beleive

 

[kevplumb]

is this model similar to the sine18, big black HE on the left?
242 vcw i beleive

similar

 

[newcomers]

Actually, it might be turbomax pro 28

 

[newcomers]

The boiler is a turbomax plus 828

 

[Agile]

Thats what I suggested when you first started posting!

I will repeat, its probably dirt in the sec HE.

Are you CORGI reg?

Tony

 

[ChrisR]

To be fair the names and numbers on these are confusing if you look at the name badge inside.

If you turn the hw temp to minimum, does it still go straight up to 85?

Does it work normally on CH?

 

[newcomers]

CH is fine.....with DHW stat right down, i think it cuts off at about 70. Thing is, ive changed both ntc's and the problem is still there, but the ntc's I put on were for a turbomax pro, but the product numbers for both boilers ntc's are the same so it should be ok to use these ones shouldnt it?

How about the unpluggin ntc thing though? Unplugging flow ntc produces error on boiler, but unplugging return ntc doesnt?

 

[Agile]

I will repeat, its probably dirt in the sec HE.

I wonder why you change the NTCs when I suggest its likely to be a blocked HE ?

Tony

 

[newcomers]

Thats what I suggested when you first started posting!

I will repeat, its probably dirt in the sec HE.

Are you CORGI reg?

Tony

You suggested it was an 824, it was actually an 828

Yes am I corgi Reg

 

[ChrisR]

824 or 828 doesn't make any difference.

with DHW stat right down, i think it cuts off at about 70

Righto, definitely dirt in the plate heat exchanger then, as ROB884 first suggested.