valliant sine 18 overheat - reset

[00sgfax00]

I have an old valliant sine 18.

halfbake posted his problem on 4/12/09. I have the same problem but I have the hot water but no heating. As soon as I put the heating on, within 4-5 minutes the whole system keeps failing so then I have no hot water or heating and I have to keep resetting the overheat switch.

My pressure is 1.2

compheat responded to Halfbake saying 'try putting some sentinel X400 in the system to loosen any sludge and do a mains flush'.

Can you please tell me how this is done. I have no idea.

Also how to pump the expansion vessel up to 1 bar ( with the system drained down)?

Many thanks in advance.

 

[compheat]

To get the x400 into the system you need to turn the boiler off and drain the system, if this is awkward to do you can just isolate and drain a radiator. you put the x400 into the rad by removing the blanking plug and use a tundish with a flexible spout/hose to pour the x400 in. You then need to turn rad back on and vent all rads before refilling and then vent rads as you refill. To top up the expansion vessel you need to look at the top back section of boiler you will find a small schrader valve like they use on car/bike tyres if you press this in and water comes out its knackered, if air comes out you can recharge by using a bike pump, pump up to .75bar approx. this boiler is very susceptable to Air locks which will either stop heat getting to your rads or cause the overheat to activate. The mains flush is a seperate issue so see how you go on with this first
Hope this is of some help.

 

[Agile]

I think the air valve is on the middle left hand side. See FAQ as it must be tested and filled exactly correctly to do the job.

You may have a jammed/seized diverter valve. That can be terminal as the actuator is no longer available seperately and the whole assembly is about £200 to buy. Sometime used parts are available ( but of course they are old and can fail at any time ).

I have got a few new actuators but I am currently trying to find then as one of my customers is waiting for one.

To top up the EXV or change diverter valve good space for access is needed on the left of the boiler!

Tony

 

[00sgfax00]

Hi Guys

Thanks for your prompt reply. I had the enginerer in yesterday and he put X400 in, but my system is cutting off within 3-4 mins not giving enough chance for the chemical to run through the system. But if I keep the hot water and the radiators (9) running at the same time then it stays on but the radiators luke warm only. Any more suggestion? Please help!!!

I asked him to recharge the expansion vessel, he said it is OK without checking anything ( I also have another external expansion vessel).

Many thanks in advance.

 

[Agile]

That does not sound like a very clever engineer!

X400 takes four weeks!

X800 takes two hours!

Unlikely to cure anything either!

Still an easy way to get paid for being useless! Take this pill and see if it makes it better.

Tony

 

[kevplumb]

http://images.google.co.uk/imgres?i...firefox-a&rls=org.mozilla:en-US:official&sa=G

 

[00sgfax00]

Hi Guys

I have PCB part no 252905, I don't know how to change it? Is it as simple and straight forward as taking it out and putting another one in in reverse order?

Thanks in advance.

 

[Agile]

I dont find them very difficult to change.

But I dont understand why you are now waving a new PCB around unless you know something which we dont.

If the 2N3055 is short circuit then it might operate the o/h stat though.

Tony

 

[00sgfax00]

Hi Tony

Thanks for your reply.

The enginneer who put in X400 for me, told me to get PCB for this boilor - saying that this might be the problem.

So now I have the part in hand and what to change it.

Also, from this evening my hot water also keeps cutting off.

Many thanks for responding Tony[/img]

 

[Agile]

Its normal in the trade for the engineer to source the part.

Then if its not the cause of the problem you dont have to pay for it.

If he asks you to get it and it does not cure the fault then guess who has had to pay for it !

It could also be the gas valve, temperature sensor etc.

But it might be the PCB as well.

Tony