Potterton Prima 60F not firing up....help please needed

[Justin Passing]

The motorised valves turn the boiler on, via the orange wire (usually) going live. The two orange wires are connected together. Look up S Plan Wiring.
You've probably had one valve (HW) seized open for years and never noticed, and now the other one has packed up .

 

[dazzystar]

Thanks. I'll have a look tonight when I get home from work. I can move both valves manually with the small lever at the top of the valve. Is that an indicator that the valve is ok? I've replaced at least one both motor on the valves and yesterday one of them was buzzing slightly and was getting very hot despite the boiler NOT being on.

Is it these orange wires that send the signal to the boiler to start via the switched live terminal?

 

[dazzystar]

Well I left everything off and this evening had the intention to check the switched live in the junction box next to the valves. I turned the programmer on and selected central heating and low and behold the boiler is giving fired up and the rads are getting hot!

Then I dropped the temperature to 0 on the room stat but the boiler won't turn off!

Any ideas?

Cheers
Daz

 

[dazzystar]

Not sure if this is important although it probably is but the valve motor on the CH side is very warm / hot!

 

[Agile]

They do run fairly warm.

Sounds as if something is keeping the demand for that zone on.

Tony

 

[dazzystar]

This was hot not warm. I don't mean so hot I couldn't touch it but almost!

What could cause the demand for CH on if the room stat was off?

 

[Agile]

Faulty programmer, faulty wiring etc.

They do get too hot to keep your hand on when the heating is on. Without heating on only gently warm is heat is conducted away by pipes.

Tony

 

[dazzystar]

Hi Tony,

Brand new programmer (probably not needed!). The CH motor was very hot as well the other day before I could get the boiler to start and all the pipes were cold.

Could it be that there is something wrong with the microswitch in the CH valve or the motor?

Daz

 

[Agile]

No, its just that you dont realise just how hot these get.

Tony

 

[DP]

I'm mad! Going to take them both back once I know what's causing the problem.

Wish you good luck in getting refund on the parts especially the PCB. Perhaps you should have read the notice spare stockists have saying PCBs cannot be returned😜

There are a few more parts in the boiler you could try changing e.g. The fan, gas valve, heat exchanger, burner to name a few. You will eventually find the needle in the haystack 😄

 

[dazzystar]

Think we've got it down to something to do with the switched live but for the life of me I don't know why the boiler now fires up but won't turn off!

 

[Agile]

Dont know if asked before.

What model pump?

When fitted?

Tony

 

[dazzystar]

I'll have a look tomorrow morning Tony and let you know.

Do you think it may be the pump or perhaps the valve microswitch?

 

[dazzystar]

Had a busy day and only just took a look at the zone valves. The HW valve indicator arm moves a lot further then the CH one. I also noticed the CH valve when opening or closing moved the motor at it's stop position as if it were a little loose.

I'm thinking that one of the microswitches is at fault and calling for heat when not needed. Is there a simple method to confirm?

 

[dazzystar]

Just discovered that since changing the programmer the room stat has no power!