Cylinder stat or 2 port?

[armyash]

Hi guys been to a job recently, 2 port was held open when I got there. Cust only has hw when ch is on.

ch will come on and off as it should so no issue there.

customer said hw has been really hot lately. Cyl stat is held on with Sellotape. Was set at 40, but the dial just spins and will not affect the boiler coming on or off if programme set to hw only. Motorised valve seems to return freely when moved manually and doesn't slip when pushed open.

I'm thinking its the cylinder stat rather than the 2 port.

Anyone else with me?

 

[Rickster123]

I'm with ya! But I'm just a house bashing installer.

 

[SimonG]

Sounds like it. Easy test. Testers on the cylinder stat connections.

 

[Atouchofgas]

Aye, if you turn the stat up or down and it doesn't do anything to the zone valve, new stat

 

[Rickster123]

More importantly ash how's things going?

 

[armyash]

Aye, if you turn the stat up or down and it doesn't do anything to the zone valve, new stat

Yeah I was turning the cylinder stat up and down with programmer set to hw and nothing happening

 

[armyash]

More importantly ash how's things going?

Going pretty well thanks!

Although having to come on and ask these types of questions means probably not where I should be

 

[Rickster123]

Going pretty well thanks!

Although having to come on and ask these types of questions means probably not where I should be

Keep asking mate because I keep learning!

 

[armyash]

This is the cylinder stat, anything I need to know if putting in a Honeywell?

 

[gassafe]

Yikes that's old... If it's s plan it's probs just 2 wire...

It's normally the 2 port at fault, much more prone to fail etc... Maybe the motor?

 

[armyash]

Yikes that's old... If it's s plan it's probs just 2 wire...

It's normally the 2 port at fault, much more prone to fail etc... Maybe the motor?

If I have the programmer on hw and manually open the hw valve it still doesn't come on. Taking a cyl stat and a 2 port just in case.

 

[tamz]

You need to but yourself a cheap multimeter Ash but a neon screwdriver will tell you a lot.
You can test the stat in 2 ways.
When on for hw only test the stat.
Live on one wire only when it is turned up and down means it is goosed (its just a switch)
or
On for hw with the stat turned up high, at the junction box test for live at the brown wire of the hw motorised valve.

 

[tamz]

Look at these animated drawings. They will show you where the power goes (or should go) when you switch something on.
Honeywell Y-Plan Explanation

 

[armyash]

You need to but yourself a cheap multimeter Ash but a neon screwdriver will tell you a lot.
You can test the stat in 2 ways.
When on for hw only test the stat.
Live on one wire only when it is turned up and down means it is goosed (its just a switch)
or
On for hw with the stat turned up high, at the junction box test for live at the brown wire of the hw motorised valve.

Thanks.

So programmer set to hw on and stat turned up, should get power on the brown?
If I don't then new cylinder stat?
If i have got power then go for the motorised valve?

 

[tamz]

Yes If you have power at the brown of the hw valve that means the power is not coming back from the stat.
You can test the stat at the junction box too (its easier) but we'll learn to walk 1st.
Look at the link i posted and look at Hw on S plans and follow the pink line from hw on at the clock (that is where it starts).
The blue line that lights up is a microswitch inside the motorised valve that gets switched on when the motor moves a small striker enough to hit the switch sending the permanent live of the grey down the orange to fire the boiler.

 

[gassafe]

I had a similar fault a few weeks back, cheapo drayton 522 not sending power to hw cyl stat! Tapped the programmer a couple times & the 2 port opened... It was relays in the programmer sticking... But this is more rare!

 

[armyash]

Update. It was the motorised valve. Wired it up before draining down and made sure it worked on demand.

Also changed his timer for the immersion. Easy swap.

What would you have charged for this? Drain, swap motorised valve, refill and test. And chane immersion timer.

 

[tamz]

£150 + vat but i wouldn't have drained it.

 

[armyash]

I charged more than that but I did drain and add inhibitor.

Tamz thanks for your advice.

Thanks for all the replies.

 

[gassafe]

If I have the programmer on hw and manually open the hw valve it still doesn't come on. Taking a cyl stat and a 2 port just in case.

It didn't come on because manually opening the valve opens the paddle, but not normally enough to activate the microswitch inside!

Glad it's all sorted tho...

 

[tamz]

If you flick the lever quickly it over runs and hits the microswitch.