H/W and H/W with C/H together but NO C/H ON IT'S OWN - HELP!

[doitall]

Sounds like a plan.

You can always email to me as well, it's in my profile if you remove the white space.

 

[Wildeman]

Thanks will do

 

[Norcon]

D Hailsham usually has too much time on his hands

Considering the time you spend on here the same could be said about yer self.
In fact D Hailsham probably has a life.
Do you?

 

[Wildeman]

Doitall - have turned the Frost Stat right up to 30 and the boiler lights and the pump starts, the valve does not move from the HW only position.

I thought I would try removing the Valve head and then if I move the valve body itself to the mid position the pump for the Central Heating gets hots and so do the radiators.

If I then move the valve body to the CH only position the pipe to the pump and from the CH side of the valve goes cold in under a minute.

This is the same if the heating is on on the programmer. With this said do you still think it is electrics seeing as I am moving the valve manually?

If you think it could still be electrics I will trace all wires and draw up a wiring diagram.

 

[doitall]

I would still like a line drawing.

 

[picasso]

if the pump is running I would check the connection between orange and boiler, if that checks out ok the boiler stat would be next.

 

[twgas]

If your not happy with cyl stat on 90˚ try tuning the boiler stat right down, this will set the system water to about 60˚, then set cyl stat on 65˚ish, this will mean the cyl stat will never satisfy and so shouls stop the valve moving to CH only (this is only temporary until problem sorted)

 

[twgas]

When you have CH only, the pump runs, but do you get 240v to the boiler?

 

[Wildeman]

thanks for the advice twgas I will try that with the stats tonight to at least keep heat in the radiators!!

When you have CH only, the pump runs, but do you get 240v to the boiler?

Yes in CH only mode, the valve moves to the correct position, the pump runs and there is 240v at the boiler. The boiler is only live when needed (it DOES NOT have a permenant live and switched live)

What is strange is if I put the CH & HW both on and turn up room stat and tank stat the valve moves to mid position and red hot water flows to radiators and HW tank, if I then remove the valve head and manually move the valve body to CH only the feed to the pump and CH go cool and no heat gets to radiators!! If I then move the valve body back to mid position there is a whoosh and sounds like a rush of water and the pipes get ref hot again!!

 

[MANDATE]

Just checking to see if you've made any headway.

I note your comments regarding the frost stat. If frost stat 'live' wire goes direct to the terminal containing the orange wire, then it has by-passed the motorised valve. This explains why valve does not move
It would make more sense if it went to the terminal containing the 'white'.
This would drive motor to CH position and operate as it should normally.

Of course at the moment the problem seems to be the 240v from valve which fails to light boiler, which is quite happy to light if 240v comes from cylinder stat or frost stat. A situation hard to accept.

 

[Wildeman]

Thanks Mandate,

I thought I was making some progress but now that is vansihing fast!!

I had the electrician back on Saturday and he completely re-wired the junction box in the airing cupboard after tracing every wire and testing them for breaks, once that was done he shorted out the stats and even the programmer and the pump, valve and boiler performed as expected.

This pretty much ruled out the wiring as the thermostat on the boiler was tested. It appears in CH only mode the boiler is cutting out on the overheat stat due to lack of water flow.

I then tried closing all the radiator valves, feed and return and then ran up the system with the valve head removed and manually moved the valve to the CH only position. The feed pipe to the pump and on the CH side of the valve became red hot. I left this running and the heat remained, I then opened a radiator on the landing only a small amount and it got red hot.

I slow went round and opened the other rads a bit and they eventaully all got red hot but then then on Sunday morning when I wanted CH only nothing but cold pipes!!

There seems to be a lot of air in the system but not sure how to cure this as no bleed in the loft or by the cylinder.

IN DESPERATION MODE NOW!!

 

[doitall]

Still waiting for the drawing.

 

[D_Hailsham]

I see my name has been mentioned, so here goes

Why do you have a 2-channel timer and a programmable stat? I know you need to be able to control the HW side, but a single channel timer will do this job. The programmable stat should be fed directly from the wiring centre L and N terminals, not via the other programmer. This will eliminate any caused by the 2-channel timer.

Now to your main problem.

We need to eliminate the valve from our enquiries, which means some temporary rewiring. But first we need to check that the valve is not sticking. We do this by removing the actuator (box on top) to reveal the valve spindle. This should rotate easily by hand (not a full rotation - less that 45°) If it does not rotate easily, try a little WD40 and a pair of pliers to free it.

If the spindle rotates OK we have to test the actuator, so replace the box on the valve.

Turn off power when connecting/ disconnecting wires This usually means unplugging the lead or removing the fuse from a spur.

Disconnect the valves Grey, Orange and White wires (make a note of which terminal they are connected to)
Turn CH OFF and HW ON at programmer(s)
Turn HW stat up - boiler should light
HW pipe only from valve should get hot
Turn HW stat down - boiler should go out.

This confirms the Call side of the HW stat is working.

Connect the White wire to a permanent supply.
Turn CH ON at programmer(s) and room stat up
Turn HW stat up
Boiler should go on
HW and CH pipes from valve should get hot.
Turn HW stat down
Boiler should go out

This confirms if valve is working in mid-position

Turn HW and CH OFF at programmer(s) and set CH and HW thermostats to low
Connect grey wire to a permanent supply
Turn CH ON and CH stat up.
Measure voltage on orange wire. Should be 240v (Boiler will not go on as orange not connected)
Turn HW ON at programmer(s) (leave HW stat low)
Orange should still measure 240v

This confirms if the valve is working in CH only

Turn CH and HW OFF at programmer(s)

Reconnect Grey, Orange and White wires to the correct terminals.

If it fails any of these test, the actuator is faulty.

If it passes the tests, the fault lies elsewhere. Either a programmer or one of the thermostats.

 

[D_Hailsham]

It appears in CH only mode the boiler is cutting out on the overheat stat due to lack of water flow.

Are you saying that in CH+HW mode the water circulates through the rads OK and they heat up properly?

I then tried closing all the radiator valves, feed and return and then ran up the system with the valve head removed and manually moved the valve to the CH only position. The feed pipe to the pump and on the CH side of the valve became red hot.

Not surprised they got red hot. There was nowhere for the water to circulate (unless the flow and return are connected together at the end or there is a bypass valve)

I then opened a radiator on the landing only a small amount and it got red hot.

That's to be expected

I slow went round and opened the other rads a bit and they eventually all got red hot

How hot is "red hot"?

There seems to be a lot of air in the system but not sure how to cure this as no bleed in the loft or by the cylinder.

Can you post a pic (use Upload Pics) of the airing cupboard showing the general layout of the cylinder, pipework etc.

 

[matt1e]

not read through all the posts but reading the first post i'm with mandate on this one faulty microswitch

to test select CH only, room stat up and when the valve reaches fully open bridge out white and orange (or get your sparkie to)
if the boiler then fires -sorted get a new actuator

matt