Y Plan - room thermo doesn't fire boiler

[Doc Lenny]

Hi

I suspect that this problem has been running for a while but not noticed as we use alot of hot water and the days are now getting colder.

The boiler, an Apollo 30B fires only when the need for hot water. Done alot of testing to try and narrow things down but still no solution. Basic Honeywell Y System with SunVic select XL programmer.

Assume that HW and CH are both on at the programmer.

If the HW needs heating then the boiler fires up. If the HW is satified and you turn the CH roomstat to max the boiler does not fire up although the mid position valve fully opens. So if both theromstats are set to max we get HW and CH no problem. Once the HW is satisfied then we have no way of heating the house.

Any clues - I suspect a wiring fault but thought I'd ask if you had encountered a similar problem.

Does the Mid position valve send a message to the boiler to ignite when the roomstat calls for it or is this done directly.

Thanks for any input.

 

[chrishutt]

The wiring of a 3 port mid position valve is quite complicated. It's been covered pretty comprehensively before - this thread for example.

//www.diynot.com/forums/viewtopic.php?t=62788&postdays=0&postorder=asc&start=0

The first thing is to make sure the whole caboodle is wired up as it should be - they often aren't.

 

[corgiman]

change the actuator i spect the mirco switch aint working

I had three of these today

oh yeah and five suprima boards (shush dont tell the potty poxi lads but two of which were they new ones so looks like potterton have finally sorted it out NOT)

 

[Doc Lenny]

So the Mid position valve is No. 1 suspect.

Thanks for the link CH, I'll have a good read.

Cheers Corgiman, mind you the valve is only about 18months old.

 

[MANDATE]

I agree fully.
Took me a while to solve the exact same problem. (well a couple of days).
Valve moved over but no power output on the orange wire. Fault deemed to be microswitch so changed actuator head. Problem fixed!
Stripped down old head, got inside microswitch and as suspected burnt contacts.

 

[chrishutt]

valve is only about 18months old.

Hardly likely to be a valve head failure. My money's on incorrect wiring.

 

[Doc Lenny]

I agree fully.
Took me a while to solve the exact same problem. (well a couple of days).
Valve moved over but no power output on the orange wire. Fault deemed to be microswitch so changed actuator head. Problem fixed!
Stripped down old head, got inside microswitch and as suspected burnt contacts.

I can confirm that orange wire becomes live when HW is calling for heat but never when CH is calling (without HW).

 

[corgiman]

I agree fully.
Took me a while to solve the exact same problem. (well a couple of days).
Valve moved over but no power output on the orange wire. Fault deemed to be microswitch so changed actuator head. Problem fixed!
Stripped down old head, got inside microswitch and as suspected burnt contacts.

I can confirm that orange wire becomes live when HW is calling for heat but never when CH is calling (without HW).

as mandate says micro switch

I agree chrishutt but i have had to return to several honeywells that I fitted a couple of years ago to change the heads, seems to be a bad lot they sent out about that time

 

[chrishutt]

Doc Lenny, when you put the CH on, does the brown wire to the motorised valve become live? And if so, does the valve open (you can feel the movement via the little metal lever than pokes out the end)? If the answer to both is yes, then is the grey wire live? If so, it's the micro switch that's the problem.

Later edit - the above is incorrect. I was mixing up 2 ports and 3 ports.

 

[Doc Lenny]

Doc Lenny, when you put the CH on, does the brown wire to the motorised valve become live? And if so, does the valve open (you can feel the movement via the little metal lever than pokes out the end)? If the answer to both is yes, then is the grey wire live? If so, it's the micro switch that's the problem.

Hi Chris, thanks for your help so far.

The only wire that is brown is one that comes from the Cylinder stat. I can confirm however that the Valve opens when the CH is called for and the room stat is on max. The grey wire that is connected to the blue wire from the tank stat is always live as long as the HW is on at the programmer, even when the stats are down to min.

Thanks

 

[MANDATE]

If the valve moves over to the CH only position and there is no power at orange wire the problem must be the microswitch.

 

[chrishutt]

Doc Lenny, when you put the CH on, does the brown wire to the motorised valve become live? And if so, does the valve open (you can feel the movement via the little metal lever than pokes out the end)? If the answer to both is yes, then is the grey wire live? If so, it's the micro switch that's the problem.

Just realized that I gave you faulty advice there! I'd also been answering another post about 2 port valves and got mixed up! What I should have said was:-

When you put the CH on, does the white wire to the motorised valve become live? The grey wire should be connected to the satisfied terminal on the cylinder stat (as well as HW off on the programmer) and the orange wire should be connected to the call-for-heat terminal on the cylinder stat, as well as the live to the boiler and pump.


Check the operating sequence on page 3 of the thread linked to before.

 

[corgiman]

I realise that other than mandate no one is actually paying any attention to me but I will crack on anyway

why **** ball about the valve/motor is moving to CH onl-y but the switch live aint proving ergo its the MS ergo change the bleeeding actuator, you would have been warm and toasty ages ago if you had

 

[Doc Lenny]

Thanks Corgiman

I will take your straight talking advise.

Let you no what happens if your interested.

 

[chrishutt]

Let you no what happens if your interested.

Please do, especially if it turns out that you wasted your money on a new valve head.