Boiler ignores Progrrammer whenever Room Stat calls for Heat

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Some time back I posted a query in this Forum about Boiler either ignoring the Room Thermostat or the Programmer.
I was suggested (by D_Hailsham and others) to get the Sunvic MoMo 3 Port Valve replaced by a Honeywell.
After getting this done (Honeywell V4073A), the Boiler is now completely ignoring the Programmer.
Whenever, the room stat is calling for Heat, the Boiler turns ON (irrespective of whether the Programmer is ON or OFF).
I have programmed it to be OFF between 10 pm and 6 am. However, whenever the room temp drops below 18 deg Centigrade around midnight (I've set the Thermostat at 18 deg C), the Boiler fires up. I've also tried switching the Programmer to OFF position during the day while the Boiler is running and it made no difference (Boiler kept running).
The Programmer is a Honeywell 6400C with 3 On/Off and 7 day setting.
The Room Thermostat is a Honeywell (Electronic)

Anyone seen this type of problem or has any ideas ?

Thanks and Regards
 
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Whenever, the room stat is calling for Heat, the Boiler turns ON (irrespective of whether the Programmer is ON or OFF).
I have programmed it to be OFF between 10 pm and 6 am. However, whenever the room temp drops below 18 deg Centigrade around midnight (I've set the Thermostat at 18 deg C), the Boiler fires up. I've also tried switching the Programmer to OFF position during the day while the Boiler is running and it made no difference (Boiler kept running).
The Programmer is a Honeywell 6400C with 3 On/Off and 7 day setting.
The Room Thermostat is a Honeywell (Electronic)

Anyone seen this type of problem or has any ideas ?

Thanks and Regards


check if the white to the valve is live 230v when the programmer heating is off.
sounds like the stat is wired to perm live.
or programmer is giving out perm live on ch.
 
what is the make and model of boiler
are you getting a voltage on sw to boiler when controls are off
it may not be 240 it could be 80v
 
Have you taken the common feed from the permanent live to the stat?
Alternatively, is the programmer knack**** and giving a permanent uotput to thestat?
 
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Sorry for the delay.
Both are Honeywell (the Programmer is a Honeywell 6400C with 3 On/Off and 7 day setting& the Room Thermostat is a Honeywell Electronic).

Problem 1 :
I haven't checked with a multimeter. However, with a tester, I can see Full Voltage (Glow) on the Red wire of the Thermostat (Contact 1) irrespective of whether the Programmer is On or Off. That suggests that it has a Permanent Live ? The 2nd Contact is not wired. The 3rd Contact (Yellow) also glows, but faint. So I think it might have a 80 V as suggested.
Shouldn't the Red only have 230 V when the Programmer is ON for CH and Yellow 0 V until the Stat switches it Live (the room temp falls below the set temp) ? If this is true, then it explains why would the Boiler start even if the Programmer is OFF (because of the Permanent Live).
But where is the 80 V coming from ?

Problem 2 :
As long as the Programmer is ON for CH, the Boiler / Pump is ON even if the Stat is not Calling for Heat. Is this because of the fact that the Valve gets its Live directly from the Programmer ?

Both these problems were present before I got the Valve replaced by an Engineer, so I don't think he wired it incorrectly. He must have done a straight replacement connection for the 5 wires (replacing Sunvic with a Honeywell). However, he did mention that the Pump didn't have the Ground connected and he grounded it.

I agree that this must be an incorrect wiring as sometimes it is the Stat which controls the Boiler (when the Programmer is OFF) and at other times it is the Programmer which runs it ignoring the Stat (when the Programmer is ON).

I would like some help from you guys in finding out what is wired wrongly and how do I diagnose and correct it.
I must admit that I have no Plumbing / Central Heating background but do have an Electrical Engineering background, so should be OK with the Electricals.

Thanks for all your contributions so far.
 
Sorry the Stat is a Wired Drayton Digistat 1 (2 cells) and the Programmer is a Honeywell 6400C with 3 On/Off and 7 day setting and the Boiler is a Potterton Suprima.
On the Stat, Only 1 (red) and 3 (yellow) are connected.
On the Programmer, apart from the Ground, 5 wires connected :
Live, Neutral, HW ON, HW OFF, CH ON
Note that the CH OFF is not connected.
 
Can you trace your red wire in the stat back to the junction box? If it is permanently live, then the feed must bypass the programmer, but you need to check all programmer configurations to establish the feed
 
I'd try to trace it.
Today morning I found that both the Red & Yellow on the Room Stat were having low Volt (tester lit dimly) when the Programmer was Off and the Boiler didn't fire. However, on turning the Programmer ON (CH), full Volt appeared on both Red & Yellow (with the Stat removed) and Boiler Fired up.
 
I have taken the Programmer out from the Backplate / Wiring Centre and checked that there are no loose strands. The Ground connection to the Programmer terminal was almost open (at the back plate).
With the Programmer disconnected, there is no Power to either Red or Yellow of the Room Stat. Red IS connected to the Red terminal of the backplate.
It is a Honeywell make and it says at the top "If using Programmer (not basic TimeClock) Cut Link 1". On mine, Link 1 is intact (not cut).
So, is it a 'basic Time Clock' and not a Programmer then ? Or do I need to cut Link 1 ?

It also says that only Switched Live (S/L), Neutral & Earth needs connecting for Basic Boilers ; however all 5 (L, S/L, N, E & Pumped Live) are needed for Pump Overrun Boilers.
Mine is a Potterton Suprema 40. Is this a Basic Boiler then ? I have a bypass pipe with a stop cock just between the Pump and the 3 way mid-position Valve though ?
If mine is a Basic Boiler, the Boiler connections seem to be wrong, as it has Switched Live, Earth and Pumped Live connected but Neutral not connected.
So, do I need to disconnect the P/L and connect the Neutral ?
On the other hand, if it is a Pump Overrun Boiler, then Neutral and Live should be connected too ?

Please help as I am confused.[[/b]
 

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