I have a Finest Gold combi boiler. it has it's own independent CH time controller as well as a wall stat linked in. reading the manual it advises that I should fit a 230/240v stat with volt free contacts. The wall stat seems to be on the blink and checking the supply voltage to the wall stat it only measures 120V which I guess will not allow the wall stat to operate. Any suggestions what the solution is, please don't tell me to replace the PCB, only did this 1 1/2 years ago. Any help would be welcome.
Halstead Finest Gold - wall stat not functioning
- Thread starter slaghuis
- Start date
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You may be measuring the voltage across the live, and switch live wires in which case you may well get 120v due to the voltage drop across the boiler components.
A bit more information may help you get a reply, for example;
What makes you think that the wall stat is faulty?
How many wires are there at the thermostat? what colours are they? and what terminals are they connected to?
A bit more information may help you get a reply, for example;
What makes you think that the wall stat is faulty?
How many wires are there at the thermostat? what colours are they? and what terminals are they connected to?
Thanks for coming back to me.
The boiler was installed in 2002, before I moved into the property. The inbuilt boiler timer control is a Grasslin timer (has 3 settings for CH control which are 1) off, 2) permanently on and 3) 24hr dial timer control which can be manually set by pushing the small fingers out to set what time of the day you wish the CH to operate. The roomstat is a Landis & Ayre type stat.
To be honest I am not entirely sure if the wall stat has ever worked. The boiler has its own CH water temp dial so it could be kicking in and out purely on this rather than turning on/off via the wall stat. I've set the wall stat (mounted in the kitchen) to 18 degrees but it feels to me that the kitchen temp is way over 18 degrees. The wall stat is not near any open windows or close to any drafty areas so I wouldn't have thought that this may be affecting it. Excuse my ignorance here but when I turn the dial on the wall stat below 15 degrees I hear a click where it turns the CH off and again when I go above 15 degrees it clicks and the central heating will work again.
I purchased a Danfoss 230V electronic volt free contact wall stat yesterday and replaced the old one with this. The central heating would not come on at all after this. A green indicator light illuminates on the wall stat but moving the temp dial on the stat up and down does nothing (1-30 degrees). There is another small red indicator light on the wall stat that flickered on and off when I neared 30 degrees on the wall stat but it is merely a quick flicker. I changed back to the old stat and as long as I turn the wall stat temp dial up until I here a click the CH will work again. Am I just being stupid here and perhaps the electronic timer is not compatible with the boiler and does it sound like the old stat is actually working?
The boiler was installed in 2002, before I moved into the property. The inbuilt boiler timer control is a Grasslin timer (has 3 settings for CH control which are 1) off, 2) permanently on and 3) 24hr dial timer control which can be manually set by pushing the small fingers out to set what time of the day you wish the CH to operate. The roomstat is a Landis & Ayre type stat.
To be honest I am not entirely sure if the wall stat has ever worked. The boiler has its own CH water temp dial so it could be kicking in and out purely on this rather than turning on/off via the wall stat. I've set the wall stat (mounted in the kitchen) to 18 degrees but it feels to me that the kitchen temp is way over 18 degrees. The wall stat is not near any open windows or close to any drafty areas so I wouldn't have thought that this may be affecting it. Excuse my ignorance here but when I turn the dial on the wall stat below 15 degrees I hear a click where it turns the CH off and again when I go above 15 degrees it clicks and the central heating will work again.
I purchased a Danfoss 230V electronic volt free contact wall stat yesterday and replaced the old one with this. The central heating would not come on at all after this. A green indicator light illuminates on the wall stat but moving the temp dial on the stat up and down does nothing (1-30 degrees). There is another small red indicator light on the wall stat that flickered on and off when I neared 30 degrees on the wall stat but it is merely a quick flicker. I changed back to the old stat and as long as I turn the wall stat temp dial up until I here a click the CH will work again. Am I just being stupid here and perhaps the electronic timer is not compatible with the boiler and does it sound like the old stat is actually working?
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Stem,
I don't think the stat is working as I have set it to 18 degrees C but the room feels a lot hotter than this. The wall stat is in the kitchen away from any draft or windows as well. As per my reply to bengasman when I turn the dial on the wall stat it clicks when I go below 15 degrees C and the CH goes off. When I turn the dial above 15 degrees it clicks and the CH will resume. Basically I don't think the wall stat is serving as any other means of control (literally only an on/off switch for the CH).
Again referring to my reply to bengasman I changed the wall stat with an electronic Danfoss 230V volt free contact type and the central heating did not come on at all on demand, I've since changed it back and just keep the old stat above 15 degrees and control the CH via the boilers integral timer control. Obviously I suspect that with the wall stat not functioning correctly I'm just wasting energy by not controlling the room temp as well.
In answer to your other questions, there are two wires at the wall stat which link into the boilers intergral control timer via a terminal block connection. The wire colours leaving the boiler timer are both orange up to the terminal block connection. From there to the wall stat someone has installed 3 core surflex cable (black, red and earth) with the earth not connected on either end. In my last post I mentioned that the voltage I measured was only 120V and after reading your last reply I went back to check again. I was not totally correct in my previous checks, there is 240V between each respective orange wire and earth and 0V between the two orange wires when the stat is turned above 15 degrees i.e when it clicks. There is 120V between the two orange wires when the stat is turned below 15 degrees i.e when it clicks again.The black and red wires of the surflex cable running to the wall stat are purely an extension of the two orange wires from the inbuilt boiler control timer. The red wire is connected to the live terminal connection on the wall stat with the black wire connected to the neutral connection of the wall stat. Will the lack of the earth cable being connected cause any operational issues to the wall stat?
I think the problem is that you are trying to use a thermostat that requires three connections with only two wires.
The two orange wires you refer to (from terminals 04 & 05 in your boiler) that then become red & black out to the thermostat are the contacts for the thermostat. When the two wires are connected together they complete the circuit and the central heating will operate, break the circuit and it will stop. (they should not be connected to anything else hence the requirement for potential free contacts)
You say the thermostat has a neutral terminal, but from what you say you don't have a neutral wire to connect to it. It is wrong to connect either of the two orange wires (that become the Red & Black) to the neutral terminal.
Based on that, you have two choices, either run a neutral wire to the thermostat, or take the thermostat you have just purchased back and get one that doesn't require a neutral connection. There are lots to choose from, most of the new digital ones for example.
Don't get too concerned about the voltages on the terminals as they are connected to a PCB you may get different readings depending what the other components connected to the PCB are doing.
The earth connection will not effect operation, but is there for safety. If the thermostat says that it should have an eath connection then you should connect it to the earth terminal at the boiler end, and the earth terminal at the thermostat end. However many thermostats are double insulated and so don't need an earth connection.
The two orange wires you refer to (from terminals 04 & 05 in your boiler) that then become red & black out to the thermostat are the contacts for the thermostat. When the two wires are connected together they complete the circuit and the central heating will operate, break the circuit and it will stop. (they should not be connected to anything else hence the requirement for potential free contacts)
You say the thermostat has a neutral terminal, but from what you say you don't have a neutral wire to connect to it. It is wrong to connect either of the two orange wires (that become the Red & Black) to the neutral terminal.
Based on that, you have two choices, either run a neutral wire to the thermostat, or take the thermostat you have just purchased back and get one that doesn't require a neutral connection. There are lots to choose from, most of the new digital ones for example.
Don't get too concerned about the voltages on the terminals as they are connected to a PCB you may get different readings depending what the other components connected to the PCB are doing.
The earth connection will not effect operation, but is there for safety. If the thermostat says that it should have an eath connection then you should connect it to the earth terminal at the boiler end, and the earth terminal at the thermostat end. However many thermostats are double insulated and so don't need an earth connection.
Hi Stem,
Thanks so much for your advice. I took the new stat that I bought back and exchanged it for a Honeywell DT90E type which can be connected without a neutral wire. Connected it all up, adjusted the setpoint below the room temp and the CH kicked in. Adjusted the setpoint above the room temp and CH dropped out. Works spot on. I've now put the setpoint to 18 degrees and left it there with a high limit of 21 degrees. Will watch over the coming weeks to see if the setpoint is comfortable enough although I suspect I will have to wait until the colder months to really find the "comfort" setpoint.
The old Landis & Gyr wall stat couldn't have ever worked properly, a pity as I've no doubt being paying for wasted energy for a few winters!
Thanks again for all your help, it's much appreciated.
Thanks for the update, It's always nice to hear how things have turned out, so I'm glad to hear it's working, & good choice of thermostat too.
It might not work as well as it could being located in the kitchen. Assuming you do cook in there, the room will be warmed by the cooking and turn off the heating to the whole house.
Anyway, should you decide to re-locate it sometime in the future, you'll know how to connect it now.
It might not work as well as it could being located in the kitchen. Assuming you do cook in there, the room will be warmed by the cooking and turn off the heating to the whole house.
Anyway, should you decide to re-locate it sometime in the future, you'll know how to connect it now.
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