I have recently had a new system boiler fitted and the heating comes on when it is switched off. The hot water is timed to come on twice daily but whenever the water is on then the heating comes on even though it is switched off. I have had a replacement valve fitted and its still the same problem. I have now also discovered that I cannot control the heating with the room thermostat as I used to. It will not operate if I try to turn the heating up. Also if it is outside of the two timed settings with both hw and ch on , I used to just put the programmer to 24hrs and turn ch on with the room thermostat but am unable to do this now. The upstairs radiators dont seem to come on at all. It seems that the ch doesnt come on if there is a full tank of hot water so I have to run hot water off in order for the boiler to fire up. Basically, I cannot have ch when I want it to come on. The only thing I have got is a tank of hot water and slightly warm radiators when the hw is on, regardless of whether ch is switched on or off. They have been back 5 or 6 times at least and are unable to fix it. Anybody got any ideas?
central heating problems
- Thread starter edgar14
- Start date
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Can you tell me a little more about the replacement valve you had fitted.
Did it ever work correctly?
I'm guessing it may be a 3port mid position valve and I'm thinking it may be faulty or it may not have been wired correctly
Did it ever work correctly?
I'm guessing it may be a 3port mid position valve and I'm thinking it may be faulty or it may not have been wired correctly
I dont think it has ever worked properly. It is a 3 way valve. At first the ch was coming on when switched off. Then I had no hot water and the valve was replaced but ch still comes on when just water programmed to come on. The radiators are only warm at this point and cannot be controlled with the room thermostat at all. When the weather was cold a few days ago I discovered that I could not get the ch on at all, all that happens is when the hw and ch are timed to come on twice daily , it heats the hw and the radiators become warm but once the tank is full thats it. I then put the programmer to 24hrs but nothing will come on
P
Phill Peck
You need to get your installer back
What boiler is it
What controls
We gonna struggle to tell you what the fault is if we don't know what you've got
What boiler is it
What controls
We gonna struggle to tell you what the fault is if we don't know what you've got
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Theyve been back 6 times, its a ideal logic + system 30 boiler with my previous programmer and thermostat. I suppose the replacement valve could also be faulty but its all the other problems that have come to light aswell
It sounds as though you can get HW only and also HW shared with CH, but not CH only.
The problem with HW and CH together is that it is only a temporary mode. Over a short time period either CH or HW is going to become satisfied and when this happens the satisfied port will close and the not satisfied port will open fully.
Its the HW that is most likely to become satisfied and the cylinder stat cuts off the power to the boiler, diverts the power to the valves grey wire, this drives the motor/valve to CH only positon.It also triggers a micro switch which supplies power out from the valves orange wire and the boiler relights without you even noticing it
If the boiler does not light in CH only mode, consider the following.
(a)Valve moved to CH only position but boiler does not light. This will be due to faulty micro switch in actuator head/
(b) Valve does not move forward from mid position.
Could be no power on the grey wire due to faulty contact at the cylinder stat or no wire from cylinder stat. Could also be due to faulty micro switch
Note If HW has not been selected the cylinder stat is not active, but the grey wire still needs power.
This is achieved by an additional wire to the grey, but this comes from the programmers HW OFF terminal.
This is mentioned because I believe systems have been found with one of these wires omitted or poor connections
The problem with HW and CH together is that it is only a temporary mode. Over a short time period either CH or HW is going to become satisfied and when this happens the satisfied port will close and the not satisfied port will open fully.
Its the HW that is most likely to become satisfied and the cylinder stat cuts off the power to the boiler, diverts the power to the valves grey wire, this drives the motor/valve to CH only positon.It also triggers a micro switch which supplies power out from the valves orange wire and the boiler relights without you even noticing it
If the boiler does not light in CH only mode, consider the following.
(a)Valve moved to CH only position but boiler does not light. This will be due to faulty micro switch in actuator head/
(b) Valve does not move forward from mid position.
Could be no power on the grey wire due to faulty contact at the cylinder stat or no wire from cylinder stat. Could also be due to faulty micro switch
Note If HW has not been selected the cylinder stat is not active, but the grey wire still needs power.
This is achieved by an additional wire to the grey, but this comes from the programmers HW OFF terminal.
This is mentioned because I believe systems have been found with one of these wires omitted or poor connections
Could it be that the wrong boiler has been installed. Apparantly a system boiler should only be installed on a pressurised system with a loop fitted and instructions on how to keep the pressure topped up. I still have the hot water cylinder in airing cupboard and the header tank in the loft. A thermostat was fitted to the cylinder aswell as I was told it could melt the plastic tank in the loft.
everything indicates the valve is the problem.
If its never worked as it should, then it may not be wired correctly and it costs nothing to check for missing wires or poor connections.
Firstly remove all power to boiler.
By doing this, any power holding the valve at CH position will cease and the valve motor will unwind back to HW position.
Now make sure HW and CH are both off and then restore the power.
With both HW and CH off there is no power going to cylinder stat or room stat, and valve is in the rest position ie HW.
In the terminal box you need to test the valves 'grey' wire
This should be 'live' because its supplied from the HW OFF terminal of the programmer. unless the connecting wire is missing.
Beside the grey being fed from the programmer,there should be another feed wire coming from the cylinder stats 'satisfied' terminal.
You need to verify both these wires exist and 240v is present, before going any further.
If its never worked as it should, then it may not be wired correctly and it costs nothing to check for missing wires or poor connections.
Firstly remove all power to boiler.
By doing this, any power holding the valve at CH position will cease and the valve motor will unwind back to HW position.
Now make sure HW and CH are both off and then restore the power.
With both HW and CH off there is no power going to cylinder stat or room stat, and valve is in the rest position ie HW.
In the terminal box you need to test the valves 'grey' wire
This should be 'live' because its supplied from the HW OFF terminal of the programmer. unless the connecting wire is missing.
Beside the grey being fed from the programmer,there should be another feed wire coming from the cylinder stats 'satisfied' terminal.
You need to verify both these wires exist and 240v is present, before going any further.
How do I know if I had a pressurised system before? It was a gravity feed with a hw cylinder and a header tank in loft. This worked perfectly well. I read in the boiler manual that a system boiler should only be fitted to a pressurised system so maybe I should have been given a heat only boiler. I rang the boiler co and they said I should have been told about the loop and about topping up the pressure but none of this was mentioned to me. I still have the hw cylinder and the tank .
What makes you think you may have had a pressurised system.
A pressurised system would be 'sealed' so 'tank' to supply water when needed and accommadate expansion of water when heated would be redundant.
A pressurised system would have a filling loop, in order to pressurise it and I think it would fairly obvious
With a pressurised system, there would also be a pressure gauge to show the pressure with heating off and on. Again it would be obvious. Without a gauge how could you adjust it to the reccommended pressure.
A pressurised system would be 'sealed' so 'tank' to supply water when needed and accommadate expansion of water when heated would be redundant.
A pressurised system would have a filling loop, in order to pressurise it and I think it would fairly obvious
With a pressurised system, there would also be a pressure gauge to show the pressure with heating off and on. Again it would be obvious. Without a gauge how could you adjust it to the reccommended pressure.
its just that the boiler company said a system boiler should only be fitted to a pressurised system. Thats why im thinking has the wrong type of boiler been installed. or has the installer changed the system somehow cos they never took away the tank in the loft. but also they never mentioned the pressurised system. There is a visual gauge just under the boiler and its on 15
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