Are my Boiler and Thermostat Working as They Should?

[BorderReiver12]

We have recently had a complete new central heating system (boiler, pipes, radiators...the lot) fitted and we are having trouble with the boiler not coming on at the time the thermostat is set for.
The boiler is a Vaillant ecoTEC and the thermostat is a Honeywell CM727 Wireless.
I have the thermostat at 16 deg c for overnight, then for 20 deg. c at 6.50 am. This very rarely works as sometimes the boiler doesn't start up until at least half an hour later and even then it will heat a small part of the radiators, then stop for a few minutes, then continue like this until it finally works properly. Sometimes the "burner on" symbol is displayed on the thermostat, even though the boiler isn't heating anything.
This morning, it worked perfectly...the pipes and radiators were heating up dead on time. Yesterday, nothing happened until 7.30am and that was when I got sick of waiting and switched the thermostat from auto to manual for a while.
Can anyone tell me if this is normal, or is there a fault with either the boiler or thermostat?
The boiler is in the loft and the thermostat is normally in the lounge, downstairs. I've tried replacing the batteries in the thermostat & that doesn't make any difference. Usually, the temperature in the room where the thermostat is, would be around 17 deg c at 6.50am, so the room temp needs to be raised by about 3 deg.

 

[D_Hailsham]

The boiler is in the loft and the thermostat is normally in the lounge, downstairs.

The CM727 is a wireless thermostats, so there are two components: the control unit and the receiver (white box with green and red lights).

1. Where is the receiver located?
2. How far, in a straight line, is the receiver from the control unit?
3. How many walls and floors directly between the two components?
4. Is the "flame" showing on the control unit when you get up?
5. What lights are there on the receiver when you get up?
6. Do you have thermostatic valves (TRVs) on any radiators?
7. If so, which rooms do not have TRVs?

 

[Agile]

Clearly something is wrong!

But as its intermittent that makes it difficult to guess what.

You dont say which model or the size of house and number of rads.

But all this is the responsibility of the installer!

Why have you not called him first?

Tony

 

[BorderReiver12]

The boiler is in the loft and the thermostat is normally in the lounge, downstairs.

The CM727 is a wireless thermostats, so there are two components: the control unit and the receiver (white box with green and red lights).

1. Where is the receiver located?
2. How far, in a straight line, is the receiver from the control unit?
3. How many walls and floors directly between the two components?
4. Is the "flame" showing on the control unit when you get up?
5. What lights are there on the receiver when you get up?
6. Do you have thermostatic valves (TRVs) on any radiators?
7. If so, which rooms do not have TRVs?

1. We only know of the control unit, so we assume that the receiver is in the loft near the boiler.
2. The distance between the control unit and the boiler is about 10m
3. 2 floors and 1 wall.
4. No
5. We've never seen the receiver...if it's in the loft, we'd need to get a ladder out of the shed.
6. We had TRV's fitted to all radiators (10).

Bringing the control unit upstairs to the bedroom (thus reducing the distance by half) didn't make any difference, sometimes it worked and sometimes it didn't.
It's baffling to me that the control unit shows a symbol indicating that the boiler is burning, when clearly it isn't as nothing is heating up.

 

[BorderReiver12]

Clearly something is wrong!

But as its intermittent that makes it difficult to guess what.

You dont say which model or the size of house and number of rads.

But all this is the responsibility of the installer!

Why have you not called him first?

Tony

Thanks,

We have notified the installer, but he's working 300 miles away at present and he would come and have a look when he returns (he'd have no choice, his girlfriend and my wife are friends). We're only checking to see if we have done anything wrong, or if it's a simple thing to rectify...like changing batteries or moving the position of the control unit. He has the same combination in his own house and it works fine.
The house is a 3 bed semi.
The Boiler is an EcoTEC Pro 28
At present, it's not a huge problem to us, but when Autumn comes around we need to make sure it's all working correctly.
A definite problem is usually easily sorted, but when it's intermittent...it's a real pain.

 

[D_Hailsham]

1. We only know of the control unit, so we assume that the receiver is in the loft near the boiler.

That's not very sensible as you can't see the lights, which can warn you if anything is wrong.

2. The distance between the control unit and the boiler is about 10m
3. 2 floors and 1 wall.

Distance is OK, but the signal will be reduced by the walls/floors. However, you say moving the control upstairs has no real effect. This could be because the receiver is too close to the boiler, which is acting as a shield to the signal.

4. No

So the control thinks the room is up to temperature!

5. We've never seen the receiver...if it's in the loft, we'd need to get a ladder out of the shed.

That would be a good idea. Don't touch anything. Just report what lights, if any, are visible on the receiver. Also measure how close the receiver is to the boiler.

6. We had TRV's fitted to all radiators (10).

There shouldn't be a TRV on the rad where the control unit is located. If you are in the habit of moving the control unit around, make sure the TRV is on maximum in the room where the control unit is located.

It's baffling to me that the control unit shows a symbol indicating that the boiler is burning, when clearly it isn't as nothing is heating up.

That's a quirk of the wireless version. On the wired version the flame only appears when the boiler is actually running. With the wireless version the flame just indicates that there is a demand for heat. This can be anything from boiler on continually to boiler on one minute every 10 minutes.

 

[BorderReiver12]

OK, I've just checked in the loft. The receiver is about 200mm from the boiler and there were no lights showing. I went to the control unit in the lounge and the flame symbol was lit, even though the room temp was 2 deg higher than the set temp. I turned it up to 25deg and went back to the loft...the green light was on and the boiler was heating up.
Both rads in the lounge are turned up full anyway.
I think it's beginning to seem to me that there's nothing I can do myself and that I should get the installer to have a look when he comes back home. His company have installed loads of these and he'll know best what to do next.
When I asked for advice here, I was hoping it was just a simple thing that could be rectified by the push of a button or replacing batteries or moving the control. Thanks for all your advice anyway, I've got a better understanding of it all now.

 

[scoobydo123]

Strange as you say that if you manually overide then it is fine this proves comms are ok

 

[Agile]

Do you have Duracel batteries in the TX unit?

Cheap ones dont work them reliably!

David, how does the wired version know the boiler has ignited?

Tony

 

[D_Hailsham]

David, how does the wired version know the boiler has ignited?

It doesn't, any more than the wireless one knows.

The wired version sends the on-off signal directly to the boiler, so it knows exactly when the boiler should be on or off and can control the flame signal directly.

The wireless version just tells the receiver that it should cycle the boiler at a certain rate and the receiver then takes over. The flame then indicates that the controller has told the receiver to provide heat. The only time the flame doesn't show is when there is zero demand for heat.

 

[BorderReiver12]

Do you have Duracel batteries in the TX unit?

Cheap ones dont work them reliably!

David, how does the wired version know the boiler has ignited?

Tony

Yes, that was one of the first things I did...put brand new Duracell batteries in.

 

[gaswizzard]

I went to the control unit in the lounge and the flame symbol was lit, even though the room temp was 2 deg higher than the set temp

Something is not right , the flame signal should not be showing when target temp is below room temp.

Temperature offset may have been changed in 'catogory1' parameters , if offset has been changed then target temp can be as much as 3 degrees +/- away fron room temp before boiler switches on/off.

 

[D_Hailsham]

Do you know if the installer switched Optimization ON?

You can tell by checking the stat first thing in the morning. You should see OPT in the bottom right corner of the screen. If Optimization is turned ON, you set the clock to when you get up, e.g 7am, and the stat works out how much earlier the heating needs to come on, depending on the overnight temperature drop. If OPT is OFF, you have to set the heating to come on earlier, say at 5am,so the house is up to temperature by 7am.

Do you have the Installation Manual? If so, check all the parameters and post them here.

 

[gaswizzard]

I think it's more so an issue with 'temp off-set' , optimisation 'on' won't show the burner symbol if target temp is below room temp , whereas 'temp off-set' will.

Seems someone has been playing.

 

[BorderReiver12]

Do you know if the installer switched Optimization ON?

You can tell by checking the stat first thing in the morning. You should see OPT in the bottom right corner of the screen. If Optimization is turned ON, you set the clock to when you get up, e.g 7am, and the stat works out how much earlier the heating needs to come on, depending on the overnight temperature drop. If OPT is OFF, you have to set the heating to come on earlier, say at 5am,so the house is up to temperature by 7am.

Do you have the Installation Manual? If so, check all the parameters and post them here.

I'll check as you suggested first thing in the morning. We do have the manuals, but those kind of things are best left to the installer. He'll do it when he gets back from Hampshire...we don't want to invalidate the warranty in any way.

Thanks to everyone for their advice...it's got me to understand a bit about heating systems.