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Discuss Ideal Vogue & Opentherm via Honeywell T6 Lyric (wired version) in the Plumbing Jobs | The Job-board area at PlumbersForums.net

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richardc1983

Hey all, apologies for the long post:

I've had a new Ideal Vogue boiler installed with a T6 wired thermostat so the OpenTherm is activated as confirmed by the boiler. I also have the outdoor sensor installed but I now understand that when OpenTherm is used it ignores the outdoor sensor and so this is just reported on the boiler display for info purchases. Indeed it is ignoring any curve and corresponding temperature that is in the boiler even though this is adjustable still. I appreciate this is a learning thermostat but it's been in now a week and it is not modulating down any further that about 50c. I have changed the max flow temp at the boiler several times in the week as the default 80C was just too much heat being kicked out when I have large radiators anyway and the rooms were becoming stifling and gas usage was high. I went down from 80-70 & now at 60C max flow temp. Possibly even put it down to 55C. My previous 12year old condensing boiler (gloworm 30cxi) I used at about 50-55C flow temp occasionally turning it up to 60C when very cold but I used to let it tick away like that all the time. This kept the house very comfortable and the thermostat rarely clicked off as an overshoot.

1. How long does it take because outside weather conditions change daily so a house could take longer to heat or quicker to cool if there is a change in the weather from day to day especially being in the U.K. Where yesterday it was 2c all day and today we have 7c.

2. What is the reason for "low load control"? There is no mention of this in the manual but I have found this online: http://getconnected.honeywell.com/en...ct_Spec_EN.pdf

If the Receiver box is connected to an OpenTherm appliance this setting is used in the demand control. When an appliance is no longer able to modulate lower the control switches from modulating control to low/off control.

By default it is set to on in the Lyric T6 menu... so if the boiler can't lower further (which I know it can and have seen it go lower) it will just turn the boiler off... What is the purpose of this and what is it to avoid? There is also a low load control in the OpenTherm information menu (see below) and so when it is turned off on the t6 it is still turned on at the boiler so does this mean the boiler has built in low load control?

3. In the OpenTherm properties under the advanced menu I have a "control set point" which shows what looks to be a flow temperature the boiler is set to achieve via the t6 however this doesn't correspond with what is on the boiler as the target flow temp e.g. The t6 will show 49c but the boiler will show 44c as its target flow temp. This value fluctuates but never matches what the boiler display shows.

4. Another issue is with a digital thermometer next to the thermostat the t6 reads about 2c out - I can only adjust the temp to +-1.5c on the lyric so this is not very accurate. I've read that on the older lyrics there was a "fine tune" feature which adjusts the target temp to match humidity and outside weather but not seen anything for the T6.

I think the thermostat has a temperature sensing fault when compared to my old digital thermostat which sensed the temp perfectly; if I have it say set at 21c the t6 might read 21c however if I then go and turn it up to 22c the thermostat will then report the room temp has changed to 22c even though the room temp hasn't changed. The same happens if I then turn it back don to 21c it will say the room temp is 21c. I will then put it back to 22c and if will report the room temp is 22c and I could then put it down to 20.5 and it will say the room temp is 21c. This same behaviour is observed whether controlled from the thermostat itself or via the lyric app and if I just put a .5C increase or decrease it will then add on or take off .5C.

I've included screenshots below on this post so you can see what I mean and you will see the time is within the same minute.





The boiler will run most the time with the burner on but is still preferring to cycle off and the t6 thermostat is not modulating it down any lower than 50c this is still too much heat output so the thermostat is cycling off as it's overshot the room temp. The boiler then shows "no demand" I have a max flow temp of 60c set as I do not like radiators being too hot. It does a great job of getting the house up to temp but to TBH I expected more modulation. My boiler is capable of flow temps of down to 40c and be in modulation mode too so when the room temp is at 21c I would expect the t6 to modulate it right down rather than have frequent boiler cycling. Appreciate though that this is early days but in a week its not done anything different to when it was first installed.

Any help would be really appreciated, Ideals call centre have been useless and the installer doesn't know how OpenTherm controls really as it was his first time fitting OpenTherm and that's because I spec'd the boiler and controls. I have also contacted Honeywell technical also but the line constantly cuts off due to "high call volume" you never get through to anyone. Both manuals are useless in explaining. I know how OpenTherm should work and I am used to inverter air conditioning systems match the output to the heat/cool demand.

Spoke with the Honeywell technical manager for the UK, he also spoke with the installer and suggested that we replace the wired unit with a new one as the temperatures going up and down does not look right. This swap took place last night, interestingly when it starts adding onto the reported temperature when you change the set point seems to happen when you use the temperature offset function of + 1.5C. I have had it at +1C and it hasn't really fluctuated as much. However that just shows that they are 1C out from the factory measured with a calibrated sensor. He also recommended to disconnect the outside sensor as well however this doesn't appear to have had any effect as Ideal tell me as soon as opentherm is connected if there is an outside sensor connected as well it just ignores this as its not looking for an outdoor sensor.

I know this is a learning thermostat but surely it should know how low the boiler can modulate down to, how is it going to learn if its cutting it off before? With it off on the thermostat the boiler stays running for longer and in the opentherm information screen on the thermostat there is a "low load control" that shows that occasionally it is turned on so looks as though when this is turned off it still is running.

With the replacement T6 done over a week ago now the same behaviour still exists. The boiler is set at a max flow temp of 60C yet the minimum it will run down to is about 52C and then the T6 thermostat prefers to cycle off as thermostat off, showing a "no demand" on the boiler. Thermostat is not installed in an extreme cold or hot location indeed time to increase by half a degree is between 5-10mins, plenty of time for it to modulate down as it goes through .5C increases.

The weird temperature thing is still happening when you adjust set points and it jumps up or back down. The low load control turned on within the advanced menu of the T6 actually causes the boiler to cycle even more as the T6 doesn't seem to think the boiler can go any lower than 52C (its 45C for the Vogue), with this turned off the burner stays on for longer but then in the end it cuts out on thermostat off. When the burner comes back on it will fire up at 47C and then slowly start modulating higher to reach 55C then the same process starts again of going no lower than 52C. Low load control has been turned off within the T6 but we still see a low load control active within the T6 opentherm values menu BUT the burner does stay on for longer and only cuts out then once it overshoots the set point. Still it wont modulate lower than 52C. Where does the T6 get the info from as to what the max min modulation is? Does the Vogue have built in "Low Load Control" and if so why is the boiler not modulating down further than 52C?

Honeywell technical manager said to give it a week which it is now 8 days and said I should see a difference but it is still doing the same and to me isn't much different to my previous boiler controller. Within the Opentherm display menu on the T6 the "control set point" (assuming this means what flow temp the T6 is asking for from the boiler) doesn't match what is on front of the Vogue boiler display. What is displayed on the front of the boiler is the flow temperature and matches what is in the service menu under "flow temp". So this is what the boiler is being asked to provide. This value changes as and when the opentherm modulates the boiler.

The issue seems to be that the boiler is not telling the T6 or vice versa what the minimum flow temp it can modulate down to OR the T6 is not asking for this so the T6 turns the burner off after 52C on low load control OR the T6 reaches thermostat off state which then leads to radiators cooling down and less comfort. Its noted that if you adjust the max flow temp on the boiler this value is not reported to the T6 until you power cycle the boiler. A press of the reset button doesn't send this info to the T6 or the T6 is not picking up on it.

Kind Regards
Richard.
 
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