Ideal boiler cycling with Nest & Opentherm

[Littlejack101]

How long have you had it running with this setup mate? I’ve had mine setup for about a week and a half and the last day or two, it’s done it a bit but not as much. It seems nest maybe ‘learning’ what water temp is required in order to maintain the temp of the thermostat. Rather than cycling as often it’s now holding around 48 deg flow temp as it approaches the target and then shuts off. I’ll keep an eye on it and let you know if it continues.

I've had this setup for a week. No idea if the boiler behaved like this before as I was not really looking! I've messed around with the boilers 'Max flow temp' but that doesn't seem to make a difference.

 

[Littlejack101]

Firstly how many rads do you have ? The Ideal logic 35 kw max has a modulation rate from 8 - 24 kw in its heating mode , there must be a heat load loss through the boiler at all times we dont know how it's installed so let's say you need at least one decent size radiator with no trv fitted is this the case ?

I've got 10 rads & a couple heated towel rails. TRV's on all the rads but are fully open downstairs where the thermostat is located. The majority of the radiators are pretty old so would not surprise me if they not kicking out a huge amount of heat.

 

[king of pipes]

Opentherm should help stop the boiler cycling so much I am using it on my own system via a Nest thermostat , heating the system to a maximum of 60 °c over a longer period the boiler modulates to a very low output and condenses all the time , are you 100% sure you stat is operating in opentherm? it needs to be configured in the settings on the stat , you can then test it in the equipment setting. Kop

 

[Littlejack101]

Opentherm should help stop the boiler cycling so much I am using it on my own system via a Nest thermostat , heating the system to a maximum of 60 °c over a longer period the boiler modulates to a very low output and condenses all the time , are you 100% sure you stat is operating in opentherm? it needs to be configured in the settings on the stat , you can then test it in the equipment setting. Kop

I was 100%, but your post prompted me to double check...I hadn't realised that the stat settings needed to be changed & was set up in on/off mode. Will see what happens now, but wanted to thank you Kop - I'd totally missed the stat set up part.

 

[king of pipes]

Can be a pita to configure sometimes you need to uninstall the app and start a fresh you should see something like this once your set up . Regards Kop

 

[king of pipes]

Can be a pain to configure sometimes often it's better to uninstall the app and download it again , once your connected you should be able to see these

 

[flyingsailor]

Firstly how many rads do you have ? The Ideal logic 35 kw max has a modulation rate from 8 - 24 kw in its heating mode , there must be a heat load loss through the boiler at all times we dont know how it's installed so let's say you need at least one decent size radiator with no trv fitted is this the case ?

Thanks King, I have 12 rads in the house, a couple are fairly large column ones and all TRVs are in the fully open position. I’ve balanced the system as best I can with an average differential between flow and return to the boiler between 13-15deg.

 

[king of pipes]

Once your set up it should be fine I'd say

 

[flyingsailor]

Opentherm should help stop the boiler cycling so much I am using it on my own system via a Nest thermostat , heating the system to a maximum of 60 °c over a longer period the boiler modulates to a very low output and condenses all the time , are you 100% sure you stat is operating in opentherm? it needs to be configured in the settings on the stat , you can then test it in the equipment setting. Kop

Hi kop, mine is setup exactly like this and does run for longer periods at lower temps but as the room temp reaches the target, the boiler doesn’t shut off, instead the pump runs and the flame ignites for a bit then goes out and repeats this continually. This maintains the target temp but wondered if it was normal or whether it should shut the boiler off and then restart it as the target temp drops a bit?

 

[king of pipes]

I don't think it should cycle so frequently even when it reaches its temperature set point mine doesn't Opentherm should modulate your boiler down to its lowest setting possible , review your settings on your Nest as my previous post , what boiler do you have ? it maybe possible to set a period of time your boiler heat between switchings ? Regards Kop