DB,Quote:
Originally Posted by DBMandrake
I don't think anything has changed in low load operation sub 10% (1 min in 10min, 6 cph) the cycle rate is sacraficed to maintain a min on time
AtM
DB,Quote:
Originally Posted by DBMandrake
I don't think anything has changed in low load operation sub 10% (1 min in 10min, 6 cph) the cycle rate is sacraficed to maintain a min on time
AtM
I've experienced this pre-beta, haven't noticed it recently.Quote:
Originally Posted by roydonaldson
By "sacrificed" do you mean that TPI cycles with less than 10% demand are just skipped ?Quote:
Originally Posted by Andy the Minion
I have had a huge issues with this 1min on 1off, i think there is another unresolved thread about it.
Im on the beta fw and i think evo works a bit better with latest fw however i dont think its fully resolved.
Before i had 4% demand on evo and boiler was fairing without any heat being able to reach rads. At the moment i can see much higher heating demand on evo ie 17% but it may be a case of evo still learning.
In my case the boiler was firing with max CH temperature for a minute rather than a lowest one when it was cycling 1min on/9 off.
Tbh if i known that this is how opentherm works i would stay with brd91.
I reached boiler installers and evohomeshop and they all put heads in the sand.
I suspect it may be a side effect of opentherm that they dont want clinets to find out.
Lets be honest this cycling wastes energy and definetly can be improved.
Before im crucified by an opentherm evangelist thats my personal opinion based on personal experience based on many reported similar cases.
What boiler do you have? EvoHome does employ on/off control with OpenTherm under low load situations, but for me it is always at lower temperatures, typically under 40C.Quote:
Originally Posted by Mid112
Have you connected an OpenTherm gateway to monitor the flow temperature request? It could be that what you are observing is the boiler firing with its startup fan rpm at say 40% before modulating down, but the requested flow temperature is soon overshot by 5C resulting in the boiler turning off, starting its anti-cycle.
You may be able to tweak some of your boiler parameters to improve e.g. if you have Intergas, but fundamentally your boiler probably can’t modulate down low enough to satisfy the kW output needed, so you end up in this on/off situation with the boiler firing at higher output for short intervals.
I have Intergas xclusive 30 - it can modulate by design to 25C by design If I remeber correctly with 30C set by default.
So what has been happening was that when there was very low heat demand ie 4% on evohome - boiler would cycle with MAX set temperature set for CH ie 70C for a minute causing pipe below boiler to be flameing hot while others rads being barely warm. It was always MAX CH set on boiler - when I changed to 60C - it was cycling with 60C instead of 70C.
During this weird cycling boiler never modulated down - it was staying constant 70C for a minute of so.
I have tweaked numerous settings on the boiler but I think getting this beta FW and changing output to 75% helped a bit.
You may be able to tweak some of your boiler parameters to improve e.g. if you have Intergas, but fundamentally your boiler probably can’t modulate down low enough to satisfy the kW output needed, so you end up in this on/off situation with the boiler firing at higher output for short intervals.
This is exactly what has been happening - but if its a case thats a clear fault to me. In my understandig if this is a case boiler should answer with min flow temp - not the highest one.
Its like buying a brand new hybrid car - advertised that car will use battery and save a fuel when driving on motorway but when its parked on your driveway it will start engine every 10 mins for 1 min with max RPM burning petrol.
Thats a pure madness or a fault
> Thats a pure madness or a fault
That doesn’t sound right, do you see your boiler responding correctly to OpenTherm lower temperatures?
What is your P057 parameter set to? If set to 2, “respond to heat demand with maximum set flow temperature (on/off function)”. That should be set to 0 or 1. Sounds like for some reason your boiler is in mode 2.
If I were you I would connect an OpenTherm gateway to check what flow temperatures EvoHome is requesting.
The boiler responds fine and modulates between 40-70c depending on actual usage.
57 is set either to 0 or 1 - it doesnt make much difference which on is actually set
Is definetely not on on/off.
I have an older Intergas boiler and don't see anything even remotely like this behaviour. Something is very wrong with your setup - it shouldn't be doing that, and it isn't doing that by design.
I rebinded and reset everything twice with evohome support.Quote:
Originally Posted by paulockenden
Swapped Opentherm for a newer one - same issue.
Just to say - this issue happens only when a demand on evehome is only a couple of % If I remeber correctly 4 or 6%.
But the latest FW has defo improved the issue and it doesnt happen, at least not that often.