Nah. But I am on meter.
Those water capture bogs are eye wateringly expensive.
Those water capture bogs are eye wateringly expensive.
Estimated consumption for Greenstar 38CDi
- Thread starter joewa
- Start date
Sponsored Links
I think I have established the culprit after 24 hours of results from the Wemo. The boiler fires every 20 minutes for 7 minutes exactly every time. In the Evohome settings there is a Minimum Cycle setting which you can adjust. The lowest setting is 3 per hour, ie every 20 minutes so I reckon that's the problem.
I've emailed Honeywell for more information. Cycling the boiler every 20 minutes with no heat demand seems bonkers.
I've emailed Honeywell for more information. Cycling the boiler every 20 minutes with no heat demand seems bonkers.
Too little information is a dangerous thing 
Too little information is a dangerous thing
I'm with you there. I'm reasonably tech savvy so get most of the principles involved here but this next bit baffles me.
Having spoken to Honeywell the recommended setting for a radiator only system is actually 6 per hour which has a shorter 'on-time' than 3 per hour. 3 per hour is designed for underfloor heating, 9-12 per hour is designed for hot air systems.
So the intention is, as well as any demand from the wireless TRV's, the boiler also heats the system 6 times per hour. The boiler however has no idea whether it is supposed to be circulating hot water through the system or heating the system.
I'm going to run it as it is for 24 hours to get a baseline then try and up the cycles to see if there is any improvement. If none then I will start to adjust the on-time.
If anyone can give me some guidance on a correct on time so the boiler is making use of its condensing function I would be very grateful. Or indeed if there is a way I can get a pro to adjust the boiler so it doesn't fire unless the CH temp is significantly lower when there is a demand.
Sponsored Links
Look on the Honeywell installer network and find an Evo "specialist" in your area.
You are missing the vital principles, no matter how tech savy you think you are.
You don't understand cycle times.
You don't understand how the system calls for heat and when.
You seem to have the product installed incorrectly. Which, if your boiler is cycling every 20 minutes with no heat demand, you most certainly have.
You don't seem to understand what the product is doing under the bonnet.
The moment someone goes on about poor energy consumption along with terms like cycle rates, base lines alarm bells are set off. Not to mention WeMo.
You are missing the vital principles, no matter how tech savy you think you are.
You don't understand cycle times.
You don't understand how the system calls for heat and when.
You seem to have the product installed incorrectly. Which, if your boiler is cycling every 20 minutes with no heat demand, you most certainly have.
You don't seem to understand what the product is doing under the bonnet.
The moment someone goes on about poor energy consumption along with terms like cycle rates, base lines alarm bells are set off. Not to mention WeMo.
According to Honeywell this is correct, according to Worcester it is not how their boilers are intended to run. Without being rude are you an Evohome installer?
I am apparently an Evo Specialist.
I have had pretty much every part of the Evo range installed in my house. I have my boiler running through a proper data logger with its internal PCB connected to manufacturer's software so I can see the demand cycles.
This is why I suggest you get a specialist in your area to come and look at the installation because, correctly installed AND configured, your boiler won't cycle unless there is demand.
Understanding what constitutes a demand is not something most people understand with Evo.
Hence my earlier comment on too much information being a bad thing. And why Honeywell only provide limited support to the end user.
Wooshitter Botch don't know they 'arris from their elbows either I'm afraid; and even less about third party control systems.
Just had a flutter checking my own Evo system. Target in the utility is 18, actual 16. Boiler chugging away..... Turns out the missus left the back door open.
I have had pretty much every part of the Evo range installed in my house. I have my boiler running through a proper data logger with its internal PCB connected to manufacturer's software so I can see the demand cycles.
This is why I suggest you get a specialist in your area to come and look at the installation because, correctly installed AND configured, your boiler won't cycle unless there is demand.
Understanding what constitutes a demand is not something most people understand with Evo.
Hence my earlier comment on too much information being a bad thing. And why Honeywell only provide limited support to the end user.
Wooshitter Botch don't know they 'arris from their elbows either I'm afraid; and even less about third party control systems.
Just had a flutter checking my own Evo system. Target in the utility is 18, actual 16. Boiler chugging away..... Turns out the missus left the back door open.
Thanks for the helpful response.
This was the reason for using the Wemo as the boiler is on a 13amp plug. Seemed the best solution as I have no business taking the casing off. I do find it a bit bizarre that there is no native data logging on the Evohome, a system which is supposed to save energy.
You're not wrong, I had to explain how a zoned heating system works to their Tech expert.
Sorry I read 'too little information'. Honeywell have actually been very helpful though and have asked me to call back with results.
I'll call a local specialist later. In your opinion will a listed installer know how to sort this or will they have just been on a one day course showing them how to program the days schedules?
This was the reason for using the Wemo as the boiler is on a 13amp plug. Seemed the best solution as I have no business taking the casing off. I do find it a bit bizarre that there is no native data logging on the Evohome, a system which is supposed to save energy.
You're not wrong, I had to explain how a zoned heating system works to their Tech expert.
Sorry I read 'too little information'. Honeywell have actually been very helpful though and have asked me to call back with results.
I'll call a local specialist later. In your opinion will a listed installer know how to sort this or will they have just been on a one day course showing them how to program the days schedules?
Apologies.... I meant "too little information", in the context of someone trying to understand something that whilst not overly complicated can be counter intuitive.
There are "Installers" and there are "Specialists". This lot here seem to be the only ones in the Worcester area.
I am not sure how a 13amp plug is helping you determine cycles and demand? Are you saying the boiler is switched on and off by the Wemo as and when Evo calls for heat? If so then that could well be exacerbating the problem.
Or does Wemo have the ability of reporting back when a relay is closed? (Genuine question as I have need of a simple way of remote monitoring the activation of a volt free switch).
Evo will do all sorts of things that you AND I don't know about. I have had things intimated to me over recent years that make it a very interesting product, but the evolution (excuse the pun) will take a while due to inherent lag in installer and public knowledge.
There are some interesting blogs by people that have hacked into the wireless signals to see what is going on, but there is nothing available from Honeywell that will enable you to do it.
There are "Installers" and there are "Specialists". This lot here seem to be the only ones in the Worcester area.
I am not sure how a 13amp plug is helping you determine cycles and demand? Are you saying the boiler is switched on and off by the Wemo as and when Evo calls for heat? If so then that could well be exacerbating the problem.
Or does Wemo have the ability of reporting back when a relay is closed? (Genuine question as I have need of a simple way of remote monitoring the activation of a volt free switch).
Evo will do all sorts of things that you AND I don't know about. I have had things intimated to me over recent years that make it a very interesting product, but the evolution (excuse the pun) will take a while due to inherent lag in installer and public knowledge.
There are some interesting blogs by people that have hacked into the wireless signals to see what is going on, but there is nothing available from Honeywell that will enable you to do it.
I can't vouch for anyone other than myself and a couple of guys who post on here.
But I do know you have your thoughts on Cycle rate totally a7se about face. And if that is as a direct result of your observations on the behaviour of your system, then I refer your politely to my post at 10:53
.Fitted this lot last week:
Not one house though.
The Wemo is the Wemo insight, so it logs when a unit demands power then returns to standby, I'm not using the function to turn it off and on remotely. The boiler power supply is unaffected by the Wemo
I've seen people use Domoticz but I'm not prepared to spend hours learning Python just for this.
If you've seen anything else I would love to have a look.
Oh and I would like to understand cycle rate a bit better if you wouldn't mind spending the time to explain?
So the Wemo doesn't know that the boiler is running for heat or hot water?
It could be the preheat hot water function or someone running a tap.
Was a while ago that I was looking in the communication protocols - back when I was using Evo 1.0 and was wanting to work out what it was doing. Since then i am several iterations into the product range and don't need anything more than what I can read from my Picolog and the boiler software.
Remember that your display is only 1 decimal place. the system is bouncing data all over the place in far more detail. Also, HIN insider Top Tip. The BDR unit does more than you think.
In my experience, the more you try and outsmart the system in the attempt to make it inherently more efficient, the more you end up leading a merry dance with it culminating in grey hair and bigger bills. Simply tell it what you want to have COMFORT wise and let it work out how to do it.
If the cost of that comfort is too high then remember, heating a building over 14 degrees is purely a luxury for YOUR benefit. The building is protected. Turn things down a degree or two.
Evo will save you money but only in relation to standard controls trying to achieve the same ends. Your building's heat loss is unaffected.
Cycle rate is relevant during a demand period. When the controls are calling for heat from the boiler. If you are getting demand periods constantly then the controls are not installed properly. 3 cycles per hour limits the number of demand calls to the boiler. You also have minimum on times. Calls to the boiler are not the same as demand periods on the schedule.
Cycle rate only affects the BDR calling on the boiler.
The BDR works out when to call the boiler based on data sent back from Evo
Evo sends data back based on the relationship between actual zone temperatures and target zone temperatures along with the rate of change. It gets all very fuzzy and happens continually.
The problem you have with your boiler is that it is not only grossly oversized, it also has a terrible minimum output level meaning that it can not cycle down low enough to match the minimal heat requirement of one or two rads meaning the boiler's own internal software will kick in causing cycling from its own regulator. Evo could only be calling 3 times and hour, but the boiler could be going on and off 12 times and hour because the poor flocker is trying to heat 800 watts of radiator with a minimum output of something stupid like 7 or 9 kW (you'll need to consult the manual as I have long since stopped caring what WB boilers can do).
This is all aside from whatever schedule you have programmed into Evo and the various demands placed on that schedule by the weather and vagaries of your property which we are not privy to.
And we haven't even mentioned the optimisation routines.
*Significant edits made since first posting this, perhaps a re-read is in order.
It could be the preheat hot water function or someone running a tap.
Was a while ago that I was looking in the communication protocols - back when I was using Evo 1.0 and was wanting to work out what it was doing. Since then i am several iterations into the product range and don't need anything more than what I can read from my Picolog and the boiler software.
Remember that your display is only 1 decimal place. the system is bouncing data all over the place in far more detail. Also, HIN insider Top Tip. The BDR unit does more than you think.
In my experience, the more you try and outsmart the system in the attempt to make it inherently more efficient, the more you end up leading a merry dance with it culminating in grey hair and bigger bills. Simply tell it what you want to have COMFORT wise and let it work out how to do it.
If the cost of that comfort is too high then remember, heating a building over 14 degrees is purely a luxury for YOUR benefit. The building is protected. Turn things down a degree or two.
Evo will save you money but only in relation to standard controls trying to achieve the same ends. Your building's heat loss is unaffected.
Cycle rate is relevant during a demand period. When the controls are calling for heat from the boiler. If you are getting demand periods constantly then the controls are not installed properly. 3 cycles per hour limits the number of demand calls to the boiler. You also have minimum on times. Calls to the boiler are not the same as demand periods on the schedule.
Cycle rate only affects the BDR calling on the boiler.
The BDR works out when to call the boiler based on data sent back from Evo
Evo sends data back based on the relationship between actual zone temperatures and target zone temperatures along with the rate of change. It gets all very fuzzy and happens continually.
The problem you have with your boiler is that it is not only grossly oversized, it also has a terrible minimum output level meaning that it can not cycle down low enough to match the minimal heat requirement of one or two rads meaning the boiler's own internal software will kick in causing cycling from its own regulator. Evo could only be calling 3 times and hour, but the boiler could be going on and off 12 times and hour because the poor flocker is trying to heat 800 watts of radiator with a minimum output of something stupid like 7 or 9 kW (you'll need to consult the manual as I have long since stopped caring what WB boilers can do).
This is all aside from whatever schedule you have programmed into Evo and the various demands placed on that schedule by the weather and vagaries of your property which we are not privy to.
And we haven't even mentioned the optimisation routines.
*Significant edits made since first posting this, perhaps a re-read is in order.
I'm beginning to think the solution may be to downsize the boiler then. The reason I bought this model was to give us potential for the future but even if we add floorspace I'll still only have one or two rads at any one time needing heat, so max 2kw. The deal on this boiler seemed to make sense as it was only £100 more than a 30KW model. Am I more likely to improve this with a lower output boiler or getting the Evohome system properly setup?
Doubt changing the boiler now is worth the cost.
Get the Evo installation checked out first and make sure that is working correctly.
All my zones are at least 3 degrees above target (I changed the utility program after that post and the rest is solar gain) and the boiler hasn't received a call to function for at least 1 hour 20 minutes ( reset the data logger). In theory nothing should happen until a little before 18:00 when the optimisation kicks in for my under floor heating on the groundfloor.
Get the Evo installation checked out first and make sure that is working correctly.
All my zones are at least 3 degrees above target (I changed the utility program after that post and the rest is solar gain) and the boiler hasn't received a call to function for at least 1 hour 20 minutes ( reset the data logger). In theory nothing should happen until a little before 18:00 when the optimisation kicks in for my under floor heating on the groundfloor.
Assuming your boiler is a combi then its sized for hot water delivery and not for heating requirements.
Part of the equation is what minimum heat output the boiler is set to give.
On most boilers that's easy to set but on Worcs, if available, it requires looking in the manual for a while which is something installers don't like wasting time on.
As pointed out the modulation range is poor and perhaps the minimum power is only 14 kW which means when the demand is less the boiler can only control itself by inefficient on/off modulation.
For most medium/larger properties a combi is not a good idea and a storage system performs far better.
Tony
Part of the equation is what minimum heat output the boiler is set to give.
On most boilers that's easy to set but on Worcs, if available, it requires looking in the manual for a while which is something installers don't like wasting time on.
As pointed out the modulation range is poor and perhaps the minimum power is only 14 kW which means when the demand is less the boiler can only control itself by inefficient on/off modulation.
For most medium/larger properties a combi is not a good idea and a storage system performs far better.
Tony
DIYnot Local
Staff member
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local
Sponsored Links
