Evohome continually bringing boiler on for one minute then off for 10 minutes

[EvilDrPorkChop]

Hi

Many thanks for the reply.

I think my concern at the moment is that when the boiler is in this mode and is on then the radiator in one of the rooms demanding heat appear to not be warming up at all, indeed it appears as cold as the ones that are not demanding heat.

I have looked at the boiler display when it is heating for the minute and it has raised the temperature from say 30 degrees to 32 degrees which does not seem to be much. I have noticed that, even when zones are 100% on and valves fully open, the Worcester boiler will take around 10 minutes to go from 30 degrees to 70 degrees heat (it starts low and as time goes on you can hear the boiler working harder as it modulates up), now this may be normal but in this case I was wondering if the lack of heat and valves near closed was causing an issue. It may be that increasing the on time to 2 minutes (so we have 2 minutes on, 8 minutes off) may be helpful with this boiler but I am trying not to change anything whilst it is learning (as well as being on twice as long may use twice as much gas)

I asked Resideo about the learning and they said it should have learnt after 2/3 weeks even if the heating not required. Now I cannot see how this can be the case as the valves would always be at 0% and nothing to learn, hence I presume I have to wait the 4 weeks from now (as the weather being colder means the valves will be moving).

I have one room where it is not up to the desired temperature, the Evohome does its 1 minute/9 minute cycle but it never gets to the set temperature on the Evohome display (it was still cycling 1/9 10 hours later and that room was the only one not getting up to temperature, this appeared worse as it was happening at night and I still have water gushing noises that are being heard as air slowly bled out over last week and counting). The HR92 has been changed in that room and the stroke is set to 1 (setting to 1 was recommended by Resideo and seems to help in the other rooms). If the temperature is set to say 1.5 degree above what is required then it will get hot (and wireless realy to boiler will read 100%) but it never quite reaches the set temperature (usally 0.5 degrees below) and the radiator will go cold. I am hoping from what you say that the Evohome will eventually tell it to open more and/or bring the boiler on for longer than the 1 minute in every 10.

You mention that the main panel says what % to close the HR92 actuator, in the single room with multiple HR92s I have noticed that even though it says a % (and all the HR92 units read the same valve position) that only (usually) one of them (in the cylcing mode) is slightly warm. I presume that even though they all say the same, they are saying what the Evohome globally thinks for that zone and this is normal operation.

I will let it think for 4 weeks and if all is well I will also update here in case anyone else has the same issues. If it has notlearnt by then I am unsure of what to do next.

Thanks
Colin

What is your system configuration? Are you on a combi or System, heat only boiler you didn't state, just that it's an 8000. If the latter has the zone valve for the heating been removed? Are you using the boiler relay?

I think you've been misinformed by Resideo. As an installer I know this is definitely incorrect, the system cannot calculate warm up/cool down times and room atributes when it isn't heating said room!

Regarding the flow temperature, I think you need to look at the boiler configuration and the flow round the system. The boiler is obviously isn't getting going as it should.

In a room with Multiple HR92s have you got it set on Multi Room or Single room in the configuration?

 

[colin_]

"I have noticed that my new Worcester boiler will by itself take around 5-10 minutes to warm from 30 - 70 degrees even if radiators are fully open (it modulates low and starts ramping up over time)."

I think this is also part of your problem, any of the few gas boilers that I have seen will get the boiler flow temp up to SP in a minute or two except from a completely cold start, this doesn't mean that the rads will though which is correct in the Evohome case?.
I read up a bit about the system and it seems to me that the HR92s do the PI learning and tell the controller what to do and in some cases can even control themselves like a true TRV?.

I have sent an email to Worcestor technical asking if the slow start up is normal and if so is there anything that can be done to make it quicker (I outlined the 1 minute on time that Evohome is doing). I will update if I get an answer from them regarding it.

I am tempted to try 3 cycles per minute and 4 minutes on to see if it helps but as per EvillDrPorkChop recommendation, I am leaving "as-is" for 4 weeks to see if it sorts itself out (unless EvillDrPorkChop recommends otherwise)

Thanks
Colin

 

[colin_]

What is your system configuration? Are you on a combi or System, heat only boiler you didn't state, just that it's an 8000. If the latter has the zone valve for the heating been removed? Are you using the boiler relay?

I think you've been misinformed by Resideo. As an installer I know this is definitely incorrect, the system cannot calculate warm up/cool down times and room atributes when it isn't heating said room!

Regarding the flow temperature, I think you need to look at the boiler configuration and the flow round the system. The boiler is obviously isn't getting going as it should.

In a room with Multiple HR92s have you got it set on Multi Room or Single room in the configuration?

It is a Worcester Greenstar 8000 Life condensing boiler (GR83000iW 30S).

The old zone valves have all been removed and it is using the Evohome wireless relay box.

I have emailed "[email protected]" asking if it is normal operation and I am awaiting a reply.

I have the multiple HR92s set for single room. There seems to be confusion on multi room operation as the Honewyell website says you can but then says it needs to be set to heating type "Zone valve" to do so (rather than "radiator valve") but when I queried Resideo they said set it to "radiator valve" and it would be ok to set to mutli room but an installer has spoken directly with Honewell and they have been told that I cannot set my configuration to multiroom ....

Thanks
Colin

 

[ShaunCorbs]

I can confirm it will soft start and after 3-5 mins it will ramp up aslong as the ntc/ sensors agree

 

[colin_]

I can confirm it will soft start and after 3-5 mins it will ramp up aslong as the ntc/ sensors agree

This may be an issue with use on the Evohome as it is bringing it in for 1 minute only and water temeprature not going up much (a couple of degrees at most) before it turns off. It may be that the Evohome will learn this as it goes on and leave it on for longer but only time will tell (and at the moment it has been doing its 1min/9 min cycling for the last 6 hours)

Thanks
Colin

 

[EvilDrPorkChop]

It is a Worcester Greenstar 8000 Life condensing boiler (GR83000iW 30S).

The old zone valves have all been removed and it is using the Evohome wireless relay box.

I have emailed "[email protected]" asking if it is normal operation and I am awaiting a reply.

I have the multiple HR92s set for single room. There seems to be confusion on multi room operation as the Honewyell website says you can but then says it needs to be set to heating type "Zone valve" to do so (rather than "radiator valve") but when I queried Resideo they said set it to "radiator valve" and it would be ok to set to mutli room but an installer has spoken directly with Honewell and they have been told that I cannot set my configuration to multiroom ***.

Thanks
Colin

The only other issue I can see if it's returning to quickly and not ramping up, as Shaun says it'll only do this if the sensors agree. You need to check your pump setting on the boiler too, it's possible this isn't helping your cause.

Regarding EvoHome. It'll bring the system on and off as it requires. It'll not just keep bringing it on for a minute, otherwise the house would never get warm. It'll more than likely learn that a zone isn't heating correctly and that it requires more heat. You need to leave it on 2 minute minimum on time, and 6 cycles per hour.

The HR92s , when you've got multiple in one room you need to leave it on Radiator valve setting, and set to Multizone. Otherwise the master HR92 will control the other HR92s, when you want each to operate independently.

The room you are having an issue with, is this a room with multiple HR92s in by any chance?

 

[colin_]

The only other issue I can see if it's returning to quickly and not ramping up, as Shaun says it'll only do this if the sensors agree. You need to check your pump setting on the boiler too, it's possible this isn't helping your cause.

Regarding EvoHome. It'll bring the system on and off as it requires. It'll not just keep bringing it on for a minute, otherwise the house would never get warm. It'll more than likely learn that a zone isn't heating correctly and that it requires more heat. You need to leave it on 2 minute minimum on time, and 6 cycles per hour.

The HR92s , when you've got multiple in one room you need to leave it on Radiator valve setting, and set to Multizone. Otherwise the master HR92 will control the other HR92s, when you want each to operate independently.

The room you are having an issue with, is this a room with multiple HR92s in by any chance?

Hi

Not sure what the pump setting is but from the manual I have "Pump range map" and default is set for Constant pressure 250mbar but I will need to get the installer to check as they may have changed it (it can do "pump output proportiional to the thermal output as well as constant values of 150,200,250,300,350,400 mbar)

If other boilers were put on for a minute (or 2), what would be the expected rise in temperature out of the boiler (from say 30 degrees -> ???) as the Worcester mostly gets to only 33 degrees and 35 if lucky.

When the temperature is well away from set point it heats up nicely (albeit 10 minutes to get rads to 70 degrees) but when near set point and requesting a small amount of heat it seems to stick in this 1/9 cycle and never alter the on time.

The reason I left it at 1 minute was if it was cycling continually 1/9 as it is now then 2/8 would use more gas, but it is something I can try.

I am unsure of the single vs multi room setting for multiple HR92 on one zone. It is currently set to single room and when near to temerpature and requesting heat then usually only one gets slightly warmer (can be any one). I was going to have it set to multi-room but according to the installer, when he rang and spoke with Honeywell they said that my system cannot use multi-room, but I was offered no explanation as to why not, especially when it can be set in the menu.

The room I am having an issue with is by itself in a single zone.

As an aside, does Evohome work better with new radiators that heat up quicker (and los heat quicker) than the older radiators (take a while to heat up but lose heat slower) as I have a few old style radiators (20+ years old) - unfortunately not in the room I am having an issue with.

Thanks
Colin

 

[colin_]

Just a further update.

As far as I can tell it is looking like my issue is due to the slow start of the boiler itself as in one minute it barely raises a couple of degrees and once that is pushed around and lost in the pipes then not much goes to the radiator.

This morning the system was calling for heat on several radiators and the Evohome doing its one minute on/9 minutes off and the radiators were still cold.

Once the hot water requested heat from the boiler it ramped up (after ~ 10 minutes) to 70 degrees and all the radiators that were requesting heat got hot (so valve definitely open enough, simply not enough heat from the boiler in one minute).

It is looking like this boiler will not work with the Evohome (which is a shame as the same installer installed both the boiler and the Evohome) as even if I set the time to the max 5 minutes min on time on the Evohome it will still only raise it a paltry 13 degrees (and that would mean the boiler was on 5 minutes, off 5 minutes, on 5 minutes . . . . which would be a big waste of gas).

The heating data from this morning was

Time offset in minutes	Degrees on boiler	Degrees increase from initial	Degrees increase from previous time point
0	27	-	-
3	30	3	3
5	40	13	10
7	50	23	10
9	60	33	10
11	66	39	6
12	69	42	3
12.5	70	43	1

 

[John.g]

Is your boiler a combi and what is its rated output.?

Will have a look at your numbers above when I return but they seem to be broadly in line with what Shaun Corbs is saying in post#14 "I can confirm it will soft start and after 3-5 mins it will ramp up as long as the ntc/ sensors agree" is it the Evohome that's causing the soft start or the boiler itself? in which case it will always take ~ 10 minutes to ramp up, so not great even if heating a HW cylinder.

 

[colin_]

It is the boiler that that does the soft start and takes ages to heat its output water to 70 degrees. The hot water will go from ~45 degrees to 60 degrees in around 20-25 minutes (dependent upon what else it is heating at that time)

Thanks
Colin