new to evoHome - existing Honeywell wireless room thermostat

[mart1711]

Interesting discussion - and nothing wrong with hi-jacking this thread. Thanks for all the responses!

I don't think you can buy either the Wi-Fi controller or the Hot water kit without the included BDR91's so you may end up with a 3rd left over BDR91.

I had to hunt around a little, but PlumbNation do sell the controller as standalone https://www.plumbnation.co.uk/site/h...fi-controller/. With hindsight, however, I should have bought the pack WITH the BDR91 though (https://www.plumbnation.co.uk/site/h...ermostat-pack/) as that would have given me a spare BDR91 for £13.50, which does appear cheap compared to other sites....sigh.

By the way, I see you have a bypass gate valve (the red knob) rather than an automatic bypass valve. While it's not critical, I'd recommend that next time you drain down your system for yearly maintenance you replace that with a modern Automatic Bypass Valve, particularly if you plan to use HR92's on all radiators and not have any bypass radiator.

As you said in your other post, this is indeed a balancing valve rather than a bypass. My bathroom rad is an always-on bypass rad.

I'm hoping to receive the CH kit on Thursday, and if that goes well I'll look into the HW kit too. Surely it must be more economical in the long run to let EvoHome manage both, rather than having HW on its own thermostat / timer clock. I did try and time it so that CH is likely on anyway when there is HW demand from the thermostat. To my mind, that means that the pump and boiler are already running anyway so in theory probably consume marginally less energy than if HW periods were timed for when CH is likely off. Not at all sure about that one, though.

WRT to draining the system - we bought this house back in 2014. It had an old Potterton Flamingo boiler that had not been serviced in 5+ years. I was luckily enough to find a good, local plumber who did NOT rip me off (I got three quotes for the same job (boiler replacement, new pump, new valves, new thermostat) with a £1500+ difference between the cheapest and the most expensive quote). He drained the system for the boiler change - the water was disgusting, so was the stench. He also advised on getting a Spirotech magnetic trap fitted, which gets cleaned out during planned yearly maintenance.

Had a rad replaced last year and again a complete system drain / refill + inhibitor. So hopefully we should be good for a couple of years! Now just left with an annoying combination of one brand new rad and a mix of old / very old ones - which means that I have one room that goes from cold to toasty in 5 minutes, where the rest of the house is still decidedly cold. The HR92s should help with that, though.

Either way - I'll report back when it's all done - sounds like it will be extremely easy with the BDR91 already in place and wired in.

Again, thanks for all the help.

Martin

[DBMandrake]

I'm hoping to receive the CH kit on Thursday, and if that goes well I'll look into the HW kit too. Surely it must be more economical in the long run to let EvoHome manage both, rather than having HW on its own thermostat / timer clock. I did try and time it so that CH is likely on anyway when there is HW demand from the thermostat. To my mind, that means that the pump and boiler are already running anyway so in theory probably consume marginally less energy than if HW periods were timed for when CH is likely off. Not at all sure about that one, though.

I'm not sure that there is actually any efficiency benefit to running HW and CH at the same time just because the boiler is "already on". Whether the boiler just cycles on and off to maintain a range around the target flow temperature (like my antique boiler) or is a modulating boiler that varies the flame size and therefore heat output of the burner to try to maintain the set flow temperature, at the end of the day heating+hot water requires more energy than heating alone or hot water alone. Either way the boiler will try to maintain the same set point but will have to work harder when both are drawing heat at the same time.

If you already have a 7 day programmable timer for your hot water then the only extra functionality you would really gain by using the Evohome hot water kit apart from combining heating and hot water control in one interface would be to see the current hot water temperature on the control panel/phone app, and have the ability to override the hot water schedule remotely. (Such as turning on the hot water remotely using your phone before you came home unexpectedly early)

You can program a different hot water schedule per day with up to 6 switch times per day but you can probably do that on your existing timer, and the schedule is only ON or OFF, you can't set different temperatures in the schedule. (Although I'm not sure why you would want to)

You can do a timed or permanent override as well. For example set hot water to be on for the next 2 hours during a period when it would normally be off. You can also adjust the hot water temperature, but that is a setting buried in the installer configuration menu, not exposed in the normal user screens.

So if you already have a good timer/programmer it may not be worth the expense - for me it made sense because I've just converted my system from gravity circulation to S-Plan and had no existing hot water timer, so I thought I might as well use the Evohome hot water kit rather than buying an independent, conventional timer and cylinder thermostat.

[HenGus]

There is a benefit in that a HW temperature range (up to 10C) can be set which reduces HW heating demand and boiler cycling/on time. In summer, my gas usage for cooking and HW is about 10kWhs a day. It was higher before Evohome. That said, RoI time is probably many years but that also applies to the rest of the Evohome system.

[bruce_miranda]

Some more potential benefits of the evohome HW kit are
1. The HW is also controlled simultaneously with the Quick Actions on the Heating side.
2. You can have a HW overrun, to dump the remain heat of the boiler into the cylinder, rather than just waste it. This feature tends not to be possible with a traditional clock, because it would simply shut off the valve when the time or thermostat has shut off.
3. The HW kit temperature sensor is more finely manageable.
4. You can set a temperature differential settings, so if the HW is hot enough, but not up to the temp set, it won't bother firing the boiler unnecessarily.

[mart1711]

Thanks all. I'll see how it all works out and then consider getting the HW kit a little later. So annoyingly today I received the Wifi controller and the HR92s...but it turns out the controller is really just the controller, without the wifi stand and thus without any power supply. I really should have gone for the pack which would have included the controller, the stand and the BDR91. Sigh. I'll return the controller only and order the kit. Shame - I was quite looking forward to getting started today....

[DBMandrake]

Some more potential benefits of the evohome HW kit are
1. The HW is also controlled simultaneously with the Quick Actions on the Heating side.

Sort of. As a new hot water kit user I find the quick actions are a bit quirky in regards to hot water.

Specifically:

1) If you use the heating off action which without a hot water kit is the quick "everything off" action it actually leaves hot water following its normal schedule, EG on when scheduled to be on. This does make sense because the action is called "heating off", and it also makes sense that during the summer for example you might want to manually turn the heating off but you would still require hot water.

However there is no "heating + hot water off" quick action to let you quickly disable both heating and hot water when you are for example leaving the house for several hours (or days) during a time when heating and hot water would normally be scheduled on - eg a Saturday or Sunday.

So you actually have to choose the heating off quick action, and then go into hot water and do a manual permanent override to off for hot water to achieve this, which I would argue isn't obvious to a non technical user. Nor would remembering to separately cancel the hot water off override in addition to cancelling the heating off quick action.

This is symptomatic of the limitations of the quick actions in general though.

2) If the heating is on and you choose the "Day Off" quick action, both heating and hot water will switch to the (by default) Saturday schedule - I am using this right now as I'm off work for 2 weeks, and this works great.

However there is a major gotcha - if I were to turn the heating off with the heating off quick action, which I would probably do during the summer, the hot water returns to the current days schedule (Thursday) instead of the day off schedule. There is no way to turn off the heating and at the same time have the hot water continue to follow the day off schedule.

This is a quite inconsistent user experience IMHO. Because on the one hand if you turn off the heating on a normal day the hot water stays on and continues to follow the same schedule, however if you go from a day off schedule to heating off you may suddenly find your hot water has gone off as well if the different day's schedule would have your hot water off at the current time.

The workaround is after using the heating off quick action, if that results in your hot water going off as well (because you were previously on the day off quick action) is to set a timed manual override for the hot water to bring it back on again until your normal night time off temperature. This works OK but feels clumsy to me and wouldn't necessarily be obvious to a non technical user.

I've said it many times before, but the quick actions are the biggest weak point of the Evohome user interface as they are quite limited and inconsistent in their operation.

2. You can have a HW overrun, to dump the remain heat of the boiler into the cylinder, rather than just waste it. This feature tends not to be possible with a traditional clock, because it would simply shut off the valve when the time or thermostat has shut off.

You could do it with a traditional timer if you added an additional timer like an MRT16-REM for the overrun but yes in general a standard timer won't allow for hot water overrun.

Keep in mind though that for hot water overrun to work on the Evohome you must be using a 3x BDR91 configuration including a boiler relay or 2x BDR91 + OpenTherm. A 2x BDR91 configuration alone can't do hot water overrun any more than a standard timer can because the boiler is fired from the zone valve limit switch.

3. The HW kit temperature sensor is more finely manageable.

Yes that's true. It's quite nice that you can set the hot water temperature anywhere from about 30 degrees to 70 degrees with a one degree resolution. And as long as you don't use hot water overrun it seems to hit the target pretty precisely - usually on the dot, but occasionally one or two degrees over.

4. You can set a temperature differential settings, so if the HW is hot enough, but not up to the temp set, it won't bother firing the boiler unnecessarily.

Yes it's nice you can adjust the differential too. Keep in mind a standard cylinder stat does already have a fairly wide differential - 8 degrees is typical for most mechanical thermostats. I actually have the differential turned down to 5 degrees on my Evohome (rather than the default 10) as I only have my hot water set to 50 degrees and don't want it falling as low as 40.

I find my cylinder loses about 1 degree per hour so a 5 degree differential still means the boiler only reheats it once about every 5 hours if no hot water is used, and only takes about 5 minutes boiler run time to get it back from 45 to 50 degrees, so I'm fairly happy with that.

[paulockenden]

However there is a major gotcha - if I were to turn the heating off with the heating off quick action, which I would probably do during the summer, the hot water returns to the current days schedule (Thursday) instead of the day off schedule. There is no way to turn off the heating and at the same time have the hot water continue to follow the day off schedule.

This is a quite inconsistent user experience IMHO.

I'm going to have to disagree with you on that one. If I have a quick action selected, and then I select a different one, I'd expect the first one to be cancelled first.

I can imagine a whole world of pain if the system allowed layering of quick actions, one on top of another.

To take your example. Select Day Off. Then select Heating Off. Then how do you cancel Day Off while leaving the heating off? You could tie yourself in knots trying to work out the logic combinations there.

I think it's pretty obvious to the user that Quick Actions are exclusive modes.

And besides, using the UI on the controller is it even POSSIBLE to select one quick action without first cancelling the previous one? I'm not convinced that it is (I don't have a controller in front of me).

[Rameses]

Sort of. As a new hot water kit user I find the quick actions are a bit quirky in regards to hot water.

Specifically:

1) If you use the heating off action which without a hot water kit is the quick "everything off" action it actually leaves hot water following its normal schedule, EG on when scheduled to be on. This does make sense because the action is called "heating off", and it also makes sense that during the summer for example you might want to manually turn the heating off but you would still require hot water.

However there is no "heating + hot water off" quick action to let you quickly disable both heating and hot water when you are for example leaving the house for several hours (or days) during a time when heating and hot water would normally be scheduled on - eg a Saturday or Sunday.

So you actually have to choose the heating off quick action, and then go into hot water and do a manual permanent override to off for hot water to achieve this, which I would argue isn't obvious to a non technical user. Nor would remembering to separately cancel the hot water off override in addition to cancelling the heating off quick action.

This is symptomatic of the limitations of the quick actions in general though.

2) If the heating is on and you choose the "Day Off" quick action, both heating and hot water will switch to the (by default) Saturday schedule - I am using this right now as I'm off work for 2 weeks, and this works great.

However there is a major gotcha - if I were to turn the heating off with the heating off quick action, which I would probably do during the summer, the hot water returns to the current days schedule (Thursday) instead of the day off schedule. There is no way to turn off the heating and at the same time have the hot water continue to follow the day off schedule.

This is a quite inconsistent user experience IMHO. Because on the one hand if you turn off the heating on a normal day the hot water stays on and continues to follow the same schedule, however if you go from a day off schedule to heating off you may suddenly find your hot water has gone off as well if the different day's schedule would have your hot water off at the current time.

The workaround is after using the heating off quick action, if that results in your hot water going off as well (because you were previously on the day off quick action) is to set a timed manual override for the hot water to bring it back on again until your normal night time off temperature. This works OK but feels clumsy to me and wouldn't necessarily be obvious to a non technical user.

I've said it many times before, but the quick actions are the biggest weak point of the Evohome user interface as they are quite limited and inconsistent in their operation.

You could do it with a traditional timer if you added an additional timer like an MRT16-REM for the overrun but yes in general a standard timer won't allow for hot water overrun.

Keep in mind though that for hot water overrun to work on the Evohome you must be using a 3x BDR91 configuration including a boiler relay or 2x BDR91 + OpenTherm. A 2x BDR91 configuration alone can't do hot water overrun any more than a standard timer can because the boiler is fired from the zone valve limit switch.

Yes that's true. It's quite nice that you can set the hot water temperature anywhere from about 30 degrees to 70 degrees with a one degree resolution. And as long as you don't use hot water overrun it seems to hit the target pretty precisely - usually on the dot, but occasionally one or two degrees over.

Yes it's nice you can adjust the differential too. Keep in mind a standard cylinder stat does already have a fairly wide differential - 8 degrees is typical for most mechanical thermostats. I actually have the differential turned down to 5 degrees on my Evohome (rather than the default 10) as I only have my hot water set to 50 degrees and don't want it falling as low as 40.

I find my cylinder loses about 1 degree per hour so a 5 degree differential still means the boiler only reheats it once about every 5 hours if no hot water is used, and only takes about 5 minutes boiler run time to get it back from 45 to 50 degrees, so I'm fairly happy with that.

To your point 1)
"However there is no "heating + hot water off" quick action to let you quickly disable both heating and hot water" - Yes there is it's called away mode

Away mode will turn off both. But only work in permanent or by day increments. In your example for days this works.
Because most Hot Water solutions offer a high degree of insulation and the degrade of loss curve is over hours and not minutes, along with the size of the tank will mean that a typical family should in theory need a scheduled amount of heat. Eg on in morning and evening, possibly a small top up in the middle (in the case of my family). If the schedule is ON this doesn't mean the the boiler is on. The boiler only comes on if within the schedule the HW drops outside your parameters. In 3 hours, you lose 3 degrees, but your differential is 5 ish then you will not need this degree of hourly control, and your boiler wouldn't ignite. Taking this even further even if you lower the temp of you tank it could still be ok for domestic needs. My family and I are fine with the HW tank dropping to high 40's during the day (in extreme circumstance) as this still provides Hot water to wash up, wash hands etc.

[DBMandrake]

I'm going to have to disagree with you on that one. If I have a quick action selected, and then I select a different one, I'd expect the first one to be cancelled first.

I can imagine a whole world of pain if the system allowed layering of quick actions, one on top of another.

To take your example. Select Day Off. Then select Heating Off. Then how do you cancel Day Off while leaving the heating off? You could tie yourself in knots trying to work out the logic combinations there.

I think it's pretty obvious to the user that Quick Actions are exclusive modes.

The fact that the quick actions are all mutually exclusive is precisely one of the major problems with the quick action feature in my opinion, and what limits its current and future functionality in artificially restrictive ways...

It's funny that you should use Day Off as your example because this is one that I believe should definitely not be mutually exclusive to other options. The purpose of the day off action is to handle the situation that people are home in the house on days that they normally wouldn't be, eg bank holidays, sick days or time taken off work.

Why should this be mutually exclusive to all other options ? Why can't I use Eco mode when I am in Day off mode ? They are completely orthogonal actions, yet the overly simplistic one mutually exclusive action at a time UI design precludes this possibility.

I've been off work for the last two weeks and the system has been in day off mode - I'm unable to use Eco mode because of this. Nor can I use Custom mode properly, because the zones that are masked off can only follow their current day schedule when Custom is active rather than a day off schedule.

Furthermore, if I decide that every day for the next X days should be treated as a day off, I should be able to set Day Off as an independent setting, either permanently or until a specific date (The day I return to work) and have that remembered until I specifically cancel Day Off or the set date expires.

I should be able to turn the heating off then on again without having to remember to manually re-enable Day Off mode every time as a second step. What's the point of being able to set that Day off mode should last for 7 days if I have to remember to work out how many days are left and manually re-select this every time just because I turned the heating off for 3 hours when I went out ? I should be able to combine Day Off with Eco and Custom modes.

In short Day Off should be a setting not a quick action, as it is not mutually exclusive. The only reason it is currently mutually exclusive is because of the overly simplistic and inflexible UI for Quick Actions. Day Off mode (as an example) could have easily been a toggleable setting on the quick action page rather than a mode in its own right.

It's just bad user interface design I'm afraid, where the requirements of real world use have outgrown the inflexible GUI design. The whole quick action system needs a ground up rework.

I described some ideas on how it could be redesigned at length in the what would you like to see thread some time ago, so this is something I've given a lot of thought, based on real world use scenarios.

Day Off also really needs to have its own independent schedule for each zone rather than just using a specified day of the week like Saturday. I find that day off is not appropriate when one member of the household has the day off and the other is staying home. The main difference between my week day and weekend schedules is that the week day schedules have earlier on times but are off during the middle of the day while the weekend schedule starts later but runs all day for the most part.

If one person is still going to work the early start is needed but the all day schedule is required for the other person - an independent schedule for day off would solve this cleanly.

And besides, using the UI on the controller is it even POSSIBLE to select one quick action without first cancelling the previous one? I'm not convinced that it is (I don't have a controller in front of me).

[/quote]
No its not possible to go directly from one quick action to another without cancelling the first one through the controller UI. It can be done from the phone app but the effect is the same - all modes are still mutually exclusive so going to one mode always cancels any previous mode.

To your point 1)
"However there is no "heating + hot water off" quick action to let you quickly disable both heating and hot water" - Yes there is it's called away mode

Away mode will turn off both. But only work in permanent or by day increments. In your example for days this works.

Thanks for that - I wasn't aware that Away mode turned off hot water, however Away mode in itself is pretty well useless for me, because as I've described before, it doesn't just drop set points to 15 degrees (or whatever your away temperature is) it also raises set points to 15 degrees even if they were already lower than 15 degrees.

As I schedule unused rooms to 5 degrees for at least part of the day they can fall below 15 degrees - this would result in unused rooms coming on when the Away action is applied to leave the house, which is totally ridiculous when Away should only reduce heating not bring on rooms that are unoccupied and scheduled to be off.

This is particularly the case if Away mode was used over multiple days - all rooms here except the bedrooms are scheduled to 5 degrees at night, leaving away mode set over night would cause most of the rooms in the house to be running to keep all rooms at 15 degrees through the night - a massive increase in gas usage over night for "away" mode versus even my normal "on" program.

Away mode should act as a cap where temperatures will be lowered to the away temperature but not raised to the away temperature. Until and if that ever happens Away mode is no use to me.

I still think it is very inconsistent UI design that Away mode will turn on heating (in unused rooms) and turn off hot water completely, and then going to heating off mode will turn off heating in all rooms but turn on hot water! This really needs a ground up rethink.

Because most Hot Water solutions offer a high degree of insulation and the degrade of loss curve is over hours and not minutes, along with the size of the tank will mean that a typical family should in theory need a scheduled amount of heat. Eg on in morning and evening, possibly a small top up in the middle (in the case of my family). If the schedule is ON this doesn't mean the the boiler is on. The boiler only comes on if within the schedule the HW drops outside your parameters. In 3 hours, you lose 3 degrees, but your differential is 5 ish then you will not need this degree of hourly control, and your boiler wouldn't ignite. Taking this even further even if you lower the temp of you tank it could still be ok for domestic needs. My family and I are fine with the HW tank dropping to high 40's during the day (in extreme circumstance) as this still provides Hot water to wash up, wash hands etc.

Yep, as I mentioned even with a 5 degree differential it only needs to top up the temperature every 5 hours, which is not a problem.

However if I am leaving the house for most of the day or even a day or two I'd like to be able to turn the hot water off. At the moment if I want to use the heating off quick action I must also perform a separate manual override for the hot water. A "heating and hot water off" action would certainly be useful - all it would need to do is set the hot water to OFF as a permanent override. A "heating and hot water on" action could reverse this.

Again the quick action UI is poorly designed - I don't know how many times I've been asked by my other half why turning the heating on is done by "cancelling the heating off quick action" - which on the iPhone UI is a somewhat counter intuitive operation. (Why would you "cancel" something to turn something on ?)

A redesign of the whole quick action system to provide some more flexibility and a more consistent UI design would be warmly welcomed...

[paulockenden]

I honestly think that for the typical user that would just make things overly complicated.

And in all the time I've had Evohome installed I can't remember ever wanting to run two quick actions in parallel.

I know you're very enthusiastic for this, but (for once) I quite strongly disagree with you.

Also, many of us have a 'wife acceptance factor' to deal with (or the reverse in the case of Mavis). I think I'd really struggle to get Mrs O to grasp layered quick actions. She struggles enough with basic Evohome as it is. In fact we had the "why can't we go back to having a simple thermostat in the hall?" conversation only a few days ago.