Tracking down random boiler demand with Evohome

[erik]

Yes, when you balance a system, you balance it with all radiators opened. When you are zoning, you're often going to have only 1 or 2 or 3 radiators open. This will totally change the balance of the system. (Except if you are using A-Exact valves from Heimeier. They can be set to automatically (non-static) balance based on desired flow instead of just adding a static resistence to the valve opening by making the opening smaller.)

But it's still good to have a somewhat balanced system. Because at least you know that all radiators will be able to get hot properly. If you don't balance at all, all hot water might travel trough your closest-to-boiler radiator and none might go to the furthest-away-from-boiler radiator.

[Wally©]

No nightmare after all... It's been there since construction 21 years ago and I've had a 'few' extra meters of flexible piping laid in the living room just a few centimeters below the actual tiles for extra comfort...

Thx for the heads-up SH...

[G4RHL]

Using a distriubtion manifold helps enormously with system balancing and if fitted with suitable valves it allows controls to be fitted on the manifold (using the same kind of thermal actuators that would be used on an underfloor heating manifold). It is popular where architectural rads are being fitted and you don't want to spoil the look of the rads with unattractive TRVs. The more enlightened plumbers/heating engineers also use similar manifolds for hot and cold water distriubtion too - the manifolds are close the the rooms requiring hot and cold water, and allow simple isolation per appliance and improved flow (or flow reduction where needed). It also allows plastic pipework to be fitted
without any breaks/fittings in ceiling/floor voids. We see this a lot in the residential properties we work in.

Thanks. Understood. It does seem though that if all radiators warm up at the same rate then there is no issue to address. Each of mine gets hot when I want them to get hot and they oblige by so performing.

[jonstatt]

I think there are two aspects to balancing here. One is the balance between radiators such that one radiator is starved of heat by another. This definitely doesn't happen in my house (3 floor town house).

The other aspect, and what I am starting to glean here, is the expectation of a fixed drop in temperature from one side of the radiator to the other (e.g. 11 degrees for a conventional boiler), irrespective of whether one radiator is grabbing heat or not. This is not a balance between radiators, but defines a standard of heat performance which EVOHOME is optimised for. Now on one hand you could say, well then it will take longer to heat up than a fully open valve, but on the other hand, it ensures are you within Evohome's optimisation routine expected parameter range. What the HR92 seems to do is when first activated (e.g. temperature is below target), the HR92 fully opens...then it should gradually taper back in until it closes. However, if too much heat arrives too quickly, it catches the system out, and the room has warmed up too fast and so the HR92 quickly closes.......then as the heat radiates evenly throughout the room, oops, the temperature is actually below target, and it opens again, hence greater thrashing of the HR92 and battery use. But then this also assumes the radiator is correctly sized for the room surely. So if you put a completely stupid sized radiator in a loo under the stairs, even if it has a drop across it, it will still heat the room too quickly for EVOHOME to react to.

[erik]

Evohome can use 2 things: controlling the boiler and controlling the hr92. So it can close the HR92 valve to 50%, but it can also request less heat from the boiler.

The HR92 should learn how much time it takes to heat up the room in a week or 2. So if the radiator is too big, the HR92 should learn. (unless the radiator is really really stupidly big of course)

[G4RHL]

You mentioned that the heating was coming on exactly 1 hour before. This makes me wonder what would happen if you had the maximum optimisation time set to 3 hours. The fact it comes on "exactly" means in it's own little ideal world, it would possible come on even sooner!! (I.e. it's hitting the hard limit you set of 1 hour) Would you try this to satisfy my curiosity? If it comes on at 3 hours, then something is really wrong here.

As mentioned yesterday I set the advance time limit for optimisation to 2 hours instead of 1. During weekdays I go out shortly before 06:30. Main bedroom is set to 20c at 07:30 (because experience tells me optimisation comes on an hour earlier) and lounge to 18c at 07:30. When I got up the bedroom was 15c and the lounge 13.5c. At 06:25 this morning as I was leaving the heating came on. I checked and it was optimisation for the main bedroom. 65 minutes before set point. Within a minute I saw that it had then come on for the lounge.

Therefore changing the start time from 1, 2 or 3 hours does not seem to trigger a new learning curve although I could not see that it would. But it does like to come on an hour early when 30 minutes for the bedroom or about 40 minutes for the lounge is all it needs.

Next check will be when I turn on my radiator in the conservatory. That has been off (HR92 removed) for a week during the conservatory's rebuild. Painting and all is done. I will switch the radiator on this evening (allowing for paint to dry) and see how quickly the temperature comes up. This radiator is the end of the line, we were told when it was put in 13 years ago that whilst it would get hot it may be a struggle. In fact it usually gets too hot to touch quite quickly.

I also yesterday adjusted my boiler's temperature control to mid way. I have no idea what that is as it's just a knob with a widening arrow on it from low to high.

My wife usually pulls my leg about me and gadgets but out Saturday evening she did tell friends the system and comfort in the house is so much better. That I think is the most important point. Well to me it is! Any readers of this forum not sure about installing Evohome, I'd say "Go for it"!

Incidentally, and nothing to do with Evohome. The conservatory is noticeably warmer even with no heating on. Due to up to date glass that is thermally efficient. The hope is we can use it all year round!

[jonstatt]

As mentioned yesterday I set the advance time limit for optimisation to 2 hours instead of 1. During weekdays I go out shortly before 06:30. Main bedroom is set to 20c at 07:30 (because experience tells me optimisation comes on an hour earlier) and lounge to 18c at 07:30. When I got up the bedroom was 15c and the lounge 13.5c. At 06:25 this morning as I was leaving the heating came on. I checked and it was optimisation for the main bedroom. 65 minutes before set point. Within a minute I saw that it had then come on for the lounge.

Therefore changing the start time from 1, 2 or 3 hours does not seem to trigger a new learning curve although I could not see that it would. But it does like to come on an hour early when 30 minutes for the bedroom or about 40 minutes for the lounge is all it needs.

Next check will be when I turn on my radiator in the conservatory. That has been off (HR92 removed) for a week during the conservatory's rebuild. Painting and all is done. I will switch the radiator on this evening (allowing for paint to dry) and see how quickly the temperature comes up. This radiator is the end of the line, we were told when it was put in 13 years ago that whilst it would get hot it may be a struggle. In fact it usually gets too hot to touch quite quickly.

I also yesterday adjusted my boiler's temperature control to mid way. I have no idea what that is as it's just a knob with a widening arrow on it from low to high.

My wife usually pulls my leg about me and gadgets but out Saturday evening she did tell friends the system and comfort in the house is so much better. That I think is the most important point. Well to me it is! Any readers of this forum not sure about installing Evohome, I'd say "Go for it"!

Incidentally, and nothing to do with Evohome. The conservatory is noticeably warmer even with no heating on. Due to up to date glass that is thermally efficient. The hope is we can use it all year round!

Thank you very much for doing the test! I was relieved to see the heating didn't come on 2 hours early (indicating it was latched to whatever limit you had set)....so although it seems to be coming on earlier than needed, it isn't "broken". I wonder if part of the reason it comes on earlier than needed is to allow for the time it takes for that heat to radiate evenly within the room. The HR92 is positioned, by definition close to a wall. It will reach a target temperature before a sofa in the middle of the room would...so I am just theorising that is to ensure the whole room is an even temperature, rather than just the locality around the radiator.

I think the temperature range on most boilers is similar, so I would suspect this means you have set it to around 65ish degrees C.

For me the primary reason to install EVOHOME was energy efficiency. Eon kept sending me notes saying I was using almost double the energy of an average home of similar size. Part of the reason I know for this is because I work from home so there is no "off" period during the middle of the day. The other part of the reason is my wife is Taiwanese and is used to a warmer temperature and struggles with room temperatures of 18 degrees for example. But fundamentally the issue was a thermostat in a hallway with a single point of measurement. The hallway always struggled to get up to temperature being a town house with 3 floors...thus the heat goes shooting up the stairwell. Although there were TRVs in all rooms, fundamentally I was keeping the whole house to TRV set temperature from 6am to midnight.

Here is the good news. I took a gas meter reading after having the system installed for 9 days, and on a rolling 30 day average, my gas consumption has already dropped 15%. I expect it to be 35-40% after a full 30 days of running the new system.

[erik]

Give your wife a warm sweater for her birthday

[jonstatt]

Give your wife a warm sweater for her birthday

LOL - Even at 20 degrees she is sometimes sitting there with a thick padded coat on!

[top brake]

Thank you very much for doing the test! I was relieved to see the heating didn't come on 2 hours early (indicating it was latched to whatever limit you had set)....so although it seems to be coming on earlier than needed, it isn't "broken". I wonder if part of the reason it comes on earlier than needed is to allow for the time it takes for that heat to radiate evenly within the room. The HR92 is positioned, by definition close to a wall. It will reach a target temperature before a sofa in the middle of the room would...so I am just theorising that is to ensure the whole room is an even temperature, rather than just the locality around the radiator.

I think the temperature range on most boilers is similar, so I would suspect this means you have set it to around 65ish degrees C.

For me the primary reason to install EVOHOME was energy efficiency. Eon kept sending me notes saying I was using almost double the energy of an average home of similar size. Part of the reason I know for this is because I work from home so there is no "off" period during the middle of the day. The other part of the reason is my wife is Taiwanese and is used to a warmer temperature and struggles with room temperatures of 18 degrees for example. But fundamentally the issue was a thermostat in a hallway with a single point of measurement. The hallway always struggled to get up to temperature being a town house with 3 floors...thus the heat goes shooting up the stairwell. Although there were TRVs in all rooms, fundamentally I was keeping the whole house to TRV set temperature from 6am to midnight.

Here is the good news. I took a gas meter reading after having the system installed for 9 days, and on a rolling 30 day average, my gas consumption has already dropped 15%. I expect it to be 35-40% after a full 30 days of running the new system.

that's great feedback, thanks

with optimisation it will continue to fine tune the start time and you should see it get closer to hitting the target as it learns your system performance

[G4RHL]

Bought mine an electric throw for Christmas!

[G4RHL]

that's great feedback, thanks

with optimisation it will continue to fine tune the start time and you should see it get closer to hitting the target as it learns your system performance

The beauty of the system is it just works. If my optimisation remains constant at coming on an hour ahead of the set point and it takes less than an hour to get to set point then the solution is an easy one, either change the set point or turn of optimisation start. I'd rather have it on though. Optimisation stop seems very efficient.

Also Rameses, the app continues to work as it should whether in wireless or roaming mode. What they did last week when the server was "maintained" I do not know but it seems the app is marginally quicker in roaming mode accessing the account.

[Rameses]

The beauty of the system is it just works. If my optimisation remains constant at coming on an hour ahead of the set point and it takes less than an hour to get to set point then the solution is an easy one, either change the set point or turn of optimisation start. I'd rather have it on though. Optimisation stop seems very efficient.

Also Rameses, the app continues to work as it should whether in wireless or roaming mode. What they did last week when the server was "maintained" I do not know but it seems the app is marginally quicker in roaming mode accessing the account.

Thanks for the update.

[G4RHL]

Optimisation. An update. I forgot to change the setting back to the minimum period of 1 hour. This morning at 05:30 the boiler fired up. A check showed optimisation had come on for one room where the temperature read 14C and was set to be 18C at 07:30. I seemed to think that it would take it 2 hours to lift the temperature 4 degrees. For the room in question about 40 minutes would be more usual. Optimisation has been on for the whole system for 7 weeks since I last did a complete reset/rebind, so I would assume by now it has optimised itself but perhaps not. It did not apply itself to any other room, several others were reading 14.5, this one room was the only one reading 14. The app showed the outside temperature at 1C but then as we know outside temperature has no effect on the activation of the system other than its cooling or heating effect on the building as a whole. I used the app to adjust the temperature back down to the overnight one (10C).

[Rameses]

Optimisation. An update. I forgot to change the setting back to the minimum period of 1 hour. This morning at 05:30 the boiler fired up. A check showed optimisation had come on for one room where the temperature read 14C and was set to be 18C at 07:30. I seemed to think that it would take it 2 hours to lift the temperature 4 degrees. For the room in question about 40 minutes would be more usual. Optimisation has been on for the whole system for 7 weeks since I last did a complete reset/rebind, so I would assume by now it has optimised itself but perhaps not. It did not apply itself to any other room, several others were reading 14.5, this one room was the only one reading 14. The app showed the outside temperature at 1C but then as we know outside temperature has no effect on the activation of the system other than its cooling or heating effect on the building as a whole. I used the app to adjust the temperature back down to the overnight one (10C).

Have you got Stored hot water?