Thermostat scheduling

[gc100]

So this is probably a daft question, but with new builds with decent airtightness, do you still schedule the heating on and off at various times, or do you just set the constant temp?

 

If so, do you control it at the main ASHP, or do you control it at the individual thermostats in each room/zone?

 

Thanks

[joth]

If you have E7 you'd want to schedule to match that. This would be far more convenient to do once, centrally.

If something in the system makes noise you might want to schedule to avoid nighttime. Again, centrally.

Otherwise I see very little need for timers. 

[Mr Punter]

For larger buildings it is worth splitting into zones where you can control time and temperature with a programmable stat for each zone.  Rather than ON or OFF I just set the required minimum temperature. for the time of day.  Leave it the same year round.

[gc100]

Thanks. We'll have 9 zones in the house and I'm trying to decide whether to spend on 'smart' theromostats. The main advantage I can see from them are really just the fine control over scheduling the heat (ie when  30 mins away from home turn heating on, when everyone leaves house turn off etc, boost heating if temp outside less than 3c etc). I don't want to have to walk around all 9 theomostats and boost them, so smart themostats would be good if I needed to do that.

 

However I'm presuming that would really be controlled centrally from the ASHP, and the zone thermostats essentially just control the manifolds??

 

 

[ProDave]

I went for Keep It Simple Stupid.

 

Simple thermostat in each room.  AND a conventional boiler programmer to schedule when the heating is on and when it is off.

 

Ours is on all day and off at night. That is mainly because I want a silent house at night and even the gentle hum of a circulating pump is too noisy so it all goes off at night.  Others do the opposite if they have E7 and have the heating only running at night.

 

It was a "challenge" to integrate a standard boiler programmer into the system.  If you did it all according to manufacturers instructions you would just use the programmer that came with the ASHP but although it can do timing functions, it is a fiendishly complicated thing to set up and does not do any of the nice normal programmer functions like advance, or timed boost etc. So I chose not to use the inbuilt timer functions and instead fit a separate more conventional programmer.

[joe90]

1 hour ago, ProDave said:

It was a "challenge" to integrate a standard boiler programmer into the system.  If you did it all according to manufacturers instructions you would just use the programmer that came with the ASHP but although it can do timing functions, it is a fiendishly complicated thing to set up and does not do any of the nice normal programmer functions like advance, or timed boost etc. So I chose not to use the inbuilt timer functions and instead fit a separate more conventional programmer.

 

+1, our ASHP controller is fiendishly complicated (fir a Luddite like me) so I used standard timers, our heating is on 24/7 but controlled by one room stat In the hallway, I am considering E7 so will time it fir that period.

[SteamyTea]

It really comes down to what you want.

Do you want a house that is at a constant temperature, regardless of usage/occupancy.

Or one that drops the temperature at certain times i.e. night, unoccupied.

Or, to take advantage of variable rate energy prices.

Or a system that preempts external weather conditions.

 

Basically, the more you want, the more complicated it gets.

 

20 minutes ago, joe90 said:

I am considering E7 so will time it fir that period.

About time I came at looked at your energy usage again, maybe watch you balance your MVHR at the same time.

[joe90]

11 minutes ago, SteamyTea said:

maybe watch you balance your MVHR at the same time.

 

What do you mean “watch”, I think it would be good for you to help me!!!!  Before I can do that I need to invent restrictors for my home made manifold, I will keep you posted.

[SteamyTea]

6 minutes ago, joe90 said:

invent restrictors

Ply, jigsaw and sticky tape.

[john0wingnut]

On 08/11/2019 at 12:59, SteamyTea said:

It really comes down to what you want.

Do you want a house that is at a constant temperature, regardless of usage/occupancy.

Or one that drops the temperature at certain times i.e. night, unoccupied.

Or, to take advantage of variable rate energy prices.

Or a system that preempts external weather conditions.

 

Basically, the more you want, the more complicated it gets.

 

About time I came at looked at your energy usage again, maybe watch you balance your MVHR at the same time.

 

all very valid points....... Im still playing with mine 2 years down the line.

 

I had mine serviced yesterday, and the chap was basically saying that I should set my stats to 20 degress (chosen temp), have the temperature differential on those at 1 degree and then change the curve accordingly down to the lowest flow temp which allows the temperature to be maintained.

 

I currently have mine setup to utilise E7 tariff, so both the hot water and heating (21 degrees) comes on between 00:30 and 07:30 and then again in the evening between 16:00 and 19:30. The stats currently have a 0.5 degree differential

 

During the day my PV charges my Powerwall, which then covers off the electricity later in the day, but the ASHP tanks it quite quickly, during the 16:00 - 19:30 session and then Im on the grid again.

 

House seems to hold its temp pretty well, so I am wondering whether to follow this guys advise, but with a slight twist that I up the required temperature during E7 time, say to 22 degrees, to get more heat into the slab, then from 07:30, set it back to the 20 degrees again until 00:30

 

 

 

[SteamyTea]

34 minutes ago, john0wingnut said:

00:30 and 07:30 and then again in the evening between 16:00 and 19:30.

I limit my E7 times with some cheap timers.

Currently comes on at 3 AM until it is no longer needed, or the normal switch off at 7 AM.

Today it there was no significant load after 5:30 AM

During that time it pulled, on average, 4.7 kW.

So just under 12 kWh for all my space heating and DHW.

Bit higher than usual, but then it is a bit cooler than usual.

Just had a look at my temperatures.  Upstairs was 17°C during the night.  Downstairs was 17.9°C

The overall mean temperature today (from midnight to now 13:30) is 18°C.  Not far off what I like as it rises during the day.

[john0wingnut]

On 04/12/2019 at 13:34, SteamyTea said:

I limit my E7 times with some cheap timers.

Currently comes on at 3 AM until it is no longer needed, or the normal switch off at 7 AM.

Today it there was no significant load after 5:30 AM

During that time it pulled, on average, 4.7 kW.

So just under 12 kWh for all my space heating and DHW.

Bit higher than usual, but then it is a bit cooler than usual.

Just had a look at my temperatures.  Upstairs was 17°C during the night.  Downstairs was 17.9°C

The overall mean temperature today (from midnight to now 13:30) is 18°C.  Not far off what I like as it rises during the day.

 

I have played around with this over the week.

 

Tesla power wall pre-charges itself during E7, based on the forecast weather.

 

DHW is now schedule for 50 degrees from 2-5am

 

Heating comes on to 21 degrees  between 3:30 and 07:30 (end of E7)

 

Setback to 19 degrees from 07:30 - 13:30

 

Heating comes on to 21 degrees from 13:30 - 17:30

 

Setback to 19 degrees from 17:30 until next day repeats. 

 

I have successfully used no peak electricity from doing this, as between the powerwall and minimal solar from our 7kw array, it covers off all electricity need from 07:30am through to 00:30

 

House is toasty as well  

[PeterW]

@john0wingnut how do you get the power wall to be the source for the out of E7 hours heating ..?

[SteamyTea]

1 hour ago, john0wingnut said:

I have successfully used no peak electricity

Do you run very light load during the day, or put the PowerWall power though your PV inverter?

[john0wingnut]

1 hour ago, PeterW said:

@john0wingnut how do you get the power wall to be the source for the out of E7 hours heating ..?

 

The powerwall powers the entire house demand, not just the heating. It has a "brain" which monitors pv generation and import export from grid, so knows when to charge and discharge etc

[john0wingnut]

1 hour ago, SteamyTea said:

Do you run very light load during the day, or put the PowerWall power though your PV inverter?

 

House background electricity use is 0.3kw. 

 

PV is straight into consumer unit, as is the Powerwall.

[SteamyTea]

4 minutes ago, john0wingnut said:

PV is straight into consumer unit, as is the Powerwall.

What size inverters are on each.

Just trying to establish how large a load you can draw without importing.

[john0wingnut]

1 minute ago, SteamyTea said:

What size inverters are on each.

Just trying to establish how large a load you can draw without importing.

 

Inverter 1 has 4Kw array and Inverter 2 has 3Kw.

 

The powerwall itself can provide 5kw peak

 

In the summer the grid usage was minimal and we still exported a load, as once powerwall charged and house using saying 0.5kw, everything else goes back to the grid. I ideally need another powerwall really. But, heatpump didnt run for most of those months, as DWH was done by the solar thermal, so solar + battery covered everything off and no pre-charging was needed during E7

 

Recent days has seen about 2-3kw max from the panels around midday, so in theory with the powerwall no grid would be required up to 8kw in peak light, but in reality its putting out about 1.5kw in winter light, so 6.5kw before grid during the day I would say at the minute

[SteamyTea]

Thanks

Shame there is not a cheap energy monitor that can show the amount and direction of usage.

[john0wingnut]

Just now, SteamyTea said:

Thanks

Shame there is not a cheap energy monitor that can show the amount and direction of usage.

 

Solaredge inverters and Powerwall do track all of this.

[SteamyTea]

1 minute ago, john0wingnut said:

Solaredge inverters and Powerwall do track all of this.

Do you bother to download the files and look at it in detail?

Where about in the country are you?

[john0wingnut]

[john0wingnut]

Just now, SteamyTea said:

Do you bother to download the files and look at it in detail?

Where about in the country are you?

 

I look at it in the apps, rather than download, but the graphical representation of the daily graph tells the story nicely in that example I posted.

[SteamyTea]

is the dark green that is negative, the imports?

[john0wingnut]

51 minutes ago, SteamyTea said:

is the dark green that is negative, the imports?

No.

Blue = home usage

White = grid import

Green = powerwall - negative below the line is charging of power wall, above is discharge / use of powerwall.

Yellow = solar