Remote control of heating without Nest/Hive or similar

[jonm01]

During the summer my DHW is simple timed, 5 times a week at ½ hour each time, not really ½ hour as after 20 minutes the boiler switches off and starts to cycle, and if it switched on again only for a few minutes before ½ hour time is over. And my tank is not very well lagged. With such little time required to maintain water to temperature if I had a tank thermostat I would not bother with any timed switch on.

I also used Nest Gen 3, which has minimum time slot of ½ hour, which is better than what was there, with minimum of one hour a day.

Central heating wise, the geofencing has not been that successful. The problem is temperature control. Turn on heating and it over shoots, and the cooling time of the hall where the wall thermostat is mounted, is too slow. And all other rooms have alternative heating, or outside doors which are used. In my house the official front door into hall is never used. And hall is the most central point of house, and is the best average temperature from all rooms, but cools slowly.

My mothers house also the hall seemed not the best location in some ways, wind direction and sun could result in kitchen getting cold, so that one fitted second thermostat in kitchen in parallel with hall one.

But geofencing really need one thermostat, did try using the TRV heads which will geofence, but again not much good as on a temperature change they take too long to adjust temperature. Be it over shooting or slow time never got geofencing to work. And heating cost is around £2 per day in winter. At £2 a day that means geofencing likely saves 50p at most per day. This winter we have both left the house for over 3 hours and under that time not worth it turning off, around 5 times, so geofencing has likely saved £2.

If it is a scheduled vacation of the home, i.e. going to work, simple timed control likely works better. If you leave the house at 8 am the heating can go off likely 7:30 am and no latter than 8 am, but geofencing will not turn it off until you have travelled some miles from home, so likely nearly 9 am before it switches off. So even with a varied return from work, the hour or so saved, is really nothing.

And all this auto technology does not work when my wife says, darn it, left my phone at home.

As to actually getting the phone out to control house temperature, yes in the summer I would look on phone and if the TRV showed over 26°C current, I would energise the plug in wifi switch/monitor to start the AC unit, because I can monitor use I know if actually energised, so know the command has worked. And returned home to a cooler room than it would have been had I not switched it on, only reason not left switched on, is the bottle for condensate is 2 litre and it would over flow if left on. The exhaust for AC goes up the flue. I have never got my phone out on a cold day to turn on central heating before I get home. In the main I have not switched it off, gone out in a hurry, and so unless geofencing does it not turned off.

Is it worth spending even £50 on remote controls to save £10 a year? Over night when heating turned off, in the morning rarely cooler than 17°C so room on average just 1.5°C cooler when heating turned off, so energy saved is so small is it really worth worrying about?

Interesting post Eric, your hot water takes only 20 minutes to heat up,? mine seems to take ( conventional open vented cylinder) easily an hour to fully heat. Do you have you boiler stat set near max?

 

[JohnD]

I found reference to "old" cylinders sometimes having a 5kW coil, and modern unvented cylinders mostly in the 12kW to 24kW range.

I have a modern blue vented cylinder, don't know its figure (but I see a similar one advertised as 16.5kW)

A 3kW immersion heats water at about 1 litre per minute.

 

[ericmark]

I would guess one the water is not cold to start with, and two likely not to full temperature, as @JohnD says possible only a 5 kW hot coil, and around 20 kW from the boiler, so after 20 minutes it starts to cycle.

The problem is there is no thermostat on the tank, so pure time, the original programmer was every day the same, and no less than 1½ hours could not get the off and on things on the dial any closer. I do worry about legionnaires as not a clue if over 60 or not, but we have loads of hot water at the taps, only if going for a bath do I use boost.

 

[rbranco]

I would guess one the water is not cold to start with, and two likely not to full temperature, as @JohnD says possible only a 5 kW hot coil, and around 20 kW from the boiler, so after 20 minutes it starts to cycle.

The problem is there is no thermostat on the tank, so pure time, the original programmer was every day the same, and no less than 1½ hours could not get the off and on things on the dial any closer. I do worry about legionnaires as not a clue if over 60 or not, but we have loads of hot water at the taps, only if going for a bath do I use boost.

You can put in a thermostat quite easy, cut away tank insulation and fit then put it into the wiring center so it breaks the zone valve HW power when satisfied.

 

[jonm01]

I found reference to "old" cylinders sometimes having a 5kW coil, and modern unvented cylinders mostly in the 12kW to 24kW range.

I have a modern blue vented cylinder, don't know its figure (but I see a similar one advertised as 16.5kW)

A 3kW immersion heats water at about 1 litre per minute.

Good point, ours is fairly old, doesn't have yellow or blue integral lagging, just strap on cylinder jacket, ( well 2 actually) it does retain heat for easily 18-24hrs, but I don't know what the coil will be.

 

[ericmark]

You can put in a thermostat quite easy, cut away tank insulation and fit then put it into the wiring center so it breaks the zone valve HW power when satisfied.

The problem is the boiler is two floors below the tank, and there is no cables between the two locations or any easy route, using wifi in some way may be possible, there were wireless tank thermostats and I fitted one to dads tank around 20 years ago, but when I looked for one, it seems no longer made, plus not so sure if wireless is a good idea in a Radio Hams home? I do use 70 cm and that could stop the wireless link. But if I could have bought the same as used for dad I would have done.

 

[rbranco]

The problem is the boiler is two floors below the tank, and there is no cables between the two locations or any easy route, using wifi in some way may be possible, there were wireless tank thermostats and I fitted one to dads tank around 20 years ago, but when I looked for one, it seems no longer made, plus not so sure if wireless is a good idea in a Radio Hams home? I do use 70 cm and that could stop the wireless link. But if I could have bought the same as used for dad I would have done.

Danfoss/EPH do one, most run in the 433mhz unfortunately but I've just seen they have mistat series and that is 868mhz.
Honeywell evohome stuff is 868mhz but that replaces all your controls