How does (my) central heating work?

iamparakeet

I'm considering smartphone heating control options, including individual radiator control. But, first, it strikes me that I have little idea how my current system works...

We moved in to a just-refurbished three-bedroom Victorian mid-terrace property last summer with a pretty new Ariston E-combi boiler. It has separate dials for heating and water temperature, plus the usual on/off/timer...



There is no wall-mounted thermostat anywhere in the house.

The eight radiators, also new, in our house have numbered valves, from blank through frost-protection to 5...



I don't know if you'd call these "thermostatic radiator valves" or what. They're not aware of the temperature around them, are they? (Or are they?) They're just controllers, right? So, if I set the temperature on the boiler to a medium, I can manually vary the rads to 0-5 of medium? Am I right?

Currently, I have these valves set around 3-5, except in unoccupied rooms. For ease of control, I then only turn the boiler heating temperature dial to turn up or down room temperature.

But I don't leave the boiler on. I also find myself turning it on and off when room temperature becomes too hot. Not at the wall but via the boiler's on/off/timer control. This seems easier than running around a big house turning radiator valves.

Do you have any pointers on how this system should be working? Any links to guides?

Am I using my system in the best and most efficient way?

Should I get a thermostat? If I do, how, then, should I control the interaction across three control components - the boiler dials, thermostat control and valve controls? And would/should I leave the boiler in permanent on or can I turn it off? I'm concerned permanent-on would actually use up *more* energy.


NB. When the heating's on, I occasionally hear the water pipes creaking away in the flooboards. What's going on?

Ultimately, I am looking at my options for smartphone central heating control. Out-of-home control through the likes of Hive, Tado, Nest or Heatmeiser Neo would be a convenience. But I think there's more money to be saved for me with individual radiator control - I work from home in one room for most of the day and I think I'm wasting money by heating the whole house.

Most of these gadgets say they will "replace your current thermostat" - I don't have a thermostat.

First I think it's worth me understanding how the current system works, so I'd like to learn.

Thanks.

macman

Those are TRV's.
The pipe noise you hear is caused by the copper expanding as the system heats up, and possibly rubbing against a joist or board.
If you get a programmer, that will control the CH temp and timing with the boiler left to 'on'. If you get a room 'stat only, that will just control the temp, with timing controlled by the boiler's timeclock.
The two central dials control the output temp of the CH and DHW circuits.

Cardew

There are loads of places on the web where you can find the User manual for your boiler - you need the model number. This is an example:


http://www.centralheating.co.uk/Boiler-Manuals/Ariston-Boiler-Manuals


The TRVs do sense the air temperature and regulate water flow. It doesn't matter what water temperature you set on the boiler, the room temperature for a setting on the TRV of, say, '3' will be the same. The hotter the water temperature - the quicker the room will reach the required temperature. Normally each number is equates to an increment of 2C - with '3' being 20C.


If you work from home in one room, then switch the TRVs right down when rooms are not occupied.


I believe it is mandatory to have a room thermostat these days for new installations. and yours is new? Are you sure there isn't a(missing) wireless thermostat?

iamparakeet

macman wrote: »

If you get a programmer, that will control the CH temp and timing with the boiler left to 'on'. If you get a room 'stat only, that will just control the temp, with timing controlled by the boiler's timeclock.

So, obviously easier to get a programmer? This way, although I leae the boiler set to "on", it can be switched off by the additional unit, depending either on temperature requirements or my manual intervention - is that right?
Surely, you can get programmable thermostats in this way? I would have thought some "thermostats" can do on/off programming, too, no?

macman wrote: »

The two central dials control the output temp of the CH and DHW circuits.

Cardew wrote: »

The TRVs do sense the air temperature and regulate water flow. It doesn't matter what water temperature you set on the boiler, the room temperature for a setting on the TRV of, say, '3' will be the same. The hotter the water temperature - the quicker the room will reach the required temperature. Normally each number is equates to an increment of 2C - with '3' being 20C.

So I should think of the boiler dials as speed of flow to the radiators, but think of the TRVs as manual setting control and they will then regulate how much hot water they need to draw from the boiler?

Strange/confused. The celsius temperature lights on the boiler do go up/down when I tweak the dial. So, if I generate hotter/quicker in the boiler, would this mean the TRVs don't need to call on as much, for example? And is that a good/bad thing?

Cardew wrote: »

If you work from home in one room, then switch the TRVs right down when rooms are not occupied.

I could go around turning them on and off at different times of the day, but I'm afraid to say I'm not doing that currently. This is why I'm interested in some of the new tech that would let me control individual radiators from a smartphone.

Cardew wrote: »

I believe it is mandatory to have a room thermostat these days for new installations. and yours is new? Are you sure there isn't a(missing) wireless thermostat?

Nowhere at all. We bought the house in the summer. Only one cable and wall plate runs to/from the boiler, and that's mains. For a thermostat, I guess there would be another cable/plate, to receive signal from a thermostat?

Thanks.

Cardew

robertandrews wrote: »

So I should think of the boiler dials as speed of flow to the radiators, but think of the TRVs as manual setting control and they will then regulate how much hot water they need to draw from the boiler?

Strange/confused. The celsius temperature lights on the boiler do go up/down when I tweak the dial. So, if I generate hotter/quicker in the boiler, would this mean the TRVs don't need to call on as much, for example? And is that a good/bad thing?

The dial on the right appears to be the programmer - to enable you to set timed periods of heating.


The adjustable dial on the left simply sets the temperature of the water circulating in the Central Heating system(i.e. the temperature of water in the radiators) it doesn't affect 'speed of flow'.


Obviously the hotter the water in the radiators, the quicker the air temperature in the room will increase. However when it reaches the temperature set on the TRV, the inlet valve to the radiators closes and no water enters the radiator.


The radiator will then cool and when the air temperature drops sufficiently the TRV will open the inlet valve and hot water will again enter the radiator.


Is that a good/bad thing?


That depends on the characteristics of your system. In general terms with a condensing boiler you need the water temperature to be lower rather than high, but the difference is not huge.

Nada666

Cardew wrote: »

There are loads of places on the web where you can find the User manual for your boiler - you need the model number. This is an example:


http://www.centralheating.co.uk/Boiler-Manuals/Ariston-Boiler-Manuals

But boiler user manuals do not usually tell you how to use the boiler. As, indeed, this one doesn't. They may tell you what each control does but do not explain how or when to use them.

This has always struck as very strange.

Yikes2014

I have a dumb question to ask. I don't know if the boiler system in my house is a combi system or not. I have a main gas central heating unit in the kitchen, a wall display which controls heating and water separately and then I have a large tank with two small tanks, a thermostat and a separate on/off switch on the wall in the cupboard. I thought that the switch in the cupboard was for an immersion heater and that it should only be used to boost the water for a bath etc, and that for the most part the water heating should be controlled from the main gas unit downstairs. However, my boyf reckons I'm wrong about this and the switch (which I think is an immersion) should be left on all the time to be economical. I wouldn't mind if it was left on all the time except the heat of the water it generates is completely impractical, it is far too hot (although he swears it is set at 65'C), and the tank sounds like its boiling all the time. Another opinion would be very helpful.

macman

Make and model of your boiler would help.
If you have a hot water tank then it's unlikely that you have a combi boiler.
The water in the hot tank should certainly not be boiling! If the 'stat is set at 65C then it sounds as if that's failed and it's continually heating. This is potentially very dangerous, so switch it off and get it looked at.
It sounds more like you have a conventional boiler which heats your CH and DHW, with an immersion heater for backup. If so, use the boiler to heat the water, because electricity is about 300% more expensive per kWh.

Yikes2014

Thank you for your reply. I think all in all its time to get someone to have a look to make sure it is operating ok.

thor

Cardew wrote: »

However when it reaches the temperature set on the TRV, the inlet valve to the radiators closes and no water enters the radiator.


The radiator will then cool and when the air temperature drops sufficiently the TRV will open the inlet valve and hot water will again enter the radiator.

If the radiator inlet valve is closed with the boiler still in heating mode(ie the thermostat setting>the room temp where it is situated) then will the pipes supplying the radiator remain hot since it is carrying the hot water?

Cardew

thor wrote: »

If the radiator inlet valve is closed with the boiler still in heating mode(ie the thermostat setting>the room temp where it is situated) then will the pipes supplying the radiator remain hot since it is carrying the hot water?

When you say 'thermostat setting' do you mean the TRV setting or a conventional room thermostat?


If there is no flow of water through the radiator then the pipes to that radiator will cool.


During a period when CH is demanded, the CH pump switches off when the room temperature reaches the temperature set on the room thermostat.


The pump will also switch off when the water circulating in the CH system(or in the boiler if no circulation) has reached water temperature set on the boiler.


As the OP has no room stat, then the TRV will regulate the air temperature but the pump will keep running.