'old' Baxi Boiler

alw1971

I have an old Baxi Solo 2 40pf boiler which was installed when the house ws built in the 90's. To be honest apart from not having instant hot water like the modern boilers it seems to keep going with minimal repair costs.
We only use the (+1hour) button for heating or hot water instead of using the thermostat and I was wondering at what number the Boiler Thermostat should be set at? Should I set it higher than 3 out of 5 (seee picture)? I presume this will make it warmer in the hour that the boiler is on?
Many Thanks

tacpot12

Increasing the thermostat on the boiler might not make the house warmer in the hour that the boiler is on. This is because the thermostat is controlling the temperature of the water coming out of the boiler, but if there is no heating load, e.g. if the hot water cylinder is up to temperature, and none of the TRVs on the radiators (if you have any) are calling for heat, then the boiler will shutdown as the water will be too hot - boilers have an overheat sensor to stop the water turning to steam and causing an explosion. So increasing the  thermostat might make a different but I doubt it. Usually it is set by the heating engineer when the boiler is installed, and never needs changing. You could turn it up, but it would be more sensible to learn how to use  your timer so that you can have the heating on for more than 1 hour. 

alw1971

Thanks for the reply

Not sure I was correct calling the dial on the boiler 'thermostat dial'? 
I choose to use the +1hour button instead of the timer so we can use it if and when and I presume using it this way it has nothing to do with the actual wall thermostat in the hallway? 
The +1hour button just turns the heating or water on for an hour and I though itlf I increased the dial in the picture it would just heat up quicker and become hotter before it cuts out after the hour is up? 

Jeepers_Creepers

The boiler heats the water, and the radiators (and hot water cylinder) cools it.

That thermostat control - for that is what it is - controls the temp of the water being issued by the boiler, probably from around 50oC at its lowest to - ooh - 90oC at max. Roughly.

Clearly, then, if you want your rads piping hot in Winter - and you probably do - you'd set that control towards 'max'. As the weather becomes more mild, you could turn that control back down to around half and it should be fine there.

That's the basics. Almost certainly, then, the higher you have that control, the hotter your rads will be when they're on, and the faster the hot cylinder will heat up too.

Do your rads have TRV valves on them? If so, then expect the rads to cool down as the set temp on these have been reached (eg' around 20oC on '3'). Ditto your hot cylinder - it'll almost certainly have a cylinder-mounted stat which should be set to at least the mid-60s oC, and once this temp has been reached it should stop receiving water from the boiler.

The cylinder stat determines the actual hot water temp. The boiler output determines how quickly it gets there. Eg, at 'max', the cylinder should get to its required temp (~67oC) in around a half-hour (I think), but if the boiler is set to half-way, it might take 3/4 hour or longer - that sort of thing.

For the rads, the same applies. The higher that boiler control, the hotter the rads will be and the faster the room will heat up. If the boiler control is set too low, the rads might not be hot enough to get the rooms up to temp in Winter.

So - do you have TRVs? What are the set to?

Do you have a cylinder thermostat? If so, what's it set to?

Do you have a wall-mounted room stat? If so, what's it set to?

In general, that boiler control should be set to whatever gives you a comfy home - but no higher. As the weather becomes more mild, you can turn it down - again whilst still giving you the desired comfort level.

tacpot12

The wall thermostat controls whether the boiler is on or off, as does the cylinder stat. 
If the wall thermostat thinks the house is cold, it will turn the boiler on. 
If the cylinder stat thinks the water in the tank is cold, it will turn the boiler on. 
If both the wall thermostat AND the cylinder stat think the house and tank are cold, the boiler will be turned on.

Note that your timer controls where the central heating is on, or whether water heating is on. If the central heating is turned off by the timer, the  wall thermostat cannot turn the boiler on. 
If water heating is turned off by the timer, the cylinder stat cannot turn the boiler on. 

The +1 Hr button on the timer can be used to turn either the heating or the water heating on for 1Hr. It does not affect the temperature of the house or the water, as these are controlled by the thermostat, but if the heating is off, the house will cool down, as will the water in the tank. 

The thermostat on the boiler controls the  temperature of the water that comes out of the boiler.
If you want to heat your house or the water in your tank more quickly, turn up the thermostat on the  boiler. Your radiators will get hotter if you do this, possibly to the  point that they will scald a child, so be careful on how much you turn it up if you have children or grandchildren that visit.

Your old Baxi boiler is not that  old in terms of how it works. All boilers, timers and thermostats basically work this way. You can get programmable thermostats that change the setpoint temperature at different times (so you have the house warmer in the day than at night, but still have the heating on). You can get "OpenTherm" thermostats that change the temperature on the boiler dial automatically as they sense the house getting warmer, or that the weather is getting warmer. Smart Thermostats have some ability to learn how you use the heating system and will turn the system on and off, and change setpoints based on what they have learned, and can be controlled remotely, but that is as sophisticated as boiler controls get.