Boiler thermostat truths?

[bhm1712]

I have been reading various websites and forums regarding what a boiler stat should be set to, and there is no clear cut answer.

Some say if you have a room stat and cylinder stat, the boiler stat should be on max, others say set it so the water temp is 75 degrees, 85 degrees etc etc....

what is the truth? or the recommended?

surely, if you set the boiler stat on maximum you will be chucking loads of excess heat energy down the flue and wasting gas?

 

[John506]

80 degrees CH

60 for domestic

 

[bhm1712]

yes, i have my HW cylinder stat set at 60,

so my system water temp should be 80 degrees? ok thanks

 

[45yearsagasman]

This has always been up for debate.It also depends on your boiler type.Older boilers with cast iron heat exchangers and mechanical boiler stats can exceed the stated 80 degrees and therefore rad surface temps can be excessive.

 

[bhm1712]

The boiler stat (boiler control) determines how hot your radiators get. It does NOT control the temperature in the house.
On older boilers, the non-condensing, lowering the boilerstat does not bring any noticeable savings in the gasuse, and is best left at a minimum of 70 degrees.

this is from the CH FAQ on here.

so is that correct about old boilers? mine is an old boiler (glow-worm space saver mk2 40br) i have got an IR thermometer which i have used to set the system water to 80 degrees, should that be ok?

 

[45yearsagasman]

Yes, if you can accurately set your flow temp you should be ok.I always worry(probably for no reason)that very young children can hurt themselves if they fall and stay in contact with rads at 80c.Rad covers or guards will prevent this.

 

[penfold46]

Yes, if you can accurately set your flow temp you should be ok.I always worry(probably for no reason)that very young children can hurt themselves if they fall and stay in contact with rads at 80c.Rad covers or guards will prevent this.

Or drunk relatives.

 

[Servotech]

The modern heating system of today is fitted with loads of secondary controls and should also be in a well insulated home.
The thinking behind running the boiler at maximum temperature is to let these controls do their job in the less a time as possible, so that they start saving you money asap.
It does make sound sense when you think about it.

 

[bhm1712]

servotech, are you by any chance the servotech who do servo drive repairs etc?

 

[45yearsagasman]

Yes, if you can accurately set your flow temp you should be ok.I always worry(probably for no reason)that very young children can hurt themselves if they fall and stay in contact with rads at 80c.Rad covers or guards will prevent this.

Or drunk relatives.

Oh Sh*t I forgot its Friday and I've invited them round tonight

 

[bengasman]

I have been reading various websites and forums regarding what a boiler stat should be set to, and there is no clear cut answer.

Extensively covered in FAQ.

Condensing boilers run better on lower temperatures. Unvented cylinders MUST be kept at 60C +

 

[scoobydo123]

Can you tell me why the unvented needs to be 60c plus?

Tks

 

[Agile]

Both vented and unvented cylinders should be set between 55° and 60° but should never exceed 60° as that will give a risk of scalding.

Generally boilers should be operated with the lowest flow temerature that will heat up the house. Thats particularly important on condensing boilers as it increases efficiency.

Non condensivg boilers with cast iron heat exchangers should not be used with a flow temperature below 65° as that can cause condensation and rusting of the boiler parts.

Tony

 

[bengasman]

Can you tell me why the unvented needs to be 60c plus?

Tks

Sorry, meant vented.

 

[picasso]

Non condensivg boilers with cast iron heat exchangers should not be used with a flow temperature below 65° as that can cause condensation and rusting of the boiler parts.

Tony

If you have a flow of 65c the return will be below the dew point and will condense in the heat exchanger, (at a differential of 10c ) I wouldent run a non condensing boiler at less than 75c on the flow.