Vaillant Boiler temperature

[chrisb2]

Q. I have a 9 year old Vaillant Eco Tec Plus 418 which heats bot the hot water and CH.
The HW tank has its own thermostat set to 55C.
There is also one downstairs room temp' thermostat in my hall.
What is the ideal Temperature setting on the Boiler for my CH.??
I have 9 Rads.
Thanks.

 

[Harry Bloomfield]

Q. I have a 9 year old Vaillant Eco Tec Plus 418 which heats bot the hot water and CH.
The HW tank has its own thermostat set to 55C.
There is also one downstairs room temp' thermostat in my hall.
What is the ideal Temperature setting on the Boiler for my CH.??
I have 9 Rads.
Thanks.

Your problem there, is that lacking the Vaillant controls, you are limited to one boiler flow temperature for both HW and CH. The flow needs to be hot enough to heat your HW so it clicks off at the HW stat, some 5C hotter than the HW stat setting.

55C is not hot enough to kill off the legionella, it needs to be 60C, which means a boiler flow of 65C-ish.

Basic on/off control means the boiler will not modulate as well as it could too.

The full Vaillant kit allows independent temperatures to be set for HW and CH will intelligently modulate the boilers output as it nears target temperature.

 

[ericmark]

I think reading the instructions your boiler can use a room thermostat connected to the ebus, so it will auto adjust the temperature to suit conditions.

 

[Harry Bloomfield]

I think reading the instructions your boiler can use a room thermostat connected to the ebus, so it will auto adjust the temperature to suit conditions.

The OP's post reads as if his system is ignoring the ebus completely, he just has basic on/off controls.

 

[Mottie]

I have a 3 year old 418. From what I understand, the boiler temperature is the maximum temperature it will reach and it modulates down at the boiler. Or maybe it’s the KW output that it modulates? Oh I don’t know, it heats my house and heats my water so that’s good enough for me. I set mine to 16kw max as that’s more than enough (10kw in summer when I’m just heating the DHW) plus at 18kw, the exhaust noise from the flue is noticeably louder.

 

[chrisb2]

Yes I think my system doesn't use an ebus. Room thermostat will adjust the room temp', while the HW Tank thermo' regulates that temp'.
Excuse my basic knowledge.
So it is recommended the boiler control should be 65C while the HW tank should be set at 60C.
Photo of my controls.
Advice?

 

[Mottie]

Speaking as a non professional, I can’t understand why the HW thermostat is at the bottom of the tank. To get my hot water coming out of the taps at 60° +, it only needs to be on about 45°. Surely 60° at the bottom of the tank would make it about 80° at the top. That’ll scald, surely?