I have a VAILLANT ecoTEC plus VC 20 CS/1-5 and reach of my radiators has a TRV. I understand that when the TRV is set to 3 and the room reaches a temperature of 20C, the TRV will prevent hot water flowing in to the radiator and instead flow to the next radiator. When all the TRV are closed, I assume the hot water bypasses all radiators and returns to the boiler. The TRV are not connected to the boiler, and I have no thermostat in the house that is connected to the boiler. How then does the boiler know that all the rooms are heated appropriately and that it should stop heating water?
How does my boiler know when my rooms are heated to 20C?
- Thread starter jamiegw
- Start date
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Your boiler reads it’s out temperature and its return temperature and adjust to suit
Correct ,modulates down then off
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The outside temperature changes the boiler Target (flow) temperature, the higher the OT, the lower the target temperature as the rads dont require their rated output, a lower target temperature results in a lower boiler return temperature which means greater boiler efficiency. the boiler will modulate until its minimum output is greater than the heat demand, the burner (gas) will then cut out at the target temp + 5C, the water will continue to circulate until the flow temp falls to target temp - 5C, the burner will then refire when the anticycle time has elapsed.
With no thermostat, the boiler will keep trying to heat the house, even when it isn't needed.
At these times, the term "greater boiler efficiency" is nonsense.
If you dislike this wasteful and useless activity, get a thermostat.
Looking on google that's a pretty new boiler so I would be very surprised if you didn't have some kind of thermostat - how do you program the timer of the boiler to switch on/off - this timer unit might have an integrated thermostat?
The engineer did this via the panel on the front of the boiler.
Definitely worth having a thermostat fitted then - we don't know the whole story but it's strange one wasn't recommended/fitted. The only drawback I think (other than initial installation cost) is that running a new cable to a wired thermostat elsewhere in the property could be invasive but there are loads of wireless options available nowadays.
If all the rads have TRVs then a roomstat isn't required, all you require is a programmer to control the times at which you want heating or, more importantly, when you don't require heating, if the HW is from a cylinder then you should have a zone valve for the CH and one for the HW cylinder, controlled by a cylinder stat.
There are still some people who say that, even though it is plainly wrong.
The engineer set it up so the heating is on between 5am and 10pm, but made no mention of any room thermostat, only the outdoor temp. sensor.
The original offer however did have a room thermostat: https://www.vaillant.co.uk/for-installers/products/sensocomfort-sensocomfort-rf-72192.html
I run my system like that most of the time even though I do have a"master" roomstat in the dining/sitting room, I leave this turned up to 30C and get excellent individual room control with standard TRVs in all rooms, to achieve the same level of control with roomstats, I would require one in every room.
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