I recently had a Glow Worm Ultracom 30cxi combi installed. My installer said that there is an exernal temp sensor availble for this model and it would be worth fitting one. What are the advantages of this? (and where could I purchase the sensor)
What are the advantages of an outside temp sensor on boiler?
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Softus said:
Yes, I suppose my question does seem a bit strange. Spoke to him on the phone about something else and he mentioned it in passing. Didn't think to go further at the time, as I was involved with another matter. He is a very busy bloke and I would fit it myself. Can anyone help?
An external sensor will allow the programmer on your boiler to determine how long it would take to reach your set (aka desired) room temperature.
Armed with this determination, it can then start the heating early enough to reach that temperature at the time you want, so the advantage is one of comfort.
If you already try to do this yourself, then it's possible that the boiler programmer will do a better job of it and save you fuel and therefore money, but if not then that extra comfort will cost you fuel.
Armed with this determination, it can then start the heating early enough to reach that temperature at the time you want, so the advantage is one of comfort.
If you already try to do this yourself, then it's possible that the boiler programmer will do a better job of it and save you fuel and therefore money, but if not then that extra comfort will cost you fuel.
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As far as I am aware all or most of the built in the boiler weather compensation do NOT alter the start up time for heating to come on.
What they do is to adjust the radiator temperature according to the amount of heat required indoors as calculated from the outside temperature.
Keeping the radiator temperature to the minimum means they are condensing more of the time and used properly can give good comfort and save up to 6% on fuel costs.
Tony
What they do is to adjust the radiator temperature according to the amount of heat required indoors as calculated from the outside temperature.
Keeping the radiator temperature to the minimum means they are condensing more of the time and used properly can give good comfort and save up to 6% on fuel costs.
Tony
There is a seperate feature called optimal start which uses an external sensor to determine how early to start the heating.
Thats a bit old fashioned now and was mostly applicable to non modulating boilers.
With a modulating boiler with weather compensation there is little need to alter the start up temperature as the changed flow temperatures will put more power into the heating to make it heat up faster anyway.
Tony
Thats a bit old fashioned now and was mostly applicable to non modulating boilers.
With a modulating boiler with weather compensation there is little need to alter the start up temperature as the changed flow temperatures will put more power into the heating to make it heat up faster anyway.
Tony
WC is a means of making up in part for a crude control system on a boiler. If your room thermostat is a simple on-off one there's more to gain than if it tells the boiler what the temperature in the house IS.
Don't let anyone tell you they replace internal temperature measurement.
Don't let anyone tell you they replace internal temperature measurement.
D
Doctor Drivel
Agile said:
Optimisation and weather compensation are mutually exclusive functions.
True Optimisation starts the boiler at the correct time to reach set point at the desired time. Say you want 20C by 8:00 am, it works out the time to bring in the boiler to reach 20C at 8:00. It saves fuel, as it can delay starting the boiler. Conversely it can extend the warm-up time if the weather outside drops.
Weather compensation is feed-forward control, as opposed to all others which is feed-back. - anticipating the coming temperature drop or rise in the building as the outside temperatures change, and acting in advance.
If a boiler is fitted with optimisation or waether compensation it is crassly foolish not to fit the outside temperature sensor - the installer is negligent.
Doctor Drivel said:
His installer seems to have been a little irreesponsible not to have advised the customer.
However at the end of the day many customers dont want to pay the considerable extra cost to supply and fit the external sensor which is usually grossly overpriced by the manufacturer.
Tony
D
Doctor Drivel
ChrisR said:
Weather compensation is well worth having with any boiler - on-off control or not. It lowers the flow and return temps promoting efficient condensing. When acting in an on-off fashion they tend to have anti boiler cycling control
The more sophisticated units have room temperature influence which lowers or raises the control slope which determines the flow temperature.
Agile said:
I fitted an external WC sensor to my Biasi M110 combi.
I couldn't locate a Biasi sensor and rang Biasi technical who at first told me Biasi's didn't support this feature and asked why I wanted to use it. They then said weather compensation is only of use in countries like Sweden.
Later I noticed in the manual that the resistance curve for the weather comp sensor was the same as the heat exchanger NTC's on the Biasi so used one of them. (Cheap)
So far it is working well. I chose a fairly steep compensation curve due to having an old house with poorly insulated solid walls. With an outside temp of 15 degC the boiler sends water to the rads at about 30 degC but with an outside temp of 5 degC it sends the water out at about 60 degC.
Dave
D
Doctor Drivel
NGBod said:Agile said:
I fitted an external WC sensor to my Biasi M110 combi.
I couldn't locate a Biasi sensor and rang Biasi technical who at first told me Biasi's didn't support this feature and asked why I wanted to use it. They then said weather compensation is only of use in countries like Sweden.
One reason why not to buy BIASI - run by idiots.
NTC's What does this mean? A clamp-on temp sensor? If so, you one of these outside in a box?
Doctor Drivel said:
NTC: A type of Thermistor based temp sensor.
NTC's: more than one of same
see http://www.thermometrics.com/assets/images/ntcnotes.pdf
Dave
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