Vaillant weather comp - lower heating curve = less gas used?

[Agile]

I am surprised that you dont have one Alec. I thought that you of all people would use them all the time. I have two!

Precisely to use if a client thinks his own non scientific assessment of how he feels is showing a problem.

To me its irrelevant what someone feels because thats subjective!

Example:

Husband has to wait in the cold for 20 min for the bus for one stop from station to the house. Comes in to house and feeling cold thinks its too cold!

Healthy wife comes in from a 20 minute fast run and thinks the house is too hot!

But its the same house at the same temperature!

Sceintific measurements dont lie ! People do !

Tony

 

[ALEC1]

Thermometers don't lie either, and yes I do have a data logger...

 

[Agile]

No I don't have a data logger, instead I get clients to concentrate on comfort level and real temperatures with their own thermometers...

Thermometers don't lie either, and yes I do have a data logger...

So you have just rushed out and bought one?

[ Note that Alec may just be proving the point that people can lie! ]

Tony

 

[ALEC1]

Haha, as I don't use it is as good as not having one, its tucked in the back of a desk draw... Sorry to mislead you...

 

[JonCa]

Hi MHOL, I realise it has been some

I've been working at home this week and noticed that the house gets quite cold during the day, with the radiators being luke warm to warm, whereas in the evenings the house feels warmer and the radiators are red hot.

At 15:31 on a Tuesday afternoon, the VRC430 is showing an external temperature of 13 C, internal temp of 18 C, however it is set to reach 21 C, which it rarely ever does, unless it is a hot sunny day!

Is it at all possible that your weather compensator is not on the N or N/W side of your home ? Seems to me that something like that could well confuse the daytime temps you achieve especially as you seem to quote measured temps rather than body perceived temps.

 

[Biggles..]

Please explain how airplane temps are stable, do you mean if the cabin conditioning is set to X deg it will remain at that as the plane increase or decreases in altitude (outside getting colder as you get higher)

Or that the inside temp is always set the same, whic its not! Cabin conditioning can be set to what ever the crew feel like, hot, cold and anywhere in between.
As can the various areas of the plane. You can have the cabin at 1 temp, the hold at another, the upper deck at 1.

All fed from the same temp bleed air and external air.

 

[Milleniumaire]

JonC, the external thermostat is on a North facing wall, which happens to be on the other side of the wall to the boiler. I'm not sure if this is luck or judgement!

Having set the heating curve to 2.3 on Wednesday night when I got home from work, the house was noticeably warmer on Thursday. When I arrived home from work on Friday, it was like walking into a sauna! It was much too warm. The hall thermostat was showing 21.5 degrees C. As a Yorkshire man, my first thought was how much extra gas was being burned and how it would affect my bills.

My wife admitted that she had been comfortable all day and hadn't felt the cold at all. During the evening I continued to feel too warm and couldn't help noticing that the boiler was constantly on and all the radiators were as hot as they've ever been (almost too hot to touch). I've now reduced the heating curve to 2.0 and I give that a try for the next few days.

The house is 15 years old and is of stone construction with a tiled roof. It started as a 4 bedroom property, but a loft conversion has given it a fifth bedroom and 3rd bathroom. It has cavity insulation and double glazing.

Up until 3 years ago it had a combi boiler and while this was okay for heating, it couldn't cope with the increased hot water demand from me, my wife and 3 sons, plus it started breaking down in Winter, so it was replaced with a Vaillant condensing boiler and unvented cylinder, which is brilliant.

 

[Agile]

When I arrived home from work on Friday, it was like walking into a sauna! It was much too warm. The hall thermostat was showing 21.5 degrees C. As a Yorkshire man, my first thought was how much extra gas was being burned and how it would affect my bills.

21° C is the standard temp for CH in the UK !

Planes have heaters in the cabin air supply to warm up the outside air. Just as well as its usually about -33° C outside at crusing altitude.

Tony

 

[tremtastic]

Got a new EcoTec 831 boiler and the VRC470F fitted yesterday. My installer advised against it, because he'd only seen problems with them. I thought it sounded like a good idea.

I had to explain heat curves to the electrician (I'm a software engineer with a maths degree so can usually work these things out). Then advise him otherwise when he wanted to fit the outside sensor to a south facing wall (no wonder he'd seen problems!).

Anyway, it's in and seems to be working OK. The heat curve is set to 1.7 and the mode to "thermostat" in our new-ish build wood frame house. The factory default setting of 1.2 is a joke right?

Only minor annoyance is the ability to only set two temperatures - Day and Night. With my old Honeywell stat I could set a hot morning temp, warm day temp, hot evening temp and cold night temp. But you can't have everything.

Anyone with any questions, let me know.

 

[scoobydo123]

is there not a set back temp as well?

 

[tremtastic]

is there not a set back temp as well?

As far as I can tell, the setback temp is the "night" temp.

Page 22 here:
http://www.vaillant.co.uk/stepone2/data/downloads/cf/43/00/VRC 470f operating instructions.pdf

 

[Milleniumaire]

I confess I like the look of the VRC470f better than my VRC430, but it does appear that Vaillant have removed this particular feature.

On the VRC430 I can set upto 3 different temperatures per day, but can't see this mentioned in the VRC470f document and as you say there are only two settings "day" and "night".

I currently have the heat curve set to 2.0 and it seems to be working well, the 1.5 set by the engineer was too cold and the 2.3 recommended by Vaillant was too hot.

It still seems to be a black art in terms of getting the temperature to the "required" temperature, maybe that's why Vaillant removed the ability to set 3 daily temperatures as in my experience, it doesn't even maintain one! For example, the required temp is set to 21 C. When the heating curve was at 1.5 it would rarely get over 18 C. When I upped the heating curve to 2.3, the temp was showing between 21.5 and 22 C. At 2.0 it tends to be around 20.5 C, which is near enough!

I'm still experimenting with the settings, although I'm now much happier in a warmer house, I'm just worried about my next gas bill!

 

[tremtastic]

It is a nice unit, but there are a couple of things missing - separate temperature timed programs as mentioned.

I'd also like an indication of when the thermostat is requesting heat. The old stat had a little flame symbol to show this. The information is buried down in the menu, but it's a bit of a pain to go hunting for it.

On the boiler itself, there's a little bar showing the current power of the flame. This is always really low (except when drawing hot water), so I'm assuming it's not using much gas at all.

It's got to be more efficient than a normal thermostat causing the flame to go full-off-full-off all day.

 

[JonCa]

It's got to be more efficient than a normal thermostat causing the flame to go full-off-full-off all day.

Bit of a question, surely the boiler is able to regulate its burn even with a simple thermostat (ok perhaps not so efficiently) OR is it utterly dependent upon the thermostat/programmer for economical functionality?

If its the thermostat/programmer that's doing the work then who makes the best/better ones, and can one rely on a good level of inter-working between a.n.other boiler and the thermostat/programmer? Presumably the inter-working will be via Open-therm.

 

[ALEC1]

there is no economic functioning of an on-off thermostat.. it has to over heat rooms to shut down, and then when every thing has cooled down it has to work pretty hard to replace lost heat quickly...