I'm having a new central heating boiler installed (there is no central heating system at the mo) and getting quotes at the moment. When I mentioned about the weather compensator to the corgi engineer giving me a quote he said it was an extra option but he didn't think it was worth it - his explanation being: If it is warmer outside then it will be warmer inside, therefore if I have got an internal thermostat the boiler will fire up until desired temperature is reached and then stop. With weather compensator, boiler will fire up later when needed. But net effect the same, the boiler will be on for the same amount of time to reach desired internal temperature. This seemed to make perfect sense, is there a flaw in this argument? He also said they were more useful for larger buildings but for single dwellings not that useful. So should I go for weather compensator?

but a weather compensator wouldn't overcome this? The weather compenstator tells the boiler when to fire (as far as I understand) so still does not control individual rooms. I do currently have thermostats in every room in my (current) house - and keep the radiators in the bedrooms at a lower setting than the living room.

A weather compensator will also modify the temp of your boiler output. The colder it is the high the temp. This means that the return temp of the water is lower and the boiler will run in condensing mode for longer.

Have a look at a viessmann boiler they have them pretty much as standard.

Posted By: fostertomFailing all that, I too can't see that a compensator would do any better than conventional controls - unless there's something else that they're doing?

I don't understand how you have come to that conclusion.

Weather comp should be standard on all boilers, and the good ones have it anyway. its an absolute no brainer, would you buy a car with a carburettor now. And most are self learning, they don't need a plumber with a degree. The Viessmann knows which components are installed and auto configures and it self learns response times for a building.

On the whole thermostats are a rather inaccurate means of controling internal temperature (accuracy +/- 1to2C) and as a consequence are liable to waste energy. As a consequence weather compensation is suposed to be a good energy efficient refinement. Weather compensation affects the flow temperature of the heating circuit so that in warm weather its lower and cold weather its higher. It is often used in underfloor heating and is well suited to condensing boilers (as this allows increased efficientcy as the boiler is kept in condensing mode for longer.) NOTE: Paraphrased from The Whole House Book.

Because of the inacurracy of thermostats a weather compensating system is meant to be an ideal refinement for super insulated structures. This is largely due the potential for autumn/spring overheating (solar gains+heating) leading to the risk of causing discomfort and the subsequent need to ventilate and dump heat (not very energy efficient!).

Hi, the waether compensator will remember the times and temps that caused to boiler to come on and off. These are mapped to a variety of graphs which can then have various slope parameters set on them by you the user. This allows it to extrapolate the temperatures based on the comparison between inside and outside over periods of time.

The usual wall room thermostat is very inaccurate and only gives on/off. If set to 20deg the boiler will run untill the room sees 20 deg before switching off, the room temp will carry on rising in temp till about say 22deg, but will have to fall to about 18 before cutting in again.

The compensator will modify the water temp and the firing to achieve the 20 deg spot on, as the exterioer temp rises throughout the day ti will continue to reduce boiler temp and firing times to maintain the set 20 deg. It will remember the times and shut off early or later even to control the temp.

Heat loads are calculated for worst case, this might be 5am, but on the same day the heat load could be down by 40% by 3pm due to the exterior warming and the thermal mass of the house. The compensator will optimise to take this into account.

Cheers

Heating controls can be a little daunting at first glance, however the more control you have of your system the more likely you are to minimise your fuel expenditure.

I in a 3 bedroomed end terrace have Weather compensation, a ground floor temperature sensor & Trv's on all my radiators. This way any cold or hot spots are equalised really efficiently.

A number of "Ye olde timers" in the heating trade run around telling people that you can't have Trv's on all the radiators & that weather compensation is designed for Baltic climates, these are the same crowd that say radiators must go under windows too.... They also advise everyone that they should have a Combi ...... I wish we could treat that crowd in the same manner the Russians treated their tzar's.

Weather compensation is ideal for locations that have varying out door temperatures (So if you live on the north or south pole you probably don't need one)
A lot of system boilers have a bypass valve fitted to deal with situations where all the TRV's are closed (If yours doesn't you can buy them for £15 from the plumbers merchants & fit it in two hours)
Windows allow heat to escape rapidly (Irellivent of double glasing) So mounting heater panels below a area of low thermal resistance is plain daft
Combi boilers are great..... If you don't have the space for a properly lagged water cylinder...... If you do have the space buy a cylinder..... You don't necessarily need header tanks however your wallet will thank you greatly if you either buy or retain at least one

I would say just a programmable room thermostat or chronostat would be good enough.

You should not be using a room thermostat!!

They are a left over technology from the last millennium!

Programme time and temperature (house at the minimum necessary temp for the activity) saves loads in UK 18 instead of 21 could be saving 15% alone.

Use a chronostat.

So long as it sets time and various different temperature it is OK.

http://www.telegraph.co.uk/earth/main.jhtml;jsessionid=TLA3SVNXYZ0FBQFIQMFSFGGAVCBQ0IV0?xml=/earth/2007/06/21/eaplumb21.xml

I wrote this article and a client today 2.12.2007 said this:

Just wanted to let you know that we LOVE the boiler. The temp in the house seems much 'smoother' although this seems an odd word...but it aptly describes the lack of huge fluctuation which usually meant we froze for a while, then had to shut all doors to heat up individual rooms, then felt too hot in the rooms and had to open the doors to compensate. We're weather compensation converts

Boilers installed in Germany and Holland have to have weather compensation because it enhances energy efficiency.

In the UK some boiler manufacturers remove the logic for a dumbed down british consumer (and installer!)

shameful really...as britain is to all intense and purposes a techno friendly society!

<blockquote><cite>Posted By: tony</cite>You should not be using a room thermostat!!

They are a left over technology from the last millennium!

Programme time and temperature (house at the minimum necessary temp for the activity) saves loads in UK 18 instead of 21 could be saving 15% alone.

Use a chronostat.</blockquote>

What about where you have rooms that don't change temperature in sync. Our new house will have some north facing rooms where temperatures will be fairly predictable but also quite a few large rooms where the temperature will vary quite a lot depending on whether the sun is out. Surely I need room thermostats to switch the UFH on/off zone by zone?

On the original point, many air source heat pumps now seem to come with weather compensators and I can't see the point.

Hi everyone..

New to this forum. So I hope this post is not out of place. I have experience with weather compensation systems. I fitted my system in August 1996, along with high efficiency hot water store. All rooms have rad stats for individual control. No other energy saving measures was introduced in this large open plan 4 bed detached house. I monitored gas use during the first year in the house with just basic stat and poorly insulated hot water tank. In the first year of use of the new system gas bills were cut by over £200 in the year, back in 1997 that was a huge amount. The system is still running with out missing a beat and saving me money, paying for itself in just over 18 months.

My understanding is that compensatory systems save energy by calculating the heat losses of the building, and only applying enough heat to maintain living space temperature. Once heat loss data is stored in the system a few days after initial start up, the computer monitors the house temperature inside and out and only fires up the boiler when losses will take the living space temperature down below desired pre-set level/s (different levels for different times). In my system there is a maximum 2 hour pre demand window, when the boiler will apply heat to the system in order to be at temperature at the pre-set time, ie getting home from work. There is also a and of heating demand period where the system will shut off if it calculates that no more heat is required before the next user pre-set temperature drop, ie just for bed. Unlike basic heating controls, the system only warms the water in the system to a temperature sufficient to meet the room space temperature requirements.

Honeywell withdrew my system the AQ6000 system due to consumers not understanding that the system was operating perfectly when radiators were only slightly warm. Customers messed up the systems by trying to get red hot radiators, which they were used to with non compensatory systems. There were so many call outs to perfect systems, Honeywell pulled the AQ6000 from domestic and commercial sales. Pity, it was and is a very good system and very affordable with short payback times.

When I got home today the inside temperature was 21degree C out side, 9 degrees C out side and circulating water 31 degree Cs, so the radiators felt mildly warm. We only see 80 degree circulating water temperatures when it is below freezing out side and the system is working at maximum to get started at the beginning of a night low temperature zone cycle.

I am currently looking for a house renovation that will enable me to start from scratch and make it as energy efficient as is economical possible. I will certainly be looking at a new compensatory system for the project, unless I can find something that offers better returns and savings.

Apologies if this not an appropriate first post.