Worcester FW100 Weather Compensation Control


3 Jan 2011
Reaction score
South Glamorgan
United Kingdom

Any one any experience ( installer or end user) of the Worcester FW100 Weather Compensation Controller to connect to a WB Greenstar CDI combi ?

Sponsored Links
Hi Bengasman

I am considering my control options for a new WB Greenstar Combi

So was wondering if anyone has fitted them or used them

how people have got on with them

are they worth having over conventional Prog Timer & Stat

what are the plus points

what are the negative points

etc etc

any / all comments welcome
If you read the sales schpiel with a magnifying glass, you will find in a back corner somewhere, that the 20% additional savings are measured over the savings compared to a se boiler i.e. se=80% efficiency, he=90% efficiency.
So it is not ( up to ) 20% extra off the gasbill, but 20% of 10% = 2% off the gasbill.
That means it is extra money to buy, extra money to install, and an extra unit that can go wrong.
Great for me as an installer, but is it worth the hassle for you to get up to 2% reduction on your gasbill?
Personally, I don't promote it.

You want to save money on your gasbill?
1. Draft proofing.
2. Insulation.
3. Turn the roomstat down 1 degree, and save 4%
4. Turn your trv's down half a point once a week, until you find certain rooms are a bit too cold. Turn those up half a notch again.
80% of trv's are constantly on max and save nothing
Sponsored Links
In contrast to Ben, I have fitted one for a customer with a big house and I thought it wa very good and particularly better than the equivalent Viessmann weather comp becase it also monitors the indoor temp and you can select the reliance placed on each,

Properly used I think they should give 3-6% improvement in efficiency which is worthwhile on a larger property.

In a small flat then dont bother.

Thanks Agile & Bengasman for your valuable comments!

Ben I guess you are spot on with at least 80% of TRVs being on MAX!

& of course the draughts/insulation advice etc.

As the FW100 is no dearer than some of WB's wireless themostat / programmers i was still thinking of giving it a try

my understanding is that the FW100 WC will give more stable room temps and at lower flow temperatures ?
You can also get a rather cheaper and rather uncommon device from Worcester which is a room stat which MODULATES the flow temperature at the boiler.

That will control the room temperature and increase the efficiency of the boiler be reducing the flow temperature thus enabling it to condense more.

I am surprised the other manufacturers dont usually make one.

Have fitted 11 or 12 of these on both cdi combi and system boilers. Bit more complicated to set up than normal controls but wellworth it in my opinion. Every customer is happy with the system apart from one, the outside temp will run pump 24/7 if temp is below set value ( lowest setting is -5) so in recent cold weather the pump ran for 10 days solid and he couldnt go to sleep with pump running.
Cheers guys

I assume Agile is referring to the WB FR 10 which must only be used in conjunction with a suitable time switch, eg MT 10 or DT 20.

Yes I was aware of these - the FR10 + the DT20 would be my choice if I dont go for the FW100 Weather Comp.

the way the FR10 lowers the flow temp on the WB boiler as it approaches the set temp seems a very good feature

just wondering Gasanstuff is it the FW100 you have fitted 11/12 of or the Themostat that modulates the boiler that Agile mentions ?
You can also get a rather cheaper and rather uncommon device from Worcester which is a room stat which MODULATES the flow temperature at the boiler.


I am surprised the other manufacturers dont usually make one.
Those that support Opentherm will allow such functionality (using an Opentherm-compatible controller of course).

There are others too but it can be a bit more difficult to determine which do given the proprietory protocols used or lack of published info at such a level.

sorry wasn't clear i have fitted 11-12 of the FW100 wc controllers. have fitted 5 vaillant 430 WC controllers aswell (dont do many vaillant anymore,they may be 460s for all i know) as above have found them to be really good products.

Really found WC to work well but do not force it onto everyone!!!!!

By the way have spare vaillant WC controller the blue backlight one (430 or 460) retired customer couldnt live with it so i replaced it.if you want it have it!!!!!
Hi gasanstuff

I just saw your post offering a Vaillant weather compensator controller.We're getting a new Vaillant boiler and I was browsing to see what controllers were available. If your controller is still available could we have it? Of course we'll send you P&P and if you want anything for it do let us know.

Many thanks; I've made you a friend so you could send me a private message

Julia A

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links