Plug in Weather Compensation for boilers

[chris watkins]

With quite a few of the boiler manufacturers offering the option of a plug in sensor to activate the built-in Weather Compensation in there products, have any of you added / used this facility? Was it easy to fit to the boiler? Is it worth while i.e. is it cost effective ? Can it be used in an older house when replacing the boiler but leaving the existing rad's & controls (it is an S plan) normal room stat & TRVs. What boilers have this, can you recommend any others I know Viessmann compacts have this.
Sorry for all the questions & thanks in advance for any help & advice you can give.
CW

 

[grahamgas]

I have wc on my 837 at home, and it works very well indeed, and saves money.
What you have to do is to retrain your customers, that on certain days they will not get too hot to touch radiators, and that the boiler will be on more frequently.
If you use the vaillant set up, using the vr65 , then you can use all your existing motorised valves etc.

 

[chris watkins]

Sorry to be a pain Grahamgas but did you use the VR65 with one of there programers controllers ?? Can you set different curves with this to suit the type of building ? I think I got prices for this & by the time you brought all the bits it worked out quite expensive (couple of hundred), where as the ones already in the newer boilers, I think, only require a sensor to be bought & installed, much cheaper ?

 

[Nostrum]

I have had to take them back out before Chris because the customer's didn't understand the principles and the curve adjustment was a pain on the Vaillant. Saying that, it was my boss's decision to remove them as he 'didn't want the hassle'

The integral unit should use the same principle really so i can't see them being any different. ATAG have them ready to go + sensor as well

I was tempted to put one on my 831 at home but seeing as it only modulates down to 6kw and my house is quite small it didn't seem worth it.

I'm looking at pushing them myself so would be interested to hear your experiences with them if you go ahead Chris.

 

[chris watkins]

Talking to Vaillant this is the next development challenge for all boiler manufacturers to get there burners to go right down, they are talking about 1 -2 kW so that they can keep working with the low flow rates (new A rated pumps) without cycling.
It seem WC is an easy add on with combi's not so with old style housing with existing controls but worthwhile doing.

I have just been looking at a Viessmann compact 100 W which for around £20 -30 you can get the sensor kit to make it work in WC mode. It looks a lot easer & cheaper than the Viallant.

 

[Nostrum]

It's what industry needs. You can get pellet boilers that range from 1-12kw but not a gas boiler. I'm not sure if it is due to the limitations of the gas valve or what. Getting a combi to modulate from 2-30kw sounds like an impossible task maybe? I suppose you could fit a buffer but then you would have to justify the potential heat loss and install cost in respect of the saving you are likely to make?

I wonder if they could adopt a system with 2 gas valves with different ranges?

Do you have any ideas where the problems lie in achieving this kind of modulation range?

My house is a typical example. It's a 2 bed mid terrace. Limited space inside so a combi seems the best method. The heat loss at -3 is probably no more than 5kw but the boilers modulation range means it is probably bouncing off the bottom all day long.

 

[chris watkins]

I think it was when I was talking the a Vaillant guy for the LLH, he was saying that they were testing the new generation of gas valves out & the only trouble had been up in the highlands, Tamz neck of the woods, were strong winds had been causing flame lift & tripping out (like going back to the old days of pilots). The tiny amounts of pressure needed for the zero rated governers to allow gas in for this small amount of heat, is always likely to cause problems, me thinks, as you say maybe time for another rethink but it is needed.
The amount of calls we get from people who have fitted or had installed a boiler, "cause they modulate to what you need don't they !!" when you try to explain that a 37 - 38kW lump in a small house an't going to work, they find out about heat loss.
The guy was saying that he had been monitoring his own larger detached house over the winter & was very surprised at just how few kW it took to hold a steady temp even on the coldest days of the year.