Weather compensator and efficiency regs

Newts · 22 Nov 2008

I've recently fit a Vaillant 838 with VRC430 weather compensator and after speaking to Vaillant had been informed that the efficiency could be improved 5% with this device. When the controller is in the boiler it is not a room stat but becomes one when placed remotely of the boiler by means of 2 core wire (their BUS system).
In order to comply to new energy efficiency standards the room stat must be in an area with a rad with lockshields in order to provide boiler interlock. This is obviously not going to happen when the controller is placed in the boiler. Now I have had a corgi inspector advising me that the installation with the controller in the boiler would count as a discrepancy due to the fact that there is no interlock provided whilst I have Vaillant telling me that the weather compensator provides even greater effiency and feel that their new device is acceptable for efficiency standards. Incidentally they are going to check and get back to me.
I must admit to being a new engineer and a bit wet behind the ears on issues such as these so is anyone able to confirm whether a compensator installed within the boiler, hence effectively a system with no room stat, is sufficient or would I have to remotely locate it elsewhere.

simond · 22 Nov 2008

It'll either be a Vaillant 438 or a 637. They don't make a 638.

The CORGI inspector is wrong. If I were you, I'd do nothing, and let him take it where he wants.

So how far he gets.

gas4you · 22 Nov 2008

I agree with Simon.

As usual the corgi inspector knows nothing.

Fitting the 430 into the boiler complies with all energy efficiency regulations.

I always fit all rads with trv's though when fitting one of these.

David937 · 22 Nov 2008

simond said:
It'll either be a Vaillant 438 or a 637. They don't make a 638.

The CORGI inspector is wrong. If I were you, I'd do nothing, and let him take it where he wants.

So how far he gets.

It could also be a 837 combi boiler.

simond · 22 Nov 2008

At least he hasn't sent us a picture.

David937 · 22 Nov 2008

mickyg · 22 Nov 2008

David937 said:
simond said:

It'll either be a Vaillant 438 or a 637. They don't make a 638.

The CORGI inspector is wrong. If I were you, I'd do nothing, and let him take it where he wants.

So how far he gets.

Click to expand...

It could also be a 837 combi boiler.

or it could be an 838exclusive just like he said in the first place

tell the inspector to do one

David937 · 22 Nov 2008

God point

Norcon · 22 Nov 2008

Vaillant wrote

VR 81 remote control device
The remote control VR 81 is recommended if the
VRC 430 is plugged into the boiler, or if the second
heating circuit is to controlled remotely.
The remote control VR 81 permits the setting of the
following parameters:
– Operating mode
– Target room temperature
In addition, the maintenance and fault messages are
given by symbols.
The data interchange is via eBUS line.

Wouldn't it make sense to have this device fitted anyway?
Let me guess. It's not available in the UK.

Newts · 23 Nov 2008

Thanks for the replies everyone. Thought that the whole point of this controller would be to INCREASE overall efficiency over a standard room stat, especially as vaillant told me it could increase efficiency by a further 5%.
The room stat is automatically switched off when it is installed within the boiler (as mine is) and it seems the boiler regulates temperature by monitering flow and return temps, the outside temp and the temp preset. Its all a learning curve for me so thanks again for the vote of confidence.

jon26 · 23 Nov 2008

Newts said:
Thanks for the replies everyone. Thought that the whole point of this controller would be to INCREASE overall efficiency over a standard room stat, especially as vaillant told me it could increase efficiency by a further 5%.
The room stat is automatically switched off when it is installed within the boiler (as mine is) and it seems the boiler regulates temperature by monitering flow and return temps, the outside temp and the temp preset. Its all a learning curve for me so thanks again for the vote of confidence.

Corgi guy's are normally 'old school' and out of touch with the modern gizmos, they probably think the Archie Kidd boilers are still the most efficient!

BigBurner · 24 Nov 2008

gas4you said:
I agree with Simon.

As usual the corgi inspector knows nothing.

Fitting the 430 into the boiler complies with all energy efficiency regulations.

How? A "control interlock" is to switch out the burner when the house requires no heat. I assume this boiler will be operating as a basic weather compensator without any room temperature influence. This means when the house is up to temp it may still be pumping heat into the house.

If this is so, the Corgi man is right.

simond · 24 Nov 2008

Wrong again.

The VRC430 is classed as an interlock because it's logic determines when the heating job is done from the flow and return temps and the external temp.

Viessmann weather comp can be configured the same way (inbside the boiler only) and meet building regs.

Looks like your internet research is letting you down, Big Burner.

If your ego wasn't so big I think you would benefit from a few manufacturers courses - you'd probably have to pay for them though.

mickyg · 24 Nov 2008

simond said:
If your ego wasn't so big I think you would benefit from a few manufacturers courses - you'd probably have to pay for them though.

Unfortunately most manufacturers only allow competent heating engineers on their courses.

BigBurner · 24 Nov 2008

simond said:
Wrong again.

The VRC430 is classed as an interlock because it's logic determines when the heating job is done from the flow and return temps and the external temp.

Viessmann weather comp can be configured the same way (inbside the boiler only) and meet building regs.

A basic weather compensator without room temperature influence does not provide a "control interlock".

Do they issue some documentation stating that the interlock requirement is met? If not then the requirement is not met.

If it operates they way you say, you will still get boiler cycling when the house is up to temperature. The boiler will cool and the control system bring in the boiler.

Does this weather compensator have the capability to have a room sensor fitted remotely? If so I would fit one.

If your ego wasn't so big I think you would benefit from a few manufacturers courses - you'd probably have to pay for them though.

The ego is with you, thinking you know how something works because a makers rep told you. I don't need a domestic maker to explain control to me as I once specialised in commercial control. I would end up taking over the course.

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Weather compensator and efficiency regs

BigBurner

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