Vaillant VC 400 Compensator

[SirBodgeAlot]

Hi all! First thread, please be gentle with me!

I'm in the process of choosing a new combi to replace a Baxi Bermuda back boiler (which is still going strong after goodness knows how many years)

I'm thinking of ordering a Vaillant EcoTec and would like to fit an outside sensor and compensator, only problem is that Vaillant do not appear to offer any sort of optimisation in any of their controls packages.

So....I already have a Danfoss programable rf room stat (TP7000 RF) with simple optimisation. Question is, can I connect the Danfoss receiver to the thermostat volt free contact input on the boiler with the VC 400 Compensator fitted in the boiler (with its time control set to 24hrs to defer to the Danfoss time programme/optimisation)?

Will this actually work? Can't tell from reading Vaillant instructions.

Any help greatly appreciated, thanks.

 

[gas4you]

I would say no.

The 400 will do all that you want, or the new 430 that has superceded it will be better.

The WC will in effect optimise the heating to the outside temperature. This will give greater benefits that the optimising stat you have now.

 

[SirBodgeAlot]

I would say no.

The 400 will do all that you want, or the new 430 that has superceded it will be better.

The WC will in effect optimise the heating to the outside temperature. This will give greater benefits that the optimising stat you have now.

Thanks for the reply.

I understand what you're saying, but I was specifically thinking about in the morning when it's cold and the heating needs to pre-empt the start time in order get to temperature before people get up. I suppose you could set the compensator to always start 1/2 hour before and it will set the flow temp according to how cold it is inside and out, but it seems a shame to do this if it is not so cold and only would have needed 15 mins.

BTW if you fit the VC 400 in the boiler the built in sensor obviously cannot be used. If you have this setup is there any way to get room temperature into the equation?

 

[simond]

The VRC430 does carry out optimisation.

Forget the VRC400 it is a legacy product.

The answer to you last question is no, why don't you fit it where the room stat is?

If fitted in the boiler the VRC430 works out how warm the house is by comparing the flow and return temperatures and time taken to change them. When it is mounted inside the boiler the air temperature sensor inside 430 is disabled.

By the way, weather comp will not work properly if you live in a house with differing levels of insulation, eg: an older house with recent extensions. Especially if you mount VRC430 in the boiler.

 

[SirBodgeAlot]

The VRC430 does carry out optimisation.

Forget the VRC400 it is a legacy product.

The answer to you last question is no, why don't you fit it where the room stat is?

If fitted in the boiler the VRC430 works out how warm the house is by comparing the flow and return temperatures and time taken to change them. When it is mounted inside the boiler the air temperature sensor inside 430 is disabled.

By the way, weather comp will not work properly if you live in a house with differing levels of insulation, eg: an older house with recent extensions. Especially if you mount VRC430 in the boiler.

Thanks Simon, good advice as we are going to extend soon.

I had a good look at the VRC430 instructions and couldn't see anything RE optimisation, will have another look, maybe I'm reading it wrong.

I was thinking of fitting it in the boiler and using the RF stat to save cabling but I can now see that is not a good idea.

Thanks for the help.

 

[SirBodgeAlot]

Simon/Dave

You're absolutely right, I've just seen the "Max. Advance Heating Time" setting in the manual. I don't know why they don't big up the optimisation function more in the sales literature, I would say it is as big a selling point as compensation.

It also doesn't mention it in the user guide so some people may be confused as to why their heating is coming on an hour earlier than they expect!

Looks like a wicked bit of kit though, I'm going to rip the old Baxi out just so I can have a play with a nice new toy!

Thanks again.

 

[simond]

Optimisation isn't really that exciting to end users, I have found. The idea of the heating coming on earlier worries some people who want it to come on exactly when they have programmed it.

For instance, if your pipes creak and tick under the bedroom floorboards you may not be thankful you got woken up 30 mins earlier than usual on a colder day!

Also most modern boilers incorporate anti-cycling, which delays the restart of the burner after an on period, irrespective of the controls fitted.

Weather Compensation delivers significant benefits because it causes the boiler to be in condensing mode for longer periods, directly influencing boiler efficiency. An optimiser alone only offers very minimal benefits in comparison.

Be careful fitting VRC430, it is complex to operate and cannot handle multiple zones in the UK derivative. If you have a larger house it is more than likely you would use less energy zoning rather than having a single large zone with VRC430.......

The best way to save energy is to reduce the temperature in areas you are not occupying at the time.

 

[sealo0]

Hi

Are you sure re second Zone? Details below from VRC430 Manual?

The VRC 430 can also be used for the control of the
following accessories:
– Circulation pump for the hot water provision in
combination with a multi-functional module VR 40
– Ventilation unit
– conventional hot water cylinder
– Vaillant layer cylinder actoSTOR
– Second heating circuit using the Vaillant Mixer
Module VR 61


Mike

 

[simond]

I chose my words carefully, if you read my post again.

Currently in the UK no products are available from Vaillant to expand the capabilities of the VRC430. Those of us who fit German boilers know that there are many functions unavailable to to the UK market.

I have to field all the questions from our customers with VRC400 and VRC430 manuals, the last one was only on Thursday quoting the same functions you describe. Even though I explained when we installed it.

If you look on Vaillant's home site in Germany you will see we get just a very limited range of their products, including boilers, not just controls.

 

[sealo0]

Hi Simond

Thanks for that. It may well explain why I have had no reply from Vaillant on the same subject.

just a throught what's stopping us getting the German versions from Germany & using them?

Mike

 

[SirBodgeAlot]

Optimisation isn't really that exciting to end users, I have found. The idea of the heating coming on earlier worries some people who want it to come on exactly when they have programmed it.

For instance, if your pipes creak and tick under the bedroom floorboards you may not be thankful you got woken up 30 mins earlier than usual on a colder day!

Also most modern boilers incorporate anti-cycling, which delays the restart of the burner after an on period, irrespective of the controls fitted.

Weather Compensation delivers significant benefits because it causes the boiler to be in condensing mode for longer periods, directly influencing boiler efficiency. An optimiser alone only offers very minimal benefits in comparison.

Be careful fitting VRC430, it is complex to operate and cannot handle multiple zones in the UK derivative. If you have a larger house it is more than likely you would use less energy zoning rather than having a single large zone with VRC430.......

The best way to save energy is to reduce the temperature in areas you are not occupying at the time.

Thanks for the info Simon.