Two zone weather comp heating possible??

[coxo]

Hi I hope someone can help - am a homeowner not an engineer!

We have new UFH downstairs and rads upstairs. I'd like one UFH zone, one rad zone and DHW. All separate and all independent. One thermostat in UFH, one upstairs for rads. Heating weather compensated.

We have a Gledhill unvented cylinder already in. Boiler and controls can be whatever is needed. What does anyone recommend?

The Vaillant VRC 470 (+ VR 81 upstairs for rads) with VR61 wiring centre looks like the answer. Will that work?

Any other suggestions? It seems really simple to me but our guy is struggling.

Thanks so much!

 

[Agile]

It is quite simple to fit the hardware!

The weather compensation is a slight problem because the operational parameters ( curve setting ) will be different between the rads and the under floor heating ( UFH ).

The other problem is that controlling the UFH temps requires controls which are not so well known.

A better solution would have been to use oversized rads upstairs which can operate on the lower temperatures required for the UFH and control the temps at the boiler.

None of this is impossible but it may well be outside the experience of your installer! It would have been better to have it installed or specified by someone more conversant with what is required.

Probably best to just control the UFH and rads at the boiler from a simple weather comp ( WC ) and see how well that performs.

It is possible to build simple circuits which alter the WC sensing resistance according to which zones are being heated.

Tony

 

[coxo]

Thanks Tony.

Your comment about controlling both UFH and rads from the boiler with simple weather comp...

Sounds perfect... can two room thermostats be fitted to that? i.e. one in UFH and one upstairs?

If so that will do the job perfect. Any recommendations on boiler / controls?

Many thanks

 

[Agile]

Strictly speaking room stats are not required with WC !

However, I would always recommend them as customers like something to fiddle with although they should be left alone!

Room stats dont work well with UFH either because of the long thermal time constant.

Others will advise you of which Vaillant products are likely to be most suitable.

Tony

 

[coxo]

okay thanks again.

Sorry to be a pain. I'll stop suggesting solutions as I'm not an engineer, but instead just what I want to achieve...

How do I achieve a constant 19 degree temperature in every room of the house (UFH down, rads up) with max efficiency (i.e. weather comp) and minimal user fiddling? All rads have TRVs by the way.

Last question! Many thanks

 

[D_Hailsham]

Strictly speaking room stats are not required with WC !

That assumes the inhabitants never want to change the room temperature.

 

[Agile]

In theory with correctly set WC and rads!

With WC in theory you leave the TRVs fully open as they dont have any purpose!

Theory and practise dont always converge!

Tony

 

[ALEC1]

vaillant have a mixing module that can be used with UFH..it operates on the principal of a mixed and unmixed circuit.It works very well.


unless you install a LLH you don't strictly get zonal control though

 

[Agile]

Strictly speaking room stats are not required with WC !

That assumes the inhabitants never want to change the room temperature.

It sounds as if you dont follow how WC works!

A room stat can only LOWER the zone temp with WC.

But it cannot INCREASE it above what the WC is set to achieve!

I always recommend a room stat and that TRVs are fitted because it gives downward control of the temps.

Its often stated that 35% of people with WC dont like it or find it impossible for them to use! Of course the fault lies with them as they are incapable of leaving it to do the job without fiddling.

Tony

 

[mickyg]

Glowworm Ultracom, Systempro, outside sensor and a couple of Climapro2 RFs.

Untitled

• mickyg
• 14 Aug 2012
• 8

 

[matt1e]

Strictly speaking room stats are not required with WC !

That assumes the inhabitants never want to change the room temperature.

It sounds as if you dont follow how WC works!

A room stat can only LOWER the zone temp with WC.

But it cannot INCREASE it above what the WC is set to achieve!

Tony

Don't be daft of course you can increase the room temp set point on a compensated system


Matt
Edit
Whoops sorry Tony Im using my phone I never noticed you were on about a connected room stat Till I zoomed in better
I will just keep my trap shut

 

[ALEC1]

Only as long as their is hydraulic seperation, and a thermostat (on-off) should not be confused with a sensor which allows the flow temp to modulate, as well as switching things on and off

 

[D_Hailsham]

Strictly speaking room stats are not required with WC !

That assumes the inhabitants never want to change the room temperature.

It sounds as if you don't follow how WC works! A room stat can only LOWER the zone temp with WC. But it cannot INCREASE it above what the WC is set to achieve!

I suppose that depends on what you mean by a "room stat". If you are talking about the traditional mechanical or digital stat, then you are quite correct.

BUt the WC "room stats" supplied with Vaillant boilers, and other WC stats, do allow you to change the room temperature. When this is is done the heating curve is automatically adjusted to give the correct result.

 

[coxo]

So would an EcoTEC Plus boiler, VRC430, VR61 and VR81 allow me to control DHW / UFH / Rads separately?

Would I need anything else?

The cylinder is an unvented Gledhill

 

[matt1e]

So would an EcoTEC Plus boiler, VRC430, VR61 and VR81 allow me to control DHW / UFH / Rads separately?

Would I need anything else?

The cylinder is an unvented Gledhill

1) Yes
2) No...... well maybe a bit of savvy setting it up
I presume you will get the necessary sensors you need with the above kits

Matt