how hot do you run you CH boiler

Best efficiency as far as the radiator is concerned is as hot as practical - the higher the deltaT between radiator and the room air then the more it radiates. If you have the heating on 24/7 then yes you can get away with low rad. temperatures, but for fastest response where the heating is timed then hotter is better. If you have intelligent thermostats like Hive or Nest then they will learn the thermal characteristics of the monitored room and minimise temperature overshoot by shutting down the boiler before the set temperature is reached.

Reply to
Andy Bennet
Loading thread data ...

I'm not seeking efficiency

I'm seeking all of the rooms at the same temp

tim

Reply to
tim...

I suspect they are talking nonsense or at crossed purposes. It may be that it can't be done with the installation you have, however if you are prepared to add controls then it looks straight forward.

If it (the compensator) is anything like mine (a VR470), then you can set the temperature for two "uncontrolled"[1] zones, and DHW separately in the programming. I also have a VR61 control module that lets you integrate traditional 240V zone valves etc into the controls.

[1] They seem to call what most people would think of as a zone controlled with valves and a thermostat, an "uncontrolled" zone. They reserve the term controlled for ones with active blending valves for UFH where the controls can directly set the UFH zone flow temperature independently of the main boiler flow temp.

Yup, have a look at:

formatting link
See the user manual section 5.2.1.2:

formatting link
That definitely allows independent control of CH and DHW temperatures.

(the VR700 has way more toys that you will need - I just picked that one because it was listed on the 400 series page. I expect the older VR470 would be fine as well)

Reply to
John Rumm

One of the problems I found with the Vaillant documentation, was that there is lots of low level detail stuff, but not so much "big picture" stuff to tell you what components you need to achieve which jobs. (perhaps that is what they train their registered installers with!)

In the end it was just a case of reading through all the detail stuff until you can mentally put together what bits are going to do what you need.

But basically you need a weather compensator, and probably an interface box to let it communicate with traditional valves etc.

In my case I went for a VR470 and a VR61 (there is also another aux mini controller / stat to monitor the upstairs temp - but you can do without that).

You use the VR470 as the interface to configure and control everything else. It acts as the central point for the timer / stat / weather compensator, and then a load of other facilities if you want them[1]. The interface box converts the demands of the controller delivered over eBus, to relays etc that can switch 240V to move 2/3 port valves.

[1] From the handy "cylinder boost", and "holiday mode", to the more esoteric UFH screed drying programs, DHW anti legionella cycle, ctrolling aux pumps like secondary circulation pumps or solar collection pumps etc.
Reply to
John Rumm

John Rumm formulated on Saturday :

All I have at the moment, is a Danfoss (I think) time clock, which sets when CH and HW are available. A three port valve. A wireless room stat and a wired HW cylinder stat.

The original boiler had just a live (when called) neutral and earth. I added an extra pair in from boiler back to pump, to enable to boiler to decide when the pump needed to be run, when the new boiler was installed.

Reply to
Harry Bloomfield

If the pipework is in the right place a two port valve will isolate the upstairs.

Reply to
invalid

efficient in what way?

Which is what I do have

I have no need for faster response. I want constant moderate temperature

tim

Reply to
tim...

I'm curious about that. You said with the boiler set to 74 degrees, the rad were too hot to touch? How can that be with the rooms at the correct temperture if they are OK at

55 degrees?
Reply to
Dave Plowman (News)

So you would need a bit of rejigging to move to split temperature operation. The VR weather comp replaces the timer and stat. You probably want a pair of two port valves in place of the mid position valve - although with a bit of thought you may be able to achieve the logic required with what you have. Swap the cylinder stat for a NTC thermistor, and add a suitable wiring centre. You would need an extra cable from the cylinder to the boiler (that threw me, I was expecting the cylinder NTC to connect to the wiring centre!), and to install an external NTC somewhere.

Doable enough, but whether its worth the hassle at this stage only you can decide. It might knock a few percent off the gas bill, and will make the place a bit more comfortable year round.

Reply to
John Rumm

If they have been sized for the typical -3 outside temp, then they ought to have loads of spare capacity with the current weather.

Reply to
John Rumm

Look at the Honeywell Evohome system

formatting link

Reply to
nothanks

on 12/01/2019, John Rumm supposed :

It sounds like a lot of work, just to get around a limitation of the boiler design. I have though, my eye on a 470 complete with the outdoor sensor.

So to check my understanding - The 470 is a complete time-clock and system monitor and room temperature sensor built into it? With the outdoor sensor, it becomes clever system able to adapt to set the boiler temperature as needed. It has the built in function to monitor an NTC on the HW cylinder and that temperature can be set separately.

Reply to
Harry Bloomfield

two different boilers (two different houses)

I have yet to try the new boiler at a lower temp

tim

Reply to
tim...

Not sure you can really call it a limitation of the design - at least they provide the facility in the first place, unlike many.

You would probably need the VR61 or similar as well to connect to the zone valves.

Yup... and an interface to pretty much anything else the system can do.

Yup.

ISTR the NTC cylinder sensor and the external sensor connect back to the boiler directly, but the overall effect is the same.

You can have independent temperature settings for CH and DHW. Needless to say that precludes the system running Y plan with the valve in mid position, and so favours modern fast recovery cylinders. (if you program CH and DHW to be active at the same time, it squeezes reheats of the DHW in between periods where the CH is satisfied (perhaps with priority to the DHW)

Reply to
John Rumm

If the Vaillant has 2 separate call for heat signals for DHW & CH it would be simple enough to split the temp, at least if the boiler has 2 separate temp settings for the 2 circuits, and the Vaillant 400 series I'm familiar with does. Where is the problem happening?

NT

Reply to
tabbypurr

IMLE it's essential to balance the system with TRVs set to max temp before using the TRVs to improve balancing as needs change.

NT

Reply to
tabbypurr

on 12/01/2019, John Rumm supposed :

.All it would need to enable a split temperature, is 2x call inputs for heat instead of the single one it has at the moment. Plus the two temperature settings in the software, to replace the single temperature. A fairly simple fix at the design stage.

That would not usually be an issue here. The DHW is usually brought up to temperature in less than 20 minutes. 20 minutes with no CH input would not be noticed.

Reply to
Harry Bloomfield

Oddly the older version of the 400 series had the separate temperature knobs on the front, although I also have vague memories of there being reported problems using weather compensation on those. So perhaps they "fixed" it by going to the system used on the 600 series.

Reply to
John Rumm

Seems to suggest its compatible with the VRC 700 weather compensating

The ecoFit Pure does not appear to have separate inputs:

formatting link
"The Control Center VR 65 offers a solution to allow Vaillant low voltage ?eBUS? controls to be used with the traditional 230 V zone valves and DHW storage cylinder in the English market.

Information about the heat required by the cylinder is forwarded by the Control Center VR 65 to the Vaillant ecoTEC heating appliance. The boiler then decides whether a hot water request has to be fulfilled and sends a signal to position the 230 V zone valves via the VR 65.

In this way, the boiler can store different target tempera- tures for heating and warm water operation. Standard 230 V components can be integrated into the Vaillant eBUS system via the Control Center VR 65."

also:

"The Control Center VR 65 is an eBUS system compo- nent. It is responsible for the communication between the DHW cylinder, the boiler and external 230 V 2- or 3-port valves.

Note! The VR 65 is designed to control one 3-port valve or two 2-port valves. Systems requiring more zone valves or a combination of 3-port and 2-port valves are not possible."

Installation:

"The C "VRT 360 Digital room temperature thermostat with daily/weekly program for time and temperature control of heating and hot water. Designed for wall mounting. There are three individually programmable time win- dows per day for heating, hot water and a hot water circulation pump. Different target room temperatures can be set for each time window. The thermostat can be set to run a weekly or a daily program. By activating the calendar function, an automatic summer/winter changeover is activated."

Which sounds like you may be able to do:

VRT360 + VR65, conventional 3 port valve, and conventional cylinder stat. No need to go fully weather comp.

Reply to
John Rumm

Better be quick.. The VR61 is obsolete and in clearance on most sites. I don't see an alternative on the valiant site.

Reply to
invalid

HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.