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  #71   Report Post  
Old January 13th 19, 10:44 AM posted to uk.d-i-y
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Default how hot do you run you CH boiler

On 13/01/2019 03:09, wrote:
On Saturday, 12 January 2019 09:28:26 UTC, Harry Bloomfield wrote:
John Rumm formulated the question :


IME many of the Vaillant boilers do support split temperature
operation, but it does depends on what controls you have them
paired with.

The 400 series Vaillant I did (probably previous model range,
since this was
= 12 years ago), actually had separate knobs on the front for
CH and DHW flow temperatures. Although that was retrofitted
into system with traditional controls that could not
distinguish between the source of the call for heat - hence the
DHW control never came into play and it ran like your system
does.

The blurb on their web site:

https://www.vaillant.co.uk/for-insta...ler-26116.html



Seems to suggest its compatible with the VRC 700 weather compensating
controls, so that ought to allow split temperature as well.


I have studied it and not found any obvious way to split the
temperature. I even spoke to Vailant and they confirmed there was
no way it could be done.


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?


The ecoFit Pure does not appear to have separate inputs:

https://www.vaillant.co.uk/downloads...ual-876622.pdf

However I just found this:

https://www.vaillant.co.uk/downloads...ons-261442.pdf

In its description it says:

"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 Control Center can be wall-mounted near to the
DHW cylinder. The hot water and heating programs as
well as all required parameters are set at the VRT 360
or VRC 400. All heating circuit connections are made at
the Control Center using a ProE plug"

of the VR360 it says:

"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.


--
Cheers,

John.

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|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

  #72   Report Post  
Old January 13th 19, 10:58 AM posted to uk.d-i-y
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Default how hot do you run you CH boiler

On 12/01/2019 22:19, John Rumm wrote:

I have though, my eye on a 470 complete with the outdoor sensor.


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


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


  #73   Report Post  
Old January 13th 19, 11:23 AM posted to uk.d-i-y
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Default how hot do you run you CH boiler

John Rumm has brought this to us :
The ecoFit Pure does not appear to have separate inputs:

https://www.vaillant.co.uk/downloads...ual-876622.pdf

However I just found this:

https://www.vaillant.co.uk/downloads...ons-261442.pdf

In its description it says:


Thanks, I am looking at that now..
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Old January 13th 19, 12:15 PM posted to uk.d-i-y
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Default how hot do you run you CH boiler

In article ,
John Rumm wrote:
On 12/01/2019 13:08, Dave Plowman (News) wrote:
In article ,
tim... wrote:
Anyhow, at my current house it is 55 and works perfectly well


You must have rather oversized rads?


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


Of course. But would you want to fiddle with boiler temperture on a cold
snap? Seems a rather old fashioned way of doing things.

--
*Gravity is a myth, the earth sucks *

Dave Plowman London SW
To e-mail, change noise into sound.
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Old January 13th 19, 12:21 PM posted to uk.d-i-y
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Default how hot do you run you CH boiler

In article ,
tim... wrote:
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?


two different boilers (two different houses)


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


Ah - right. With my Viessmann which has weather comp, the rads in the main
room - no TRVs - would perhaps be too hot to touch when the system first
comes on - but soon drop back to a lower temp. If you ran it 24/7, unless
it was very cold, they've never be too hot to touch - although the rads I
have include a faceplate which doesn't get up to the full water temp
(Thermapanels - bought more for the look than this feature, many years ago)

--
*All generalizations are false.

Dave Plowman London SW
To e-mail, change noise into sound.


  #76   Report Post  
Old January 13th 19, 12:50 PM posted to uk.d-i-y
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Default how hot do you run you CH boiler

On Sunday, 13 January 2019 10:34:57 UTC, Harry Bloomfield wrote:
tabbypurr wrote :


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?


It is a Vaillant 418 ECOfit Pure. It only has one input for call for
heat, a permanent supply, plus an output for the pump. It also only has
a single temperature setting, which I presently have set for max (75C).
From cold, the boiler runs flat out until its output nears 75C, then it
begins to modulate its heat output gradually down.

We like the HW hot, so have it set at 75C for HW. The HW is set to come
on for an hour per day, to bring the tank up to temperature, though
when more HW is needed like when taking a bath, we press a 1 hour
override button.

75C is unnecessary for the CH and not as economic as 60C would be, so I
am looking for a workaround to allow for split HW v CH boiler
temperatures.

My first attempt at a split was a disaster...

I added an adjustable thermostat to the CH pipe, just past the 3 port
valve, wired to interrupt the CH call for heat wire when the pipe got
to 60C. Which it did perfectly, but that caused the boiler to cycle
frequently on and off, as the pipe temperature rapidly cooled and
reheated. It also defeated the boiler's ramping down (modulating) its
output.

Another way I had thought of, was to fool the boilers own output
temperature sensor, so when the call is for CH, it sees a false higher
than actual temperature. I could probably manage that, with an extra
call for CH wire back to the boiler (easy), a simple relay and a bit of
jiggery pockery in the boiler sensor circuit. As it is a brand new
boiler, I am reluctant to start modifying it and risk the guarantee.


So if you'd bought a used 418 ecotec you'd have just what you need.
There is one option that may work in some cases: reduce the maximum power output the boiler is allowed to deliver. Then you get efficiency from modulation & cycling with pump overrun becomes acceptable.


NT
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Old January 13th 19, 03:00 PM posted to uk.d-i-y
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Default how hot do you run you CH boiler

On 13/01/2019 10:58, [email protected] wrote:
On 12/01/2019 22:19, John Rumm wrote:

I have though, my eye on a 470 complete with the outdoor sensor.


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


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


Yup the VR470 has been superseded as well. A VRT350 looks like a
replacement if you don't need the weather compensation. The VR65 looks
like a possible replacements for the 61.




--
Cheers,

John.

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| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/
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Old January 13th 19, 03:51 PM posted to uk.d-i-y
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Default how hot do you run you CH boiler



Look at the Honeywell Evohome system
http://www.heatingcontrols.honeywell.../evohome-Main/


The site exists, but not with the www.



--
Graham.

%Profound_observation%
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Old January 13th 19, 03:53 PM posted to uk.d-i-y
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Default how hot do you run you CH boiler

On 13/01/2019 15:00, John Rumm wrote:
On 13/01/2019 10:58, [email protected] wrote:
On 12/01/2019 22:19, John Rumm wrote:

I have though, my eye on a 470 complete with the outdoor sensor.

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


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


Yup the VR470 has been superseded as well. A VRT350 looks like a
replacement if you don't need the weather compensation. The VR65 looks
like a possible replacements for the 61.




none of it did what I wanted..
just two boiler ons with individual temperature control.

I have seven dual port valves and I want them controlled by timer stats.

I took the easy route and wire or'd the end switches and no additional
panel for the boiler.
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Old January 13th 19, 05:17 PM posted to uk.d-i-y
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Default how hot do you run you CH boiler

On 12/01/2019 13:54, Max Demian wrote:
On 12/01/2019 10:19, RJH wrote:
On 11/01/2019 23:33, Max Demian wrote:
On 11/01/2019 18:52, tim... wrote:
I had a new Combi fitted today (in the to-be-moved-to house).

Fitters told me that I should run this at 74 degrees.

Which I thought far too high, as

1) it makes the radiators too hot to touch
2) basic thermodynamics suggest that a better temperature profile
will result from having the radiators at the lower temperate for
longer period than a higher temperature for a shorter period

I tried to explain this but was met with

"The recommended temperature is required for the condenser to have
any effect"

The instruction manual for my Ideal says that the 'e' setting is best
for condensing, which is quite hot. I don't understand this as I
would have thought that the cooler the returning water temperature
the more condensing.


Just found the manual for my Ideal Logic:

"The Logic + Combi is a high efficiency combination boiler which is
most efficient when operating in condensing mode.

The boiler will operate in this mode if the CH temperature control (C)
is set to the ‘e’ position (economy mode) or below. This control
should be set to a maximum for very cold periods".


I downloaded the manual and it omits the critical "or below".


How odd. I've sent you my version of the manual - 2010 I think.

--
Cheers, Rob


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