We have been installing a system supplied by Eco hometec. (ec31hs)
Its a mixture of under floor heating and thermostatic valve controlled
The underfloor heating (all one zone) is on the ground floor of a new
well insulated extension whilst the rads are in the older stone built
farmhouse and the top floor of the same extension.
The boiler has a programmer built in but we have been supplied with a
cm67 programmable thermostat. I am a little disappointed with the
information we have been supplied with. Originally the system was to
have radiators only with an outside temp' sensor allowing the boiler to
control the heating.
It seems that including under floor heating means the outside sensor is
not much use.
It seems we are supposed to install the cm67 in the room that is to be
used most in the UFH area. There are no zone valves at all. The manifold
is an 'invisible heating' compact. According to the wiring diagrams it
seems the cm67 should be wired back to the 240v rail on the boiler
Will the cm67 not switch off the boiler once the UFH area is warm
If the older part of the house has a rad with an open TRV how will the
boiler switch on without sending more warm water through the UFH
There is a thermostatic regulating valve on the UFH manifold flow with
a probe to measure the water temperature in the manifold.
I have one of this range of MAN boilers although not this specific
You should be able to use the outside sensor *and* the programmer.
If you use what is basically a "standard" thermostat like this - in
the sense that it is an on/off control then there are terminals to
deal with that.
It depends on how you connect up and the function number that you set.
MAN also supply a modulating room thermostat/controller the RE2132
which is actually made by Siemens. This one, together with the
boiler controller does all that the CM67 does and more and without
having to turn the boiler on and off. You can adjust the relative
sensitivity to the inside and outside temperature measurements and the
ratio between the two. Eco Hometec can supply these as well.
There is a better translation of the manual with more information from
the other MAN distributor, MHS boilers.
These are for the higher power versions of the boiler but a lot of the
information is the same.
There are two versions (possibly more) of the boiler controller - one
has DIP switches and is described in the links above to set the
function number, the other has the setting on the panel menu in the
installer section. It looks like MHS have removed the PDF of the
non-DIP switch version, so if that is what you have, send me a mail
and I'll forward you a copy. It does give a better explanation for
You should be able to achieve zoning as well by the use of motorised
I too wondered what the problem was with using the proportional
(modulating) control, either outside or inside, but I think it's the use of the
thermostatic blending valve to lower the u/f heating temperature. To me it
looks like the blending valve will reduce the u/f flow temp to a constant 40
or 50, or whatever the required setting is, which will override the modulating
action on the boiler.
In a rad system it will mod down from 80 or 70 to 50 or 40 so you can get
proportional control over the boiler & rad heat output. I think this action is
clipped if you use a (flow) thermostatic blender, which of course you must
do to protect the installation.
So, I think I understand the problem, just can't think of the solution yet.
I am not sure that that is completely true, although I see what you
are saying. The boiler is using outside temperature sensing and
indoor temperature sensor if available. More directly it senses the
flow and return temperatures of the water. The controller controls
the fan (and burn rate) and also modulates the pump to between 30 and
THe effect of the blending valve, as seen by the boiler is to affect
the heat load (expressed as flow rate and temperature drop. In that
sense it is not a lot different to a set of radiators.
It will be influenced but not prevented, because in effect the blender
is an attempt to match the temperature requirements of the UFH to what
the boiler might want to do at the top end.
If several circuits are combined in parallel - e.g. the UFH and the
TRV controlled radiators, the boiler will see a mix of heating loads
and respond to the total. In a zoned system, one may have to
balance one load against another anyway.
For example, I have my house zones as normal TRV controlled radiators
(at present) and then a separate circuit to heat my workshop. The
two circuits are connected using a stainless steel plate heat
exchanger. The primary side of the heat exchanger is connected as
though it is another heating zone. The flow resistance through this
is probably lower than the heating zones and I have fitted a balancing
valve to reduce the flow if needed.
In fact if I monitor the boiler behaviour using the PC software, I can
get graphs of temperatures, pump level and fan speed (burn rate).
The workshop circuit has its own thermostat/controller driving a
separate pump. A flow switch next to the heat exchanger senses the
flow and opens a zone valve on the primary side.
If the workshop circuit is cold, I notice a brief temperature drop at
the boiler return and it modulates up the burn rate and the pump a
little to compensate that.
Hence I think that for this kind of purpose, the exercise can be
looked at in total load terms.
I read on their web site that there is a two temperature model boiler,
so UFH can be at one temperature and radiators at another. I read it
that it was all done inside the boiler and pipes are just connected to
it? This sounds very handy. How does this work?
Something to do with the low temperature of the UFH apparently.
Something specific to IH's manifold?
Again it seems that choosing UFH in addition to the rads scuppers its
Very handy Thank you.
This boiler does not have DIP switches :(
I spoke with IH and ECO today and they have suggested using CM67's
linked to a honeywell 2 port valve to control the rads and the UFH.
This makes sense to me but it looks as though we will lose some of the
The UFH zone valve will be controlled for temperature and time by the
CM67, the manifold pump and boiler will be switched on via the grey and
orange wires of the zone valve (I think!)
The rads will have a separate cm67 to provide a different time programme
which will open and close a 2 port valve which will allow the TRV's to
control the room temperatures. (The cm67 will be set for a temperature
of 30 degrees.)
The boiler will have no on-off time programmed in.
Does this make sense?
Will the radiator circuit need another system pump?
Please excuse the questions but we'd like to get it right....
I don't see why. As a minimum you should be able to arrive at having
the outside temperature sensor as one of the terms in setting the
output level of the boiler even if you are switching the heat demand
on and off from another source.
I don't think that you can use the RE2132 controller at the same time
as another room thermostat, but you could have it as the controller in
one of the areas if you like.
However, even without that, the boiler will giave an appropriate
modulated power level when you have a set of simple switched zones
OK, that's like mine. If you would like to send me an email, I will
send you a PDF of MHS's manual for that. It explains the function
numbers quite well.
It will still modulate very well to match the total load.
I don't see why it should, unless I have missed something
I do have an external sensor and the cable for it is installed in the
building fabric; I'll connect it up.
Thanks for the input; I feel as if I've had to work quite hard at
getting the detail out of Ecohometec and I'm not exactly happy about
As usual I've had more sense in here!
Have you had your boiler long? How is your experience of it?
I didn't have quite the complexity of different systems that you have
(although my workshop arrangement which is certainly different
thermally to the rest of the system); but what I did was to produce a
set of questions and sent it to them before buying. Only when the
answers were satisfactory did they get the order.
I found it necessary to play with the various adjustments for the
control slope to provide a good match between that and the thermal
behaviour of the house. I did this a little over a few weeks. It
would be pretty difficult to work it out ahead of time.
Since spring 2002 and it has performed really well. Gas savings
compared with the previous 65% efficient boiler have been the
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