Any brainy people out there who can help me with this space heating control
problem? None of the manufacturers (Honeywell, Danfoss etc.) seem to be able
to...

I am planning to install underfloor heating (UFH) and radiators in each room
in my house. I want the underfloor heating to keep the rooms warm when the
outside temperature falls below 21°C (the house temperature set point).
However, if the temperature continues to fall, the output of the UFH will be
insufficient to maintain the room temperature at 21°C. The thermal
characteristic of each room is different of course but, generally speaking,
when the outside temperature has fallen to about 12°C, the radiators should
switch on to supplement the underfloor heating.

Is there a way to automatically switch on the room radiators *only when* the
underfloor heating has reached its maximum output capability?

I don't want the radiators to be on when the outside temperature is at or
above 12°C. At 11°C the radiators should come on "a bit", at 10°C they
should output "a bit more" - you get the picture.

(Note: Underfloor heating is slower to respond than radiators. If the
outside temperature falls rapidly from 21°C to 12°C, say, it would be useful
for the radiators to turn on immediately until the UFH cranks up to its
maximum output. Then the radiators could switch off and handover heating to
the UFH.)

Hope that I've explained this OK.

In article , John Aston
wrote:
I want the underfloor heating to keep the rooms warm when the
outside temperature falls below 21°C (the house temperature
set point).

The inside temperature of an occupied but otherwise unheated
building will always be a few degrees above the outside temperature
because of the gains from lighting, cooking, appliances and body
heat. So your assumption above probably needs to be adjusted.

The test as to whether you need the additional radiator heat is
surely whether the inside temp is acceptable or otherwise - though
this of course will depend on the outside temp. If you control your
radiator circuit though a Honeywell CM67 programmable stat with
optimiser the optimiser will estimate whether the programmed
temperature will be reached anyway, and if so will turn off the
rads. One of the other regulars here can probably give a better
explanation of the optimisation algorithm.

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser http://www.sda.co.uk/qsedbuk.htm

Tony Bryer wrote in message
...

The test as to whether you need the additional radiator heat is
surely whether the inside temp is acceptable or otherwise - though
this of course will depend on the outside temp.

Agreed.

The rads could be on and the UFH could be off and the internal temperature
of the house could be acceptable, but I'd rather it was the UFH that was
(mostly) supplying the warmth.

If you control your
radiator circuit though a Honeywell CM67 programmable stat with
optimiser the optimiser will estimate whether the programmed
temperature will be reached anyway, and if so will turn off the
rads. One of the other regulars here can probably give a better
explanation of the optimisation algorithm.


Thanks, I had a quick read about the CM67 at
http://content.honeywell.com/uk/homes/files/pag113.pdf

The CM67 seems to add some outside temperature-dependence to control of the
switch-on time (does it do anything else?) I'm not sure how I can use it to
switch off the rads once the UFH is up to speed.

"John Aston" wrote in message
.. .

Any brainy people out there who can help
me with this space heating control
problem? None of the manufacturers
(Honeywell, Danfoss etc.) seem to be able
to...

I am planning to install underfloor heating
(UFH) and radiators in each room
in my house. I want the underfloor heating
to keep the rooms warm when the
outside temperature falls below 21°C
(the house temperature set point).
However, if the temperature continues
to fall, the output of the UFH will be
insufficient to maintain the room temperature
at 21°C.

Design and install the UFH to operate at -3C outside and have appropriate
controls to modulate the heating system. Abandon the rads

The thermal characteristic of each
room is different of course but, generally speaking,
when the outside temperature has fallen
to about 12°C, the radiators should
switch on to supplement the underfloor heating.

Why?

Is there a way to automatically switch
on the room radiators *only when* the
underfloor heating has reached its
maximum output capability?

I don't want the radiators to be
on when the outside temperature is at or
above 12°C.

Have a thermostat in a weatherproof box on the north wall of the house.
That is the simplest way.

At 11°C the radiators should come
on "a bit", at 10°C they should output
"a bit more" - you get the picture.

Modulate.

(Note: Underfloor heating is slower to
respond than radiators. If the
outside temperature falls rapidly from
21°C to 12°C, say, it would be useful
for the radiators to turn on immediately
until the UFH cranks up to its
maximum output. Then the radiators
could switch off and handover heating to
the UFH.)

Hope that I've explained this OK.

What you are doing is half cocked. Either have full UFH or full rads. A
good modulating condensing boiler with load compensation control will
modulate the rads to suit. So why have expensive UFH when the rads, which
you have anyhow, can do it all.

It is possible to do what you want. A two stage controller will work and
modulate both using modulating 3-way valves. These are commercial products
and are very expensive. A simple way is have an outside stat to hold off
the rads and an inside stat to cut them off when inside setpoint is reached.
The rads will only be used as a boost in an off-on control. This may mean
two stats next to each other on the wall. One for UFH and one for rads. Or
modulating UFH controls and on-off for the assist rads. But why bother!

IMM wrote in message ...

"John Aston" wrote in message
.. .


Design and install the UFH to operate at -3C outside and have appropriate
controls to modulate the heating system. Abandon the rads

Wish I could avoid installing the rads! But my house is old and draughty,
and underfloor heating on its own will not provide sufficient output to keep
it warm on very cold days.

I could install just radiators and forget the UFH, but I prefer the heat
given off by UFH. Just my personal taste, really.

(I am, of course, also trying to draught-proof and insulate the house as
best as I can.)

The thermal characteristic of each
room is different of course but, generally speaking,
when the outside temperature has fallen
to about 12°C, the radiators should
switch on to supplement the underfloor heating.

Why?


See above. On its own, the UFH can only keep the house about 9°C warmer than
the outside (this is a conservative calculation based on the U-values of the
house). I need the rads to boost the heating when the weather gets cold.

snip

What you are doing is half cocked. Either have full UFH or full rads. A
good modulating condensing boiler with load compensation control will
modulate the rads to suit. So why have expensive UFH when the rads, which
you have anyhow, can do it all.

See above.

"John Aston" wrote in message
.. .

IMM wrote in message
...

"John Aston" wrote in message
.. .


Design and install the UFH to operate at -3C outside and have
appropriate
controls to modulate the heating system. Abandon the rads

Wish I could avoid installing the rads! But my house is old and draughty,
and underfloor heating on its own will not provide sufficient output to
keep
it warm on very cold days.

I could install just radiators and forget the UFH, but I prefer the heat
given off by UFH. Just my personal taste, really.

(I am, of course, also trying to draught-proof and insulate the house as
best as I can.)

You have answered your problem. The money your would have spent on a UFH
system spend on heavy insulation, glazing and draft proofing. Have a
modulating condensing boiler on rads. Sorted.

The thermal characteristic of each
room is different of course but, generally speaking,
when the outside temperature has fallen
to about 12°C, the radiators should
switch on to supplement the underfloor heating.

Why?


See above. On its own, the UFH can only keep
the house about 9°C warmer than
the outside (this is a conservative calculation
based on the U-values of the
house). I need the rads to boost the heating
when the weather gets cold.

Does the house have wood or solid floors?

In an earlier contribution to this discussion,
John Aston wrote:

Any brainy people out there who can help me with this space heating
control problem? None of the manufacturers (Honeywell, Danfoss etc.)
seem to be able to...

I am planning to install underfloor heating (UFH) and radiators in
each room in my house. I want the underfloor heating to keep the
rooms warm when the outside temperature falls below 21°C (the house
temperature set point). However, if the temperature continues to
fall, the output of the UFH will be insufficient to maintain the room
temperature at 21°C. The thermal characteristic of each room is
different of course but, generally speaking, when the outside
temperature has fallen to about 12°C, the radiators should switch on
to supplement the underfloor heating.

Is there a way to automatically switch on the room radiators *only
when* the underfloor heating has reached its maximum output
capability?

I don't want the radiators to be on when the outside temperature is
at or above 12°C. At 11°C the radiators should come on "a bit", at
10°C they should output "a bit more" - you get the picture.

(Note: Underfloor heating is slower to respond than radiators. If the
outside temperature falls rapidly from 21°C to 12°C, say, it would be
useful for the radiators to turn on immediately until the UFH cranks
up to its maximum output. Then the radiators could switch off and
handover heating to the UFH.)

Hope that I've explained this OK.

You'll presumably have 2 zones - on for the UFH and one for the rads. Have a
separate room stat for each zone (2 x CM67's would be fine) but set the stat
controlling the UFH slightly higher than the one controlling the rads. Then,
if the UFH is able to maintain the temperature on its own, the rads won't
come on. If you want to take outside temperature into account, have an
outside stat and wire it in series with room stat controlling the rads.
Then, the rads won't come on regardless of the inside temperature if the
outside is above (say) 12 degrees. [You could use a CM67 for this too -
mounted *inside*, but using a remote temperature sensor which is outside. If
you muck about with its setup parameters, you can achieve a degree of
proportionality between (say) 10 and 12 degrees.]
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

In article , Set Square wrote:
[You could use a CM67 for this too - mounted *inside*, but using
a remote temperature sensor which is outside.

I stand to be corrected but thought that the only thing the CM67's
external sensor did was to give you the facility to check the
outside temperature from inside. I wasn't aware that it also acted
as a weather compensator.

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser
http://www.sda.co.uk/qsedbuk.htm

On Wed, 03 Nov 2004 18:23:34 GMT, Tony Bryer
wrote:

In article , Set Square wrote:
[You could use a CM67 for this too - mounted *inside*, but using
a remote temperature sensor which is outside.

I stand to be corrected but thought that the only thing the CM67's
external sensor did was to give you the facility to check the
outside temperature from inside. I wasn't aware that it also acted
as a weather compensator.


That is what it does - outside display, not control from the sensor.





--

..andy

To email, substitute .nospam with .gl

"Tony Bryer" wrote in message
...
In article , Set Square wrote:
[You could use a CM67 for this too - mounted *inside*, but using
a remote temperature sensor which is outside.

I stand to be corrected but thought that the only thing the CM67's
external sensor did was to give you the facility to check the
outside temperature from inside. I wasn't aware that it also acted
as a weather compensator.

I don't, to my knowledge.

In an earlier contribution to this discussion,
Tony Bryer wrote:

In article , Set Square wrote:
[You could use a CM67 for this too - mounted *inside*, but using
a remote temperature sensor which is outside.

I stand to be corrected but thought that the only thing the CM67's
external sensor did was to give you the facility to check the
outside temperature from inside. I wasn't aware that it also acted
as a weather compensator.

The CM67 allows you to connect an outside sensor (not sure what this does!)
and/or a *remote* sensor - which allows you to "control" the temperature at
a different location from that of the stat body itself. What I am suggesting
is to use a remote sensor, but to mount it *outside*. The stat then thinks
that's it controlling the outside temperature (which of course it isn't!)
but it's connected in series with another inside room stat, and serves to
stop the rads coming on when it's warm outside. Once they *do* come on -
because it's cold outside, they're actually controlled by the inside room
stat. [This solution requires three stats in all - 2 for the rads and one
for the UFH!]
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

On Wed, 3 Nov 2004 19:04:39 -0000, "Set Square"
wrote:

In an earlier contribution to this discussion,
Tony Bryer wrote:

In article , Set Square wrote:
[You could use a CM67 for this too - mounted *inside*, but using
a remote temperature sensor which is outside.

I stand to be corrected but thought that the only thing the CM67's
external sensor did was to give you the facility to check the
outside temperature from inside. I wasn't aware that it also acted
as a weather compensator.

The CM67 allows you to connect an outside sensor (not sure what this does!)
and/or a *remote* sensor - which allows you to "control" the temperature at
a different location from that of the stat body itself. What I am suggesting
is to use a remote sensor, but to mount it *outside*. The stat then thinks
that's it controlling the outside temperature (which of course it isn't!)
but it's connected in series with another inside room stat, and serves to
stop the rads coming on when it's warm outside. Once they *do* come on -
because it's cold outside, they're actually controlled by the inside room
stat. [This solution requires three stats in all - 2 for the rads and one
for the UFH!]


Sorry, you're right. In the older version of the product, you
couldn't do this (I used to have one), but the new one has a choice
for how the connected sensor is used. However, it does appear that
the choice is one function or the other from the menu settings - not
that it matters here......



--

..andy

To email, substitute .nospam with .gl

In an earlier contribution to this discussion,
Andy Hall wrote:

On Wed, 3 Nov 2004 19:04:39 -0000, "Set Square"
wrote:

In an earlier contribution to this discussion,
Tony Bryer wrote:

In article , Set Square wrote:
[You could use a CM67 for this too - mounted *inside*, but using
a remote temperature sensor which is outside.

I stand to be corrected but thought that the only thing the CM67's
external sensor did was to give you the facility to check the
outside temperature from inside. I wasn't aware that it also acted
as a weather compensator.

The CM67 allows you to connect an outside sensor (not sure what this
does!) and/or a *remote* sensor - which allows you to "control" the
temperature at a different location from that of the stat body
itself. What I am suggesting is to use a remote sensor, but to mount
it *outside*. The stat then thinks that's it controlling the outside
temperature (which of course it isn't!) but it's connected in series
with another inside room stat, and serves to stop the rads coming on
when it's warm outside. Once they *do* come on - because it's cold
outside, they're actually controlled by the inside room stat. [This
solution requires three stats in all - 2 for the rads and one for
the UFH!]


Sorry, you're right. In the older version of the product, you
couldn't do this (I used to have one), but the new one has a choice
for how the connected sensor is used. However, it does appear that
the choice is one function or the other from the menu settings - not
that it matters here......

Yes, you're right - it is one or the other but not both. I couldn't quite
remember when I wrote it, but have since looked it up. As you say, it
doesn't matter in this case - a remote sensor mounted outside is all you
need. A somewhat unorthodox use for a CM67 though!
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

"Andy Hall" wrote in message
...
On Wed, 3 Nov 2004 19:04:39 -0000, "Set Square"
wrote:

In an earlier contribution to this discussion,
Tony Bryer wrote:

In article , Set Square wrote:
[You could use a CM67 for this too - mounted *inside*, but using
a remote temperature sensor which is outside.

I stand to be corrected but thought that the only thing the CM67's
external sensor did was to give you the facility to check the
outside temperature from inside. I wasn't aware that it also acted
as a weather compensator.

The CM67 allows you to connect an outside sensor (not sure what this
does!)
and/or a *remote* sensor - which allows you to "control" the temperature
at
a different location from that of the stat body itself. What I am
suggesting
is to use a remote sensor, but to mount it *outside*. The stat then
thinks
that's it controlling the outside temperature (which of course it isn't!)
but it's connected in series with another inside room stat, and serves to
stop the rads coming on when it's warm outside. Once they *do* come on -
because it's cold outside, they're actually controlled by the inside room
stat. [This solution requires three stats in all - 2 for the rads and one
for the UFH!]


Sorry, you're right. In the older version of the product, you
couldn't do this (I used to have one), but the new one has a choice
for how the connected sensor is used. However, it does appear that
the choice is one function or the other from the menu settings - not
that it matters here......


Isn't the problem, though, that the radiators have a faster response than
the UFH. Assuming it's cold enough outside for the radiators to be on, they
will raise the room temperature relatively quickly. The UFH will see that
the room temperature is rising and throttle back on its output. The eventual
"steady state" position will be determined by how quickly the radiators and
UFH respond to the demand for heating.

What about using a boiler with a modulated output flow temperature (a cooler
flow temperature when it's warmer outside)? The radiators would have no
thermostatic valves but would simply have a flow temperature defined by the
external temperature, acting as a boost to the UFH. The UFH would be
controlled by the room thermostat.

The max primary flow temperature could fall off linearly from 70 deg to 50
deg, say, as the outside temperature increases from 0 to 10 deg C. (A
drawback of this would be that the domestic hot water cylinder would take
longer to heat, I guess, but then that must be true of any boiler with a
modulating heat output.)

"Set Square" wrote in message
...
In an earlier contribution to this discussion,
John Aston wrote:

Any brainy people out there who can help me with this space heating
control problem? None of the manufacturers (Honeywell, Danfoss etc.)
seem to be able to...

I am planning to install underfloor heating (UFH) and radiators in
each room in my house. I want the underfloor heating to keep the
rooms warm when the outside temperature falls below 21°C (the house
temperature set point). However, if the temperature continues to
fall, the output of the UFH will be insufficient to maintain the room
temperature at 21°C. The thermal characteristic of each room is
different of course but, generally speaking, when the outside
temperature has fallen to about 12°C, the radiators should switch on
to supplement the underfloor heating.

Is there a way to automatically switch on the room radiators *only
when* the underfloor heating has reached its maximum output
capability?

I don't want the radiators to be on when the outside temperature is
at or above 12°C. At 11°C the radiators should come on "a bit", at
10°C they should output "a bit more" - you get the picture.

(Note: Underfloor heating is slower to respond than radiators. If the
outside temperature falls rapidly from 21°C to 12°C, say, it would be
useful for the radiators to turn on immediately until the UFH cranks
up to its maximum output. Then the radiators could switch off and
handover heating to the UFH.)

Hope that I've explained this OK.

You'll presumably have 2 zones - on for the UFH
and one for the rads.

No. Two heating stages.

Have a separate room stat for each
zone (2 x CM67's would be fine) but set the stat
controlling the UFH slightly higher than the one controlling the rads.
Then,
if the UFH is able to maintain the temperature on its own, the rads won't
come on. If you want to take outside temperature into account, have an
outside stat and wire it in series with room stat controlling the rads.
Then, the rads won't come on regardless of the inside temperature if the
outside is above (say) 12 degrees. [You could use a CM67 for this too -
mounted *inside*, but using a remote temperature sensor which is outside.
If
you muck about with its setup parameters, you can achieve a degree of
proportionality between (say) 10 and 12 degrees.]
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

"Set Square" wrote in message
...
In an earlier contribution to this discussion,
John Aston wrote:

Any brainy people out there who can help me with this space heating
control problem? None of the manufacturers (Honeywell, Danfoss etc.)
seem to be able to...

I am planning to install underfloor heating (UFH) and radiators in
each room in my house. I want the underfloor heating to keep the
rooms warm when the outside temperature falls below 21°C (the house
temperature set point). However, if the temperature continues to
fall, the output of the UFH will be insufficient to maintain the room
temperature at 21°C. The thermal characteristic of each room is
different of course but, generally speaking, when the outside
temperature has fallen to about 12°C, the radiators should switch on
to supplement the underfloor heating.

Is there a way to automatically switch on the room radiators *only
when* the underfloor heating has reached its maximum output
capability?

I don't want the radiators to be on when the outside temperature is
at or above 12°C. At 11°C the radiators should come on "a bit", at
10°C they should output "a bit more" - you get the picture.

(Note: Underfloor heating is slower to respond than radiators. If the
outside temperature falls rapidly from 21°C to 12°C, say, it would be
useful for the radiators to turn on immediately until the UFH cranks
up to its maximum output. Then the radiators could switch off and
handover heating to the UFH.)

Hope that I've explained this OK.

You'll presumably have 2 zones - on for the UFH and one for the rads. Have
a
separate room stat for each zone (2 x CM67's would be fine) but set the
stat
controlling the UFH slightly higher than the one controlling the rads.
Then,
if the UFH is able to maintain the temperature on its own, the rads won't
come on. If you want to take outside temperature into account, have an
outside stat and wire it in series with room stat controlling the rads.
Then, the rads won't come on regardless of the inside temperature if the
outside is above (say) 12 degrees. [You could use a CM67 for this too -
mounted *inside*, but using a remote temperature sensor which is outside.
If
you muck about with its setup parameters, you can achieve a degree of
proportionality between (say) 10 and 12 degrees.]

What an expensive way to do something so simple.

"John Aston" wrote in message ...

I am planning to install underfloor heating (UFH) and radiators in each room
in my house.

It could be done, quite easily (but expensively), with a BMS (building
management system) outstation. These are like small computer devices,
without a screen or keyboard; they are used solely to monitor and
control building services. Have a look at the Trend website, for
example. However, they're only marketed for commercial buildings and
the entry level costs (for an outstation, programming, a PC supervisor
and the necessary software) is likely to be in 4 figures. If that
hasn't put you off, any of the Trend suppliers, TTCs, would be happy
to quote you. There are many other BMS manufacturers.

Varying the heat output according to the outside air temperature
(weather compensated/ outdoor reset) is a common control strategy. If
this is a existing building in which the heat output from UFH would be
inadequate to cope with the heat losses, it may be better to have the
perimeter radiators running continuously, to counteract cold
convection currents produced by the glazing. You will have two
separate heating systems in one room, which isn't ideal, but it
shouldn't be a major problem.

I believe the domestic systems, e.g., Honeywell Hometronic, are less
flexible, and primitive in comparison with BMS; I've had no dealings
with them, so can't comment. The necessary programming is kept to a
minimum because many domestic installers won't need to be be familiar
with the BMS type control strategies.

"Aidan" wrote in message
om...
"John Aston" wrote in message
...

I am planning to install underfloor heating (UFH) and radiators in each
room
in my house.

It could be done, quite easily (but expensively),
with a BMS (building management system)
outstation.

The simplest and best is to have a two stage modulating controller. Each
stage modulates a 3-way mixing valve, one for UFH and one for the rads. One
internal sensor would do it to maintain a setpoint. No need for anything
outside. A commercial setup so expensive, but better than a BMS system, and
cheaper.

Varying the heat output according to the outside air temperature
(weather compensated/ outdoor reset) is a common control strategy. If
this is a existing building in which the heat output from UFH would be
inadequate to cope with the heat losses, it may be better to have the
perimeter radiators running continuously, to counteract cold
convection currents produced by the glazing.

The UFH should do this as the whole floor is a heater. He could have rad
[perimeter rads on a weather compensator to give background heat and the UFH
topping up. The response would be sluggish as the UFH would be slow in
raising the temperature. Best have the UFH as background and quick to
respond rads to top up.

So, that would be a UFH setup on a weather compensator modulating a valve.
When the valve is fully open indicating it is on full, it activates a
microswitch to turn on the rads which operate on their own stat. The rads
then take the room up to say 22C when the setpoint is reached the rads off,
but the UFH is on which you don't want. A weather compensator which has
room influence, set to 22C, would then have modulated down, maybe to off,
the UFH, until the room is below setpoint then it comes on. This way the
UFH may take control and only bring in the rads for boost.

That would "probably" be the cheapest option.

"IMM" wrote in message
...

snip

Best have the UFH as background and quick to
respond rads to top up.


Yes, that's what I want.

So, that would be a UFH setup on a weather compensator modulating a valve.
When the valve is fully open indicating it is on full, it activates a
microswitch to turn on the rads which operate on their own stat. The rads
then take the room up to say 22C when the setpoint is reached the rads
off,
but the UFH is on which you don't want. A weather compensator which has
room influence, set to 22C, would then have modulated down, maybe to off,
the UFH, until the room is below setpoint then it comes on. This way the
UFH may take control and only bring in the rads for boost.


I don't quite understand this. Is the UFH flow temperature a function of the
internal temperature and the external temperature, or just the external
temperature only?

Please could you explain what a weather compensator with room influence is?

Thanks.

John Aston wrote:

"IMM" wrote in message
...

snip

Best have the UFH as background and quick to
respond rads to top up.



Yes, that's what I want.


So, that would be a UFH setup on a weather compensator modulating a valve.
When the valve is fully open indicating it is on full, it activates a
microswitch to turn on the rads which operate on their own stat. The rads
then take the room up to say 22C when the setpoint is reached the rads

off,

but the UFH is on which you don't want. A weather compensator which has
room influence, set to 22C, would then have modulated down, maybe to off,
the UFH, until the room is below setpoint then it comes on. This way the
UFH may take control and only bring in the rads for boost.



I don't quite understand this. Is the UFH flow temperature a function of the
internal temperature and the external temperature, or just the external
temperature only?

Please could you explain what a weather compensator with room influence is?

Don't go there. IMM's command of the English language is less even than
his comprehension of heating issues.


Thanks.

"The Natural Philosopher" wrote in message
...
John Aston wrote:

"IMM" wrote in message
...

snip

Best have the UFH as background and quick to
respond rads to top up.



Yes, that's what I want.


So, that would be a UFH setup on a weather compensator modulating a
valve.
When the valve is fully open indicating it is on full, it activates a
microswitch to turn on the rads which operate on their own stat. The
rads
then take the room up to say 22C when the setpoint is reached the rads

off,

but the UFH is on which you don't want. A weather compensator which has
room influence, set to 22C, would then have modulated down, maybe to
off,
the UFH, until the room is below setpoint then it comes on. This way
the
UFH may take control and only bring in the rads for boost.



I don't quite understand this. Is the UFH flow temperature a function of
the
internal temperature and the external temperature, or just the external
temperature only?

Please could you explain what a weather compensator with room influence
is?

Don't go there. IMM's command of the English language is less even than
his comprehension of heating issues.

If you have something useful to add please do, otherwise keep quiet. This
man is after a cost effective solution and all you do is act the goat.

"IMM" wrote in message
...

snip

Best have the UFH as background and quick to
respond rads to top up.


Yes, that's what I want.

So, that would be a UFH setup on a weather compensator modulating a valve.
When the valve is fully open indicating it is on full, it activates a
microswitch to turn on the rads which operate on their own stat. The rads
then take the room up to say 22C when the setpoint is reached the rads
off,
but the UFH is on which you don't want. A weather compensator which has
room influence, set to 22C, would then have modulated down, maybe to off,
the UFH, until the room is below setpoint then it comes on. This way the
UFH may take control and only bring in the rads for boost.


I don't quite understand this. Is the UFH flow temperature a function of the
internal temperature and the external temperature, or just the external
temperature only?

Please could you explain what a weather compensator with room influence is?

Thanks.

"Aidan" wrote in message
om...
"John Aston" wrote in message
...

I am planning to install underfloor heating (UFH) and radiators in each
room
in my house.

It could be done, quite easily (but expensively), with a BMS (building
management system) outstation.(snipped).

This reads like SPAM to me.
Tom

"Tom" wrote in message ...

This reads like SPAM to me.
Tom

No spam, Tom. I'm just telling the OP what I've learnt through years
of dealing with commercial Trend controlled plant. BMS is great stuff
& can control almost anything. I lament the fact that it's price makes
it, or anything comparable, inaccessible for all domestic users except
the very affluent. And BMS technicians.

The only other solution AFAIK, other than the domestic heating control
systems suggested by others, is through commercial PLC controllers. I
know zilch about PLCs.

PS. The plumber would have supported your cylinder on a platform to
increase the pressure differential (& the flow rate) generated by
gravity circulation from the boiler. There probably used to be a
gravity circulation system; it would make no appreciable difference
with a fully pumped system.

IMM also wrote:

"The simplest and best is to have a two stage modulating controller."

Who makes such a controller and which model is it?

If you're suggesting discreet controllers (i.e., 1
analogue/thermistor input & 1 analogue/0-10V output per controller)
these are, in my experience, a waste of space compared to a BMS
outstation (multiple analogue or digital inputs and outputs configured
by the software).


"When the valve is fully open indicating it is on full, it activates a
microswitch to turn on the rads which operate on their own stat."


The OP has stated elsewhere, UFH in a solid floor has a huge thermal
inertia.
If the room temperature falls, causing the demand to increase to 100%,
it could be an hour or more before the UFH is actually emitting 100%
of it's output. In the time it takes to turn on the radiators, the
room temperature could have increased (e.g., dawn). Once the setpoint
is reached and the UFH output reduces, the UFH will be emitting excess
heat for another hour, despite the space temperature having exceeded
the setpoint. The heating output will lag behind the room temperature.
The OP seems to have a good grasp of the problem.


In comparison, weather compensation will react to outdoor air
temperature and increase the UFH output. It will take some time for
the low outside air temperature to affect the indoor temperature and
it will also take some time for the UFH output to respond to the
increase demand. Weather compensation ain't perfect (e.g. it takes no
account of solar gains or wind cooling) but it's pretty good.
Ii'sprobably good for this application.

In the first few lines you had said;
"One internal sensor would do it to maintain a setpoint. No need for
anything outside."

Later on you say: "So, that would be a UFH setup on a weather
compensator (i.e., outdoor air temperature sensor) modulating a
valve."

You've got me mystified, International Man of Mystery.

"Aidan" wrote in message
om...
"Tom" wrote in message
...

This reads like SPAM to me.
Tom

No spam, Tom. I'm just telling the OP what I've learnt through years
of dealing with commercial Trend controlled plant. BMS is great stuff
& can control almost anything. I lament the fact that it's price makes
it, or anything comparable, inaccessible for all domestic users except
the very affluent. And BMS technicians.

The only other solution AFAIK, other than the domestic heating control
systems suggested by others, is through commercial PLC controllers. I
know zilch about PLCs.

They are unsuitable for this application.

PS. The plumber would have supported your cylinder on a platform to
increase the pressure differential (& the flow rate) generated by
gravity circulation from the boiler. There probably used to be a
gravity circulation system; it would make no appreciable difference
with a fully pumped system.

IMM also wrote:

"The simplest and best is to have a two stage modulating controller."

Who makes such a controller and which model is it?

If you're suggesting discreet controllers (i.e., 1
analogue/thermistor input & 1 analogue/0-10V output per controller)
these are, in my experience, a waste of space compared to a BMS
outstation (multiple analogue or digital inputs and outputs configured
by the software).


"When the valve is fully open indicating it is on full, it activates a
microswitch to turn on the rads which operate on their own stat."


The OP has stated elsewhere, UFH in a solid floor has a huge thermal
inertia.
If the room temperature falls, causing the demand to increase to 100%,
it could be an hour or more before the UFH is actually emitting 100%
of it's output. In the time it takes to turn on the radiators, the
room temperature could have increased (e.g., dawn). Once the setpoint
is reached and the UFH output reduces, the UFH will be emitting excess
heat for another hour, despite the space temperature having exceeded
the setpoint. The heating output will lag behind the room temperature.
The OP seems to have a good grasp of the problem.


In comparison, weather compensation will react to outdoor air
temperature and increase the UFH output. It will take some time for
the low outside air temperature to affect the indoor temperature and
it will also take some time for the UFH output to respond to the
increase demand. Weather compensation ain't perfect (e.g. it takes no
account of solar gains or wind cooling) but it's pretty good.
Ii'sprobably good for this application.

In the first few lines you had said;
"One internal sensor would do it to maintain a setpoint. No need for
anything outside."

Later on you say: "So, that would be a UFH setup on a weather
compensator (i.e., outdoor air temperature sensor) modulating a
valve."

You've got me mystified, International Man of Mystery.

"Aidan" wrote in message
om...
"Tom" wrote in message
...

This reads like SPAM to me.
Tom

No spam, Tom. I'm just telling the OP what I've learnt through years
of dealing with commercial Trend controlled plant. BMS is great stuff
& can control almost anything. I lament the fact that it's price makes
it, or anything comparable, inaccessible for all domestic users except
the very affluent. And BMS technicians.

BMS is clearly commercial, although there are some domestic home automation
products that will monitor and switch on CH, not do the controls.

The only other solution AFAIK, other than the domestic heating control
systems suggested by others, is through commercial PLC controllers. I
know zilch about PLCs.

They are unsuitable for this application as better and cheaper solutions are
around.

IMM also wrote:

"The simplest and best is to have a two stage modulating controller."

Who makes such a controller and which model is it?

Landis & Staefa do v good one, I have an old one still in its box in the
garage. Forget the model number. All the large controls people will do
one.

If you're suggesting discreet controllers (i.e., 1
analogue/thermistor input & 1 analogue/0-10V
output per controller)

I am.

these are, in my experience,
a waste of space compared to a BMS
outstation (multiple analogue or digital inputs
and outputs configured by the software).

Simulated proportional feedback controls are "excellent" and do a wonderful
job. BMS system have come a lot way and that they now can control, whereas
the originals were monitoring and simple digital (on-off in BMS terminology)
switching systems. I have experience with Landis & Gyr Visonic and
Honeywell Delta systems. There is no reason why domestic BMS system cannot
be cheaply available. All is needed is an I/O module where the valves,
sensors, relays, etc are connected, and the module to a P/C and the
appropriate software. Simple and easy. Not rocket science. The skill is
setting it up, which the avearge DIYer will have a hard time doing. Getting
a plumber to set one up will be near impossible.

"When the valve is fully open indicating it
is on full, it activates a
microswitch to turn on the rads which
operate on their own stat."

The OP has stated elsewhere, UFH in a
solid floor has a huge thermal
inertia.
If the room temperature falls, causing the
demand to increase to 100%,
it could be an hour or more before the UFH
is actually emitting 100%
of it's output. In the time it takes to turn
on the radiators, the room temperature
could have increased (e.g., dawn).

The UFH valve will open full allowing full heat to the UFH. It will
probably not be enough. If so then the rads come in to boost. When set
point is near it starts to back off and the rads immediately are modulated
down and then to off, with the UFH still full on.

Once the setpoint
is reached and the UFH output reduces,
the UFH will be emitting excess
heat for another hour,

The UFH is will be undersized, that is the point. On mild days only UFH
will be required.

despite the space temperature having exceeded
the setpoint. The heating output will lag behind
the room temperature.

That is UFH for you, but this will be an undersized UFH system. The
instances when the rads come in, the UFH will not be coping.

The OP seems to have a good grasp of the problem.

I'm not sure he has. He needs to see if a UFH system will cope first. If
not abandon the UFH and stick to rads modulated by a good load compensated
condensing boiler.

In comparison, weather compensation
will react to outdoor air
temperature and increase the UFH output.

Compensation is feed forward control, it reduces the cold and hot spots and
prevents temp under and overshoot.

It will take some time for
the low outside air temperature to affect
the indoor temperature and
it will also take some time for the UFH
output to respond to the
increase demand.

That is why weather compensation is "vital" with UFH.

Weather compensation ain't perfect
(e.g. it takes no account of solar gains
or wind cooling) but it's pretty good.
Ii'sprobably good for this application.

You can have room, wind and solar influence with a compensator. Extra
modules and sensors.

In the first few lines you had said;
"One internal sensor would do it to maintain a setpoint. No need for
anything outside."

That is using a two stage controller.

Later on you say: "So, that would be
a UFH setup on a weather
compensator (i.e., outdoor air temperature
sensor) modulating a valve."

Two different solutions. The two stage controller will be expensive as it
is commercial. Cheaper domestic compensators are available.

You've got me mystified, International Man of Mystery.

All clear now?

"IMM" wrote in message ...


Who makes such a controller and which model is it?

Landis & Staefa do v good one, I have an old one still in its box in the
garage. Forget the model number. All the large controls people will do
one.

Translation; 'Such controllers are not currently available.'

I was hoping you could tell me where I'd find these controllers. It
seems not.


There is no reason why domestic BMS system cannot
be cheaply available.

It isn't cheaply available though.

All is needed is an I/O module where the valves, sensors, relays, etc are connected, and the module to a P/C and the appropriate software. Simple and easy. Not rocket science. The skill is setting it up, which the avearge DIYer will have a hard time doing. Getting a plumber to set one up will be near impossible.



Translation;"Domestic BMS is not currently available.

Simple and easy to a man of your many indisputable talents. Completely
beyond us mere mortals and, probably, the OP.


All clear now?

As mud.

"John Aston" wrote in message ...
None of the manufacturers (Honeywell, Danfoss etc.) seem to be able
to...

Also, Try Tekmar.

http://www.tekmarcontrols.com/index.html

I know of them, but have no experience of them. Their controllers seem
to be widely used for UFH. The link is the US site, they have a UK
representative who should be able to advise you. I think you may find
that you need different control values (PID constants ) for the UFH
and the rad systems & this may be beyond the scope of such heating
controllers.