RE: Anyone heard of Keith Harrison Electrical ?

["Mike Griffiths" <mike@xxxxxxxxxxxx>]

I don't think you will need to control the other thermostats Gareth
The mass of the floor is really the key and you are better off just
turning the heating on when and how you want it via a schedule within
cbus or comfort
I wasted a lot of time on my system playing with thermostats connected
to the under floor heating I' m afraid it just doesn't work

I now use the thermostats for other things

Remember you cant just turn on or off under floor heating
Think of a very large Electric storage heater
YOU DO NEED THE  ONE UNDER THE FLOOR THOUGH!!!!!
That stops the system overheating\

Mike


________________________________

From: ukha_d@xxxxxxx [mailto:ukha_d@xxxxxxx] On Behalf
Of Gareth Cook
Sent: 20 February 2006 14:00
To: ukha_d@xxxxxxx
Subject: Fw: [ukha_d] Anyone heard of Keith Harrison Electrical ?

I think the best solution would be to re-locate the thermostats they
provide all in one place (Node1 - CBUS Consumer Unit area). We can
extend
the floor thermostat easily then into these units, but the next issue is

we have to have our thermostats. This is because we would set the
supplied
thermostats to 40 degrees on continuous, and then switch on via CBUS
relays depending on the value of the replacement thermo sensor plumbed
into Comfort.

As yet, I still haven't found a thermostat that will work with Comfort
properly

As we get closer to the install, if I cant find a sensor that works,
I'll
have to forgoe the HA portion and just install it as most of the rest of

the planet does.

G.

Gareth Cook
Tools and Process Architect
IBM SWG Sales - Lotus Park, Staines, TW18 3AG
Office: +44 (0)1784 445166 - Mobile: +44 (0)7980 445166
AIM Chat : TheBoyG - MSN Chat : chat@xxxxxxx
email: g@xxxxxxx


----- Forwarded by Gareth Cook/UK/IBM on 20/02/2006 13:56 -----

Discussion
Main Topic

ukha_d@xxxxxxx
Today 13:54

.
Subject:
.
RE: [ukha_d] Anyone heard of Keith Harrison Electrical ?
.
Category:



With electric UFH you must use a floor stat to prevent potential damage
to
the floor so yes, there will be one per room. These can then be wired in
series with a room stat or other control device (timeclock, Comfort with
room sensor or stat for example) so HA control should not any more
difficult
than with any other heating system. You could run the system without any
room stat control and simply adjust the heating to the room via the
individual floor stats. As long as you star wire the supplies back to
Node
0
then you can change the zoning and control arrangements as you see fit
at
any time.



The varying of voltage to provide modulated output will give a smoother
response than simple thermostatic switching and can be more energy
efficient. However you can replicate this to some extent by using
time-proportioning control based on the room temp if Comfort allows
simple
logic programming. This method means you vary the on-off cycle depending

on
the load. At full load the system is simply on. As you approach setpoint

you
begin to switch the load off for increasing amounts of time until it is
fully off if you exceed setpoint. A bit of trial and error with the
timing
and scale (how close to setpoint this feature kicks in) will give you a
similar effect to the fully modulated control offered by the flash
system.
As the floor has an amount of thermal inertia it should not need to be
switched very quickly so standard relays should still work well. If the
time
period was very quick then solid state relays would be the better
option.



Where you may have problems is if the supplier/manufacturer of the UFH
system only has one particular floor stat option which combines floor
protection with time control and air temp control in a flashy digital
stat.
In this case you have two options - buy the complete package and bypass
the
control options you don't need. Pros - no warranty issues with the UFH
supplier and no different to their standard installs so they do not need

to
know that it is to be controlled by a separate system, easy to return to
"standard" control if you move and take the HA with you. Cons -
more
expensive. Otherwise why not go back to the supplier and ask if they can
give you the specs for a basic floor stat option that you could source
and
supply instead and then continue as before.



Neil B.



_____

From: ukha_d@xxxxxxx [mailto:ukha_d@xxxxxxx] On Behalf
Of
Gareth Cook
Sent: 20 February 2006 12:12
To: ukha_d@xxxxxxx
Subject: [ukha_d] Anyone heard of Keith Harrison Electrical ?



Been speaking to the Underfloor heating company - and they've mentioned
they pass the one or two HA queries they get over to them...

It apprears the thermostats they sell vary the voltage to the floor, and

have a thermostats that measured floor temperature (underneath the wood)

to ensure the floor doesnt go above 27 degrees. They say there is a
possible module you can add on but not sold in this country.

With this system, you have to have a thermostat PER room - and that
means
no central control. Also, if the voltage is variable, then I cant just
hang it off a CBUS relay.

G.

Gareth Cook
Tools and Process Architect
IBM SWG Sales - Lotus Park, Staines, TW18 3AG
Office: +44 (0)1784 445166 - Mobile: +44 (0)7980 445166
AIM Chat : TheBoyG - MSN Chat : chat@xxxxxxx
email: g@xxxxxxx









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