How much power does my thermostat use?
 

Hi,

As winter seems to be arriving, I'm finally going to install my
Honeywell CMT927 (wireless programmable thermostat) this weekend. I'm
an incorrigible miser when it comes to electricity (delighted now that
carbon footprints are all the rage, I can hop on that bandwaggon, but
my stinginess has nothing as noble as environmental concern behind
it). Anyway, I was going to just take the power feed from the same FCU
as the boiler. But it has occurred to my parsimonious mind that it's
pretty wasteful having the thermostat running for six months of the
year when it's not doing anything. So I'm inclined to give it its own
FCU so I can turn it off next spring, but does anyone have any idea
how much power these things actually use? The documentation that came
with it doesn't say, and I can't even find the thing on Honeywell's
website.

Cheers!

Martin

How much power does my thermostat use?
 

"Martin Pentreath" wrote in message
ps.com...
Hi,

As winter seems to be arriving, I'm finally going to install my
Honeywell CMT927 (wireless programmable thermostat) this weekend. I'm
an incorrigible miser when it comes to electricity (delighted now that
carbon footprints are all the rage, I can hop on that bandwaggon, but
my stinginess has nothing as noble as environmental concern behind
it). Anyway, I was going to just take the power feed from the same FCU
as the boiler. But it has occurred to my parsimonious mind that it's
pretty wasteful having the thermostat running for six months of the
year when it's not doing anything. So I'm inclined to give it its own
FCU so I can turn it off next spring, but does anyone have any idea
how much power these things actually use? The documentation that came
with it doesn't say, and I can't even find the thing on Honeywell's
website.

Cheers!

Martin


Get a life - there are more important things to worry about - like people
buying stupid outside Xmas lights from China every year so they can enjoy
Xmas.

I guess the answer is 'negligible'

How much power does my thermostat use?
 

Martin Pentreath wrote:
Hi,

As winter seems to be arriving, I'm finally going to install my
Honeywell CMT927 (wireless programmable thermostat) this weekend. I'm
an incorrigible miser when it comes to electricity (delighted now that
carbon footprints are all the rage, I can hop on that bandwaggon, but
my stinginess has nothing as noble as environmental concern behind
it). Anyway, I was going to just take the power feed from the same FCU
as the boiler. But it has occurred to my parsimonious mind that it's
pretty wasteful having the thermostat running for six months of the
year when it's not doing anything. So I'm inclined to give it its own
FCU so I can turn it off next spring, but does anyone have any idea
how much power these things actually use? The documentation that came
with it doesn't say, and I can't even find the thing on Honeywell's
website.

Cheers!

Martin


http://europe.hbc.honeywell.com/prod...6uk07r1006.pdf

Back of a fag packet calcs suggest about £1.50 in electricity for the
closed season, so an FCU would pay for itself in about 3 years.

Well worth it, no?

How much power does my thermostat use?
 

Martin Pentreath wrote:

as the boiler. But it has occurred to my parsimonious mind that it's
pretty wasteful having the thermostat running for six months of the
year when it's not doing anything. So I'm inclined to give it its own
FCU so I can turn it off next spring, but does anyone have any idea
how much power these things actually use? The documentation that came
with it doesn't say, and I can't even find the thing on Honeywell's
website.

Strap it to your hot water cylinder so all that energy is not wasted in
the summer.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

How much power does my thermostat use?
 

Hi Rumble,

http://europe.hbc.honeywell.com/prod...6uk07r1006.pdf

Thanks very much, that eluded me. It still doesn't give the power
consumption though.

Back of a fag packet calcs suggest about £1.50 in electricity for the
closed season, so an FCU would pay for itself in about 3 years.

This is based on an assumption that it uses 4 watts of power for six
months I think. Might it not use more?

Well worth it, no?

Hmmmm, better than my fag-packet calculations for my loft insulation,
and not such a dusty job ;-)

How much power does my thermostat use?
 

Martin Pentreath wrote:

snip


Back of a fag packet calcs suggest about £1.50 in electricity for the
closed season, so an FCU would pay for itself in about 3 years.

This is based on an assumption that it uses 4 watts of power for six
months I think. Might it not use more?


Something like that (I think I used 5W for 5 months). On balance
though, I think 5W is very pessimistic for the radio receiver. With the
radio receiver in standby, it could be using as little as 25mW, so
assuming that the power supply is 50% efficient the unit would be
pulling 50mW - and in this mode would run for about 2 years on a unit of
electricity.

How much power does my thermostat use?
 

On Thu, 27 Sep 2007 13:55:03 -0700, Martin Pentreath wrote:

I'm finally going to install my Honeywell CMT927 (wireless programmable
thermostat) this weekend. I'm an incorrigible miser when it comes to
electricity

The amount of energy you save by using it (sensibly) will far out strip
the amount of energy it will consume for the entire year.

Even if you say it takes 5W (unlikely) thats only 43.8 kWhrs/year or about
the same as an average boiler running for 2hrs.

--
Cheers
Dave. pam is missing e-mail

How much power does my thermostat use?
 

wrote:
On 28 Sep,
Martin Pentreath wrote:

This is based on an assumption that it uses 4 watts of power for six
months I think. Might it not use more?

The electronics will take next to nothing. the main consumption will be the
actual switching relay when actuated, This is unlikely to be more than a
watt, and wouldn't be consuming power when the heating is off.

If you use an impulse relay (as used by the battery powered prog stats)
then you will only take power as it switches.

My prog stat is about 4 years old, and still on its first set of AAs.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

How much power does my thermostat use?
 

In message om, Martin
Pentreath writes
Hi,

As winter seems to be arriving, I'm finally going to install my
Honeywell CMT927 (wireless programmable thermostat) this weekend. I'm
an incorrigible miser when it comes to electricity (delighted now that
carbon footprints are all the rage, I can hop on that bandwaggon, but
my stinginess has nothing as noble as environmental concern behind
it). Anyway, I was going to just take the power feed from the same FCU
as the boiler. But it has occurred to my parsimonious mind that it's
pretty wasteful having the thermostat running for six months of the
year when it's not doing anything. So I'm inclined to give it its own
FCU so I can turn it off next spring, but does anyone have any idea
how much power these things actually use? The documentation that came
with it doesn't say, and I can't even find the thing on Honeywell's
website.

Switch it off when you're not using it then

ha ha

--
geoff

How much power does my thermostat use?
 

In message om, Martin
Pentreath writes
Hi Rumble,

http://europe.hbc.honeywell.com/prod...6uk07r1006.pdf

Thanks very much, that eluded me. It still doesn't give the power
consumption though.

Back of a fag packet calcs suggest about £1.50 in electricity for the
closed season, so an FCU would pay for itself in about 3 years.

This is based on an assumption that it uses 4 watts of power for six
months I think. Might it not use more?

You will have probably used more power using your computer to ask the
question ...

--
geoff