Hi. I am in the process of completing a home-brew central heating
controller which will be able to measure the temperature outside of the
house as well as in 3 rooms inside.

Our house faces north/south and I plan to mount the outside sensor just
under the eaves but do I mount it on the northerly side or the
southerly?

Obviously, the northerly side never sees the sun but I am concerned that
the sensor may be affected by stored heat, or should that be cold so,
has anyone got any advice please?
--
Phil

---
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In article , Phil writes
Hi. I am in the process of completing a home-brew central heating
controller which will be able to measure the temperature outside of the
house as well as in 3 rooms inside.

Our house faces north/south and I plan to mount the outside sensor just
under the eaves but do I mount it on the northerly side or the
southerly?

Obviously, the northerly side never sees the sun but I am concerned that
the sensor may be affected by stored heat, or should that be cold so,
has anyone got any advice please?

You don't want it to experience any solar gain so put it on the North
side.

Thermistors are low cost sensors and pretty standard in commercial gear,
10k at 25degC is a typical example that would be fine on a long line
using twisted pair (phone or cat5e). I didn't bother using shielded
cable.

A simple IP68 outdoor junction box will be fine for a housing and
sticking the sensor to the lid would give it a low thermal mass with a
response as least as fast as the weather.
--
fred
it's a ba-na-na . . . .

On Thursday 19 December 2013 16:21 Phil wrote in uk.d-i-y:

Hi. I am in the process of completing a home-brew central heating
controller which will be able to measure the temperature outside of the
house as well as in 3 rooms inside.

Our house faces north/south and I plan to mount the outside sensor just
under the eaves but do I mount it on the northerly side or the
southerly?

Obviously, the northerly side never sees the sun but I am concerned that
the sensor may be affected by stored heat, or should that be cold so,
has anyone got any advice please?

On the north wall definately assuming you are in the northern hemisphere!


--
Tim Watts Personal Blog: http://squiddy.blog.dionic.net/

http://www.sensorly.com/ Crowd mapping of 2G/3G/4G mobile signal coverage

On 19/12/2013 16:21, Phil wrote:
Hi. I am in the process of completing a home-brew central heating
controller which will be able to measure the temperature outside of the
house as well as in 3 rooms inside.

Our house faces north/south and I plan to mount the outside sensor just
under the eaves but do I mount it on the northerly side or the southerly?

Obviously, the northerly side never sees the sun but I am concerned that
the sensor may be affected by stored heat, or should that be cold so,
has anyone got any advice please?

The mine for my weather compensator recommended the north side, and out
of direct sun.


--
Cheers,

John.

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

Phil wrote:

Hi. I am in the process of completing a home-brew central heating
controller which will be able to measure the temperature outside of the
house as well as in 3 rooms inside.

Our house faces north/south and I plan to mount the outside sensor just
under the eaves but do I mount it on the northerly side or the
southerly?

Obviously, the northerly side never sees the sun but I am concerned that
the sensor may be affected by stored heat, or should that be cold so,
has anyone got any advice please?

Keep in mind that even if you place the sensor on a north-facing
wall, between the Spring and Autumn equinoxes the sun rises and sets
north of east and west respectively, and between those times the
sensor might give falsely-warm readings through being in the sun.
Probably not an issue in full summer, but you can get really cold
nights/days in March and April, and perhaps early May.

One of my garden fences faces north, and I had to place a temperature
sensor on it where the morning sun can't shine on it, by hiding it
behind a fence post. Evening sun isn't an issue as it sets here in
summer at about 4:30pm due to 70' high trees on the ridge-line at the
back of the house.
--
Terry Fields

On Thursday, 19 December 2013 16:21:18 UTC, Phil wrote:

Our house faces north/south and I plan to mount the outside sensor just
under the eaves but do I mount it on the northerly side or the
southerly?
Obviously, the northerly side never sees the sun but I am concerned that
the sensor may be affected by stored heat, or should that be cold so,
has anyone got any advice please?


Both. Position two sensors such that one of them is always in the shade and use the lower reading. Keep them spaced as far from the wall as you reasonably can - 0.5m perhaps om a stalk of some kind. That way you avoid the boundary layer of warmer air that rises up the walls in still winter conditions.

John

"Phil" wrote in message ...
Hi. I am in the process of completing a home-brew central heating
controller which will be able to measure the temperature outside of the
house as well as in 3 rooms inside.

Our house faces north/south and I plan to mount the outside sensor just
under the eaves but do I mount it on the northerly side or the southerly?

Obviously, the northerly side never sees the sun but I am concerned that
the sensor may be affected by stored heat, or should that be cold so,
has anyone got any advice please?
--
You are one a hiding to nothing.
These devices have long been available and took decades to perfect, some
don't work well even now.
So anything you make is unlikely to work well.

Go out and buy one.

On Dec 19, 2013, Phil wrote
(in article ):

Hi. I am in the process of completing a home-brew central heating
controller which will be able to measure the temperature outside of the
house as well as in 3 rooms inside.

Our house faces north/south and I plan to mount the outside sensor just
under the eaves but do I mount it on the northerly side or the
southerly?

Obviously, the northerly side never sees the sun but I am concerned that
the sensor may be affected by stored heat, or should that be cold so,
has anyone got any advice please?


Temperature always varies a lot around heated buildings. If you really need
to measure the true ambient outside temperature accurately you need to
construct (or buy) a proper Stevenson Screen and mount it some distance away
from your house. The official recommendation is a distance of twice the
height of the building (or so I believe).

--
Mike Lane

On Thursday 19 December 2013 19:42 harryagain wrote in uk.d-i-y:


"Phil" wrote in message ...
Hi. I am in the process of completing a home-brew central heating
controller which will be able to measure the temperature outside of the
house as well as in 3 rooms inside.

Our house faces north/south and I plan to mount the outside sensor just
under the eaves but do I mount it on the northerly side or the southerly?

Obviously, the northerly side never sees the sun but I am concerned that
the sensor may be affected by stored heat, or should that be cold so,
has anyone got any advice please?
--
You are one a hiding to nothing.
These devices have long been available and took decades to perfect, some
don't work well even now.
So anything you make is unlikely to work well.

Go out and buy one.

By that theory, toasters should actually be able to evenly and repeatibly
toast bread by now!

--
Tim Watts Personal Blog: http://squiddy.blog.dionic.net/

http://www.sensorly.com/ Crowd mapping of 2G/3G/4G mobile signal coverage

On 19/12/2013 19:42, harryagain wrote:
"Phil" wrote in message ...
Hi. I am in the process of completing a home-brew central heating
controller which will be able to measure the temperature outside of the
house as well as in 3 rooms inside.

Our house faces north/south and I plan to mount the outside sensor just
under the eaves but do I mount it on the northerly side or the southerly?

Obviously, the northerly side never sees the sun but I am concerned that
the sensor may be affected by stored heat, or should that be cold so,
has anyone got any advice please?
--
You are one a hiding to nothing.
These devices have long been available and took decades to perfect, some
don't work well even now.

Since they are basically a small plastic box with a thermister inside.

So anything you make is unlikely to work well.

I have reasonable confidence that anything one makes will work equally
as well as a commercial one, and that the performance will be more than
adequate for most applications.

Go out and buy one.

yeah right

--
Cheers,

John.

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

On 19/12/2013 19:02, John Rumm wrote:
On 19/12/2013 16:21, Phil wrote:
Hi. I am in the process of completing a home-brew central heating
controller which will be able to measure the temperature outside of the
house as well as in 3 rooms inside.

Our house faces north/south and I plan to mount the outside sensor just
under the eaves but do I mount it on the northerly side or the southerly?

Obviously, the northerly side never sees the sun but I am concerned that
the sensor may be affected by stored heat, or should that be cold so,
has anyone got any advice please?

The mine for my weather compensator recommended the north side, and out

^^^
instructions that came with



--
Cheers,

John.

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

On Thu, 19 Dec 2013, "fred" writ:

In article , Phil writes
Hi. I am in the process of completing a home-brew central heating
controller which will be able to measure the temperature outside of the
house as well as in 3 rooms inside.

Our house faces north/south and I plan to mount the outside sensor just
under the eaves but do I mount it on the northerly side or the
southerly?

Obviously, the northerly side never sees the sun but I am concerned that
the sensor may be affected by stored heat, or should that be cold so,
has anyone got any advice please?

You don't want it to experience any solar gain so put it on the North
side.

Thermistors are low cost sensors and pretty standard in commercial
gear, 10k at 25degC is a typical example that would be fine on a long
line using twisted pair (phone or cat5e). I didn't bother using
shielded cable.

I already have TMP36 remote solid state sensors using STP cable and they
are pretty accurate. Certainly within 0.5C from -20C to +50C on a 5
metre cable. I have had them tested at work. You really must have STP as
any noise messes up the readings as I found out when I tried them with
UTP cable (

A simple IP68 outdoor junction box will be fine for a housing and
sticking the sensor to the lid would give it a low thermal mass with a
response as least as fast as the weather.

Thanks for the suggestion, I hadn't thought of IP68 boxes.
--
P

In message , Percy writes
On Thu, 19 Dec 2013, "fred" writ:

In article , Phil writes
Hi. I am in the process of completing a home-brew central heating
controller which will be able to measure the temperature outside of the
house as well as in 3 rooms inside.

Our house faces north/south and I plan to mount the outside sensor just
under the eaves but do I mount it on the northerly side or the
southerly?

Obviously, the northerly side never sees the sun but I am concerned that
the sensor may be affected by stored heat, or should that be cold so,
has anyone got any advice please?

You don't want it to experience any solar gain so put it on the North
side.

Thermistors are low cost sensors and pretty standard in commercial
gear, 10k at 25degC is a typical example that would be fine on a long
line using twisted pair (phone or cat5e). I didn't bother using
shielded cable.

I already have TMP36 remote solid state sensors using STP cable and
they are pretty accurate. Certainly within 0.5C from -20C to +50C on a
5 metre cable. I have had them tested at work. You really must have STP
as any noise messes up the readings as I found out when I tried them
with UTP cable (

A simple IP68 outdoor junction box will be fine for a housing and
sticking the sensor to the lid would give it a low thermal mass with a
response as least as fast as the weather.

Thanks for the suggestion, I hadn't thought of IP68 boxes.

I was about to reply to fred but you got in first. I too, have TMP36
sensors and I'm using the circuit given by the manufacturer which seems
to be wrong. What remote V to I converter are you using?

I also agree that the IP68 box idea is good.
--
Phil

In message , harryagain
writes

"Phil" wrote in message ...
Hi. I am in the process of completing a home-brew central heating
controller which will be able to measure the temperature outside of the
house as well as in 3 rooms inside.

Our house faces north/south and I plan to mount the outside sensor just
under the eaves but do I mount it on the northerly side or the southerly?

Obviously, the northerly side never sees the sun but I am concerned that
the sensor may be affected by stored heat, or should that be cold so,
has anyone got any advice please?
--
You are one a hiding to nothing.
These devices have long been available and took decades to perfect, some
don't work well even now.
So anything you make is unlikely to work well.

Go out and buy one.


Are you for real? I would put my home-brew against any similar
commercially unit any day. I use high stability components and the
software does what I want, how I want it. It hasn't dropped off of the
end of a Chinese production line.

Here's the basic spec of my controller:

Clock accurate to 500mS per day with battery backup
16 Analogue to Digital sensing ports
16 controllable outputs with relays, if required, to control pumps,
motorised valves, outside lights, internal lights etc.
Supports up to 8 remote keypads with LCD displays
Fully programmable ON/OFF time periods and temperatures

Total component cost including sensors but not the relays, GBP15.00.

The software writing is the really fun part.

So, where can I buy an equivalent controller and for how much?
--
Phil

In message ,
writes
On Thursday, 19 December 2013 16:21:18 UTC, Phil wrote:

Our house faces north/south and I plan to mount the outside sensor just
under the eaves but do I mount it on the northerly side or the
southerly?
Obviously, the northerly side never sees the sun but I am concerned that
the sensor may be affected by stored heat, or should that be cold so,
has anyone got any advice please?


Both. Position two sensors such that one of them is always in the
shade and use the lower reading. Keep them spaced as far from the wall
as you reasonably can - 0.5m perhaps om a stalk of some kind. That way
you avoid the boundary layer of warmer air that rises up the walls in
still winter conditions.

John

Sounds like a good idea. I'll give it some thought.
--
Phil

In article , Percy writes
On Thu, 19 Dec 2013, "fred" writ:

Thermistors are low cost sensors and pretty standard in commercial
gear, 10k at 25degC is a typical example that would be fine on a long
line using twisted pair (phone or cat5e). I didn't bother using
shielded cable.

I already have TMP36 remote solid state sensors using STP cable and they
are pretty accurate. Certainly within 0.5C from -20C to +50C on a 5
metre cable. I have had them tested at work. You really must have STP as
any noise messes up the readings as I found out when I tried them with
UTP cable (

Useful device, thanks.

I figured the coarse and robust measurements of thermistors would suit
this app if you were rolling your own system hardware and software.

Being 2 terminal devices they lend themselves well to balanced 2 wire
measurement, noise in one limb is equally induced in the other,
resulting in cancelling of noise if measured in balanced mode.

In a single ended voltage output device though (like TMP36) you get no
benefit from twisted pairs although using a pair for the output and 0V
should give the least susceptible result.

In either case, the way to avoid noise it filter it out or integrate the
analogue output as response time is not important.

There are direct digital output devices available from Dallas that would
do the job too. Another poster here has used them in his home automation
system, search for Andrew Gabriel as poster and Dallas and you should
find the devices he used. I think they're under a fiver each and have
good application notes for interface software too. They have a large
fanbase that has resulted in quite a few apps being written for them.
It's recommended to range check your input, ignoring any results that
are dramatically out from the norm as this weeds out received data that
have been corrupted by (much heavier) noise.

A simple IP68 outdoor junction box will be fine for a housing and
sticking the sensor to the lid would give it a low thermal mass with a
response as least as fast as the weather.

Thanks for the suggestion, I hadn't thought of IP68 boxes.

Good for corrosion protection (condensation) and to protect from insect
ingress. Some view it as inevitable that condensation will occur in
outside enclosures (the boxes aren't vapur tight) so they drill a tiny
(1mm) hole at the very bottom to allow drainage, the small hole
minimising the risk of insects nesting. Another trick is to seal the
sensor in adhesive lined heatshrink or to dip the wired assembly in
thick varnish. Marginal increase in thermal lag but protects from
corrosion.
--
fred
it's a ba-na-na . . . .