Has anyone else seen the Honeywell CMT927 wireless stat relay unit lose
the plot after power cycling?

I've been working on a system with one and find that the relay unit is
failing to recognise the wireless stat after powering down the boiler &
controls for maintenance. Last time it worked if the temp was set using
manual mode but failed to respond in auto and then sorted itself out the
day later to work fine on auto too.

I've seen this on another CMT927 install in the past which sorted itself
out after I did something minor to kick start it but I can't remember
what.

Anyone else seen this?

I'm not viewing this as a boiler issue but for info, one's a Vokera
Excell and one's a Worcester Bosch 24 something, both combis. Boilers
are out of the loop as I'm viewing the demand via the mimic LED on the
relay box.
--
fred
BBC3, ITV2/3/4, channels going to the DOGs

On Wed, 07 Oct 2009 18:47:29 +0100, fred wrote:

Has anyone else seen the Honeywell CMT927 wireless stat relay unit lose
the plot after power cycling?

I have several CM927s in installations I've done and, although none gets
power cycled frequently AFAIK, I've never had this issue. Sounds like a
bad 'un.



--
John Stumbles -- http://yaph.co.uk

Press any key to continue or any other key to exit

In article , YAPH
writes
On Wed, 07 Oct 2009 18:47:29 +0100, fred wrote:

Has anyone else seen the Honeywell CMT927 wireless stat relay unit lose
the plot after power cycling?

I have several CM927s in installations I've done and, although none gets
power cycled frequently AFAIK, I've never had this issue. Sounds like a
bad 'un.

I agree it sounds bad but I've had it on another install too.

The common feature in both is that for a period the systems were subject
to repeated switchings on and off via a switched FCU so I wonder if
there was something inductive (like a boiler LV supply transformer)
kicking back on switching off and causing corruption of the EEPROM data
in the relay box. Not something I would expect from a Honeywell but who
knows, maybe time for a suppressor at the relay box.

On the current one I went back today and did a factory reset on the
wireless box and a re-binding to the relay unit and all appears well.
The other was an isolated occurrence but it hasn't been power cycled
since.

The installs were a year apart so I'm not suspecting a batch problem.

I know a few have them here but none have reported problems.

Thanks for the feedback.
--
fred
BBC3, ITV2/3/4, channels going to the DOGs

In article ,
YAPH writes:
On Wed, 07 Oct 2009 18:47:29 +0100, fred wrote:

Has anyone else seen the Honeywell CMT927 wireless stat relay unit lose
the plot after power cycling?

I have several CM927s in installations I've done and, although none gets
power cycled frequently AFAIK, I've never had this issue. Sounds like a
bad 'un.

I don't know this one, but could it be a battery died somewhere,
either in the remote, or backup battery to handle mains outages?

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

In article , Andrew Gabriel
writes
In article ,
YAPH writes:
On Wed, 07 Oct 2009 18:47:29 +0100, fred wrote:

Has anyone else seen the Honeywell CMT927 wireless stat relay unit lose
the plot after power cycling?

I have several CM927s in installations I've done and, although none gets
power cycled frequently AFAIK, I've never had this issue. Sounds like a
bad 'un.

I don't know this one, but could it be a battery died somewhere,
either in the remote, or backup battery to handle mains outages?

It's _the_ Honeywell 7 day programmable wireless stat.

The wireless stat batteries are good and following a factory reset and
re-binding of stat to relay unit so it does imply some kind of
corruption.

They claim, "EEPROM memory holds the user program indefinitely" but I
can see that may be the wireless unit only and perhaps they have gone
the dirty way of a battery in the relay unit which I suspect would be
more susceptible to corruption than EEPROM. I would be surprised though,
little EEPROMs are dirt cheap.

Now that's it working again I'm forbidden to dismantle anything to take
a look, next time I'll pop open the relay box and report the findings.
--
fred
BBC3, ITV2/3/4, channels going to the DOGs

On Thu, 08 Oct 2009 21:22:30 +0100, fred wrote:

Thanks for the feedback.

Well thank you, too: I'll watch out for it on the ones I've put in.



--
John Stumbles -- http://yaph.co.uk

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