replying to IMM, john coen wrote:
have to be careful sending an unprogrammed live feed back through to other
stat, Stats are tempermental

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for full context, visit https://www.homeownershub.com/uk-diy...run-33024-.htm

On 29/09/2017 21:14, john coen wrote:
replying to IMM, john coen wrote:
have to be careful sending an unprogrammed live feed back through to other
stat, Stats are tempermental

Did they have pump overruns in 2003?

Given the OP (ARW) is an electrician you might think he knows this and a
lot more besides.

This might assist you with posting to a newsgroup, albeit through a website:
https://tools.ietf.org/html/rfc1855

- If you are sending a reply to a message or a posting be sure you
summarize the original at the top of the message, or include just
enough text of the original to give a context.

On 29/09/2017 21:23, Fredxxx wrote:


Did they have pump overruns in 2003?


Yes - long before that. My c1990 Baxi Solo (still going strong!) has
one. They came in with the physically smaller boilers with aluminium
heat exchangers - designed for fully pumped systems - whose residual
heat could cause them to overheat if the flow stopped immediately when
the flame was cut.

Having said that, the over-run logic on my boiler is somewhat flawed -
and there are some circumstances which can still result in an overheat
trip - so I have added a timer as well.
--
Cheers,
Roger
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On 29/09/2017 22:37, Roger Mills wrote:
On 29/09/2017 21:23, Fredxxx wrote:


Did they have pump overruns in 2003?


Yes - long before that. My c1990 Baxi Solo (still going strong!) has
one. They came in with the physically smaller boilers with aluminium
heat exchangers - designed for fully pumped systems - whose residual
heat could cause them to overheat if the flow stopped immediately when
the flame was cut.

Having said that, the over-run logic on my boiler is somewhat flawed -
and there are some circumstances which can still result in an overheat
trip - so I have added a timer as well.

I did add the comment with tongue firmly in cheek!

I recall fitting a boiler 20 years ago which in my opinion had the
overrun timer set for far too long.

On 29/09/2017 22:37, Roger Mills wrote:
On 29/09/2017 21:23, Fredxxx wrote:


Did they have pump overruns in 2003?


Yes - long before that. My c1990 Baxi Solo (still going strong!) has
one. They came in with the physically smaller boilers with aluminium
heat exchangers - designed for fully pumped systems - whose residual
heat could cause them to overheat if the flow stopped immediately when
the flame was cut.

Having said that, the over-run logic on my boiler is somewhat flawed -
and there are some circumstances which can still result in an overheat
trip - so I have added a timer as well.

On my 25 year old boiler the overrun is controlled by a micro-switch
which in turn is switched on/off mechanically by a (bi??) metal arm
attached to the water temperature sensor. After around 15 years the
overrun started cutting out too early, just after the boiler stopped
heating. Easily fixed by adjusting the screw on the metal arm so that
the micro-switch again operated when the water was still hot.

--
mailto: news {at} admac {dot] myzen {dot} co {dot} uk

Roger Mills wrote:
On 29/09/2017 21:23, Fredxxx wrote:


Did they have pump overruns in 2003?


Yes - long before that. My c1990 Baxi Solo (still going strong!) has
one. They came in with the physically smaller boilers with aluminium
heat exchangers - designed for fully pumped systems - whose residual
heat could cause them to overheat if the flow stopped immediately when
the flame was cut.

Having said that, the over-run logic on my boiler is somewhat flawed -
and there are some circumstances which can still result in an overheat
trip - so I have added a timer as well.

My (I guess) 1986 (still going strong, but probably not very efficient)
Thorn Apollo has one, but I don't know if it's still contributing to the
overall heating effort. Perhaps I'll notice if/when it breaks?

In article ,
Fredxxx wrote:
Did they have pump overruns in 2003?

I built one for my BE boiler in the '70s. To get the heat out of its cast
iron heat exchanger to where it was most needed.

--
*Ham and Eggs: Just a day's work for a chicken, but a lifetime commitment

Dave Plowman London SW
To e-mail, change noise into sound.

On 29/09/17 21:14, john coen wrote:
replying to IMM, john coen wrote:
have to be careful sending an unprogrammed live feed back through to other
stat, Stats are tempermental


Most stats are dry no-volt contact types (including electronic ones
which typically have an output relay which you can hear as it goes "click").

Heating systems quite often end up with control elements wired in
parallel, eg frost stats so it's not uncommon.