INstall NEST thermostat into system with no current thermostat
 

Afternoon folks,

My current heating hot/water setup is a 25 year old boiler (in good order, no plans to replace), a Randall 103 old-school timer, the water is gravity fed with big cold tank in the loft and a yellow cylinder in the airing cupboard, a circulation pump, NO motorised valve and every radiator has a thermostatic valve.

This is unsatisfactory as the Randall offers no flexibility at all, and the minimum run time for each on/off cycle is about an hour, and throughout that on cycle the pump runs continuously.

I wish to install a nice Nest thermostat and have total control over the hot water and heating and get rid of the stone-age Randall timer clock. I already know that I will need to install a motorised valve in the airing cupboard plumbing.

The installation guides for Nest concentrate on simply replacing an existing stat, which I don't have, so I'm a little unsure on what will need doing.

I'm after some advice on what will need wiring and how.

Thanks in advance.
Jon

INstall NEST thermostat into system with no current thermostat
 

On Sat, 15 Oct 2016 06:26:43 -0700 (PDT)
Jon Parker wrote:

Afternoon folks,

My current heating hot/water setup is a 25 year old boiler (in good
order, no plans to replace), a Randall 103 old-school timer, the
water is gravity fed with big cold tank in the loft and a yellow
cylinder in the airing cupboard, a circulation pump, NO motorised
valve and every radiator has a thermostatic valve.

This is unsatisfactory as the Randall offers no flexibility at all,
and the minimum run time for each on/off cycle is about an hour, and
throughout that on cycle the pump runs continuously.

I wish to install a nice Nest thermostat and have total control over
the hot water and heating and get rid of the stone-age Randall timer
clock. I already know that I will need to install a motorised valve
in the airing cupboard plumbing.

The installation guides for Nest concentrate on simply replacing an
existing stat, which I don't have, so I'm a little unsure on what
will need doing.

I'm after some advice on what will need wiring and how.

Thanks in advance.
Jon

I would suggest you start he

http://www.honeywelluk.com/products/...Wired-Systems/

Lots of other sites linked from that one.

--
Davey.

INstall NEST thermostat into system with no current thermostat
 

In article ,
Jon Parker wrote:
Afternoon folks,

My current heating hot/water setup is a 25 year old boiler (in good
order, no plans to replace), a Randall 103 old-school timer, the water
is gravity fed with big cold tank in the loft and a yellow cylinder in
the airing cupboard, a circulation pump, NO motorised valve and every
radiator has a thermostatic valve.

Rather basic and rather outdated - even when new.

This is unsatisfactory as the Randall offers no flexibility at all, and
the minimum run time for each on/off cycle is about an hour, and
throughout that on cycle the pump runs continuously.

I wish to install a nice Nest thermostat and have total control over the
hot water and heating and get rid of the stone-age Randall timer clock.
I already know that I will need to install a motorised valve in the
airing cupboard plumbing.

IMHO, best to change to a three way valve where the pump is used to do the
hot water cylinder too. Allows easy control of both heating and hot water
independently. Will also likely give faster re-heat of the water.

The installation guides for Nest concentrate on simply replacing an
existing stat, which I don't have, so I'm a little unsure on what will
need doing.

Going to need a fair bit of modification no matter what.

I'm after some advice on what will need wiring and how.

Thanks in advance. Jon

--
*My wife and I had words. But I didn't get to use mine.

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

INstall NEST thermostat into system with no current thermostat
 

"Jon Parker" wrote in message
...
Afternoon folks,

My current heating hot/water setup is a 25 year old boiler (in good order,
no plans to replace),

it might be in good order but it will be using up to twice as much gas as a
modern equivalent

you might find that the economics stack up for a replacement

tim

INstall NEST thermostat into system with no current thermostat
 

tim... wrote:

Jon Parker wrote:

My current heating hot/water setup is a 25 year old boiler (in good order,
no plans to replace),

it might be in good order but it will be using up to twice as much gas as a
modern equivalent

My cast iron lump (Ideal RS440) is older than the O/P's, it has a SEDBUK
rating of 78.5%, most new (e.g. Worcester Bosch) condensers seem to be
about 90.3%.

The difference is nowhere near double, for an 11.8% improvement I also
have no plans to replace.

INstall NEST thermostat into system with no current thermostat
 

On 15/10/2016 14:26, Jon Parker wrote:
Afternoon folks,

My current heating hot/water setup is a 25 year old boiler (in good order, no plans to replace), a Randall 103 old-school timer, the water is gravity fed with big cold tank in the loft and a yellow cylinder in the airing cupboard, a circulation pump, NO motorised valve and every radiator has a thermostatic valve.

This is unsatisfactory as the Randall offers no flexibility at all, and the minimum run time for each on/off cycle is about an hour, and throughout that on cycle the pump runs continuously.

I wish to install a nice Nest thermostat and have total control over the hot water and heating and get rid of the stone-age Randall timer clock. I already know that I will need to install a motorised valve in the airing cupboard plumbing.

The installation guides for Nest concentrate on simply replacing an existing stat, which I don't have, so I'm a little unsure on what will need doing.

I'm after some advice on what will need wiring and how.

Thanks in advance.
Jon

Let's consider the traditional approach and then refine it to add a bit
more automation.

In order to get independent control of the heating and hot water, the
solution requiring the least changes to the plumbing is to convert your
system to a C-Plan system.

This requires a 2-channel programmer, a 2-port motorised valve with
3-terminal change-over auxiliary contacts in the HW circuit, a room stat
to control the heating and a cylinder stat to control the domestic hot
water temperature. See
http://wiki.diyfaq.org.uk/index.php/...ty_DHW:_C-Plan

The wiring is very cunning, and you must stick religiously to the valve
wiring shown in the diagram - otherwise it won't work.

So that's the basics. If you wish, you can combine the functions of the
CH timer and room stat by using a programmable thermostat - either wired
or wireless.

You can almost certainly use a Nest device instead. You mention that the
instructions talk about replacing the thermostat. You need to interpret
that in terms of where the thermostat would have been in a
straight-forward C-Plan system. I don't know whether Nest can control
the hot water too. If so, that part of it would presumably replace the
cylinder stat.

Having said all that, C-Plan is a bit of a compromise. It's a lot better
than you currently have since it provides independent control of HW and
CH *and* provides boiler interlock - which means that it doesn't waste
energy keeping the boiler and/or pump ticking over when all demands are
satisfied.

Depending on how the plumbing is currently arranged, you *may* be able
to convert your system to an S-Plan instead. This would mean that HW and
CH were *both* pumped - enabling the HW to heat much more quickly rather
than having to rely on gravity (thermo-syphon) circulation. To do that,
you'd need a single hot outlet from the boiler, passing immediately
through the pump before being split into two circuits. Each circuit
would need its own 2-port motorised valve.

Yet another alternative is a Y-Plan - which is also fully pumped, and
uses a single 3-port mid-position valve rather than two 2-port valves.
The cylinder stat wiring is a bit more complicated for Y-Plan, and I
don't know how easily you could "Nestify" it.
--
Cheers,
Roger
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INstall NEST thermostat into system with no current thermostat
 

On Sat, 15 Oct 2016 19:38:45 +0100, Andy Burns
wrote:

tim... wrote:

Jon Parker wrote:

My current heating hot/water setup is a 25 year old boiler (in good order,
no plans to replace),

it might be in good order but it will be using up to twice as much gas as a
modern equivalent

My cast iron lump (Ideal RS440) is older than the O/P's, it has a SEDBUK
rating of 78.5%, most new (e.g. Worcester Bosch) condensers seem to be
about 90.3%.

The difference is nowhere near double, for an 11.8% improvement I also
have no plans to replace.

The installation of a room stat and separate CH and HW controls would
help the OP save more than 11.8% IMHO. A new boiiler may not.





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